Impaired autophagic degradation of lncRNA ARHGAP5-AS1 promotes chemoresistance in gastric cancer.
Zhu Liyuan,Zhu Yiran,Han Shuting,Chen Miaoqin,Song Ping,Dai Dongjun,Xu Wenxia,Jiang Tingting,Feng Lifeng,Shin Vivian Y,Wang Xian,Jin Hongchuan
Cell death & disease
Chemoresistance remains the uppermost disincentive for cancer treatment on account of many genetic and epigenetic alterations. Long non-coding RNAs (lncRNAs) are emerging players in promoting cancer initiation and progression. However, the regulation and function in chemoresistance are largely unknown. Herein, we identified ARHGAP5-AS1 as a lncRNA upregulated in chemoresistant gastric cancer cells and its knockdown reversed chemoresistance. Meanwhile, high ARHGAP5-AS1 expression was associated with poor prognosis of gastric cancer patients. Intriguingly, its abundance is affected by autophagy and SQSTM1 is responsible for transporting ARHGAP5-AS1 to autophagosomes. Inhibition of autophagy in chemoresistant cells, thus, resulted in the upregulation of ARHGAP5-AS1. In turn, it activated the transcription of ARHGAP5 in the nucleus by directly interacting with ARHGAP5 promoter. Interestingly, ARHGAP5-AS1 also stabilized ARHGAP5 mRNA in the cytoplasm by recruiting METTL3 to stimulate mA modification of ARHGAP5 mRNA. As a result, ARHGAP5 was upregulated to promote chemoresistance and its upregulation was also associated with poor prognosis in gastric cancer. In summary, impaired autophagic degradation of lncRNA ARHGAP5-AS1 in chemoresistant cancer cells promoted chemoresistance. It can activate the transcription of ARHGAP5 in the nucleus and stimulate mA modification of ARHGAP5 mRNA to stabilize ARHGAP5 mRNA in the cytoplasm by recruiting METTL3. Therefore, targeting ARHGAP5-AS1/ARHGAP5 axis might be a promising strategy to overcome chemoresistance in gastric cancer.
Identification and validation of an individualized autophagy-clinical prognostic index in gastric cancer patients.
Qiu Jieping,Sun Mengyu,Wang Yaoqun,Chen Bo
Cancer cell international
Background:The purpose of this study is to perform bioinformatics analysis of autophagy-related genes in gastric cancer, and to construct a multi-gene joint signature for predicting the prognosis of gastric cancer. Methods:GO and KEGG analysis were applied for differentially expressed autophagy-related genes in gastric cancer, and PPI network was constructed in Cytoscape software. In order to optimize the prognosis evaluation system of gastric cancer, we established a prognosis model integrating autophagy-related genes. We used single factor Cox proportional risk regression analysis to screen genes related to prognosis from 204 autophagy-related genes in The Atlas Cancer Genome (TCGA) gastric cancer cohort. Then, the generated genes were applied to the Least Absolute Shrinkage and Selection Operator (LASSO). Finally, the selected genes were further included in the multivariate Cox proportional hazard regression analysis to establish the prognosis model. According to the median risk score, patients were divided into high-risk group and low-risk group, and survival analysis was conducted to evaluate the prognostic value of risk score. Finally, by combining clinic-pathological features and prognostic gene signatures, a nomogram was established to predict individual survival probability. Results:GO analysis showed that the 28 differently expressed autophagy-related genes was enriched in cell growth, neuron death, and regulation of cell growth. KEGG analysis showed that the 28 differently expressed autophagy-related genes were related to platinum drug resistance, apoptosis and p53 signaling pathway. The risk score was constructed based on 4 genes (GRID2, ATG4D,GABARAPL2, CXCR4), and gastric cancer patients were significantly divided into high-risk and low-risk groups according to overall survival. In multivariate Cox regression analysis, risk score was still an independent prognostic factor (HR = 1.922, 95% CI = 1.573-2.349, P < 0.001). Cumulative curve showed that the survival time of patients with low-risk score was significantly longer than that of patients with high-risk score (P < 0.001). The external data GSE62254 proved that nomograph had a great ability to evaluate the prognosis of individual gastric cancer patients. Conclusions:This study provides a potential prognostic marker for predicting the prognosis of GC patients and the molecular biology of GC autophagy.
miR-30 decreases multidrug resistance in human gastric cancer cells by modulating cell autophagy.
Du Xinming,Liu Bing,Luan Xuerong,Cui Qing,Li Leping
Experimental and therapeutic medicine
Chemotherapy is an important treatment modality for gastric cancer, and multidrug resistance (MDR) represents a major obstacle for successful cancer chemotherapy. There is a lack of research on whether microRNA (miR)-30a regulation affects the chemosensitivity of resistant gastric cancer cells, and mechanisms underlying the effects of miR-30a on drug resistance and cell autophagy require further investigation. In the present study, the expression of miR-30a and its effects in cisplatin (CDDP)-resistant human gastric cancer cells were investigated. A CDDP-resistant variant of the SGC-7901 cell line (SGC-7901/CDDP) was established by exposing the cells to gradually increasing drug concentrations, and miR-30a expression was detected by reverse transcription-semi quantitative polymerase chain reaction (RT-sqPCR). To examine the effect of miR-30a expression in the SGC-7901/CDDP cells, miR30a mimics or negative control miRNA were transfected into the cells, and a Cell Counting Kit-8 assay was performed to analyze the chemosensitivity of the different cell groups. RT-sqPCR and western blot analysis were also used to measure mRNA and P-glycoprotein expression, and the light chain (LC)3-II/LC3-I ratio. Furthermore, apoptosis induced by the chemotherapeutic CDDP in the different groups was assessed using flow cytometry. The results demonstrated that low expression of miR-30a was associated with chemoresistance in gastric cancer cells, and in the chemoresistant cell line SGC7901/CDDP, CDDP-induced apoptosis was weakened. Additionally, it was demonstrated that the LC3-II/LC3-I ratio was elevated in SGC7901/CDDP cells compared with chemosensitive SGC7901 cells (P<0.001), which could be attenuated by upregulating miR-30a expression (P<0.001 vs. SGC7901/CDDP control cells). These results suggested that autophagy may contribute to drug resistance in gastric cancer cells, and that the reduction of LC3-II in response to miR-30a overexpression may inhibit chemoresistance-associated autophagy in gastric cancer cells.
The Role of Autophagy in Gastric Cancer Chemoresistance: Friend or Foe?
Xu Jing-Li,Yuan Li,Tang Yan-Cheng,Xu Zhi-Yuan,Xu Han-Dong,Cheng Xiang-Dong,Qin Jiang-Jiang
Frontiers in cell and developmental biology
Gastric cancer is the third most common cause of cancer-related death worldwide. Drug resistance is the main inevitable and vital factor leading to a low 5-year survival rate for patients with gastric cancer. Autophagy, as a highly conserved homeostatic pathway, is mainly regulated by different proteins and non-coding RNAs (ncRNAs) and plays dual roles in drug resistance of gastric cancer. Thus, targeting key regulatory nodes in the process of autophagy by small molecule inhibitors or activators has become one of the most promising strategies for the treatment of gastric cancer in recent years. In this review, we provide a systematic summary focusing on the relationship between autophagy and chemotherapy resistance in gastric cancer. We comprehensively discuss the roles and molecular mechanisms of multiple proteins and the emerging ncRNAs including miRNAs and lncRNAs in the regulation of autophagy pathways and gastric cancer chemoresistance. We also summarize the regulatory effects of autophagy inhibitor and activators on gastric cancer chemoresistance. Understanding the vital roles of autophagy in gastric cancer chemoresistance will provide novel opportunities to develop promising therapeutic strategies for gastric cancer.
Cucurbitacin B induces autophagy and apoptosis by suppressing CIP2A/PP2A/mTORC1 signaling axis in human cisplatin resistant gastric cancer cells.
Liu Xuewen,Duan Chao,Ji Juanli,Zhang Te,Yuan Xiaoning,Zhang Yunfei,Ma Wenjing,Yang Jingyuan,Yang Linsen,Jiang Zhiguo,Yu Huiliang,Liu Ying
Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a human oncoprotein that is overexpressed in multiple kinds of tumors including gastric cancer (GC). Mammalian target of rapamycin complex 1 (mTORC1) over-activation is detected in GC and many other cancers. Previous study found that CIP2A/mTORC1 controls cell growth and autophagy through direct association. CIP2A plays an 'oncogenic nexus' in several cancer types to participate in the tumorigenic transformation and chemoresistance. In the present study, we investigated whether Cucurbitacin B (CuB), a natural compound found in Cucurbitaceae, can be used in cisplatin (DDP)-resistant human GC cell line SGC7901/DDP. Results demonstrated that CuB treatment significantly suppressed SGC7901/DDP cell proliferation, induced caspase-dependent apoptosis, and autophagy. The activation of autophagy was mediated through CuB-induced inhibition of mTORC1. Furthermore, CuB inhibited mTORC1 via the activation of protein phosphatase 2A (PP2A) which is mediated by CIP2A inhibition. These findings indicated that CuB can inhibit the proliferation, induce caspase-dependent apoptosis, and autophagy of SGC7901/DDP cells by suppressing CIP2A/PP2A/mTORC1 signaling axis. Thus, CuB may be a novel effective candidate to treat DDP-resistant human GC cells.
LncRNA MALAT1 potentiates autophagy‑associated cisplatin resistance by regulating the microRNA‑30b/autophagy‑related gene 5 axis in gastric cancer.
Xi Zhiwen,Si Jinchun,Nan Jun
International journal of oncology
Gastric cancer (GC) is the fourth most common type of cancer worldwide and chemoresistance is a major obstacle to successful GC treatment. In the present study, reverse transcription‑quantitative polymerase chain reaction analysis was used to measure the expression of metastasis‑associated lung adenocarcinoma transcript 1 (MALAT1) and microRNA (miR)‑30b. Western blot analysis was conducted to detect the protein expression of autophagy‑related gene 5 (ATG5), p62 and LC3 (LC3‑I and LC3‑II). Cell viability and half maximal inhibitory concentration were determined by the Cell Counting Kit‑8 assay. The green fluorescent protein (GFP)‑LC3‑positive cell percentage was determined by the GFP‑LC3 puncta experiment. Luciferase reporter and RNA immunoprecipitation assays were used to explore the molecular associations among MALAT1, miR‑30b and ATG5. MALAT1 was found to be highly expressed in CDDP‑resistant AGS(AGS/CDDP) cells and CDDP‑resistant HGC‑27 (HGC‑27/CDDP) cells. Cell viability was markedly increased in MALAT1‑overexpressing AGS/CDDP cells, but was notably reduced in MALAT1‑depleted HGC‑27/CDDP cells. Moreover, MALAT1 potentiated CDDP resistance by facilitating autophagy in AGS/CDDP and HGC‑27/CDDP cells. Further investigations demonstrated that MALAT1 inhibited miR‑30b expression by direct interaction. Moreover, miR‑30b abolished MALAT1‑induced CDDP resistance by inhibiting autophagy in AGS/CDDP and HGC‑27/CDDP cells. Furthermore, ATG5 was found to be a target of miR‑30b. miR‑30b weakened resistance to CDDP by inhibiting autophagy in AGS/CDDP and HGC‑27/CDDP cells, while this effect was abrogated by increased ATG5 expression. Additionally, MALAT1 sequestered miR‑30b from ATG5 to increase ATG5 expression in AGS/CDDP and HGC‑27/CDDP cells. Therefore, MALAT1 potentiated autophagy‑related CDDP resistance through suppressing the miR‑30b/ATG5 axis in AGS/CDDP and HGC‑27/CDDP cells, indicating that it may represent a promising target for the reversal of chemoresistance in GC.
Inhibition of autophagy by bafilomycin A1 promotes chemosensitivity of gastric cancer cells.
Li Liang-Qing,Xie Wen-Jun,Pan Dun,Chen Hui,Zhang Lin
Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine
Autophagy is an intracellular degradation pathway that delivers organelles or protein to the lysosome and has been recently implicated in the resistance of gastric cancer to chemotherapy. This study aimed to investigate whether blocking autophagy is a new approach for the treatment of chemoresistant gastric cancer. SGC-7901 gastric cancer cell line was treated with 5-fluorouracil (5-FU) or/and autophagy inhibitor bafilomycin A1. Cell viability and growth were evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) and clonogenic assay. Apoptosis was evaluated by flow cytometry. Cell migratory and invasive ability were evaluated by migration and invasion assays. Autophagy was evaluated by scanning electron microscopic, acridine orange staining, and Western blot analysis. We observed that 5-FU induced autophagy in SGC-7901 cells. Bafilomycin A1 decreased the viability and clone formation, inhibited the invasive and migratory ability, and increased the apoptosis of SGC-7901 cells. Taken together, our data suggest that chemotherapy-induced autophagy contributes to gastric cancer chemoresistance, and the inhibition of autophagy is a promising strategy for gastric cancer therapy.
[Research progress in the role of microRNA-155 in regulation of autophagy and diagnosis and treatment for gastric cancer].
Chen Gang,Zhang Minmin,Li Yumin
Zhong nan da xue xue bao. Yi xue ban = Journal of Central South University. Medical sciences
China is one of the regions with a high incidence of gastric cancer worldwide. Low detection rate and poor curative effect lead to unsatisfied prognosis and low five-year survival rate. Surgery combined with radiotherapy and chemotherapy is the mainstream comprehensive treatment scheme, however, multi-drug resistance may gradually prevail in the chemotherapy process. Chemotherapy, miRNA and autophagy interact with each other, but the mechanism is complex. MiR-155 is abnormally expressed in gastric cancer, which could promote autophagy, inhibit apoptosis, and interact with Helicobacter pylori to induce gastric cancer. Through its regulatory effect on autophagy, miR-155 can be used to treat gastric cancer, improve chemotherapy sensitivity and reverse drug resistance. The high expression of miR-155 in gastric cancer tissues suggests poor prognosis.
MicroRNA-148a-3p enhances cisplatin cytotoxicity in gastric cancer through mitochondrial fission induction and cyto-protective autophagy suppression.
Li Bowen,Wang Weizhi,Li Zheng,Chen Zheng,Zhi Xiaofei,Xu Jianghao,Li Qing,Wang Lu,Huang Xiaoxu,Wang Linjun,Wei Song,Sun Guangli,Zhang Xuan,He Zhongyuan,Zhang Lu,Zhang Diancai,Xu Hao,El-Rifai Wael,Xu Zekuan
Cisplatin (CDDP) resistance is a major clinical problem associated with poor prognosis in gastric cancer (GC) patients. In this study, we performed integrated analysis of TCGA data from microRNAs (miRNAs) expression matrix of GC patients who received CDDP-based chemotherapy with GEO dataset which contains differential miRNAs expression profiles in CDDP-resistant and -sensitive cell lines. We identified miR-148a-3p downregulation as a key step involved in CDDP resistance. Using a cohort consisting 105 GC patients who received CDDP-based therapy, we found that miR-148a-3p downregulation was associated with a decrease in patients' disease-free survival (DFS, P = 0.0077). A series of experiment data demonstrated that: 1) miR-148a-3p was downregulated in CDDP-resistant GC cell lines; 2) miR-148a-3p reconstitution sensitized CDDP-resistant cells to CDDP treatment through promoting mitochondrial fission and decreasing AKAP1 expression level; 3) AKAP1 played a novel role in CDDP resistance by inhibiting P53-mediated DRP1 dephosphorylation; 4) miR-148a-3p reconstitution in CDDP-resistant cells inhibits the cyto-protective autophagy by suppressing RAB12 expression and mTOR1 activation. Taken together, our study demonstrates that miR-148a-3p could be a promising prognostic marker or therapeutic candidate for overcoming CDDP resistance in GC.
MicroRNA-495-3p inhibits multidrug resistance by modulating autophagy through GRP78/mTOR axis in gastric cancer.
Chen Sheng,Wu Jian,Jiao Kai,Wu Qiong,Ma Jiaojiao,Chen Di,Kang Jianqin,Zhao Guodong,Shi Yongquan,Fan Daiming,Zhao Guohong
Cell death & disease
Multidrug resistance (MDR) accounts for poor prognosis in gastric cancer (GC). MicroRNAs (miRNAs) are critical regulators of MDR via modulation of the target genes. The present study revealed that miR-495-3p could act via a target gene, GRP78, to regulate the process of autophagy and inhibit MDR. Based on the in vitro and in vivo gain-of-function or loss-of-function experiments, overexpression of miR-495-3p was sufficient to reverse the MDR to four chemotherapeutics in vitro and inhibit the tumor growth in vivo. Moreover, GRP78 was positively associated with the occurrence of autophagy. Thus, reducing the expression of GRP78 by siRNA resulted in autophagy-suppressive activity similar to that of miR-495-3p on mammalian target of rapamycin (mTOR) and its substrates activation and autophagy inhibition, while restoring GRP78 attenuated the anti-autophagy effects caused by miR-495-3p. Clinically, either miR-495-3p downregulation or GRP78 upregulation was associated with malignant phenotypes in patients with GC. In conclusion, these findings demonstrate that miR-495-3p is an important regulator of autophagy balance and MDR by modulating the GRP78/mTOR axis. In addition, miR-495-3p and GRP78 could be used as prognostic factors for overall survival in GC, which implicates miR-495-3p as a therapeutic target in cancer.
MiR-181a suppresses autophagy and sensitizes gastric cancer cells to cisplatin.
Zhao Jing,Nie Yuqiang,Wang Hong,Lin Yong
A number of chemotherapy drugs can induce autophagy. This inducible autophagy is a pro-survival mechanism and contributes to the development of acquired drug resistance. Emerging evidence indicates that miRNA regulates autophagy via targeting autophagy related genes and is involved in drug resistance. We previously demonstrated that miR-181a plays an important role in gastric cancer. The present study aimed to explore the effect of miR-181a on autophagy regulation and cisplatin resistance. We revealed that miR-181a is a novel negative regulator of autophagy in cisplatin-resistant cells SGC7901/CDDP. Then we indicated that ATG5 was a potential target of miR-181a. Furthermore, overexpression of miR-181a significantly enhanced the sensitivity of SGC7901/CDDP cells to cisplatin in vitro and reduced the volumes of gastric tumor xenografts in nude mice. Our finding provides evidence that miR-181a functions as a primary autophagy-related modulator and reverses cisplatin-resistance in GC cells.
Propofol facilitates cisplatin sensitivity via lncRNA MALAT1/miR-30e/ATG5 axis through suppressing autophagy in gastric cancer.
Zhang Yun-Fei,Li Chang-Sheng,Zhou Yi,Lu Xi-Hua
AIMS:Recently, chemoresistance has been recognized as an obstacle in the treatment of gastric cancer (GC). The aim of this study was to investigate the biological functions and underlying mechanisms of propofol in GC chemoresistance. MAIN METHODS:CCK-8 assay, flow cytometry and immunofluorescent staining were performed to assess the IC concentration, cell apoptosis and autophagy activity of cisplatin in both GC chemosensitive cells (SGC7901) and chemoresistant cells (SGC7901/CDDP). The expression pattern of MALAT1 in GC cells was detected by qRT-PCR. The shRNAs and overexpressing plasmids were employed for the loss or gain-of-function. Dual-luciferase reporter assay was subjected to verify the binding relationship between MALAT1 and miR-30e. Besides, ATG5 mRNA and protein levels were determined using qRT-PCR and western blot analysis. Furthermore, GC xenograft mice model was established to validate the in vitro findings. KEY FINDINGS:Chemoresistant GC cells presented higher IC of cisplatin, increased autophagy activity and stronger expression of MALAT1. The application of propofol promoted cell apoptosis and reduced the activity of autophagy through downregulating MALAT1. Silencing of MALAT1 inhibited chemo-induced autophagy, whereas MALAT1 overexpression promoted autophagy in GC cells. Mechanistic researches demonstrated that MALAT1 could bind with miR-30e to regulate ATG5 expression, thus causing the suppression of autophagy. In vivo GC xenograft model treated with both propofol and cisplatin also showed significantly decreased tumor size and weight, which was enhanced by knockdown of MALAT1. SIGNIFICANCE:Altogether, our study revealed a novel mechanism of propofol of lncRNA MALAT1/miR-30e/ATG5 mediated autophagy-related chemoresistance in GC, casting new lights on the understanding of propofol.
LINC00641/miR-582-5p mediate oxaliplatin resistance by activating autophagy in gastric adenocarcinoma.
Hu Yunfeng,Su Yani,Lei Xia,Zhao Hong,Wang Lelin,Xu Tian,Guo Jing,Yang Weiwei,Zhang Xiaozhi
The poor prognosis of gastric adenocarcinoma is partly due to chemotherapy failure, especially the oxaliplatin-based chemotherapy. However, the specific mechanism of oxaliplatin resistance is unclear. We aim to find the roles that LINC00641 and miR-582-5p play in regulating oxaliplatin resistance. Quantitative reverse transcriptase-PCR was used to evaluate the expression of LINC00641 and microRNA-582-5p (miR-582-5p) in gastric cancer both in vivo and in vitro. Transwell and CCK-8 assays were performed; and LC3 I/II and p62 were detected by western blot to evaluate the activation of autophagy. LINC00641 expression was associated with prognosis and oxaliplatin resistance in patients with gastric adenocarcinoma. The expression of LINC00641 was higher in gastric cancer tissues; whereas miR-582-5p was down-regulated in gastric cancer tissues. Moreover, LINC00641 was highly expressed in oxaliplatin-resistant cell lines and miR-582-5p was down-regulated. In addition, LINC00641 negatively regulated the expression of miR-582-5p. With regard to biological functions, down-regulation of LINC00641 suppressed cell migration and proliferation. Further experiments indicated that down-regulation of LINC00641 inhibited the autophagy process, making gastric cancer cells more sensitive to oxaliplatin. LINC00641 and miR-582-5p are biomarkers for predicting overall survival, as they were involved in regulating oxaliplatin resistance by altering autophagy in gastric adenocarcinoma.
Adapting and Surviving: Intra and Extra-Cellular Remodeling in Drug-Resistant Gastric Cancer Cells.
Russi Sabino,Verma Henu Kumar,Laurino Simona,Mazzone Pellegrino,Storto Giovanni,Nardelli Anna,Zoppoli Pietro,Calice Giovanni,La Rocca Francesco,Sgambato Alessandro,Lucci Valeria,Falco Geppino,Ruggieri Vitalba
International journal of molecular sciences
Despite the significant recent advances in clinical practice, gastric cancer (GC) represents a leading cause of cancer-related deaths in the world. In fact, occurrence of chemo-resistance still remains a daunting hindrance to effectiveness of the current approach to GC therapy. There is accumulating evidence that a plethora of cellular and molecular factors is implicated in drug-induced phenotypical switching of GC cells. Among them, epithelial-mesenchymal transition (EMT), autophagy, drug detoxification, DNA damage response and drug target alterations, have been reported as major determinants. Intriguingly, resistant GC phenotype may be the result of GC cell-induced tumor microenvironment (TME) remodeling, which is currently emerging as a key player in promoting drug resistance and overcoming cytotoxic effects of drugs. In this review, we discuss the possible mechanisms of drug resistance and their involvement in determining current GC therapies failure.
CCL2-SQSTM1 positive feedback loop suppresses autophagy to promote chemoresistance in gastric cancer.
Xu Wenxia,Wei Qi,Han Mengjiao,Zhou Bingluo,Wang Hanying,Zhang Jianbing,Wang Qiang,Sun Jie,Feng Lifeng,Wang Shouyu,Ye Yang,Wang Xian,Zhou Jianwei,Jin Hongchuan
International journal of biological sciences
Chemotherapy is one of the most important approaches for the treatment of various cancers. However, tumor cells often develop resistance to chemotherapeutic drugs. The tumor microenvironment reconstituted by various cytokines secreted from immune cells was recently found to play important roles in affecting therapeutic response of tumor cells. Herein, we reported that tumor cells can secrete autocrine cytokines to confer chemoresistance by inactivating proapoptotic autophagy. Through cytokine screening, we found that drug resistant cancer cells secreted more CCL2 than drug sensitive cells. Such secreted CCL2 could not only maintain chemoresistance in drug-resistant cancer cells but also confer drug resistance to drug-sensitive cancer cells. CCL2 attenuated drug-induced cytotoxicity by activating PI3K-Akt-mTOR signaling to inhibit proapoptotic autophagy and increase SQSTM1 expression. CCL2 expression in primary carcinoma tissues also correlated well with SQSTM1 expression. Either CCL2 knock-down or autophagy induction successfully reversed drug resistance of tumor cells. Moreover, increased expression of SQSTM1 in turn activated CCL2 transcription via NF-κB signal pathway, representing a positive feedback loop to maintain drug resistance. Therefore, our results provided a new insight to understand drug resistance, and indicated the potential value of CCL2 as a biomarker and intervention target for chemotherapy resistance.
miR-874 regulates multiple-drug resistance in gastric cancer by targeting ATG16L1.
Huang Haijin,Tang Jie,Zhang Lei,Bu Yanzhi,Zhang Xiaoyu
International journal of oncology
Chemotherapy is an important treatment option for gastric cancer (GC); however, chemotherapy usually fails due to drug resistance, particularly multidrug resistance (MDR). In our previous studies, microRNA (miR)‑874 was demonstrated to serve an important role in tumour growth, apoptosis and angiogenesis. In the present study, the precise roles and underlying mechanisms of miR‑874 in MDR were investigated in GC. The overexpression of miR‑874 reversed cancer cell drug resistance in vitro. According to reporter gene and western blot assays, Autophagy‑related 16‑like 1 (ATG16 L1) was identified as a direct target of miR‑874. ATG16L1 was also demonstrated to be positively associated with autophagy. Reducing the expression of ATG16L1 and inhibiting the occurrence of autophagy sensitized GC cells to chemotherapy. Thus, the miR‑874/ATG16L1/autophagy regulatory loop was demonstrated to serve an important role in MDR in GC. Furthermore, miR‑874 may be used as a prognostic factor in GC. Overall, miR‑874 could inhibit autophagy and sensitize GC cells to chemotherapy via the target gene ATG16L1, highlighting the potential clinical application of miR‑874 in chemotherapeutic resistance.
Inhibition of CD133 Overcomes Cisplatin Resistance Through Inhibiting PI3K/AKT/mTOR Signaling Pathway and Autophagy in CD133-Positive Gastric Cancer Cells.
Lu Ruiqi,Zhao Gang,Yang Yulong,Jiang Zhaoyan,Cai Jingli,Hu Hai
Technology in cancer research & treatment
Cisplatin is widely used as the standard gastric cancer treatment, but the relapse and metastasis are common as intrinsic or acquired drug resistance. CD133 has been widely known to be associated with chemoresistance in various cancer cells. In this study, we focused on investigating the function and mechanism of CD133 underlying cisplatin resistance in gastric cancer cell line KATO-III. We detected CD133 expression by using quantitative real-time polymerase chain reaction and Western blot and found that expression of CD133 was upregulated in cisplatin resistance of KATO-III cells (Cis-KATO-III) compared with KATO-III cells, indicating the role of CD133 in regulating cisplatin resistance of KATO-III cells. Then we sorted the Cis-KATO-III cells into CD133-positive (CD133) pools and measured the proliferation and apoptosis after the cell is transfected with pc-CD133 and sh-CD133 by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay and flow cytometry. The results showed that the inhibition of CD133 inhibited the cell viability and promoted the cell apoptosis after cisplatin treatment. Furthermore, we found that inhibition of CD133 downregulated the expression of PI3K/AKT and promoted the expression of mammalian target of rapamycin, thus inhibited the autophagic activity in the Cis-KATO-III cells after cisplatin treatment. Besides, we also verified the effects of CD133 . The results indicated that inhibition of CD133 enhanced the Cis-KATO-III cell sensitivity to cisplatin by regulating PI3K/AKT/mTOR signaling pathway. In summary, our data provide new insight that CD133 activates the PI3K/AKT/mTOR signaling transduction pathway, resulting in activation of autophagy and cisplatin resistance of Cis-KATO-III cells. These results may offer a novel therapeutic target in cisplatin-resistant gastric cancer.
Autophagy Facilitates Metadherin-Induced Chemotherapy Resistance Through the AMPK/ATG5 Pathway in Gastric Cancer.
Pei Guoqing,Luo Meng,Ni Xiaochun,Wu Jugang,Wang Shoulian,Ma Yiwen,Yu Jiwei
Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology
BACKGROUND/AIMS:Metadherin (MTDH) is overexpressed in some malignancies and enhances drug resistance; however, its role in gastric cancer (GC) and the underlying mechanisms remain largely unexplored. Here, we explore the mechanism by which MTDH induces drug resistance in GC. METHODS:We analysed the level of MTDH in GC and adjacent normal gastric mucosal tissues by real-time quantitative PCR (q-PCR). We also analysed the level of autophagy by western blot analysis, confocal microscopy, and transmission electron microscopy after MTDH knockdown and overexpression, and examined fluorouracil (5-FU) resistance by Cell Counting Kit-8 at the same time. Finally, GC patient-derived xenograft tumours were used to demonstrate 5-FU resistance. An AMPK pathway inhibitor was applied to determine the molecular mechanisms of autophagy. RESULTS:MTDH expression was significantly increased in the GC specimens compared with that in the adjacent normal gastric mucosal tissues. Further study showed a positive correlation between the expression level of MTDH and 5-FU resistance. MTDH overexpression in MKN45 cells increased the levels of P-glycoprotein (P-gp) and promoted 5-FU resistance, while inhibition of MTDH showed the opposite result. The simultaneous inhibition of autophagy and overexpression of MTDH decreased the levels of P-gp and inhibited 5-FU resistance. Moreover, MTDH induced AMPK phosphorylation, regulated ATG5 expression, and finally influenced autophagy, suggesting that MTDH may activate autophagy via the AMPK/ATG5 signalling pathway. Our findings reveal a unique mechanism by which MTDH promotes GC chemoresistance and show that MTDH is a potential target for improved chemotherapeutic sensitivity and GC patient survival. CONCLUSIONS:MTDH-stimulated cancer resistance to 5-FU may be mediated through autophagy activated by the AMPK/ATG5 pathway in GC.
Autophagy regulation and its role in gastric cancer and colorectal cancer.
Zhou Huangyan,Yuan Min,Yu Qiongfang,Zhou Xiaoyan,Min Weiping,Gao Dian
Cancer biomarkers : section A of Disease markers
BACKGROUND:Autophagy is associated with the occurrence, development, cellular adaptation, progression, treatment and prognosis of gastric cancer (GC) and colorectal cancer (CRC). The effect of autophagy in these two cancers has attracted our attention. OBJECTIVE:The aim of this study was to describe the functional and regulatory mechanisms associated with autophagy in GC and CRC. METHODS:We reviewed recent publications describing the role of autophagy in GC and CRC, including the functional characteristics, clinical significance and regulatory mechanisms. RESULTS:Autophagy plays context-dependent dual roles in the development and progression of GC and CRC. It can either promote tumor growth and cell survival or can contribute to tumor suppression and promote cell death. Both of these effects employ complex regulatory networks, such as those mediated by p53, PI3K/Akt/mTOR, Ras and microRNA. Among the cellular process associated with these pathways, autophagy is a potential target for anti-tumor therapy. CONCLUSION:Autophagy is associated with both tumorigenic and protective effects in cancer. However, the role of autophagy in GC and CRC remains unclear. Although the translation of the basic science of autophagy into clinical practice is a long process, the modulation of autophagy as a potential therapeutic approach in GC and CRC merits further investigation.
CISD2 enhances the chemosensitivity of gastric cancer through the enhancement of 5-FU-induced apoptosis and the inhibition of autophagy by AKT/mTOR pathway.
Sun Yi,Jiang Yingming,Huang Jintuan,Chen Hao,Liao Yi,Yang Zuli
Gastric cancer (GC) is a prevalent upper gastrointestinal tumor characterized by high morbidity and mortality due to imperfect screening systems and the rapid development of resistance to 5-fluorouracil (5-FU). CDGSH iron sulfur domain 2 (CISD2) has been recently regarded as a candidate oncogene in several types of tumors. It is, therefore, necessary to investigate its biological function and clinical significance in gastric cancer. In this study, the down-regulated expression level of CISD2 in GC compared with adjacent normal tissues was evaluated by quantitative RT-PCR and Western blotting. An immunohistochemical analysis indicated that CISD2 expression in GC was significantly correlated with age (P = 0.002), Lauren's classification (P = 0.001), and differentiation (P = 0.049). Two cell lines, MKN1 and BGC823, were used to analyze the role of CISD2 in gastric carcinogenesis and response to 5-FU through CCK-8 assays, the RT-CES system, Transwell assays, flow cytometry, and confocal fluorescence microscopy. The overexpression of CISD2 resulted in reduced cellular growth and proliferation, inhibition of metastatic ability, and increased apoptosis. 5-FU treatment increased endogenous as well as exogenous overexpression of CISD2 in GC cells. Further investigation revealed that CISD2 enhanced sensitivity to 5-FU via an increase in apoptosis and inhibition of protective autophagy through the activation of the AKT/mTOR pathway. In conclusion, CISD2 is down-regulated in gastric cancer, and its effects on the inhibition of cellular proliferation, metastatic ability, and increased chemotherapy sensitivity are mediated by antagonism to 5-FU-induced autophagy through the AKT/mTOR pathway.
Inhibition of autophagy promotes metastasis and glycolysis by inducing ROS in gastric cancer cells.
Qin Wenjie,Li Chao,Zheng Wen,Guo Qingqu,Zhang Yuefeng,Kang Muxing,Zhang Bo,Yang Bin,Li Baozhong,Yang Haijun,Wu Yulian
Autophagy defect has been shown to be correlated with malignant phenotype and poor prognosis of human cancers, however, the detailed mechanisms remain obscure. In this study, we investigated the biological changes induced by autophagy inhibition in gastric cancer. We showed that inhibition of autophagy in gastric cancer cells promotes epithelial-mesenchymal transition (EMT) and metastasis, alters metabolic phenotype from mitochondrial oxidative phosphorylation to aerobic glycolysis and converts cell phenotype toward malignant, which maybe further contribute to chemoresistance and poor prognosis of gastric cancer. We also identified that the EMT and metabolism alterations induced by autophagy inhibition were dependent on ROS-NF-κB-HIF-1α pathway. More importantly, scavenging of ROS by the antioxidant N-acetylcysteine (NAC) attenuated activation of NF-κB and HIF-1α in autophagy-deficient gastric cancer cells, and autophagy inhibition induced metastasis and glycolysis were also diminished by NAC in vivo. Taken together, our findings suggested that autophagy defect promotes metastasis and glycolysis of gastric cancer, and antioxidants could be used to improve disease outcome for gastric cancer patients with autophagy defect.
Autophagy and its role in gastric cancer.
Cao Yijing,Luo Yichen,Zou Juan,Ouyang Jun,Cai Zhihong,Zeng Xi,Ling Hui,Zeng Tiebing
Clinica chimica acta; international journal of clinical chemistry
Autophagy, which is tightly regulated by a series of autophagy-related genes (ATGs), is a vital intracellular homeostatic process through which defective proteins and organelles are degraded and recycled under starvation, hypoxia or other specific cellular stress conditions. For both normal cells and tumour cells, autophagy not only sustains cell survival but can also promote cell death. Autophagy-related signalling pathways include mTOR-dependent pathways, such as the AMPK/mTOR and PI3K/Akt/mTOR pathways, and non-mTOR dependent pathways, such as the P53 pathway. Additionally, autophagy plays a dual role in gastric carcinoma (GC), including a tumour-suppressor role and a tumour-promoter role. Long-term Helicobacter pylori infection can impair autophagy, which may eventually promote tumourigenesis of the gastric mucosa. Moreover, Beclin1, LC3 and P62/SQSTM1 are regarded as autophagy-related markers with GC prognostic value. Autophagy inhibitors and autophagy inducers show promise for GC treatment. This review describes research progress regarding autophagy and its significant role in gastric cancer.
Inhibition of MGMT-mediated autophagy suppression decreases cisplatin chemosensitivity in gastric cancer.
Lei Yuanyuan,Tang Li,Hu Jiaxi,Wang Sumin,Liu Yaojiang,Yang Min,Zhang Jianwei,Tang Bo
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie
Cisplatin (DDP) is the first-line drug for the treatment of gastric cancer (GC). However, DDP resistance is common. Autophagy, which is closely related to chemoresistance, is a process of resolving and recycling proteins and damaged cellular organs. Additionally, O-6-methylguanine-DNA methyltransferase (MGMT) is responsible for alkylating drug resistance. However, the relationship between autophagy and MGMT in response to DDP in GC is still unknown. In the present study, we determined that autophagy induced by DDP decreases chemosensitivity in GC cell lines. DDP may have induced autophagy in GC by inhibiting MGMT to increase autophagy-related gene (ATG) 4B. Inhibition of MGMT-mediated ATG4B suppression resulted in autophagy induction and DDP resistance. In vivo, combined DDP and autophagy inhibitor chloroquine (CQ) enhanced the anti-tumor effect of DDP; additionally, the negative correlation of MGMT and ATG4B was confirmed. High expression of MGMT and low expression of ATG4B were significantly correlated with favorable five-year survival rate (P < 0.05) in 66 clinicopathologically characterized GC cases. Our study demonstrate that DDP inhibits MGMT-mediated autophagy suppression to decrease chemosensitivity in GC, which provides a novel therapeutic strategy to promote DDP chemosensitivity in GC.
miR-21 modulates cisplatin resistance of gastric cancer cells by inhibiting autophagy via the PI3K/Akt/mTOR pathway.
Gu Yifan,Fei Zhewei,Zhu Ronghua
Resistance to cisplatin (DDP) remains a major obstacle in the control of gastric cancer (GC) progression. A previous study revealed that microRNA-21 (miR-21) contributes to DDP resistance in GC cells via the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway. The aim of the current study was to explore the mechanisms underlying the cytoprotective function of miR-21. In this study, DDP-resistant GC cells were obtained by continuous exposure of human gastric adenocarcinoma cells to increasing concentrations of DDP. Western blot analysis was used to evaluate activation of the PI3K/Akt/mechanistic target of rapamycin kinase (mTOR) pathway. The level of miR-21 was altered by transfection of miR-21 mimic and inhibitor. Autophagy was assessed by detecting autophagosome formation, Beclin-1 and LC3 expression. An Annexin V-propidium iodide assay was performed to estimate the survival and death of GC cells. GC cells became refractory to the growth inhibition and apoptosis induced by DDP treatment, activation of Akt and mTOR were increased in DDP-resistant GC cells. Inhibition of autophagy decreased the sensitivity of GC cells to DDP, and autophagy induction produced the opposite effect. DDP-resistant GC cells expressed higher levels of miR-21 compared with the parent cells. Transfection of GC cells with miR-21 mimics contributed to restored DDP resistance by suppressing autophagy, while miR-21 inhibitor sensitized DDP-resistant GC cells by promoting autophagy. In conclusion, the results demonstrated that miR-21 is associated with DDP resistance in GC cells by inhibiting autophagy via the PI3K/Akt/mTOR pathway, and autophagy inducers could be therapeutic targets for the effective treatment of DDP resistance in GC.
Kallikrein-related peptidase 6 induces chemotherapeutic resistance by attenuating auranofin-induced cell death through activation of autophagy in gastric cancer.
Kim Tae Woo,Lee Seon-Jin,Kim Jong-Tae,Kim Sun Jung,Min Jeong-Ki,Bae Kwang-Hee,Jung Haiyoung,Kim Bo-Yeon,Lim Jong-Seok,Yang Young,Yoon Do-Young,Choe Yong-Kyung,Lee Hee Gu
Kallikrein-related peptidase 6 (KLK6) is a biomarker of gastric cancer associated with poor prognosis. Mechanisms by which KLK6 could be exploited for chemotherapeutic use are unclear. We evaluated auranofin (AF), a compound with cytotoxic effects, in KLK6-deficient cells, and we investigated whether KLK6 expression induces autophagy and acquisition of drug resistance in gastric cancer. Using cultured human cells and a mouse xenograft model, we investigated how KLK6 affects antitumor-reagent-induced cell death and autophagy. Expression levels of KLK6, p53, and autophagy marker LC3B were determined in gastric cancer tissues. We analyzed the effects of knockdown/overexpression of KLK6, LC3B, and p53 on AF-induced cell death in cancer cells. Increased KLK6 expression in human gastric cancer tissues and cells inhibited AF-induced cell motility due to increased autophagy and p53 levels. p53 dependent induction of KLK6 expression increased autophagy and drug resistance, whereas KLK6 silencing decreased the autophagy level and increased drug sensitivity. During AF-induced cell death, KLK6 and LC3B colocalized to autophagosomes, associated with p53, and were then trafficked to the cytosol. In the xenograft model of gastric cancer, KLK6 expression decreased AF-induced cell death and KLK6-induced autophagy increased AF resistance. Taken together, the data suggest that the induction of autophagic processes through KLK6 expression may increase acquisition of resistance to AF. Our findings may contribute to a new paradigm for tumor therapeutics.
Down-regulation of ASIC1 suppressed gastric cancer via inhibiting autophagy.
Zhang Qiong,Wu Shiwu,Zhu Jinhai,Chai Damin,Gan Huaiyong
As autophagy has anti-apoptosis effect and accelerates cell survival, many studies start to target autophagy as a therapeutic strategy for cancer. Acid-sensing ion channels (ASICs) was reported to activate autophagy. However, whether ASICs can regulate gastric cancer through autophagy is unknown. The differentially expressed genes in normal gastric tissue and gastric cancer tissue in patients were investigated by RNA-seq. Expression of ASIC1 and autophagy related 5 (ATG5) was further confirmed by real-time PCR. Effects of knockdown expression of ASIC1 and ATG5 on the growth of gastric SGC-7901 cells were assayed by CCK-8 kit. The animal survival rate and tumor volume in murine heterotopic xenograft model was assayed. The expression of autophagy related genes was enriched in gastric cancer tissue in patients, including ASIC1 and ATG5. Knockdown expression of ASIC1 and ATG5 inhibits the growth of SGC-7901 cells, respectively. ASIC1 regulates ATG5 gene expression in SGC-7901 cells. ASIC1 knockdown extended the survival rate of animals and inhibited the tumor volume in the murine heterotopic xenograft model. This study showed that downregulation of ASIC1 inhibits gastric cancer growth via decreasing autophagy, therefore strongly suggests a therapeutic role for ASIC1 in gastric cancer.
Autophagy regulates chemoresistance of gastric cancer stem cells via the Notch signaling pathway.
Li L-Q,Pan D,Zhang S-W,-Y-Xie D,Zheng X-L,Chen H
European review for medical and pharmacological sciences
OBJECTIVE:Gastric cancer is the most common gastrointestinal malignancy and the leading cause of cancer-related deaths in East Asia. Increasing evidence has revealed that autophagy is closely associated with tumor initiation and progression. The present work aimed to investigate the role of autophagy in adjuvant chemotherapy for gastric cancer. MATERIALS AND METHODS:Gastric cancer stem cells (CSCs) were isolated from gastric cancer cell lines using the cell surface markers CD44 and CD54 and cultured in a three-dimensional cell culture system. Western blotting was used to detect their protein expression levels in gastric CSCs. In addition, the cells were treated with inhibitors to investigate the underlying mechanisms of autophagy. RESULTS:After isolation of gastric CSCs expressing CD44 and CD54, Western blot analysis showed that the levels of the autophagic marker LC3II were markedly enhanced in CD44+CD54+ gastric CSCs. Moreover, the ratio of LC3II/LC3I protein levels was higher in CD44+CD54+ gastric CSCs than in non-CSCs. By contrast, both a chemotherapeutic agent (5-fluorouracil) and autophagy inhibitor (chloroquine) exhibited an inhibitory effect on the cell viability of gastric CSCs, and their combination further enhanced such inhibitory effects. Mechanistically, the addition of Notch inhibitor decreased the cell viability of gastric CSCs treated with 5-fluorouracil and chloroquine. In addition, 5-fluorouracil and chloroquine both increased the expression of Notch1 in gastric CSCs. CONCLUSIONS:These findings show that autophagy regulated drug sensitivity of gastric cancer cells through the Notch signaling pathway.
DJ-1 Alters Epirubicin-induced Apoptosis via Modulating Epirubicinactivated Autophagy in Human Gastric Cancer Cells.
Pan Xue-Kai,Su Fei,Xu Li-Hua,Yang Zhang-Shuo,Wang Dan-Wen,Yang Li-Jie,Kong Fan-Zheng,Xie Wei,Feng Mao-Hui
Current medical science
Epirubicin, which is a conventional chemotherapeutic drug for gastric cancer, has innate and adaptive chemoresistance. Recent studies revealed that epirubicin could induce autophagy as a defensive mechanism in drug resistance of mammary carcinoma. Another study implied that DJ-1 may be a chemoresistance-related gene. But the association between DJ-1 and drug resistance of epirubicin in gastric cancer is still ambiguous. In the present report, we explored whether and how DJ-1 conduced to epirubicin-induced apoptosis in gastric cancer. Epirubicin dose-dependently increased the expression of DJ-1 and induced autophagy. Knockdown of DJ-1 notably enhanced epirubicin-induced cell apoptosis, whereas overexpression of DJ-1 attenuated epirubicin-induced cell apoptosis. Further studies revealed that down-regulation of DJ-1 modulated epirubicinactivated autophagy which augmented epirubicin-induced apoptosis. In conclusion, our results validated that DJ-1 reduced epirubicin-induced apoptosis in gastric cancer cells via modulating epirubicin-activated autophagy.
Autophagy inhibition enhances PD-L1 expression in gastric cancer.
Wang Xiaojuan,Wu William K K,Gao Jing,Li Zhongwu,Dong Bin,Lin Xiaoting,Li Yilin,Li Yanyan,Gong Jifang,Qi Changsong,Peng Zhi,Yu Jun,Shen Lin
Journal of experimental & clinical cancer research : CR
BACKGROUND:Autophagy, a process for degrading intracellular substances to maintain basal metabolic turnover, is known to be perturbed in gastric cancer. Programmed cell death-1 (PD-1) with its ligand (PD-L1) are important immune checkpoint proteins and their regulation by autophagy has been reported in mouse melanoma and human ovarian cancer. Here, we explored the interplay between autophagy and the PD1/PD-L1 axis in gastric cancer. METHODS:The expression of PD-L1 in gastric cancer cells was detected by Western blot and flow cytometry analysis. The effect of autophagy inhibition on PD-L1 expression was examined in vitro and in vivo. The molecular mechanisms of the regulation of PD-L1 by autophagy were evaluated in gastric cancer cell lines. The clinical relevance of autophagy-related markers p62/SQSTM1 and LC3 with PD-L1 was evaluated in 137 patients with gastric cancer. RESULTS:We found that inhibition of autophagy by pharmacological inhibitors or small interfering RNAs increased the levels of PD-L1 in cultured gastric cancer cells and in xenografts. Interferon (IFN)-γ also promoted PD-L1 gene transcription, whose action was enhanced by autophagy inhibition. Mechanistically, autophagy inhibition led to the accumulation of p62/SQSTM1 and activation of nuclear factor (NF)-κB, in which NF-κB inhibition or p62/SQSTM1 knockdown attenuated PD-L1 induction by autophagy inhibition. Immunohistochemical staining of primary tumor tissues of 137 patients with gastric cancer showed that LC3 and p62/SQSTM1 protein levels were positively correlated with PD-L1 (LC3, p < 0.001; p62/SQSTM1, p < 0.05). The expression of PD-L1 was also positively correlated with tumor lymphocyte infiltration (p < 0.001). CONCLUSIONS:We discovered that autophagy regulates PD-L1 expression in gastric cancer through the p62/SQSTM1-NF-κB pathway. Pharmacological modulation of autophagy may thus influence the therapeutic efficacy of PD-L1 blockade in gastric cancer.
WASF3 Knockdown Sensitizes Gastric Cancer Cells to Oxaliplatin by Inhibiting ATG12-Mediated Autophagy.
Nie Yanli,Liang Xinjun,Liu Sanhe,Guo Fang,Fang Na,Zhou Fuxiang
The American journal of the medical sciences
BACKGROUND:Gastric cancer is one of the most aggressive tumors, usually resulting in metastasis, and therapies for advanced gastric cancer remain limited. Drug resistance is the main reason for chemotherapeutic failure in gastric cancer. Wiskott-Aldrich syndrome protein family member 3 (WASF3) is required for invasion and metastasis of different cancers. However, there has been little study of WASF3 expression involvement in gastric cancer. In this study, we explored the role of WASF3 in the sensitivity of gastric cancer to oxaliplatin, and the underlying mechanisms. METHODS:We silenced WASF3 using WASF3-siRNA in MGC803 cells. Then, CCK-8, flow cytometry and transwell assay were performed to study the effect of WASF3 silencing on proliferation, migration, invasiveness and apoptosis of MGC803 cells. Moreover, we evaluated the potential mechanism in vitro to determine the sensitization to oxaliplatin induced by WASF3. RESULTS:WASF3 silencing by small interfering RNA inhibited the proliferation, migration and invasiveness of gastric cancer cells. We also observed that WASF3 knockdown promoted cell apoptosis and enhanced oxaliplatin sensitivity. Furthermore, the sensitization to oxaliplatin induced by WASF3 knockdown depended on the inhibition of Atg12-mediated autophagy. CONCLUSIONS:Our analysis demonstrates WASF3 targeting is a new potential therapeutic strategy for gastric cancer.
Inhibition of autophagy improves resistance and enhances sensitivity of gastric cancer cells to cisplatin.
Hou Guiqin,Bai Yiru,Jia Ang,Ren Yandan,Wang Yang,Lu Jie,Wang Peng,Zhang Jianying,Lu Zhaoming
Canadian journal of physiology and pharmacology
Autophagy plays critical roles in tumorigenesis, while the effects of autophagy on chemoresistance of cancer cells had great disparity. This study aims to explore the impacts of autophagy on the sensitivity and resistance of gastric cancer cells to cisplatin (DDP). We firstly demonstrated that there was stronger autophagy activity in gastric cancer SGC-7901 cells than that in DDP-resisting SGC-7901/DDP cells. Then, we discovered that inhibiting autophagy by chloroquine (CQ) significantly enhanced the proliferation-inhibiting and apoptosis-inducing effects of DDP to SGC-7901 and SGC-7901/DDP cells. Moreover, CQ could partially reverse the resistance of SGC-7901/DDP cells to DDP in a concentration-dependent manner. However, the autophagy inducer everolimus (RAD001) had no obvious effects on the sensitivity of gastric cells to DDP. Mechanistically, we demonstrated that CQ might enhance the sensitivity of SGC-7901cells and improve the resistance of SGC-7901/DDP cells to DDP through inhibiting the mTORC1 pathway, especially to SGC-7901/DDP cells. Additionally, we found interfering Beclin-1 using Beclin-1 shRNA also enhanced the proliferation-inhibiting and apoptosis-inducing effects of DDP on gastric cancer cells by inhibiting phosphorylation of Akt. Our study shows that inhibiting autophagy could improve the chemoresistance and enhanced sensitivity of gastric cancer cells to DDP and provide a rationale for the administration of cisplatin combined with CQ for treating patients with gastric cancer.
METase/lncRNA HULC/FoxM1 reduced cisplatin resistance in gastric cancer by suppressing autophagy.
Xin Lin,Zhou Qi,Yuan Yi-Wu,Zhou Li-Qiang,Liu Li,Li Shi-Hao,Liu Chuan
Journal of cancer research and clinical oncology
BACKGROUND:Autophagy plays an important role in regulating cisplatin (CDDP) resistance in gastric cancer cells. However, the underlying mechanism of methioninase (METase) in the regulation of autophagy and CDDP resistance of gastric cancer cells is still not clear. MATERIALS AND METHODS:Western blot was used to detect the levels of autophagy-related proteins, multidrug-resistant 1 (MDR-1), and FoxM1 protein. LncRNA HULC was detected by qRT-PCR. Cell viability was detected using CCK-8 assay. The interaction between lncRNA HULC and FoxM1 was confirmed by RNA pull-down and RIP assay. RESULTS:Lentiviral vector carrying METase (LV-METase) suppressed autophagy and CDDP resistance of drug-resistant gastric cancer cells. LncRNA HULC was significantly downregulated in drug-resistant gastric cancer cells transfected with LV-METase. Besides, we found that lncRNA HULC interacted with FoxM1. In addition, METase suppressed autophagy to reduce CDDP resistance of drug-resistant gastric cancer cells through regulating HULC/FoxM1, and interfering HULC suppressed autophagy to reduce CDDP resistance of drug-resistant gastric cancer cells through regulating FoxM1. Finally, interfering HULC inhibited tumor growth in vivo. CONCLUSION:METase suppressed autophagy to reduce CDDP resistance of drug-resistant gastric cancer cells through regulating HULC/FoxM1 pathway.