Project description:Cisplatin-resistant gastric cancer (GC) occurs in patients with GC treated with cisplatin-based chemotherapy, which results in disease progression and early recurrence during the treatment. To understand the initiation and developmental mechanism underlying cisplatin-resistant GC, we developed cisplatin resistant SGC7901 cells (SGC7901/DDP) from the parental cells (SGC7901/S) by continuous exposure to increasing concentrations of cisplatin and subjected these two cell lines to RNA sequencing analysis. Overall design: mRNA profiles of cisplatin resistant SGC7901 cells (SGC7901/DDP) and the parental cells (SGC7901/S) were generated by deep sequencing, using BGISEQ-500.
Project description:BACKGROUND:To investigate the mechanism of lentiviral vector carrying methioninase enhances the sensitivity of drug-resistant gastric cancer cells to Cisplatin. METHODS:Death receptors, anti-apoptotic protein, NF-κB, and TRAIL pathway-related factors were detected. The influence of LV-METase transfection on cell viability and pathway-related proteins were assessed by MTT method and western blot, respectively. Different treatments (NF-κB or caspase-3 inhibitor induction, TRAIL supplement, etc.) were performed in gastric cancer cells and the above parameters were analysed. Moreover, the connection between miR-21 and NF-κB or caspase-8 was determined by Chip and luciferase assay, respectively. LV-METase transfection drug-resistant gastric cancer cells were injected subcutaneously into mice. RESULTS:The expression of free MET, miR-21-5p, MDR1, P-gp, and DR5 was significantly increased in drug-resistant gastric cancer cell lines. When cells were transfected with LV-METase, intracellular TRAIL signalling was activated while NF-κB pathway was inhibited. Besides, enhanced TRAIL signalling or repressed NF-κB pathway can promote the sensitivity of drug-resistant strains to Cisplatin, and the combination shows more sensitive to sensitisation. LV-METase promoted TRAIL expression by reducing NF-κB, thereby contributing to the downregulation of P-gp and enhancing the susceptibility of drug-resistant gastric cancer cells to Cisplatin. Furthermore, miR-21 regulated by NF-κB mediated the expression of P-gp protein via inhibiting caspase-8, thus regulating Cisplatin-induced cell death. CONCLUSIONS:Our results suggest that LV-METase has potential as a therapeutic agent for gastric cancer treatment.
Project description:Gastric cancer is the third most common malignancy in China, with a median 5-year survival of only 20%. Cisplatin has been used in first-line cancer treatment for several types of cancer including gastric cancer. However, patients are often primary resistant or develop acquired resistance resulting in relapse of the cancer and reduced survival. Recently, we demonstrated that the reduced expression of base excision repair protein XRCC1 and its upstream regulator JWA in gastric cancerous tissues correlated with a significant survival benefit of adjuvant first-line platinum-based chemotherapy as well as XRCC1 playing an important role in the DNA repair of cisplatin-resistant gastric cancer cells. In the present study, we demonstrated the role of JWA in cisplatin-induced DNA lesions and aquired cisplatin resistance in five cell-culture models: gastric epithelial cells GES-1, cisplatin-sensitive gastric cancer cell lines BGC823 and SGC7901, and the cisplatin-resistant gastric cancer cell lines BGC823/DDP and SGC7901/DDP. Our results indicated that JWA is required for DNA repair following cisplatin-induced double-strand breaks (DSBs) via XRCC1 in normal gastric epithelial cells. However, in gastric cancer cells, JWA enhanced cisplatin-induced cell death through regulation of DNA damage-induced apoptosis. The protein expression of JWA was significantly decreased in cisplatin-resistant cells and contributed to cisplatin resistance. Interestingly, as JWA upregulated XRCC1 expression in normal cells, JWA downregulated XRCC1 expression through promoting the degradation of XRCC1 in cisplatin-resistant gastric cancer cells. Furthermore, the negative regulation of JWA to XRCC1 was blocked due to the mutation of 518S/519T/523T residues of XRCC1, and indicating that the CK2 activated 518S/519T/523T phosphorylation is a key point in the regulation of JWA to XRCC1. In conclusion, we report for the first time that JWA regulated cisplatin-induced DNA damage and apoptosis through the CK2-P-XRCC1-XRCC1 pathway, indicating a putative drug target for reversing cisplatin resistance in gastric cancer.
Project description:Platinum based therapy is commonly used in the treatment of advanced gastric cancer. However, resistance to chemotherapy is a major challenge that causes marked variation in individual response rate and survival rate. In this study, we aimed to identify the expression of GTSE1 and its correlation with cisplatin resistance in gastric cancer cells.Methylation profiling was carried out in tissue samples from gastric cancer patients before undergoing neoadjuvent therapy using docetaxel, cisplatin and 5FU (DCX) and in gastric cancer cell lines. The correlation between GTSE1 expression and methylation in gastric cancer cells was determined by RT-PCR and MSP respectively. GTSE1 expression was knocked-down using shRNA's and its effects on cisplatin cytotoxicity and cell survival were detected by MTS, proliferation and clonogenic survival assays. Additionally, the effect of GTSE1 knock down in drug induced apoptosis was determined by western blotting and apoptosis assays.GTSE1 exhibited a differential methylation index in gastric cancer patients and in cell lines that correlated with DCX treatment response and cisplatin sensitivity, respectively. In-vitro, GTSE1 expression showed a direct correlation with hypomethylation. Interestingly, Cisplatin treatment induced a dose dependent up regulation as well as nuclear translocation of GTSE1 expression in gastric cancer cells. Knock down of GTSE1 enhanced cisplatin cytotoxity and led to a significant reduction in cell proliferation and clonogenic survival. Also, loss of GTSE1 expression caused a significant increase in P53 mediated apoptosis in cisplatin treated cells.Our study identifies GTSE1 as a biomarker for cisplatin resistance in gastric cancer cells. This study also suggests the repressive role of GTSE1 in cisplatin induced apoptosis and signifies its potential utility as a therapeutic target for better clinical management of gastric cancer patients.
Project description:Cisplatin is used to treat multiple types of solid tumor, including gastric cancer. Although cisplatin initially exhibits good efficacy, therapeutic failure often occurs owing to the development of chemoresistance. To the best of our knowledge, the underlying mechanism of cisplatin resistance remains unknown. The aim of the present study was to assess whether taxol resistance gene 1 (TXR1) has a role in cisplatin response in gastric cancer. The expression of TXR1 in fresh-frozen tissues of patients with gastric cancer who were sensitive or resistance to cisplatin was assessed. The level of TXR1 expression was significantly higher in cisplatin-resistant specimens than that in cisplatin-sensitive specimens. Next, the gastric cancer SGC-7901 cell line was exposed to cisplatin to establish a cisplatin-resistance subline, termed SGC-7901/DDP, which exhibited a 6-fold increases in the level of resistance. TXR1 expression was elevated in SGC-7901/DDP cells. Overexpression of TXR1 induced cisplatin resistance in SGC-7901 cells. Downregulation of TXR1 reversed the drug resistance caused by elevation of TXR1 expression in SGC-7901/DDP cells. Animal experiments proved the effect of TXR1 in inducing cisplatin resistance in vivo. Further investigation revealed that TXR1 regulated cisplatin resistance via apoptosis. In conclusion, TXR1 is worthy of further in-depth study as a potential therapeutic target in patients with gastric cancer.
Project description:Background and Aim: Human SLFN11 gene encodes a protein with structural similarity to RNA helicases, which was reported to sensitize cancer cells to DNA-damaging agents. This study explored the epigenetic regulation and mechanism of SLFN11 in human gastric cancer. Methods: Eight human gastric cancer cell lines and 201 cases of primary gastric cancer were analyzed. Methylation specific PCR, flow cytometry, xenograft mouse model and siRNA technique were employed. Results: SLFN11 was methylated in 29.9% (60/201) of primary gastric cancer. The expression of SLFN11 was regulated by promoter region methylation. Methylation of SLFN11 was significantly associated with tumor size (p < 0.05). SLFN11 suppressed gastric cancer growth both in vitro and in vivo and enhanced the ability of cisplatin to induce S-phrase arrest and apoptosis in gastric cancer cells. Conclusions: SLFN11 is frequently methylated in human gastric cancer, and its expression is regulated by promoter region methylation. Our results demonstrate that SLFN11 is a tumor suppressor in human gastric cancer, and methylation of SLFN11 may serve as a cisplatin resistant marker in human gastric cancer.
Project description:Cisplatin is a cytotoxic platinum compound that triggers DNA crosslinking induced cell death, and is one of the reference drugs used in the treatment of several types of human cancers including gastric cancer. However, intrinsic or acquired drug resistance to cisplatin is very common, and leading to treatment failure. We have recently shown that reduced expression of base excision repair protein XRCC1 (X-ray repair cross complementing group1) in gastric cancerous tissues correlates with a significant survival benefit from adjuvant first-line platinum-based chemotherapy. In this study, we demonstrated the role of XRCC1 in repair of cisplatin-induced DNA lesions and acquired cisplatin resistance in gastric cancer by using cisplatin-sensitive gastric cancer cell lines BGC823 and the cisplatin-resistant gastric cancer cell lines BGC823/cis-diamminedichloridoplatinum(II) (DDP). Our results indicated that the protein expression of XRCC1 was significantly increased in cisplatin-resistant cells and independently contributed to cisplatin resistance. Irinotecan, another chemotherapeutic agent to induce DNA damaging used to treat patients with advanced gastric cancer that progressed on cisplatin, was found to inhibit the expression of XRCC1 effectively, and leading to an increase in the sensitivity of resistant cells to cisplatin. Our proteomic studies further identified a cofactor of 26S proteasome, the thioredoxin-like protein 1 (TXNL1) that downregulated XRCC1 in BGC823/DDP cells via the ubiquitin-proteasome pathway. In conclusion, the TXNL1-XRCC1 is a novel regulatory pathway that has an independent role in cisplatin resistance, indicating a putative drug target for reversing cisplatin resistance in gastric cancer.
Project description:Cisplatin is the major chemotherapeutic drug in gastric cancer, particularly in treating advanced gastric cancer. Tumour cells often develop resistance to chemotherapeutic drugs, which seriously affects the efficacy of chemotherapy. GPR30 is a novel oestrogen receptor that is involved in the invasion, metastasis and drug resistance of many tumours. Targeting GPR30 has been shown to increase the drug sensitivity of breast cancer cells. However, few studies have investigated the role of GPR30 in gastric cancer. Epithelial-mesenchymal transition (EMT) has been shown to be associated with the development of chemotherapeutic drug resistance. In this study, we demonstrated that GPR30 is involved in cisplatin resistance by promoting EMT in gastric cancer. GPR30 knockdown resulted in increased sensitivity of different gastric cancer (GC) cells to cisplatin and alterations in the epithelial/mesenchymal markers. Furthermore, G15 significantly enhanced the cisplatin sensitivity of GC cells while G1 inhibited this phenomenon. In addition, EMT occurred when AGS and BGC-823 were treated with cisplatin. Down-regulation of GPR30 with G15 inhibited this transformation, while G1 promoted it. Taken together, these results revealed the role of GPR30 in the formation of cisplatin resistance, suggesting that targeting GPR30 signalling may be a potential strategy for improving the efficacy of chemotherapy in gastric cancer.
Project description:Cisplatin remains to be primary chemotherapeutic drug for gastric cancer patients, especially for advanced stage ones. However, primary or acquired resistance often occurs with the mechanisms being not well understood, which results in relapse of the cancer and poor survival. Herein, we found that HER2 upregulation was associated with cisplatin resistance. We observed that cisplatin-resistant gastric cancer cells underwent a morphological change similar to epithelial-mesenchymal transition (EMT) which is mediated by HER2 overexpression. When specific monoclonal antibody Herceptin, small molecular targeted drug CP724714, or small interfering RNA against HER2 was applied, the EMT-like phenotypic change was dramatically reversed. More importantly, the IC50 and Resistance Index of resistant gastric cancer cells to cisplatin were also decreased by any of these treatments.We demonstrated that expression and amplification of HER2 positively correlated with expression of EMT-related transcription factor Snail in gastric cancer tissues. Furthermore, for the first time, we found that HER2/Snail double positive gastric cancer patients had poorer survival than single positive or double negative counterparts, which provided experimental evidence for the necessity of HER2/Snail double testing in gastric cancer. In conclusion, this study provides some clues of the association of cisplatin resistance with HER2 upregulation-induced EMT in gastric cancer cells.
Project description:To determine the signaling networks that are dysregulated in cisplatin-resistant non-small cell lung cancer, noncoding RNA expression data were obtained from, and compared between, the lung adenocarcinoma cell line, A549, and its cisplatin-resistant derivative, A549/CDDP. Noncoding RNA expression data from a cisplatin-sensitive lung adenocarcinoma cancer cell line (A549) were collected and compared to noncoding RNA expression data from a cisplatin-resistant cell line (A549/CDDP). 3 independent experiments were completed for both the sensitive and resistant cell lines.