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CTBP1 strengthens the cisplatin resistance of gastric cancer cells by upregulating RAD51 expression.

ABSTRACT: Drug resistance is a key factor affecting the treatment of gastric cancer. The resistance of gastric cancer cells to anticancer drugs, such as cisplatin (DDP), remains a major challenge to patient recovery. The present study aimed to investigate the roles of C-terminal-binding protein 1 (CTBP1) in the DDP resistance of gastric cancer cells and to determine its regulatory effect on DNA repair protein RAD51 homolog 1 (RAD51). The DDP-resistant human gastric cancer AGS and HGC cell lines, AGS/DDP and HGC-27/DDP, respectively, were established and CTBP1 expression was detected by western blotting. In addition, Cell Counting Kit-8, colony formation and flow cytometry assays were performed to detect the proliferation and apoptosis of these two cell lines following CTBP1 knockdown. The expression levels of apoptosis-related proteins were detected by western blotting. In addition, RAD51 was overexpressed in CTBP1 knockdown cells, and proliferation and apoptosis were subsequently determined using the aforementioned methods. The results demonstrated that CTBP1 expression was notably increased in DDP-resistant gastric cancer cells. Furthermore, CTBP1 knockdown suppressed the proliferation and induced the apoptosis of AGS/DDP and HGC-27/DDP cells. Notably, CTBP1 promoted RAD51 expression in DDP-resistant gastric cancer cells. Overexpression of RAD51 in CTBP1 knockdown AGS/DDP and HGC-27/DDP cells rescued the proliferation and alleviated the apoptosis of these cells. Taken together, the results of the present study suggested that CTBP1 may enhance the DDP resistance of gastric cancer cells by activating RAD51 expression, thus providing a potential novel therapy (CTBP1 knockdown) for the clinical treatment of patients with gastric cancer.

SUBMITTER: Wu Y

PROVIDER: S-EPMC8490970 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Objective: Redox adaptation plays a critical role in cancer cells’ drug tolerance and sensitivity. The antioxidative response is induced by nuclear factor erythroid 2-related factor 2 (Nrf2), which triggers the transcriptional activation of genes related to chemosensitivity, glutathione synthesis, and cell protection. Although Nestin1 is known to regulate cellular redox homeostasis by regulating Nrf2 in lung cancer cells, its regulatory effect on the antioxidative state of bladder cancer (BC) cells remains unclear. Methods: The oxidative stress levels in two cisplatin-treated BC cell lines (T24 and J82) were examined using 2’,7’-dichlorofluorescin diacetate staining and real-time quantitative reverse transcription-PCR (RT-qPCR) assays. The cell viability, growth, and apoptosis were determined using CCK-8, colony formation, and flow cytometric assays, respectively. The mRNA and protein levels of Nestin1, Nrf2, and several antioxidant enzymes were quantified using RT-qPCR and western blot assays. A mouse xenograft model was used to determine the effect of Nestin1 on the T24 tumor growth in vivo. Results: Cisplatin treatment induced reactive oxygen species (ROS) generation and antioxidative damage in the T24 and J82 cells, reducing their viability and growth and triggering their apoptosis. Moreover, the Nestin1 and Nrf2 protein levels were enhanced in both treated cell lines. Loss- and gain-of-function assays indicated that Nestin1 expression was positively correlated with the Nrf2 protein expression in the BC cells. Nestin1 overexpression reduced the ROS generation, alleviated the redox disorder, promoted cell viability, and reduced apoptosis, but its silencing had the opposite effects. Importantly, Nestin1 overexpression enhanced the chemoresistance of BC cells to cisplatin in vivo, but its knockdown improved the chemosensitivity of the cells and increased their apoptosis. Conclusion: These results provide a theoretical basis for further targeting the transcription factors, including Nestin1 and Nrf2, in the treatment of BC with cisplatin.

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.

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CTBP1 strengthens the cisplatin resistance of gastric cancer cells by upregulating RAD51 expression.

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