Abstract
Cisplatin chemoresistance is a clinical obstacle in the treatment of gastric cancer (GC). Enhanced DNA repair capacity may lead to cisplatin resistance. However, the detailed molecular mechanism of GC cisplatin resistance specifically involving nucleotide excision repair (NER) is not clear. However, the mechanism through which the NER pathway contributes to cisplatin resistance in GC is still unclear. In light of the crucial role of microRNAs (miRNAs) in regulating protein expression and biological behavior, we aimed to analyze the expression and function of miR-192-5p in the NER pathway and its role in cisplatin resistance in GC. Comet assays were performed to measure the amount of DNA damage and repair in the SGC7901 and SGC7901/DDP GC cell lines by observing the tail length. MiRNA expression levels in SGC7901/DDP and SGC7901 cells were detected by microarray. Quantitative real-time PCR (qRT-PCR) was carried out to confirm the expression level of miR-192-5p. Lentiviral vector transfection modifies miR-192-5p levels in SGC7901/DDP and SGC7901 cells. The IC50 values of cisplatin-treated cells were assessed by MTT assays. The protein level was determined by Western blot and immunohistochemistry. With enhanced DNA repair, the expression levels of ERCC3 and ERCC4 in SGC 7901DDP cells increased, while miR-192-5p was significantly downregulated in SGC7901/DDP compared with SGC7901 cells. ERCC3 and ERCC4 were identified as the main targets of miR-192-5p. Forced expression of miR-192-5p in SGC7901/DDP cells significantly inhibited the expression of ERCC3 and ERCC4, making GC cells more sensitive to cisplatin in vitro and in vivo. In contrast, knockdown of miR-192-5p expression in SGC7901 cells increased the expression of ERCC3 and ERCC4, resulting in cisplatin resistance in vitro and in vivo. MiR-192-5p partially reversed GC cisplatin resistance by targeting ERCC3 and ERCC4, which participate in the NER pathway, suggesting that miR-192-5p may be a potential biomarker and therapeutic target for GC cisplatin resistance.