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Background: Cisplatin is the first-line chemotherapeutic drug for non-small cell lung cancer (NSCLC), and emerging evidences suggests that targeting circular RNAs (circRNAs) is an effective strategy to increase cisplatin-sensitivity in NSCLC, but the detailed mechanisms are still not fully delineated., Methods: Cell proliferation, viability and apoptosis were examined by using the cell counting kit-8 (CCK-8) assay, trypan blue staining assay and Annexin V-FITC/PI double staining assay, respectively. The expression levels of cancer associated genes were measured by using the Real-Time qPCR and Western Blot analysis at transcriptional and translated levels. Dual-luciferase reporter gene system assay was conducted to validated the targeting sites among hsa_circRNA_103809, miR-377-3p and 3' untranslated region (3'UTR) of GOT1 mRNA. The expression status, including expression levels and localization, were determined by immunohistochemistry (IHC) assay in mice tumor tissues., Results: Here we identified a novel hsa_circRNA_103809/miR-377-3p/GOT1 signaling cascade which contributes to cisplatin-resistance in NSCLC in vitro and in vivo. Mechanistically, parental cisplatin-sensitive NSCLC (CS-NSCLC) cells were subjected to continuous low-dose cisplatin treatment to generate cisplatin-resistant NSCLC (CR-NSCLC) cells, and we found that hsa_circRNA_103809 and GOT1 were upregulated, while miR-377-3p was downregulated in CR-NSCLC cells but not in CS-NSCLC cells. In addition, hsa_circRNA_103809 sponged miR-337-3p to upregulate GOT1 in CS-NSCLC cells, and knock-down of hsa_circRNA_103809 enhanced the inhibiting effects of cisplatin on cell proliferation and viability, and induced cell apoptosis in CR-NSCLC cells, which were reversed by downregulating miR-377-3p and overexpressing GOT1. Consistently, overexpression of hsa_circRNA_103809 increased cisplatin-resistance in CS-NSCLC cells by regulating the miR-377-3p/GOT1 axis. Finally, silencing of hsa_circRNA_103809 aggravated the inhibiting effects of cisplatin treatment on NSCLC cell growth in vivo., Conclusions: Analysis of data suggested that targeting the hsa_circRNA_103809/miR-377-3p/GOT1 pathway increased susceptibility of CR-NSCLC cells to cisplatin, and this study provided novel targets to improve the therapeutic efficacy of cisplatin for NSCLC treatment in clinic.

Cisplatin (CDDP) is a commonly used drug for gallbladder cancer (GBC) chemotherapy. However, resistance to CDDP treatment results in relapse. Therefore, there is a need for the development of more effective treatment strategies to overcome chemoresistance. Dual-specificity phosphatase 1 (DUSP1) was reported to be involved in the resistance of a number of chemotherapeutic agents and was revealed to be highly expressed in CDDP-resistant GBC cells and CDDP-treated tumor types compared with normal cells or tissues in the present study. DUSP1 was revealed to inhibit the cytotoxicity of CDDP in two GBC cell lines, SGC996 and GBC-SD. P38 mitogen-activated protein kinases may be involved in the mechanism of chemoresistance. Furthermore, the number of DNA double-strand breaks in SGC996 OE cells was reduced compared with SGC996 vector cells indicating DUSP1 may attenuate the chemotherapeutic efficiency. Due to its potency against CDDP treatment, DUSP1 may be a promising target to overcome chemoresistance in GBC therapy. [ABSTRACT FROM AUTHOR]