Knockdown of TRIM65 Inhibits Autophagy and Cisplatin Resistance in A549/DDP Cells by Regulating MiR-138-5p/ATG7

Cisplatin resistance is the main cause of treatment failure in patients with non-small-cell lung cancer (NSCLC). Autophagy is a key mechanism of resistance to chemotherapy. Given that tripartite motif (TRIM)-containing proteins are involved in the regulation of autophagy and chemoresistance, we aimed to study the functions of TRIM protein members in autophagy-mediated chemoresistance of NSCLC. We found that TRIM65 was significantly increased in cisplatin-resistant NSCLC cell line (A549/DDP) as compared to the parental cell line (A549). Knockdown of TRIM65 can enhance cisplatin-induced apoptosis and inhibit autophagy in A549/DDP cells, as indicated by Annexin V/PI staining, caspase3 activity test, and LC3-II immunofluorescence staining. Additionally, knockdown of TRIM65 significantly decreased the expression of an important autophagy mediator, ATG7, which was a potential target of miR-138-5p. miR-138-5p inhibitor significantly abolished the effects of TRIM65 knockdown on autophagy and cisplatin-induced apoptosis. Moreover, TRIM65 induced the ubiquitination and degradation of TNRC6A, resulting in the suppressed expression of miR-138-5p. TRIM65 knockdown inhibited the growth of tumors derived from A549/DDP cells. Furthermore, cisplatin-resistant NSCLC tissues displayed higher expression of TRIM65 mRNA and lower expression of miR-138-5p as compared to cisplatin non-resistant ones. miR-138-5p expression was negatively correlated with TRIM65 mRNA in NSCLC tissues. Collectively, the present study indicates that TRIM65 knockdown attenuates autophagy and cisplatin resistance in A549/DDP cells via regulating miR-138-5p.