MicroRNA-1 overexpression increases chemosensitivity of non-small cell lung cancer cells by inhibiting autophagy related 3-mediated autophagy.

Non-small cell lung cancer (NSCLC) is a major type of lung cancer. Drug resistance is a enormous obstacle for cancer treatment. Copious microRNAs (miRNAs) have been demonstrated to be implicated in drug resistance in NSCLC. In the present study, RT-qPCR assay revealed that microRNA-1 (miR-1) expression was downregulated in DDP resistant NSCLC tissues and cells. Western blot assay presented a remarkable increase of LC3B-II/LC3B-I ratio and a notable decline of p62 level in DDP resistant NSCLC cells, while these effects were weakened by miR-1. GFP-LC3 puncta experiment showed that ectopic expression of miR-1 induced a noticeable downregulation of GFP-LC3 positive cell percentage in DDP resistant NSCLC cells. Bioinformatical analysis and luciferase assay revealed that autophagy related 3 (ATG3) was a target of miR-1. Also, Western blot and RT-qPCR assays manifested that ATG3 was highly expressed in DDP resistant NSCLC tissues and cells. Additionally, miR-1 inhibited ATG3 expression and ATG3 upregulation abolished miR-1-meidated autophagy inhibition in DDP resistant NSCLC cells. Cell Counting Kit-8 (CCK-8) assay showed that the half maximal inhibitory concentration (IC50 ) of cisplatin (DDP) was reduced in miR-1-enforced DDP resistant NSCLC cells, but was restored following the overexpression of ATG3. Flow cytometry experiments further showed that miR-1 overexpression induced a significant upregulation of apoptotic rate and ATG3 restoration weakened miR-1-induced apoptosis in DDP resistant NSCLC cells. Collectively, our study validated that miR-1 overexpression improved DDP sensitivity of NSCLC cells by inhibiting ATG3-mediated autophagy, providing a potential therapeutic target for easing chemoresistance of anti-tumor drugs.