MiR-199a-5p-HIF-1α-STAT3 positive feed-back loop contributes to the progression of NSCLC

Background Non-small cell lung cancer (NSCLC), is the most common malignancy worldwide. MiR-199a-5p has been reported to play important roles in multiple tumors, inclusive of NSCLC. Whereas, little is definitively known pertaining to its explicit mechanism of action in NSCLC. Methods Expression of miR-199a-5p and HIF-1α mRNA were quantified employing qRT-PCR. H1299 and A549 cells were transiently transfected with miR-199a-5p mimics or inhibitors. Then CCK-8 assays, flow cytometry analysis, Transwell assay were implemented for detecting cell proliferation, cell cycle, apoptosis, migration and invasion of NSCLC cells, respectively. HIF-1α, STAT3 and p-STAT3 expression were detected via Western blotting. Bioinformatic analysis and dual-luciferase assay were performed for monitoring interaction between miR-199a-5p, HIF-1α and STAT3. Xenograft models were established with nude mice for further analyzing Bevacizumab resistance of NSCLC. Results MiR-199a-5p expression was markedly attenuated in NSCLC tissues and cell lines. Overexpression of miR-199a-5p constrained proliferation, migration, invasion but induced apoptosis of NSCLC cells. HIF-1α was identified as a direct target of miR-199a-5p. Further study confirmed a positive feed-back loop between miR-199a-5p, HIF-1α and STAT3. Co-transfection of HIF-1α or STAT3 overexpression plasmids counteracted effects of miR-199a-5p. Further study substantiated that feed-back loop might be in association with the Bevacizumab resistance of NSCLC cells . Conclusion MiR-199a-5p constrained the progression and Bevacizumab resistance of NSCLC by suppressing HIF-1α and STAT3, while HIF-1α/STAT3 axis suppressed the expression of miR-199a-5p, which forms a positive feed-back loop to promote the sustaining progression of NSCLC.