miR-20b promotes growth of non-small cell lung cancer through a positive feedback loop of the Wnt/β-catenin signaling pathway

microRNAs (miRNAs or miRs) are endogenous noncoding single-stranded RNA molecules that can regulate gene expression by targeting the 3′-untranslated region and play an important role in many biological and pathological processes, such as inflammation and cancer. In this study, we found that miR-20b was significantly increased in human non-small cell lung cancer (NSCLC) cell lines and patient tissues, suggesting that it may possess a carcinogenic role in lung cancer. This miRNA promoted the proliferation, migration and invasion of NSCLC cells by targeting and downregulating the expression of adenomatous polyposis coli (APC), which is a negative regulator of the canonical Wnt signaling pathway. Wnt signaling activation may increase transcription of miR-20b. Therefore, miR-20b and canonical Wnt signaling were coupled through a feed-forward positive feedback loop, forming a biological regulatory circuit. Finally, an in vivo investigation further demonstrated that an increase in miR-20b promoted the growth of cancer cells. Overall, our findings offer evidence that miR-20b may contribute to the development of NSCLC by inhibiting APC via the canonical Wnt signaling pathway.