miR-374a-CCND 1-pPI3KJAKT-c-JUN feedback loop modulated by PDCD4 suppresses cell growth, metastasis, and sensitizes nasopharyngeal carcinoma to cisplatin

miR-374a has been reported to function as an oncogene during tumor pathogenesis. In this study, miR-374a is observed to reduce nasopharyngeal carcinoma (NPC) cell proliferation, migration, invasion, metastasis and cisplatin (DDP) resistance in vitro and in vivo. Mechanistic analyses indicate that miR-374a directly targets CCND1 to inactivate pPI3K/pAKT/c-JUN forming a negative feedback loop, as well as suppressing downstream signals related to cell cycle progression and epithelial mesenchymal transition (EMT). Interestingly, we also observed that miR-374a direct targeting of CCND1 is modulated by tumor suppressor PDCD4 via suppressing pPl3K/pAICT/c-JUN signaling. In clinical specimens, miR-374a was positively and negatively correlated with expression of PDCD4 and CCND1, respectively. Our studies are the first to demonstrate that the miR-374a-CCND1-pPl3K/AKT-c-JUN feedback loop induced by PDCD4 supresses NPC cell growth, metastasis and chemotherapy resistance.