Overexpression of Mitochondria Mediator Gene TRIAP1 by miR-320b Loss Is Associated with Progression in Nasopharyngeal Carcinoma

The therapeutic strategy for advanced nasopharyngeal carcinoma (NPC) is still challenging. It is an urgent need to uncover novel treatment targets for NPC. Therefore, understanding the mechanisms underlying NPC tumorigenesis and progression is essential for the development of new therapeutic strategies. Here, we showed that TP53-regulated inhibitor of apoptosis (TRIAP1) was aberrantly overexpressed and associated with poor survival in NPC patients. TRIAP1 overexpression promoted NPC cell proliferation and suppressed cell death in vitro and in vivo, whereas TRIAP1 knockdown inhibited cell tumorigenesis and enhanced apoptosis through the induction of mitochondrial fragmentation, membrane potential alteration and release of cytochrome c from mitochondria into the cytosol. Intersecting with our previous miRNA data and available bioinformatic algorithms, miR-320b was identified and validated as a negative regulator of TRIAP1. Further studies showed that overexpression of miR-320b suppressed NPC cell proliferation and enhanced mitochondrial fragmentation and apoptosis both in vitro and in vivo, while silencing of miR-320b promoted tumor growth and suppressed apoptosis. Additionally, TRIAP1 restoration abrogated the proliferation inhibition and apoptosis induced by miR-320b. Moreover, the loss of miR-320b expression was inversely correlated with TRIAP1 overexpression in NPC patients. This newly identified miR-320b/TRIAP1 pathway provides insights into the mechanisms leading to NPC tumorigenesis and unfavorable clinical outcomes, which may represent prognostic markers and potential therapeutic targets for NPC treatment.
Author Summary The therapeutic strategy for advanced nasopharyngeal carcinoma (NPC) is still challenging. The most urgent need for NPC is novel treatment targets. Therefore, understanding the mechanisms underlying NPC tumorigenesis and progression is essential for the development of new therapeutic strategies. Here, we identified TRIAP1 could serve as a prognostic biomarker in NPC, and function as an oncogene in NPC tumorigenesis and mitochondrial apoptosis through inhibiting the release of cytochrome c. Moreover, miR-320b post-transcriptionally regulated TRIAP1 expression, and exhibited inhibitory effects on proliferation and promoted apoptosis through targeting TRIAP1. Thus, our study provides new insights into the mechanisms of NPC tumorigenesis and progression and identifies novel therapeutic targets for NPC treatment.