MicroRNA-324-5p–CUEDC2 Axis Mediates Gain-of-Function Mutant p53-Driven Cancer Stemness

Abstract

Regulation of cancer stemness has recently emerged as a new gain-of-function (GOF) property of mutant p53. In this study, we identify miR-324-5p as a critical epigenetic regulator of cancer stemness and demonstrate its role in mediating GOF-mutant p53-driven stemness phenotypes. We report that miR-324–5p is upregulated in human cancer cell lines and non–small cell lung carcinoma (NSCLC) tumors carrying TP53 GOF mutations. Mechanistically, we show that GOF mutant p53 upregulates miR-324–5p expression via c-Myc, an oncogenic transcription factor in cancer cells. Our experimental results suggest that miR-324–5p–induced CSC phenotypes stem from the downregulation of CUEDC2, a downstream target gene of miR-324–5p. Accordingly, CUEDC2 complementation diminishes elevated CSC marker expression in miR-324–5p–overexpressing cancer cells. We further demonstrate that mutant p53 cancer cells maintain a low level of CUEDC2 that is rescued upon miR-324–5p inhibition. Importantly, we identify CUEDC2 downregulation as a novel characteristic feature of TP53-mutated human cancers. We show that activation of NF-κB due to downregulation of CUEDC2 by miR-324–5p imparts stemness in GOF mutant p53 cancer cells. Finally, we provide evidence that TP53 mutations coupled with high miR-324–5p expression predict poor prognosis in patients with lung adenocarcinoma. Thus, our study delineates an altered miR-324–5p-CUEDC2-NF-κB pathway as a novel regulator of GOF mutant p53-driven cancer stemness.