Dual Suppressive Effect of miR-34a on the FOXM1/eEF2-Kinase Axis Regulates Triple-Negative Breast Cancer Growth and Invasion

Recent studies indicated that dysregulation of noncoding RNAs (ncRNA) such as miRNAs is involved in pathogenesis of various human cancers. However, the molecular mechanisms underlying miR-34a are not fully understood in triple-negative breast cancer (TNBC). We performed functional assays on TNBC cell lines to investigate the role of miR-34a in FOXM1/eEF2K signaling axis. TNBC tumor xenograft models were used for therapeutic delivery of miR-34a. In this study, we investigated the role of p53-driven ncRNA miR-34a and found that miR-34a is associated with significantly longer patient survival in TNBC and inversely correlated with levels of proto-oncogenic , which was associated with significantly shorter overall patient survival. We showed that miR-34a directly binds to the 3'-untranslated region of and mRNAs and suppresses their expression, leading to inhibition of TNBC cell proliferation, motility, and invasion. Notably, restoring miR-34a expression recapitulated the effects of inhibition of and , the transcription factor for and the direct target of p53, in TNBC cell lines, whereas overexpression of and rescued the effects and signaling pathways mediated by miR-34a. Moreover, therapeutic delivery of miR-34a nanoparticles by systemic intravenous administration delayed tumor growth of two different orthotopic TNBC tumor xenograft models by inhibiting eEF2K and FOXM1, intratumoral proliferation and angiogenesis, and inducing apoptosis. Overall, our findings provide new insights into the tumor suppressor role of miR-34a by dual-targeting of FOXM1/eEF2K signaling axis and suggest that miR-34a-based gene therapy may be a potential therapeutic strategy in TNBC. .