miR‐451a suppresses the proliferation and migration of high‐grade serous ovarian cancer by targeting RAB5A through the Ras/Raf/MEK/ERK pathway

Background Ovarian cancer is one of the most common cancers in women. Profiles changes of microRNAs (miRNAs) are closely linked to malignant tumors. In the present study, we investigated expression of miR‐451a in high‐grade serous ovarian cancer (HGSOC). We also investigated the potential pathological roles and the likely mechanism of miR‐451a in the development of HGSOC using animal models and cell lines. Methods Using bioinformatics techniques and a real‐time PCR, we analyzed differently expressed miRNAs in HGSOC compared to normal tissue. MTT (i.e. 3‐[4, 5‐dimethyl thiazol‐2‐yl]‐2,5‐diphenyl tetrazolium bromide), EDU (i.e. 5‐ethynyl‐2′‐deoxyuridine) and transwell assays were performed to investigate the effect of miR‐451a on the proliferation and migration of HGSOC SKOV‐3 cells. A dual luciferase reporter assay was performed to verify the targeting relationship of miR‐451 and RAB5A (one of the Rab GTPase proteins that regulates endocytosis and vesicle transport). Also, we analyzed levels of the RAB5A mRNA and protein by real‐time PCR, western blotting and immunohistochemistry assays in HGSOC cells and tissues. Finally, we performed in vivo experiments using HGSOC mice. Results miR‐451a was substantially upregulated in HGSOC and associated with favorable clinical characteristics. miR‐451a knockdown significantly increased growth and metastasis of HGSOC cell line SKOV‐3 through Ras/Raf/mitogen‐activated protein kinase kinase (MEK)/extracellular signal‐regulated kinase (ERK) signaling. In addition, RAB5A, an early endosome marker, was shown to be a direct target of miR‐451a. Moreover, RAB5A is correlated with unfavorable clinical features and shows independent prognostic significance in HGSOC. Conclusions We found that the miR‐451a/RAB5A axis is associated with tumorigenesis and progression through the Ras/Raf/MEK/ERK pathway, providing prognostic indicators and therapeutic targets for patients with HGSOC. miR‐451a was substantially downregulated in HGSOC, which is associated with unfavorable clinical characteristics. RAB5A, for which upregulation increased tumor growth and metastasis considerably, is a direct target of miR‐451a. The miR‐451a/RAB5A axis is associated with tumorigenesis and progression through the Ras/Raf/mitogen‐activated protein kinase kinase (MEK)/extracellular signal‐regulated kinase (ERK) pathway.