Effects of microRNA-126 on cell proliferation, apoptosis and tumor angiogenesis via the down-regulating ERK signaling pathway by targeting EGFL7 in hepatocellular carcinoma.

Cheng Gong,Guang Li,Zhi-Su Liu,Han-Han Liu,Jing Fang

doi:10.18632/oncotarget.17283

Abstract

This study intends to explore the effects of microRNA-126 (miR-126) on cell proliferation, apoptosis, and tumor angiogenesis in hepatocellular carcinoma (HCC) by regulating epidermal growth factor-like domain 7 (EGFL7) through extracellular signal-regulated kinase (ERK) signaling. HCC tissues and adjacent normal tissues were obtained from 184 HCC patients. HCC cells were separately transfected with recombinant plasmids. Western blotting and qRT-PCR were applied to detect miR-126 and EGFL7, ERK, Fas/FasL, Bcl-2, Caspase mRNA and protein levels. CCK8 and TUNEL were performed to determinate cell proliferation and apoptosis. Flow cytometry was used to analyze cell cycle distribution. Rats model of HCC was constructed, and tumor weight and the number of new blood vessels were recorded after 3 weeks of tumor transplantation. Compared with the adjacent normal tissues, HCC tissues exhibited lower miR-126 expression, and higher EGFL7, and ERK mRNA and protein levels. Overexpression of miR-126 in HCC cell lines suppressed EGFL7, ERK, Bcl-2, and P-ERK, and increased apoptotic-associated proteins Fas/FasL and Caspase-3, and it inhibited cell proliferation and induced cell apoptosis. Overexpression of miR-126 in nude mice resulted in reduced tumor weight and less new blood vessels in tumors. The inhibition of miR-126 decreased cell apoptosis, and enhanced cell proliferation and tumor angiogenesis. This study demonstrates that miR-126 might decrease cell proliferation, induce apoptosis, and inhibit tumor angiogenesis in HCC by inhibiting EGFL7 via down-regulating the ERK signaling pathway.

Highlights

Hepatocellular carcinoma (HCC) is the sixth most common cancer and the third leading cause of cancer mortality worldwide [1]
We showed that miR-126 was significantly reduced in hepatocellular carcinoma (HCC) tissues, and the elevation of miR-126 could decrease cell proliferation, induce cell apoptosis, and inhibit angiogenesis in HCC cells
Further experiments indicated that the function of miR-126 in HCC is achieved by targeting epidermal growth factor-like domain 7 (EGFL7) and subsequently regulating of the extracellular signalregulated kinase (ERK) signaling pathway

Summary

Introduction

Hepatocellular carcinoma (HCC) is the sixth most common cancer and the third leading cause of cancer mortality worldwide [1]. Modern therapeutic strategies are relatively effective, HCC patients have an unsatisfactory prognosis owing to tumor metastasis and intrahepatic recurrence [3]. MiRNAs functions in various physiological processes, including cell proliferation, differentiation, apoptosis, invasion, metastasis metabolism, and maturation. Their aberrant expression may modulate www.impactjournals.com/oncotarget these pathological processes in human cancers through altered regulation of critical oncogenes or tumor suppressors [6, 7]. The abnormal expressions of miRNAs have been presented in HCC to affect the development and progression [8,9,10]

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Results

Conclusion