miR-320a in serum exosomes promotes myocardial fibroblast proliferation via regulating the PIK3CA/Akt/mTOR signaling pathway in HEH2 cells

Qing-Gao Wang; Brian Chi-Yan Cheng; Ya-Zhou He; Li-Juan Li; Yun Ling; Gan Luo; Li Wang; Shan Liang; Yi Zhang

doi:10.3892/etm.2021.10305

miR-320a in serum exosomes promotes myocardial fibroblast proliferation via regulating the PIK3CA/Akt/mTOR signaling pathway in HEH2 cells

Exp Ther Med. 2021 Aug;22(2):873. doi: 10.3892/etm.2021.10305. Epub 2021 Jun 14.

Authors

Qing-Gao Wang¹, Brian Chi-Yan Cheng², Ya-Zhou He¹, Li-Juan Li¹, Yun Ling³, Gan Luo⁴, Li Wang⁴, Shan Liang¹, Yi Zhang⁴

Affiliations

¹ Department of Cardiology, First Affiliated Hospital, Guangxi University of Chinese Medicine, Nanning, Guangxi Zhuang Autonomous Region 530023, P.R. China.
² College of Professional and Continuing Education, The Hong Kong Polytechnic University, Hong Kong 999077, SAR, P.R. China.
³ School of Nursing, Guangxi University of Chinese Medicine, Nanning, Guangxi Zhuang Autonomous Region 530200, P.R. China.
⁴ Department of Pharmacology, School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 102488, P.R. China.

Abstract

MicroRNAs (miRNAs/miRs) serve an important role in the pathogenesis of chronic heart failure (CHF). A number of reports have illustrated the regulatory effect of serum exosomal miRNA on myocardial fibrosis. The present study aimed to investigate the expression of miR-320a in serum exosomes, as well as the effect of miR-320a on myocardial fibroblast proliferation. Serum exosome samples from 10 patients with CHF and 5 healthy volunteers were obtained and characterized. mRNA and protein expression levels were measured via reverse transcription-quantitative PCR and western blotting, respectively. The content of soluble growth stimulation expressed gene 2 (sST2) was determined via ELISA. HEH2 cell viability and apoptosis were detected by performing MTT assays and flow cytometry, respectively. The results demonstrated that serum miR-320a expression levels and sST2 content were significantly increased in patients with CHF compared with healthy controls, and the expression of serum miR-320a was significantly correlated with clinical CHF indexes. miR-320a expression levels were significantly increased in exosomes isolated from patients with CHF compared with those isolated from healthy controls. Phosphoinositide-3-kinase catalytic α polypeptide gene (PIK3CA) expression levels and sST2 content were increased in HEH2 cells following transfection with miR-320a mimics compared with NC-mimic, whereas miR-320a inhibitor displayed contrasting effects by reduced the cell viability and apoptosis in myocardial fibroblasts compared with the NC-inhibitor group. The protein expression levels of collagen I, collagen III, α-smooth muscle actin, phosphorylated (p)-mTOR (ser 2448)/mTOR, p-Akt (ser 473)/Akt, p-Akt (thr 308)/Akt and PIK3CA were significantly increased in miR-320a mimic-transfected HEH2 cells compared with the NC-mimics groups. By contrast, miR-320a inhibitor notably downregulated the expression levels of these proteins compared with the NC-inhibitor group. Collectively, the results of the present study demonstrated that miR-320a promoted myocardial fibroblast proliferation via regulating the PIK3CA/Akt/mTOR signaling pathway in HEH2 cells, suggesting that serum exosomal miR-320a may serve as a potential biomarker for the diagnosis of CHF.

Keywords: CHF; HEH2 cells; PIK3CA/Akt/mTOR signaling pathway; exosome; myocardial fibrosis.

Grants and funding

Funding: The present study was supported by the Construction Project of First-class Disciplines of Guang Xi (grant no. 2018XK070), the Fund of Key Subjects of Guang Xi Universities (grant no. 2017XK03) and Young Scientist Program of Beijing University of Chinese Medicine.