ABC | Volume 111, Nº2, August 2018

Original Article Pioglitazone Induces Cardiomyocyte Apoptosis and Inhibits Cardiomyocyte Hypertrophy Via VEGFR-2 Signaling Pathway Wenliang Zhong, 1,2 Wen Jin, 3 Shanghua Xu, 1 Yanqing Wu, 1 Shunxiang Luo, 1 Minlie Liang, 1 Lianglong Chen 2 Department of Cardiology, The First Hospital of Nanping City, affiliated to Fujian Medical University, 1 Nanping, Fujian - China Department of Cardiology, Union Hospital, Fujian Medical University, 2 Fuzhou, Fujian – China Cardiovascular Department, Guangdong N°.2 Provincial People’s Hospital, 3 Guangzhou, Guangdong – China Mailing Address: Wenliang Zhong • Department of Cardiology, The First Hospital of Nanping City, N°. 317 Zhongshan Road, Nanping, Fujian - China E-mai: WL.Zhong@tom.com Manuscript received October 20, 2017, revised manuscript January 23, 2018, accepted March 14, 2018 DOI: 10.5935/abc.20180108 Abstract Background: Pioglitazone has been widely used as an insulin-sensitizing agent for improving glycemic control in patients with type 2 diabetes mellitus. However, cardiovascular risk and protective effects of pioglitazone remain controversial. Objectives: In this study, we investigated whether pioglitazone affects cardiomyocyte apoptosis and hypertrophy by regulating the VEGFR-2 signaling pathway. Methods: Cardiomyocytes were enzymatically isolated from 1- to 3-day-old Sprague-Dawley rat ventricles. Effects of pioglitazone and the VEGFR-2-selective inhibitor apatinib on cardiomyocyte apoptotic rate was determined using flow cytometry, and hypertrophy was evaluated using [ 3 H]-leucine incorporation. The protein expressions of unphosphorylated and phosphorylated VEGFR-2, Akt, P53, and mTOR were determined by Western-Blotting. Analysis of variance (ANOVA) was used to assess the differences between groups. Results: Pioglitazone and VEGFR-2-selective inhibitor apatinib reduced rat cardiomyocyte viability and cardiomyocyte hypertrophy induced by angiotensin II in vitro. Furthermore, in the same in vitro model, pioglitazone and apatinib significantly increased the expression of Bax and phosphorylated P53 and decreased the expression of phosphorylated VEGFR-2, Akt, and mTOR, which promote cardiomyocyte hypertrophy. Conclusions: These findings indicate that pioglitazone induces cardiomyocyte apoptosis and inhibits cardiomyocyte hypertrophy by modulating the VEGFR-2 signaling pathway. (Arq Bras Cardiol. 2018; 111(2):162-169) Keywords: Apoptosis; Myocytes, Cardiac; Cardiomegaly; Heart Failure/physiopathology; Antihypertensive Agents; Thiazolidinediones; Insulin Resistance Introduction Heart failure (HF) is the most common consequence of cardiovascular diseases and the leading cause of cardiovascular mortality worldwide. 1 Basic pathophysiology of HF is cardiac remodeling, which involves a number of cellular changes including cardiomyocyte hypertrophy, loss of cardiomyocytes due to apoptosis, necrosis, fibroblast proliferation and fibrosis. 2 Recent fundamental and clinical studies have demonstrated that diabetes mellitus (DM) drives cardiac remodeling, including myocardial hypertrophy and cardiomyocytes loss, via glucotoxicity and lipotoxicity, eventually resulting in HF. 3 Intensive glucose control was shown to reduce the occurrence of major cardiovascular events including HF, but did not improve the overall survival rate in patients with type 2 DM, compared to patients receiving standard therapy. 3 Thiazolidinediones, including pioglitazone, have been widely used as peroxisome proliferator-activated receptor (PPAR)- γ agonists and insulin-sensitizing agents for improving glycemic control in patients with type 2 DM. However, cardiovascular risks of pioglitazone remain controversial. One view is that intensive glycemic control with pioglitazone or rosiglitazone increases the risk of HF (OR ≤ 2.1; 95% CI 1.08–4.08) based on meta-analyses of randomized clinical trials. 4-6 Rosiglitazone was more likely to induce HF than pioglitazone. 7 Additionally, animal experiments confirmed the increased risk of HF with pioglitazone treatment, as pioglitazone augmented cardiac damage in isoproterenol- induced HF rat model and induced rat ventricular hypertrophy in acute toxicity experiments. 8,9 However, another point of view is that pioglitazone use does not significantly increase the risk of myocardial infarction or cardiac death, based on the PROspective pioglitAzone Clinical Trial In macroVascular Events (PROactive) data, 10 and that pioglitazone can suppress overload-induced cardiac hypertrophy by inhibiting AKT/GSK3 β and MAPK signaling pathways. 11 Vascular endothelial growth factor receptors (VEGFR) are considered critical factors for cardiac hypertrophy and HF. 162