Angiotensin II (Ang II) has been shown to function as a key role in neovascularization of hepatocellular carcinoma (HCC), but little is known its underlying mechanisms. The aim of this study was to explore the role of Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway in Ang II-induced HCC angiogenic factors production. Herein, we found that Ang II upregulated angiogenic factors production such as vascular endothelial growth factor (VEGF), angiopoietin-2 (Ang-2) and Tie-2 in MHCC97H cells in a time- and concentration-dependent manner. And VEGF and Ang-2 caused a significant increase in angiogenic tube formation. Especially, Ang II-induced angiogenic tube formation was blunted by VEGF small interfering RNA (siRNA) and Ang-2 siRNA, respectively. The JAK2 inhibitor AG490 partly attenuated the effects of Ang II. Moreover, Ang II- induced JAK2 and STAT3 phosphorylation was significantly suppressed by losartan but not PD123319. Meanwhile, STAT3 phosphorylation and suppressor of cytokine signaling 3 (SOCS3) expression induced by Ang II were evidently impaired by AG490. More importantly, SOCS3 siRNA remarkably reinforced Ang II-induced VEGF, Ang-2 and Tie-2 generation in MHCC97H cells. Taken together, the present study demonstrates that Ang II induces angiogenic factors production partly via AT1/ JAK2/STAT3/SOCS3 signaling pathway in MHCC97H cells. These findings may provide important insights into the potential mechanism with respect to the AT1/ JAK2/ STAT3/SOCS3 signaling pathway associated with Ang II-induced angiogenesis in the pathogenesis of HCC.
Copyright © 2012 S. Karger AG, Basel.