Morphine promotes angiogenesis by activating PI3K/Akt/HIF-1α pathway and upregulating VEGF in hepatocellular carcinoma

Abstract

Background: Hepatocellular carcinoma (HCC) is characterized by the neo-angiogenesis induced by tumor and adjacent cells. It is a leading cancer-related cause of death. Morphine has effects on angiogenesis with pro-angiogenic or anti-angiogenic phonotypes. This study explores the function of morphine on cancer cell growth, angiogenesis and the underlying mechanism in HCC. Methods: Morphine was used to treat BEL-7402 or HCC-LM3 cells and human umbilical vein endothelial cells (HUVECs) were subsequently incubated in the conditioned media (CM) of HCC cells. The potential effects of cell proliferation, migration and tube formation of CM-treated HUVECs were investigated. Furthermore, the angiogenesis regulated factors of VEGFA, PIGF, ANG-1, ANG-2, FGF-1 and FGF-2 were assessed. siRNA and LY294002 were further used to explore the mechanism mediating the effects of morphine on the angiogenesis pathway. The neovascularization effect by morphine was confirmed through the use of human HCC cancer heterotopic mouse model in vivo. Results: A significantly increased cell proliferation, migration, and tube formation effect of HUVECs induced by the CM from HCC cell lines treated with morphine was observed. More VEGFA secretion in CM from LM3 or BEL-7402 cell lines was found than the controls (P=0.03 and P=0.027, respectively). VEGFA knock-down could significantly reverse cell proliferation, migration and tube formation induced by the CM from HCC cell lines with morphine treatment. Further molecular experiments indicated that VEGFA secretion was activated by morphine potentially through the PI3K/Akt/HIF-1α pathway. Morphine-induced neovascularization was also observed by the IHC of CD31 and VEGFA. Conclusions: Morphine promotes angiogenesis in hepatocellular carcinoma possibly through the activation of the PI3K/Akt/HIF-1α pathway and VEGFA stimulation.