Bone morphogenetic protein 7 reverses epithelial-mesenchymal transition induced by hypoxia in hepatocellular carcinoma cells

Abstract

Objective To investigate the impact of bone morphogenetic protein 7 (BMP-7) on epitheIial-mesenchymal transition (EMT) and promoted invasiveness induced by hypoxia in hepatocellular carcinoma cells (HCCs),and to explore a potential intervention for HCC metastasis by EMT reversion.Methods mRNA and protein expression levels of three epithelial or mesenchymal marker genes E-cadherin,Snail and Vimentin in SMMC-7721 cells were detected by using reverse transcription-polymerase chain reaction (RT-PCR) or Western blotting under normoxic and anaerobic (1％) culture.E-cadherin,Snail and Vimentin expression levels were semi-quantitatively determined by using MUVB-20 system,and invasion of cells through Matrigel was assayed by using a Transwell system.Meanwhile,the impact of BMP-7 (50 μg/L) on the expression of epithelial or mesenchymal marker genes and the cell invasion was investigated as well using the methods mentioned above.Results mRNA expression of E-cadherin was reduced,and that of Snail and Vimentin increased in a time-dependent manner after hypoxia in HCC cells.The relative quantity of E-cadherin mRNA was decreased from 1.299 ± 0.095 to 0.542 ± 0.092,and that of Snail and Vimentin increased from 0.189 ±0.021 to 715 ±0.053 and from 0.182 ±0.046 to 0.773 ±0.064,respectively (P ＜ 0.05).Accordingly,protein expression of E-cadherin was reduced from 0.806 ± 0.093 to 0.456 ± 0.074,and that of Vimentin increased from 0.471 ± 0.091 to 0.831 ± 0.057 (P ＜ 0.05).Cell invasive capacity was remarkably enhanced under hypoxic stress in a time-dependent fashion (P ＜ 0.05),and cell number through Transwell chamber was increased from 32.33 ± 3.22 to 76.67 ± 7.09 after 24-h treatment of hypoxia.Administration of BMP-7 up-regulated the expression of E-cadherin mRNA and downregulated the expression of Snail and Vimentin as compared to control,and the differences between the groups were of statistical significance (P<0.05).Consequently,BMP-7 notably reduced the elevated invasive capacity induced by hypoxic stress,and cell number through Matrigel was decreased from 75.43±7.76 to 33.34±5.86(P<0.05).Conclusion BMP-7reverses EMT mediated by hypoxia and in turn diminishes invasion in HCC cells,and it can serve as a potential novel therapeutic agent for HCC metastasis. Key words: Carcinoma,hepatocellular; Bone morphogenetic protein 7; Hypoxia