Curcumin Inhibit VEGF Expression Via IGF-1Pathway In Hypoxia-induced HepG2Human Hepatocellular Carcinoma Cells

Curcumin (diferuloylmethane), isolated from the rhizome of the plant perennial herb Curcuma longa, is a yellow colored polyphenol. The curcumin has been shown to inhibit tumour cells proliferation, apotosis, invasion, metastasis, angiogenesis and suppress multiple signaling pathways, which linked with inflammatory cytokines and enzymes, transcription factors, and gene products. It is the third generation of cancer chemopreventive drug. However, the mechanism of the anti-angiogenesis for curcumin are not well understand.The cell signal transductton system has been implicated to play a key role in tumorigenesis and development of cancer. It is well known that hepatocellular carcinoma (HCC) is the fifth largest cause of cancer. The most important characteristic of HCC is the uncontrollable cells proliferation as a solid tumor with plentiful blood vessels, which lead to a new hypoxia microenvironment. The research have shown that the IGF-1pathway is closely associated with tumor angiogenesis in hypoxia microenvironment. The aims of the present study are to investigated whether the curcumin mediated VEGF expression via IGF-1pathway in hypoxia-induced HepG2cells and to elucidated the cellular and molecular mechanism.To observe the effect of HepG2cell vitality and HIF-la, IGF-1R, VEGF expressions by hypoxia induced. We set up the hypoxia model by the cobalt chloride (CoC12) and MTT assay was used to observe the influence of hypoxia on HepG2cells vitality. RT-PCR, Western-blotting and Confocal immunofluorescence microscopy assay were used to detect the HIF-la, IGF-1R, VEGF expressions. To study secreting of VEGF in hypoxia induced HepG2by ELASA. The result indicated that CoC12induced HepG2cells anoxic in time-does dependent, the cytotoxicity incressed with the higher concentration and more time of incubation. Immunofluorescence observed that the expression IGF-1R on the hypoxia induced HepG2cells. The HIF-la mRNA and protein had significant positive correlations with the VEGF mRNA and protein expressions in the dose-dependent and time-dependent.To observe whether curcumin mediated the inhibition of VEGF expression via IGF-1pathway in hypoxia-induced HepG2cells. The effect of curcumin on cell survival in hypoxia induced HepG2cells was conducted by MTT assay. RT-PCR, Western-blotting and ELASA were used to detect the HIF-la,1GF-1R,VEGF, P-Akt and P-Erkl/2expressions. The result showed that curcumin inhibited hypoxia-induced HepG2cells vitality in time-does dependent. Curcumin suppressed VEGF and1GF-1R expression at both protein and mRNA levels, Curcumin inhibit hypoxia-inducible factor-1(HIF-1α)protein accumulation without altering HIF-la mRNA levels.In summary, the expression of VEGF mRNA and protein may be regulated by the accumulation of IGF-1R and HIF-la in hypoxia induced HepG2cells. Morever, Curcumin suppressed VEGF expression mainly by blocking the activation of IGF/PI3K signaling pathway in hypoxia induced HepG2cells, which may provide a novel potential mechanism for the anticancer activities of curcumin in human hepatocellular carcinoma.