Different Regulation Effects of Gekko Sulfated Glycopeptide in Breast and Liver Cancer Cell Lines

Background:Our previous work demonstrated that Gekko sulfated glycopeptide extracted from the Chinese gecko Shou gong(Gekko swinhonis Guenther)could inhibit tumor growth by regulating basic fibroblast growth factor.However,basic fibroblast growth factor has opposing effects on growth in breast and liver cancers.Direct effects and mechanisms of Gekko sulfated glycopeptide on tumor growth remain unclear and are ripe for further exploration.Methods:Differential regulation by Gekko sulfated glycopeptide and bFGF were studied in established human breast cancer MCF-7 cells and hepatocarcinoma HepG2 cells.Cell proliferation was evaluated with a Trypan blue exclusion assay.Cell cycle phases were measured by flow cytometry.Basic fibroblast growth factor,transforming growth factor-β1,and p21WAF1/CIP1 mRNA and protein expression levels were detected by real-time PCR(mRNA)and ELISA(protein).Changes in phosphorylated extracellular signal-regulated kinase levels were analyzed by Western blot.Results:Data indicated that Gekko sulfated glycopeptide inhibited the proliferation of HepG2 cells(P<0.001)and also blocked basic fibroblast growth factor-stimulated proliferation of these cells(P=0.001).Gekko sulfated glycopeptide was shown to increase transforming growth factor-β1 and p21WAF1/CiP1 expression(P<0.01)and partially compensate for reductions therein induced by basic fibroblast growth factor.Conversely,in MCF-7 cells,Gekko sulfated glycopeptide alone had no observable effect on transforming growth factor-β1 and p21WAF1/CiP1 expression.Gekko sulfated glycopeptide did,however,enhance basic fibroblast growth factor-induced inhibition of cell proliferation and transforming growth factor-β1 and p21WAF1/CiP1 expression in the MCF-7 cells(P=0.001,P<0.01,P<0.01,respectively).Gekko sulfated glycopeptide was shown to suppress basic fibroblast growth factor secretion in both HepG2 and MCF-7 cell lines(P<0.05 and P<0.01,respectively)and inhibited extracellular signal-regulated kinase 1/2 phosphorylation facilitated by basic fibroblast growth factor.Gekko sulfated glycopeptide alone decreased phosphorylated extracellular signal-regulated kinase in HepG2 cells but did not visibly affect phosphorylated extracellular signal-regulated kinase levels in MCF-7 cells.Conclusions:Gekko sulfated glycopeptide,a basic fibroblast growth factor inhibitor,differentially regulates growth in different cancer cell lines,and these differences may be determined by the opposing effects of basic fibroblast growth factor on transforming growth factor-β1 and p21WAF1/CiP1 levels in breast and liver cancer cells.