肝刺激物促肝细胞增殖信号转导途径的初步研究

目的：探讨新生牛肝肝刺激物(hepatic stimulator substance，HSS)促进SMMC7721肝癌细胞增殖的信号转导途径。方法：对新生牛肝进行多步分离，采用^3H-Td RDNA掺入法检测分离物的促增殖活性，从而获得具增殖刺激活性的HSS；Western印迹方法检测其对肝癌细胞MAPK Thr202／Tyr204的磷酸化作用并检测其对SPK的激活作用。结果：经多步分离纯化，获得了活性较高的HSS粗提物，Western印迹法结果显示HSS粗提物能明显提高MAPK的磷酸化水平，并能激活细胞内的SPK活性。结论：HSS对细胞的增殖刺激可能是通过SPK和MAPK途径发挥作用。

Preliminary studies of hepatic stimulator substance signaling on inducing proliferation of human hepatoma cells

Objective:To get sight into the signaling pathway of induction of proliferation of hepatocyte by hepatic stimulator substance(HSS). Methods: The HSS extracted from weanling cattle liver was isolated and purified using multiple chromatographic techniques. Bioactivity of HSS was confirmed with its ability to proliferate hepatoma cells in vitro. MAPK activation marked by phosphorylation at Thr202/Tyr204 was determined by Western blot, and sphingosine kinase(SPK) activity and sphingosine 1-phosphate(S1P) formation was measured as described. Results: HSS from weanling liver increased DNA synthesis by 3.5 fold over the negative control. HSS could activate SPK, increase intracellular S1P level and phosphorylation of MAPK. Conclusion: HSS stimulates proliferation of hepatoma cells through the activation of SPK and the phosphorylation of MAPK.