泛素-蛋白酶体途径降解胰腺癌细胞系中凝溶胶蛋白

Degradation of gelsolin in pancreatic cancer cell lines by ubiquitin-proteasome pathway

目的探讨胰腺癌中泛素-蛋白酶体途径对凝溶胶蛋白(gelsolin)的降解作用。方法用特异性蛋白酶体抑制剂lactacystin处理胰腺癌细胞系BxPC-3和PANC-1,经Western blot检测凝溶胶蛋白的表达,免疫沉淀细胞内凝溶胶蛋白,分析沉淀蛋白的泛素化。结果BxPC-3细胞系经lactacystin作用12h后,细胞内凝溶胶蛋白含量较对照组和处理前明显升高(P<0.05),而且细胞内的凝溶胶蛋白表现出与泛素分子的相互作用。结论泛素-蛋白酶体途径对凝溶胶蛋白的降解作用,可能是胰腺癌中凝溶胶蛋白表达降低的原因之一。

Objective To explore the role of ubiquitin-proteasome pathway for the gelsolin protein degradation in pancreatic cancer. Methods Pancreatic cancer cell lines BxPC-3 and PANC-1 were first treated with specific 26s proteasome inhibitor lactacystin. Immunoblots of cell lysates were probed for gelsolin expression. To determine whether gelsolin was conjugated to ubiquitin, proteins extracted from the ceils with or without lactacystin were immunoprecipitated with anti-gelsolin antibody, followed by Western blot analysis. Results The expression of gelsolin protein increased obviously after treatment with lactacystin in BxPC-3 ceils for 12 h. Using anti-gelsolin antibody to immunoprecipitate gelsolin protein and followed by Western blot using anti-ubiquitin monoclonal antibody, it was found that inhibition of proteasome pathway by lactacystin resulted in accumulation of ubiquitylated forms of gelsolin protein. In PANC-1 cell line, there was no significant changes of gelsolin after treatment with lactacystin. Conclusion Ubiquitin-proteasome dependent degradation may be an important regulatory mechanism for gelsolin downregulation in pancreatic cancer ceils.