人肝癌相关新基因编码产物LAPTM4B的鉴定及其生物学特性

Identification and characterization of LAPTM4B encoded by a human hepatocellular carcinoma-associated novel gene

目的 :鉴定由肝细胞癌 (HCC)相关新基因LAPTM 4B编码的蛋白质并研究其生物学特性。方法 :以Westernblot、免疫组化及双向电泳鉴定新基因的表达产物 ;以免疫共沉淀等方法研究分子间的相互作用。结果 :LAPTM4B基因编码相对分子质量分别为 35× 10 3 和 2 4× 10 3 、等电点分别为 9.0 7和 4 .6 5的两种异型分子。它们在肝癌组织及肝癌细胞系的表达显著上调 ,而相对分子质量为 35× 10 3 者尤为明显 ,并与细胞分化程度相关。LAPTM4B蛋白可与整合素α 6亚单位及表皮生长因子 (EGF)受体形成信号复合物。结论 :LAPTM4B 35蛋白在人肝癌组织及细胞系过表达 ,并可能通过与细胞表面的整合素受体及EGF受体形成复合物而参与细胞外基质成分所启动的信号转导。

Objective: To identify and characterize the novel proteins encoded by a HCC associated novel gene, LAPTM4B (lysosomeassociated protein transmembrane 4 beta). Methods: The novel proteins was identified by Western blot,immunohistochemistry and 2D electrophoresis; the molecular interactions were studied by co immunoprecipitation. Results: LAPTM4B encoded two isoforms of proteins with molecular weight 35×10 3 and 24×10 3 and pI 9.07 and 4.65, respectively. The expression levels of LAPTM4B proteins in HCC tissues and cell lines were upregulated and related to differentiation, and most dramatically raised for 35×10 3 one. It was demonstrated that LAPTM4B-integrin α6 and LAPTM4B-EGFR signaling complexes were formed when BEL 7402 cells were seeded on laminin substrate. Conclusion: The LAPTM4B 35 protein is overexpressed in human HCC tissues and cell lines and may involve in signal transduction triggered by extracellular matrix via interaction with integrin α6 and EGFR on cell surface.