人肝癌相关新基因编码产物LAPTM4B的鉴定及其生物学特性

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。

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

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 x 10(3) and 24 x 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 x 10(3) one. It was demonstrated that LAPTM4B--integrin alpha 6 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 alpha 6 and EGFR on cell surface.