title: KAI1/CD82 decreases Rac1 expression and cell proliferation through PI3K/Akt/mTOR pathway in H1299 lung carcinoma cells.
abstract: Although the KAI1/CD82 protein has been reported to inhibit cell metastasis in many studies, its mechanism of action has not yet been fully elucidated. In the present study, we investigated the possible effects of KAI1/CD82 on the metastatic phenotype in H1299 lung carcinoma cells. These studies were based on the pivotal role that the acquisition of motile phenotype plays on the initial steps of metastasis. KAI1/CD82-mediated morphological changes were observed using phase contrast microscopy. We report here, that a KAI1/CD82-induced phenotypic change was involved in the decrease of Rac1 expression and GTPase activity. However, we found that KAI1/CD82 did not regulate Rac1 mRNA levels. This suggests the existence of another regulatory mechanism of Rac1 protein maturation or activation. To identify the signaling pathway of Rac1 regulation, we investigated the PI3K/Akt/mTOR pathway, since the PI3K/Akt pathway regulates Rac1 activation and mTOR is known to play a regulatory role in protein translation. H1299/CD82-transfectants showed lower mTOR expression and cell growth than the control group. The data obtained from this study suggested that KAI1/CD82 decreased the metastatic phenotype of H1299 lung carcinoma cells by down-regulating Rac1 expression through the PI3K/Akt/mTOR pathway.
authors.affiliation: Department of General Surgery, Wonkwang University School of Medicine, Iksan-City, Jeonbuk, Republic of Korea.
authors.forename: Un-Jong
authors.initials: UJ
authors.lastname: Choi
authors.forename: Bo-Keun
authors.initials: BK
authors.lastname: Jee
authors.forename: Young
authors.initials: Y
authors.lastname: Lim
authors.forename: Kweon-Haeng
authors.initials: KH
authors.lastname: Lee
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D006801:Humans; D051861:Kangai-1 Protein / Q000235:genetics / Q000378:metabolism*; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009362:Neoplasm Metastasis; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases; D020830:rac1 GTP-Binding Protein / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D051861:Kangai-1 Protein; D019869:Phosphatidylinositol 3-Kinases; D011494:Protein Kinases; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D020830:rac1 GTP-Binding Protein; C497688:CD82 protein, human; C107953:RAC1 protein, human; C546842:MTOR protein, human