title: Signal transduction from N-cadherin increases Bcl-2. Regulation of the phosphatidylinositol 3-kinase/Akt pathway by homophilic adhesion and actin cytoskeletal organization.
abstract: Associated with the metastatic progression of epithelial tumors is the dynamic regulation of cadherins. Whereas E-cadherin is expressed in most epithelium and carcinomas, recent studies suggest that the up-regulation of other cadherin subtypes in carcinomas, such as N-cadherin, may function in cancer progression. We demonstrate that a signal transduction cascade links the N-cadherin.catenin adhesion complex to up-regulation of the anti-apoptotic protein Bcl-2. In suspension, aggregates of DU-145 cells, an E-cadherin expressing human prostate carcinoma line, survive loss of integrin-dependent adhesion by a different anti-apoptotic signaling pathway than the N-cadherin expressing lines PC3 and PC3N. N-cadherin intercellular adhesion mediates a 3.5-fold increase in Bcl-2 protein expression, whereas the level of the proapoptotic protein Bax remains constant. Only N-cadherin ligation in PC3 cells, which express both N-cadherin and E-cadherin, is sufficient to induce activation of Akt/protein kinase B. N-cadherin homophilic ligation initiates phosphatidylinositol 3-kinase-dependent activation of Akt resulting in Akt phosphorylation of Bad on serine 136. Following N-cadherin homophilic adhesion phosphatidylinositol 3-kinase was identified in immunoprecipitates of the N-cadherin.catenin complex. The recruitment of phosphatidylinositol 3-kinase to the adhesion complex is dependent on ligation of N-cadherin and an organized actin cytoskeleton because cytochalasin D blocks the recruitment. We propose that N-cadherin homophilic adhesion can initiate anti-apoptotic signaling, which enhances the Akt cell survival pathway in metastatic cancer.
authors.affiliation: Cancer Biology Graduate Program, University of Arizona Health Sciences Center, Tucson, Arizona 85724, USA.
authors.forename: Nhan L
authors.initials: NL
authors.lastname: Tran
authors.forename: Deanna G
authors.initials: DG
authors.lastname: Adams
authors.forename: Richard R
authors.initials: RR
authors.lastname: Vaillancourt
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Heimark
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D017209:Apoptosis; D015820:Cadherins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion; D002470:Cell Survival; D018076:DNA, Complementary / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008856:Microscopy, Fluorescence; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis*; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D014407:Tumor Cells, Cultured; D016596:Vinculin / Q000378:metabolism; D051028:bcl-2-Associated X Protein
chemical_list: D000199:Actins; D015820:Cadherins; D002118:Calcium; D018076:DNA, Complementary; D005982:Glutathione Transferase; D019869:Phosphatidylinositol 3-Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2; D016596:Vinculin; D051028:bcl-2-Associated X Protein; C494826:BAX protein, human; C494918:AKT1 protein, human