title: Fibronectin protects prostate cancer cells from tumor necrosis factor-alpha-induced apoptosis via the AKT/survivin pathway.
abstract: Integrins are cell surface heterodimeric transmembrane receptors that, in addition to mediating cell adhesion to extracellular matrix proteins modulate cell survival. This mechanism may be exploited in cancer where evasion from apoptosis invariably contributes to cellular transformation. The molecular mechanisms responsible for matrix-induced survival signals begin to be elucidated. Here we report that the inhibitor of apoptosis survivin is expressed in vitro in human prostate cell lines with the highest levels present in aggressive prostate cancer cells such as PC3 and LNCaP-LN3 as well as in vivo in prostatic adenocarcinoma. We also show that interference with survivin in PC3 prostate cancer cells using a Cys84--> Ala dominant negative mutant or survivin antisense cDNA causes nuclear fragmentation, hypodiploidy, cleavage of a 32-kDa proform caspase-3 to active caspase-3, and proteolysis of the caspase substrate poly(ADP-ribose) polymerase. We demonstrate that in the aggressive PC3 cell line, adhesion to fibronectin via beta1 integrins results in up-regulation of survivin and protection from apoptosis induced by tumor necrosis factor-alpha (TNF-alpha). In contrast, survivin is not up-regulated by cell adhesion in the non-tumorigenic LNCaP cell line. Dominant negative survivin counteracts the ability of fibronectin to protect cells from undergoing apoptosis, whereas wild-type survivin protects non-adherent cells from TNF-alpha-induced apoptosis. Evidence is provided that expression of beta1A integrin is necessary to protect non-adherent cells transduced with survivin from TNF-alpha-induced apoptosis. In contrast, the beta1C integrin, which contains a variant cytoplasmic domain, is not able to prevent apoptosis induced by TNF-alpha in non-adherent cells transduced with survivin. Finally, we show that regulation of survivin levels by integrins are mediated by protein kinase B/AKT. These findings indicate that survivin is required to maintain a critical anti-apoptotic threshold in prostate cancer cells and identify integrin signaling as a crucial survival pathway against death receptor-mediated apoptosis.
authors.affiliation: Department of Cancer Biology and the Cancer Center, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA.
authors.forename: Mara
authors.initials: M
authors.lastname: Fornaro
authors.forename: Janet
authors.initials: J
authors.lastname: Plescia
authors.forename: Sophie
authors.initials: S
authors.lastname: Chheang
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tallini
authors.forename: Yong-M
authors.initials: YM
authors.lastname: Zhu
authors.forename: Michael
authors.initials: M
authors.lastname: King
authors.forename: Dario C
authors.initials: DC
authors.lastname: Altieri
authors.forename: Lucia R
authors.initials: LR
authors.lastname: Languino
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism; D000256:Adenoviridae / Q000235:genetics; D000409:Alanine / Q000737:chemistry; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D002448:Cell Adhesion; D016923:Cell Death; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival; D003545:Cysteine / Q000737:chemistry; D053938:DNA Fragmentation; D018076:DNA, Complementary / Q000378:metabolism; D004789:Enzyme Activation; D005353:Fibronectins / Q000378:metabolism*; D005799:Genes, Dominant; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D051034:Inhibitor of Apoptosis Proteins; D019012:Integrin beta1 / Q000378:metabolism; D008297:Male; D008856:Microscopy, Fluorescence; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D009363:Neoplasm Proteins; D016376:Oligonucleotides, Antisense / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D000077022:Survivin; D013997:Time Factors; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: C107489:BIRC5 protein, human; D018076:DNA, Complementary; D005353:Fibronectins; D051034:Inhibitor of Apoptosis Proteins; D019012:Integrin beta1; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D016376:Oligonucleotides, Antisense; D011518:Proto-Oncogene Proteins; D000077022:Survivin; D014409:Tumor Necrosis Factor-alpha; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020169:Caspases; D003545:Cysteine; D000409:Alanine