Differential effects of phosphatidylinositol-3/Akt-kinase inhibition on apoptotic sensitization to cytokines in LNCaP and PCc-3 prostate cancer cells.
Alterations in phosphatidylinositol 3'-kinase (PI3'-kinase) and Akt activation frequently occur in prostate cancer and may disrupt apoptotic induction by such cytokines as tumor necrosis factor (TNF) and TNF-related apoptosis-inducing ligand (TRAIL). To examine the role of PI3' phosphorylation in the cellular response to cytokines, two prostate cancer cell lines with constitutively activated PI3'-kinase cascades (LNCaP and PC-3) were examined for direct sensitivity to cytokines. TNF or TRAIL alone failed to activate apoptosis in either LNCaP or PC-3 cells, and drug-mediated inhibition of the PI3k/Akt cascade caused only minimal activation of apoptosis in either cell line. Suppression of PI3'-kinase/Akt signaling markedly enhanced the apoptotic activity of both TNF and TRAIL in LNCaP cells but not in PC-3 cells. Adenovirus-mediated PTEN/MMAC1 expression in LNCaP cells reduced Akt activation, activated apoptosis, and sensitized cells to TNF but not to TRAIL. Together, these results suggest that PI3'-kinase signaling inhibits both TNF-mediated and TRAIL-mediated apoptosis but may represent one of several apoptotic resistance mechanisms that inhibit cytokine-mediated killing of prostate cancer cells.
Beresford
S A
SA
Department of Bioimmunotherapy, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA.
Davies
M A
MA
Gallick
G E
GE
Donato
N J
NJ
D000730:Androstadienes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000276:immunology*; D016207:Cytokines / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D008297:Male; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000276:immunology / Q000473:pathology*; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000187:drug effects; D014407:Tumor Cells, Cultured; D000077191:Wortmannin
D000730:Androstadienes; D016207:Cytokines; D004791:Enzyme Inhibitors; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D000077191:Wortmannin; C494918:AKT1 protein, human