title: Targeted induction of apoptosis via TRAIL and cryoablation: a novel strategy for the treatment of prostate cancer.
abstract: Adjuvant therapies contribute to the successful treatment of cancer. Our previous reports have shown that combining cryoablation with cytotoxic agents enhances cell death. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a cytotoxic agent that preferentially induces apoptosis in a variety of human cancer cells. Human prostate cancer cells (PC-3) are resistant to many cytodestructive agents, including cryoablation and TRAIL. Here, we evaluated the effects of TRAIL combined with cryoablation on PC-3 and normal prostate (RWPE-1) cell death. Exposure of PC-3 cells to freezing (-10 degrees C) or TRAIL (500 ng/ml) results in minimal cell death, whereas a complete loss of viability is observed with the simultaneous combination. The synergistic effect was found to be due to a marked increase in apoptosis. Western blot analysis revealed a significant level of caspase-8 and -3 cleavage between 12 and 24 h post-exposure. Caspase activation assays provided similar results and also indicated a role for caspase-9. Inhibitors to caspase-8 and -9 along with a pan-caspase inhibitor were incorporated to determine which pathway was necessary for the combined efficacy. Inhibition of caspase-8 significantly blocked the combination-induced cell death compared to cells that did not receive the inhibitor (63% compared to 10% viable). The addition of the caspase-9 inhibitor resulted in only a minimal protection. Importantly, the combination was not effective when applied to normal prostate cells. The results describe a novel therapeutic model for the treatment of prostate cancer and provide support for future in vivo studies.
authors.affiliation: Cell Preservation Services Inc., Owego, NY 13827, USA. DClarke@CellPreservation.com
authors.forename: D M
authors.initials: DM
authors.lastname: Clarke
authors.forename: A T
authors.initials: AT
authors.lastname: Robilotto
authors.forename: R G
authors.initials: RG
authors.lastname: VanBuskirk
authors.forename: J G
authors.initials: JG
authors.lastname: Baust
authors.forename: A A
authors.initials: AA
authors.lastname: Gage
authors.forename: J M
authors.initials: JM
authors.lastname: Baust
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D061945:Caspase Inhibitors; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D003452:Cryosurgery; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000601:surgery / Q000628:therapy*; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000494:pharmacology*
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D053221:TNF-Related Apoptosis-Inducing Ligand; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone