Increased resistance to trail-induced apoptosis in prostate cancer cells selected in the presence of bicalutamide.
BACKGROUND
Following prolonged treatment with the non-steroidal anti-androgen bicalutamide (Casodex), LNCaP cells have become resistant to this drug. Previously, we found that the bicalutamide-refractory subline LNCaP-Bic acquires a growth advantage and does not respond to androgenic stimulation. In the present study, we have asked whether changes in response to the tumor-selective apoptosis inducer TNF-related apoptosis-inducing ligand (TRAIL) occur in LNCaP-Bic cells.


METHODS
LNCaP and LNCaP-Bic cells were incubated with increasing concentrations of TRAIL and apoptosis rate was analyzed using FACS. Expression of death receptors (DR), adaptor protein Fas-associated death domain (FADD), members of the Bcl-2 family, and caspases were investigated by Western blot.


RESULTS
The percentage of cells undergoing apoptosis was lower in LNCaP-Bic in comparison to LNCaP cells. There were no major differences in death receptor expression between control LNCaP and bicalutamide-selected cells. Surprisingly, treatment with TRAIL increased the levels of Bcl-2 by 50% in LNCaP-Bic cells. The ratio cleaved caspase/procaspase-8 was substantially lower in LNCaP-Bic cells.


CONCLUSIONS
Reduced sensitivity to TRAIL-induced apoptosis is a novel mechanism relevant to resistance to bicalutamide in prostate cancer. Inability of TRAIL to cause programmed cell death might be caused by multiple perturbations in the TRAIL-signaling pathway.
Mitterberger
Michael
M
Department of Urology, Innsbruck Medical University, Innsbruck, Austria.
Neuwirt
Hannes
H
Cavarretta
Ilaria T
IT
Hobisch
Alfred
A
Culig
Zoran
Z
D000726:Androgen Antagonists / Q000494:pharmacology*; D000813:Anilides / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000032:analysis; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008297:Male; D009570:Nitriles / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000737:chemistry / Q000473:pathology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D053218:Receptors, Death Domain / Q000032:analysis / Q000187:drug effects; D053221:TNF-Related Apoptosis-Inducing Ligand / Q000008:administration & dosage / Q000494:pharmacology*; D014105:Tosyl Compounds / Q000494:pharmacology*; D051028:bcl-2-Associated X Protein / Q000032:analysis
D000726:Androgen Antagonists; D000813:Anilides; D000970:Antineoplastic Agents; D009570:Nitriles; D019253:Proto-Oncogene Proteins c-bcl-2; D053218:Receptors, Death Domain; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014105:Tosyl Compounds; D051028:bcl-2-Associated X Protein; C053541:bicalutamide; D020169:Caspases