Doxazosin induces apoptosis of benign and malignant prostate cells via a death receptor-mediated pathway.
Quinazoline-based alpha1-adrenoceptor antagonists such as doxazosin and terazosin have been previously shown to induce apoptosis in prostate cancer cells via an alpha1-adrenoceptor-independent pathway, involving activation of transforming growth factor-beta1 (TGF-beta1) signaling. In this study, the molecular events initiating this apoptotic effect were further investigated in vitro using the human androgen-independent prostate cancer cells PC-3 and the human benign prostate epithelial cells BPH-1. Quantitative microarray assays were done in PC-3 and BPH-1 cells after treatment with doxazosin (25 micromol/L, 6 and 24 hours) to identify the early gene changes. Transient changes in the expression of several apoptosis regulators were identified, including up-regulation of Bax and Fas/CD95 and down-regulation of Bcl-xL and TRAMP/Apo3. Moreover, there were significant changes in the expression pattern of signaling components of the extracellular matrix such as integrins alpha2, alphaV, beta1, and beta8. Western blot analysis revealed activation of caspase-8 and caspase-3 within the first 6 to 12 hours of treatment with doxazosin in both PC-3 and BPH-1 cells. Doxazosin-induced apoptosis was blocked by specific caspase-8 inhibitors, supporting the functional involvement of caspase-8 in doxazosin-induced apoptosis. The effect of doxazosin on recruitment of Fas-associated death domain (FADD) and procaspase-8 to the Fas receptor was examined via analysis of death-inducing signaling complex formation. Doxazosin increased FADD recruitment and subsequent caspase-8 activation, implicating Fas-mediated apoptosis as the underlying mechanism of the effect of doxazosin in prostate cells. These results show that doxazosin exerts its apoptotic effects against benign and malignant prostate cells via a death receptor-mediated mechanism with a potential integrin contribution towards cell survival outcomes.
Garrison
Jason B
JB
Department of Molecular and Cellular Biochemistry, University of Kentucky College of Medicine, Lexington, Kentucky, USA.
Kyprianou
Natasha
N
D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D053181:Caspase 8; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D017292:Doxazosin / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D053200:Fas-Associated Death Domain Protein; D015870:Gene Expression / Q000187:drug effects; D020869:Gene Expression Profiling; D006801:Humans; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D010766:Phosphorylation; D011467:Prostate / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D014162:Transfection; D019014:fas Receptor / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D000317:Adrenergic alpha-Antagonists; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D019014:fas Receptor; D051057:Proto-Oncogene Proteins c-akt; C505530:CASP8 protein, human; D053181:Caspase 8; D020169:Caspases; D017292:Doxazosin