title: Sulforaphane increases the efficacy of anti-androgens by rapidly decreasing androgen receptor levels in prostate cancer cells.
abstract: Prostate cancer (PCa) cells utilize androgen for their growth. Hence, androgen deprivation therapy (ADT) using anti-androgens, e.g. bicalutamide (BIC) and enzalutamide (ENZ), is a mainstay of treatment. However, the outgrowth of castration resistant PCa (CRPC) cells remains a significant problem. These CRPC cells express androgen receptor (AR) and utilize the intratumoral androgen towards their continued growth and invasion. Sulforaphane (SFN), a naturally occurring isothiocyanate found in cruciferous vegetables, can decrease AR protein levels. In the present study, we tested the combined efficacy of anti-androgens and SFN in suppressing PCa cell growth, motility and clonogenic ability. Both androgen-dependent (LNCaP) and androgen-independent (C4-2B) cells were used to monitor the effects of BIC and ENZ, alone and in combination with SFN. Co-exposure to SFN significantly (p<0.005) enhanced the anti-proliferative effects of anti-androgens and downregulated expression of the AR-responsive gene, prostate specific antigen (PSA) (p<0.05). Exposure to SFN decreased AR protein levels in a time- and dose-dependent manner with almost no AR detected at 24 h with 15 µM SFN (p<0.005). This rapid and potent AR suppression by SFN occurred by both AR protein degradation, as suggested by cycloheximide (CHX) co-exposure studies, and by suppression of AR gene expression, as evident from quantitative RT-PCR experiments. Pre-exposure to SFN also reduced R1881-stimulated nuclear localization of AR, and combined treatment with SFN and anti-androgens abrogated the mitogenic effects of this AR-agonist (p<0.005). Wound-healing assays revealed that co-exposure to SFN and anti-androgens can significantly (p<0.005) reduce PCa cell migration. In addition, long-term exposures (14 days) to much lower concentrations of these agents, SFN (0.2 µM), BIC (1 µM) and/or ENZ (0.4 µM) significantly (p<0.005) decreased the number of colony forming units (CFUs). These findings clearly suggest that SFN may be used as a promising adjunct agent to augment the efficacy of anti-androgens against aggressive PCa cells.
authors: Department of Urology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
authors: Namrata
authors: N
authors: Khurana
authors: Department of Urology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
authors: Sudha
authors: S
authors: Talwar
authors: Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
authors: Partha K
authors: PK
authors: Chandra
authors: Amity Institute of Biotechnology, Amity University, Noida, U.P. 201313, India.
authors: Pankaj
authors: P
authors: Sharma
authors: Department of Urology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
authors: Asim B
authors: AB
authors: Abdel-Mageed
authors: Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
authors: Debasis
authors: D
authors: Mondal
authors: Department of Urology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
authors: Suresh C
authors: SC
authors: Sikka
mesh_terms: D000726:Androgen Antagonists / Q000494:pharmacology*; D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D004357:Drug Synergism; D004359:Drug Therapy, Combination; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D017879:Isothiocyanates / Q000494:pharmacology*; D008297:Male; D008856:Microscopy, Fluorescence; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D013454:Sulfoxides; D014407:Tumor Cells, Cultured
chemical_list: C410798:AR protein, human; D000726:Androgen Antagonists; D016588:Anticarcinogenic Agents; D014408:Biomarkers, Tumor; D017879:Isothiocyanates; D012333:RNA, Messenger; D011944:Receptors, Androgen; D013454:Sulfoxides; C016766:sulforaphane