3-nitrotyrosine and Prostatic-Neoplasms

Tocopherols, the major forms of vitamin E, exist as alpha-tocopherol (α-T), β-T, γ-T and δ-T. The cancer preventive activity of vitamin E is suggested by epidemiological studies, but recent large-scale cancer prevention trials with high dose of α-T yielded disappointing results. Our hypothesis that other forms of tocopherols have higher cancer preventive activities than α-T was tested, herein, in a novel prostate carcinogenesis model induced by 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP), a dietary carcinogen, in the CYP1A-humanized (hCYP1A) mice. Treatment of hCYP1A mice with PhIP (200 mg/kg b.w., i.g.) induced high percentages of mouse prostatic intraepithelial neoplasia (mPIN), mainly in the dorsolateral glands. Supplementation with a γ-T-rich mixture of tocopherols (γ-TmT, 0.3% in diet) significantly inhibited the development of mPIN lesions and reduced PhIP-induced elevation of 8-oxo-deoxyguanosine, COX-2, nitrotyrosine, Ki-67 and p-AKT, and the loss of PTEN and Nrf2. Further studies with purified δ-T, γ-T or α-T (0.2% in diet) showed that δ-T was more effective than γ-T or α-T in preventing mPIN formations and p-AKT elevation. These results indicate that γ-TmT and δ-T could be effective preventive agents of prostate cancer.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Anticarcinogenic Agents; Cyclooxygenase 2; Cytochrome P-450 CYP1A2; Deoxyguanosine; Diet; Disease Models, Animal; Humans; Imidazoles; Ki-67 Antigen; Male; Mice, Transgenic; NF-E2-Related Factor 2; Phosphorylation; Prostatic Intraepithelial Neoplasia; Prostatic Neoplasms; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Signal Transduction; Tocopherols; Tyrosine

Carboxypeptidase-D (CPD) cleaves C-terminal arginine for conversion to nitric oxide (NO) by nitric oxide synthase (NOS). Prolactin (PRL) and androgens stimulate CPD gene transcription and expression, which increases intracellular production of NO to promote viability of prostate cancer (PCa) cells in vitro. The current study evaluated whether hormonal upregulation of CPD and NO promote PCa cell viabilty in vivo, by correlating changes in expression of CPD and nitrotyrosine residues (products of NO action) with proliferation marker Ki67 and associated proteins during PCa development and progression.. Fresh prostate tissues, obtained from 40 men with benign prostatic hyperplasia (BPH) or PCa, were flash-frozen at the time of surgery and used for RT-qPCR analysis of CPD, androgen receptor (AR), PRL receptor (PRLR), eNOS, and Ki67 levels. Archival paraffin-embedded tissues from 113 men with BPH or PCa were used for immunohistochemical (IHC) analysis of CPD, nitrotyrosines, phospho-Stat5 (for activated PRLR), AR, eNOS/iNOS, and Ki67.. RT-qPCR and IHC analyses showed strong AR and PRLR expression in benign and malignant prostates. CPD mRNA levels increased ∼threefold in PCa compared to BPH, which corresponded to a twofold increase in Ki67 mRNA levels. IHC analysis showed a progressive increase in CPD from 11.4 ± 2.1% in benign to 21.8 ± 3.2% in low-grade (P = 0.007), 40.7 ± 4.0% in high-grade (P < 0.0001) and 50.0 ± 9.5% in castration-recurrent PCa (P < 0.0001). Immunostaining for nitrotyrosines and Ki67 mirrored these increases during PCa progression. CPD, nitrotyrosines, and Ki67 tended to co-localize, as did phospho-Stat5.. CPD, nitrotyrosine, and Ki67 levels were higher in PCa than in benign and tended to co-localize, along with phospho-Stat5. The strong correlation in expression of these proteins in benign and malignant prostate tissues, combined with abundant AR and PRLR, supports in vitro evidence that the CPD-Arg-NO pathway is involved in the regulation of PCa cell proliferation. It further highlights a role for PRL in the development and progression of PCa.

Topics: Carboxypeptidases; Humans; Ki-67 Antigen; Male; Neoplasm Grading; Nitric Oxide Synthase Type III; Phosphorylation; Prolactin; Prostate; Prostatic Hyperplasia; Prostatic Neoplasms; Receptors, Androgen; Receptors, Prolactin; Signal Transduction; STAT5 Transcription Factor; Testosterone; Tyrosine; Up-Regulation

Recent reports place prostate cancer (PCa) as third cause of death in the World among males, in Mexico it is the leading cause of male death. In this study, we studied molecular markers and one genetic marker related in tissues with PCa and benign prostatic hyperplasia (BPH): The Mn-superoxide dismutase (Mn-SOD) gen and protein, prostate specific antigen (PSA) and 3-nitrotyrosine (3-NT). It was evaluated if various markers of oxidative stress show altered expression in prostate cancer and BPH.. 80 biopsies were obtained. The conditions to amplify and evaluate the immunoreactivity of the genes of interest (Mn-SOD and 3-NT) and the correlation between PSA and Mn-SOD immunoreactivity in prostate cancer and benign prostatic hyperplasia were standardized.. Gene overexpression and Mn-SOD and 3-NT immunoreactivity were greater in prostate cancer with respect to the BPH group. Correlation between levels of PSA and the Mn-SOD immunoreactivity was not observed.. The above results suggest that the parameters evaluated can be used as tumor markers making the determinations in biopsies of patients suspected of prostate cancer.

Topics: Gene Expression Regulation, Neoplastic; Genetic Markers; Humans; Male; Prostatic Neoplasms; Superoxide Dismutase; Tyrosine

Immunotherapy may provide valid alternative therapy for patients with hormone-refractory metastatic prostate cancer. However, if the tumor environment exerts a suppressive action on antigen-specific tumor-infiltrating lymphocytes (TIL), immunotherapy will achieve little, if any, success. In this study, we analyzed the modulation of TIL responses by the tumor environment using collagen gel matrix-supported organ cultures of human prostate carcinomas. Our results indicate that human prostatic adenocarcinomas are infiltrated by terminally differentiated cytotoxic T lymphocytes that are, however, in an unresponsive status. We demonstrate the presence of high levels of nitrotyrosines in prostatic TIL, suggesting a local production of peroxynitrites. By inhibiting the activity of arginase and nitric oxide synthase, key enzymes of L-arginine metabolism that are highly expressed in malignant but not in normal prostates, reduced tyrosine nitration and restoration of TIL responsiveness to tumor were achieved. The metabolic control exerted by the tumor on TIL function was confirmed in a transgenic mouse prostate model, which exhibits similarities with human prostate cancer. These results identify a novel and dominant mechanism by which cancers induce immunosuppression in situ and suggest novel strategies for tumor immunotherapy.

Topics: Adenocarcinoma; Animals; Arginase; Arginine; CD8-Positive T-Lymphocytes; Cell Line, Tumor; Humans; Interferon-gamma; Lymphocyte Count; Lymphocytes, Tumor-Infiltrating; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Nitric Oxide Synthase; Organ Culture Techniques; Prostatic Neoplasms; T-Lymphocyte Subsets; Tyrosine

The risk for prostate cancer seems to be reduced by certain antioxidant compounds (vitamins E and A, and selenium).. Antioxidant enzymes and oxidative damage products were localized in normal prostatic epithelium and malignant glands in primary and metastatic prostatic adenocarcinomas, using well-characterized antibodies and immunoperoxidase techniques.. Antioxidant enzymes and four markers of oxidative damage were compared in basal and secretory cells of normal prostatic epithelium and prostate adenocarcinoma cells, and each cell type had unique patterns of enzymes and oxidative damage products. One marker of oxidative damage, a fluorophore derived from 4-hydroxy-2-nonenal-lysine adduction, was found in secretory cells of normal but not malignant epithelium, demonstrating a different oxidative metabolism in normal vs. malignant prostate epithelium. Metastatic lesions from primary prostate cancer had higher levels of manganese superoxide dismutase and nuclear oxidative damage products than did primary tumors.. Antioxidant enzymes and oxidative damage products are modulated in metastatic compared to primary prostate cancer.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Adenocarcinoma; Antibodies, Monoclonal; Antioxidants; Bone Neoplasms; Catalase; Deoxyguanosine; Glutathione Peroxidase; Humans; Immunoenzyme Techniques; Lipofuscin; Male; Prostate; Prostatic Neoplasms; Reactive Oxygen Species; Superoxide Dismutase; Tyrosine