Activity and content of antioxidant enzymes in prostate tumors

To investigate the antioxidant enzyme system in blood of men with benign hyperplasia of prostate (BHP) and with prostate adenocarcinoma (CaP). Methods: The spectrophotometrical methods were applied to study content and activity changes of superoxide-dismutase (SOD), catalase (CAT), ceruloplasmin (Cp), tripeptide glutathione (GSH), glutathione-peroxidase (GSH-Px), and glutathione-reductase (GR). Lipid peroxidation was evaluated using thiobarbituric acid (TBA)-test. Blood plasma and erythrocytes of men with prostate tumors served as the material for the studies; n = 15 for each group. Results: SOD activity was increased in BHP (24.65 ± 1.20 U/µl) and decreased in CaP (11.45 ± 0.89 U/µl), CAT activity remained unaltered in BHP (12.41 ± 0.85 mcat/ml) and was slightly declined in CaP (9.52 ± 0.56 mcat/ml). Cp was increased in both kind of tumors, especially in CaP (54.27 ± 7.22 mg%), as well as GSH (0.736 ± 0.07 µM/l) and GR (0.031 ± 0.002 µM/g.Hemogl/min). GSH-Px was sharply increased in BHP (0.67 ± 0.05 µM/g.Hemogl/min) and reduced in CaP (0.16 ± 0.01 µM/g.Hemogl/min). Conclusion: The development of BHP reflects relatively weakly on blood system as activity and content of antioxidant enzymes are not revealing marked changes in this disease. The significant changes are revealed in case of CaP, showing the reduced functional state of blood antioxidant enzyme system.Цель: исследование системы антиоксидантных ферментов в крови больных c доброкачественной гиперплазией простаты (ДГП) и аденокарциномой простаты (АКП). Методы: изменения содержания и активности супероксид-дисмутазы (СОД), каталазы (КАТ), церулоплазмина (ЦП), трипептида глютатиона (ВГ), глутатион-пероксидазы (ГП) и глутатион-редуктазы (ГР) были изучены спектрофотометрическими методами. Перекисное окисление липидов оценивали с помощью тиобарбитуровой кислоты (TBК-тест). Материалом для исследовании служили плазма крови и эритроциты больных с опухолями простаты, n = 15 для каждой группы. Результаты: активность СОД повышалась в ДГП (24,65 ± 1,20 ед./мкл) и снижалась в АКП (11,45 ± 0,89 ед./мкл). Активность КАТ оставалась неизмененной в ДГП (12,41 ± 0,85 мкат/мл) и слегка снижалась в АКП (9,52 ± 0,56 мкат/мл). Содержание ЦП повышалось в обоих типах опухолей, в особенности в АКП (54,27 ± 7,22 mg%), так же как ВГ (0,736 ± 0,07 мкM/л) и ГР (0,031 ± 0,002 мкМ/г.гемогл/мин). Активность ГП резко возрастала в ДГП (0,67 ± 0,05 мкМ/г.гемогл/мин) и снижалась в АКП (0,16 ± 0,01 мкМ/г.гемогл/мин). Выводы: развитие ДГП сравнительно слабо отражается на системе крови, так как содержание и активность антиоксидантных ферментов не показывают заметных изменении при этой болезни. Значительные изменения были выявлены в группе больных с АКП, что указывало на подавление функционального состояния системы антиоксидантных ферментов крови

Nrf2 Expression Is Regulated by Epigenetic Mechanisms in Prostate Cancer of TRAMP Mice

Nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) is a transcription factor which regulates the expression of many cytoprotective genes. In the present study, we found that the expression of Nrf2 was suppressed in prostate tumor of the Transgenic Adenocarcinoma of Mouse Prostate (TRAMP) mice. Similarly, the expression of Nrf2 and the induction of NQO1 were also substantially suppressed in tumorigenic TRAMP C1 cells but not in non-tumorigenic TRAMP C3 cells. Examination of the promoter region of the mouse Nrf2 gene identified a CpG island, which was methylated at specific CpG sites in prostate TRAMP tumor and in TRAMP C1 cells but not in normal prostate or TRAMP C3 cells, as shown by bisulfite genomic sequencing. Reporter assays indicated that methylation of these CpG sites dramatically inhibited the transcriptional activity of the Nrf2 promoter. Chromatin immunopreceipitation (ChIP) assays revealed increased binding of the methyl-CpG-binding protein 2 (MBD2) and trimethyl-histone H3 (Lys9) proteins to these CpG sites in the TRAMP C1 cells as compared to TRAMP C3 cells. In contrast, the binding of RNA Pol II and acetylated histone H3 to the Nrf2 promoter was decreased. Furthermore, treatment of TRAMP C1 cells with DNA methyltransferase (DNMT) inhibitor 5-aza-2′-deoxycytidine (5-aza) and histone deacetylase (HDAC) inhibitor trichostatin A (TSA) restored the expression of Nrf2 as well as the induction of NQO1 in TRAMP C1 cells. Taken together, these results indicate that the expression of Nrf2 is suppressed epigenetically by promoter methylation associated with MBD2 and histone modifications in the prostate tumor of TRAMP mice. Our present findings reveal a novel mechanism by which Nrf2 expression is suppressed in TRAMP prostate tumor, shed new light on the role of Nrf2 in carcinogenesis and provide potential new directions for the detection and prevention of prostate cancer