Superoxide dismutase analog (Tempol: 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine 1-oxyl) treatment restores erectile function in diabetes-induced impotence.

We hypothesized that the administration of the superoxide dismutase (SOD) mimetic Tempol (4-hydroxy-2, 2, 6, 6-tetramethylpiperidine 1-oxyl) may reverse diabetes-induced erectile dysfunction. To test this hypothesis, reactive oxygen species-related genes (SOD1, SOD2, GP x 1, CAT, NOS2, NOS3) were tested, erectile functional studies and immunohistochemical analysis were carried out in diabetic rats treated with or without Tempol. Thirty Sprague-Dawley (3-4 months old) rats were divided into three groups (n=10 each), 20 with diabetes (diabetic control and Tempol treatment) and 10 healthy controls. At 12 weeks after the induction of diabetes by streptozotocin and Tempol treatment, all groups underwent in vivo cavernous nerve stimulation. Rat crura were harvested and the expression of antioxidative defense enzymes were examined by semi-quantitative reverse transcriptase PCR (RT-PCR). To confirm the RT-PCR results, we carried out immunohistochemistry (IHC) for catalase (CAT) and iNOS (NOS2). Nitration of tyrosine groups in proteins was also examined by IHC. Mean intracavernous pressure in the diabetic group was significantly lower than in the healthy controls (P <0.001) and was reversed by Tempol treatment (P <0.0108). NOS2 protein expression was significantly increased in diabetic animals compared with healthy controls and Tempol restored NOS2 protein level. Nitrotyrosine was also higher in diabetic animals and although Tempol treatment decreased its formation, it remained higher than that found in healthy controls. This study suggests that Tempol treatment increased erectile function through modulating oxidative stress-related genes in diabetic rats. This is the first report about the relationship between diabetes-induced erectile dysfunction and oxidative stress, and antioxidative therapy using the superoxide dismutase mimetic, Tempol, to restore erectile function.

Potential mechanism for the effects of dexamethasone on growth of androgen-independent prostate cancer.

BACKGROUND: Dexamethasone, a synthetic glucocorticoid, has clinical benefit in patients with hormone-refractory prostate cancer (HRPC), but the mechanisms responsible for its effects are unknown. The nuclear factor-kappaB (NF-kappaB)-dependent cytokine interleukin (IL) 6 (IL-6) is thought to stimulate growth of HRPC. Because dexamethasone interferes with NF-kappaB activation, we determined whether dexamethasone inhibits prostate cancer growth by working through the glucocorticoid receptor (GR) to interfere with NF-kappaB-IL-6 pathway. METHODS: Three human prostate cancer cell lines (DU145, PC-3, and LNCaP) were assessed for GR expression and responsiveness to dexamethasone. Levels of GR, NF-kappaB, and the cytoplasmic NF-kappB inhibitor IkappaBalpha were determined by western blotting and of IL-6 by enzyme immunoassay. The subcellular localization of NF-kappaB was analyzed by immunofluorescence. The effects of dexamethasone (thrice weekly injections of 1 microg/mouse) on DU145 xenografts in nude and severe combined immunodeficient (SCID) mice were evaluated. GR expression in human prostate cancers was assessed by immunohistochemistry. All statistical tests were two-sided. RESULTS: Dexamethasone dose dependently decreased GR levels and inhibited the growth of DU145 and PC-3 but not LNCaP cells (DU145 cells, P< .001; PC-3 cells, P = .009). Dexamethasone increased IkappaBalpha protein levels and the cytosolic accumulation of NF-kappaB in DU145 cells and decreased secreted IL-6 levels to 37 pg/mL (95% confidence interval [CI] = 33 pg/mL to 41 pg/mL), compared with 164 pg/mL (95% CI = 162 pg/mL to 166 pg/mL) secreted by ethanol-treated control cells. Dexamethasone inhibited the growth of DU145 xenografts in nude (P = .006) and SCID (P = .026) mice without affecting GR levels. Eight of 16 human prostate cancers expressed GR at high levels (>or=30% GR-positive cells). CONCLUSION: Dexamethasone inhibited the growth of GR-positive cancers, possibly through the disruption of the NF-kappaB-IL-6 pathway.

Clinical evaluation of human telomerase catalytic subunit in bladder washings from patients with bladder cancer.

PURPOSE: We examined the expression of mRNA of human telomerase reverse transcriptase (hTERT), a catalytic subunit of the telomerase complex, in bladder washings as a tumor marker for the detection of bladder cancer. MATERIALS AND METHODS: Bladder washings were obtained from 63 patients. We examined the expression of hTERT mRNA by the nested reverse transcription-polymerase chain reaction (RT-PCR) method and also measured the relative expressions of hTERT mRNA and beta(2)-microglobulin (beta(2)-MG) in these samples by RT-PCR analysis. Correlations between the relative expression of hTERT mRNA and clinical features were analyzed. We also compared the sensitivity of this assay with that of urinary cytology. RESULTS: By nested RT-PCR, we detected three false-positive cases (11%) in the control group. Therefore, the relative expression values of hTERT mRNA and beta(2)-MG correlated strongly with tumor size, but not with multiplicity or histologic grade. When the cut-off value of the expression was fixed at 0.27%, the sensitivity and specificity of this assay were 74% and 93%, respectively. This assay was more sensitive than urinary cytology for the detection of bladder cancer. CONCLUSION: These results suggest that the relative expression of hTERT mRNA in bladder washings is useful in screening for bladder cancer. Relative expression is of assistance in diagnosing bladder cancer.

Loss of p73 induction in a cisplatin-resistant bladder cancer cell line.

BACKGROUND: Cisplatin (CDDP) plays an important role in the treatment of transitional-cell carcinoma (TCC), but resistance develops. The mechanism is not entirely understood. METHODS: To assess acquired resistance to CDDP, we established a CDDP-resistant subclone, CL8-2, of T24, which is a bladder cancer cell line. We examined the changes in the various pathways leading to apoptosis in the parent line and CL8-2. RESULTS: The drug caused apoptosis of T24 cells but not CL8-2 cells. The CL8-2 cells were 6.4 times more resistant to CDDP than was T24. In both cell lines, the mismatch repair genes hMLH-1 and hMSH-2 were expressed at high levels. The p53 protein was not detected in either cell line but p73 protein was induced by CDDP treatment in T24 cells, which was followed by activation of caspases 3, 8, and 9. This phenomenon was not observed in CL8-2 cells. CONCLUSION: These results suggest that loss of p73 induction may lead to CDDP resistance of TCC.