Decreased gene expression of steroid 5 alpha-reductase 2 in human prostate cancer: implications for finasteride therapy of prostate carcinoma

BACKGROUND: Steroid 5alpha-reductase 2 (SRD5A2) catalyzes the conversion of testosterone to the more potent androgen, DHT, in the prostate. The therapeutic influence of SRD5A2 inhibitor finasteride on prostate cancer is currently unknown. The direction and extent of changes in SRD5A2 expression in disease tissues is a relevant issue in this regard. METHODS: The expression differences of SRD5A2 in tissues representative of normal, benign, and malignant growth in the human prostate were examined in parallel by comparative analysis of relevant microarray gene expression data. Semiquantitative RT-PCR was used to further verify the gene expression differences of SRD5A2. RESULTS: Consistently decreased expression of SRD5A2 was observed in 25 prostate cancer samples when compared to 25 matched normal samples and nine BPH samples. Expression differences among these samples for six other genes were presented in parallel as indicators of the direction and extent of expression changes. These additional genes include SRD5A1, Hepsin (overexpressed in prostate cancer), AMACR (overexpressed in prostate cancer), Keratin 8 (epithelial marker), smooth muscle actin (stromal marker), Nell2 (overexpressed in BPH). Semiquantitative RT-PCR verified the expression differences for SRD5A2 in six normal, six BPH, and six prostate cancer samples. CONCLUSIONS: Results from this study, combined with those from previous studies, indicate an association of prostate cancer with reduced 5alpha-reductase enzymatic activity as a result of remarkably decreased expression of the SRD5A2 gene. The implications of this study for finasteride therapy of prostate cancer are discussed.     

Usefulness of prostate-specific antigen (PSA) rise as a marker of prostate cancer in men treated with dutasteride: lessons from the REDUCE study

Study Type – Prognostic (RCT) Level of Evidence 1b What's known on the subject? and What does the study add? Previous studies used the decrease in PSA after 6 months of dutasteride treatment as a new ‘baseline’ PSA value from which subsequent rises may serve as a warning for prostate cancer; however, PSA tends to continue to decrease as dutasteride treatment continues. By comparing positive biopsy rates in the REDUCE study using any rise from nadir in the dutasteride arm and standard PSA decision criteria (NCCN) in the placebo arm, we demonstrated that the ability to detect prostate cancer and high grade prostate cancer is maintained with dutasteride treatment.

OBJECTIVES

? To determine if dutasteride‐treated men can be monitored safely and adequately for prostate cancer based on data from the Reduction by Dutasteride in Prostate Cancer Events (REDUCE) study. ? To analyse whether the use of treatment‐specific criteria for repeat biopsy maintains the usefulness of prostate‐specific antigen (PSA) level for detecting high grade cancers.

PATIENTS AND METHODS

? The REDUCE study was a randomized, double‐blind, placebo‐controlled investigation of whether dutasteride (0.5 mg/day) reduced the risk of biopsy‐detectable prostate cancer in men with a previous negative biopsy. ? The usefulness of PSA was evaluated using biopsy thresholds defined by National Comprehensive Cancer Network guidelines in the placebo group and any rise in PSA from nadir (the lowest PSA level achieved while in the study) in the dutasteride group. ? The number of cancers detected on biopsy in the absence of increased/suspicious PSA level as well as sensitivity, specificity, positive predictive value and negative predictive value for high grade prostate cancer detection were analysed by treatment group. ? Prostate cancer pathological characteristics were compared between men who did and did not meet biopsy thresholds.

RESULTS

? Of 8231 men randomized, 3305 (dutasteride) and 3424 (placebo) underwent at least one prostate biopsy during the study and were included in the analysis. ? If only men meeting biopsy thresholds underwent biopsy, 25% (47/191) of Gleason 7 and 24% (7/29) of Gleason 8–10 cancers would have been missed in the dutasteride group, and 37% (78/209) of Gleason 7 and 22% (4/18) Gleason 8–10 cancers would have been missed in the placebo group. ? In both groups, the incidence of Gleason 7 and Gleason 8–10 cancers generally increased with greater rises in PSA. ? Sensitivity of PSA kinetics was higher and specificity was lower for the detection of Gleason 7–10 cancers in men treated with dutasteride vs placebo. ? Men with Gleason 7 and Gleason 8–10 cancer meeting biopsy thresholds had greater numbers of positive cores, percent core involvement, and biopsy cancer volume vs men not meeting thresholds.

CONCLUSION

? Using treatment‐specific biopsy thresholds, the present study shows that the ability of PSA kinetics to detect high grade prostate cancer is maintained with dutasteride compared with placebo in men with a previous negative biopsy. ? The sensitivity of PSA kinetics with dutasteride was similar to (Gleason 8–10) or higher than (Gleason 7–10) the placebo group; however, biopsy decisions based on a single increased PSA measurement from nadir in the dutasteride group resulted in a lower specificity compared with using a comparable biopsy threshold in the placebo group, indicating the importance of confirmation of PSA measurements.     

The effect of nimesulide, a selective cyclooxygenase-2 inhibitor, on Ets-1 and Ets-2 expression in head and neck cancer cell lines

BACKGROUND: The protooncogenes Ets-1 and Ets-2 are involved in carcinogenesis of different tumors. Nimesulide, a selective cyclooxygenase-2 (COX-2) inhibitor, has antiproliferative effects on tumor cells. The question arises whether nimesulide influences Ets-1 and Ets-2 synthesis in head and neck tumors. METHODS: Expression of Ets-1 and Ets-2 was analyzed in tumor tissues by immunohistochemistry. The influence of nimesulide and an extracellular signal-regulated kinase (ERK) inhibitor on cell proliferation of two head and neck cancer cell lines and Ets-1 and Ets-2 expression was determined by automated cell counting and Western blotting, respectively. RESULTS: Immunohistochemistry showed a high expression of Ets-1 and Ets-2 in tumor tissues. In both cell lines, Ets-1 and Ets-2 expression were reduced after 24 and 48 hours by nimesulide. CONCLUSION: Both Ets-1 and Ets-2 are overexpressed in head and neck cancer specimens. Inhibition of Ets-1 and Ets-2 expression in head and neck cancer cell lines by nimesulide might explain the proapoptotic property of this COX-2 inhibitor.     

Prognostic significance of cyclooxygenase-2 and DNA topoisomerase IIalpha expression in oral carcinoma

BACKGROUND: Despite recent advances in the diagnosis and treatment of oral carcinoma, outcomes remain disappointing. The identification of new prognostic factors is necessary to improve survival. To determine the prognostic significance of cyclooxygenase (COX)-2 and DNA topoisomerase (DNA-Topo) IIalpha expression in patients with oral carcinoma, we immunohistochemically examined these enzymes and studied their relation to overall 5-year survival. METHODS: Surgical specimens were obtained from 160 patients with oral carcinoma, 80 with and 80 without regional lymph node metastasis. The specimens were immunostained for COX-2 and DNA-Topo IIalpha as an index of cell proliferative activity. COX-2 immunoreactivity and clinicopathological data were analyzed, and 5-year survival was calculated by the Kaplan-Meier method. RESULTS: COX-2 expression in primary lesions was higher in cases with lymph node metastasis than in those without lymph node metastasis. An increase in tumor size was associated with increased COX-2 expression. In most cases with lymph node metastasis, COX-2 expression was higher in metastatic lesions than in primary lesions. As COX-2 expression increased, the DNA-Topo IIalpha labeling index significantly increased and the overall 5-year survival rate decreased. CONCLUSION: Expression of COX-2 and DNA-Topo IIalpha were related to lymph node metastasis, cell proliferative activity, and overall 5-year survival rate in oral carcinoma. These enzymes may therefore be valuable diagnostic and prognostic indices in oral carcinoma.     

The restorative effect of a selective cyclooxygenase-2 inhibitor on urothelial cell-cell interactions after partial bladder outlet obstruction in rats

OBJECTIVE: To determine the changes in cyclooxygenase-2 (COX-2), E-cadherin and alpha-catenin expression after partial bladder outlet obstruction (PBOO), and whether a selective COX-2 inhibitor (celecoxib) might inhibit COX-2 expression and have beneficial effects on urothelial cell-to-cell interactions in rats subjected to PBOO. MATERIALS AND METHODS: Thirty-six male rats were divided into six equal groups; celecoxib was administered after creating PBOO for 1 and 4 weeks in groups 1 and 2, respectively. Two further obstructed groups (3 and 4, PBOO for 1 and 4 weeks, respectively) received no treatment. Sham-operated animals served as controls (group 5 and 6, assessed at 1 and 4 weeks, respectively). After 1 and 4 weeks of PBOO or a sham procedure the bladder weight was recorded before sampling the bladder for Western blotting and immunohistological analysis, to assess the expressions of COX-2 and adherens proteins, E-cadherin and alpha-catenin. Urothelial cell-to-cell interactions were evaluated using electron microscopy. RESULTS: The bladder mass increased rapidly during the first 7 days after PBOO in groups 1-4 compared with 5 and 6 (P < 0.05). While the bladder mass then continued to increase for the next 21 days in group 4, it was constant in group 2 (P < 0.001). Immunohistochemical staining and Western blotting analyses showed that E-cadherin and alpha-catenin expression were reversibly decreased in rats with PBOO, while COX-2 protein expression was up-regulated. After giving celecoxib there was a significant decrease in COX-2 expression and a restoration of intercellular adherens junctions and desmosomes, as assessed on electron microscopy and expression of adherens proteins combined. CONCLUSION: The increase in COX-2 expression attributable to hypoxia and the tensile strength of bladder wall was attenuated by celecoxib. Selective COX-2 inhibitors have important restorative effects on intercellular adherens junctions and desmosomes in PBOO.     

Suppressed TGF-beta1 expression is correlated with up-regulation of matrix metalloproteinase-13 in keloid regression after flashlamp pulsed-dye laser treatment

BACKGROUND AND OBJECTIVES: Flashlamp pulsed-dye lasers (PDLs) has shown effectiveness in the treatment of keloids. In this study, we investigated whether PDL treatments decreased transforming growth factor-beta1 (TGF-beta1)-induction and up-regulation of matrix metalloproteinase (MMP) expression in keloid regression. STUDY DESIGN/MATERIALS AND METHODS: Keloid tissues obtained from 10 patients with intra-lesional or punch biopsies before and 7 days after PDL treatments [fluence per pulse was 10-18 J/cm2 (mean 14.0 J/cm2)]. Immunohistochemical (IHC) staining of TGF-beta1 and MMP-1 and MMP-13 expressions in keloid tissue was performed. Western blot analysis of MMP-1 and MMP-13 expressions in extracellular matrix was evaluated. RESULTS: IHC staining indicated that expression of TGF-beta1 was significantly reduced in keloid tissues after PDL irradiation. MMP-13 but not MMP-1 expression on IHC staining significantly increased in extracellular matrix of keloid tissues after PDL treatment. Western blot analysis also showed MMP-13 but not MMP-1 significant increased in keloid tissues after PDL treatment. CONCLUSIONS: Regression of keloids regressed after PDL treatments are associated with down-regulation of TGF-beta1 expression and up-regulation of MMP-13 activity.     

High expression of PSM-E correlated with tumor grade in prostate cancer: a new alternatively spliced variant of prostate-specific membrane antigen

BACKGROUND: Prostate-specific membrane antigen (PSMA) overexpressed in prostate cancer (PCa) has been targeted for therapy and diagnosis of PCa. In the current study, PSMA cDNA was cloned from PCa tissue by RT-PCR. After sequencing, a new spliced variant of PSMA (PSM-E) was discovered and its specificity in PCa was evaluated. METHODS: PSM-E and PSMA mRNA were measured in LNCaP, PC-3 and prostate or nonprostatic malignancies. Following transfection of PC-3 with PSM-E cDNA in the pcDNA3.0 vector, PSM-E expression was measured by immunofluorescence and Western-blot. PSM-E and PSMA mRNA levels were quantified by a real-time PCR assay in normal prostate (n = 7), benign prostatic hyperplasia (BPH) (n = 22) and PCa (n = 41). The correlation between their levels and tumor grade was analyzed. RESULTS: PSM-E cDNA is identical to PSMA except for a 97-nucleotide region and a 93-nucleotide region. PSM-E and PSMA mRNA were detected in PCa and LNCaP, not in PC-3; PSMA could be detected in some nonprostatic tumors whereas PSM-E not. The expression of PSM-E protein was detected in transfected cells. Significant difference of PSM-E mRNA levels was observed among normal prostate, BPH and PCa (P < 0.001), and PSM-E levels increased with increasing Gleason score (r = 0.514, P < 0.001). PSMA mRNA levels were higher in BPH and PCa than in normal prostate (P < 0.001), but no difference between BPH and PCa, no significant correlation was observed between PSMA levels and Gleason score (r = 0.229, P = 0.057). CONCLUSIONS: PSM-E may be a potential prognostic indicator for PCa progression and may be a new target antigen for therapy of PCa.     

Overexpression of cyclooxygenase-2 in human prostate carcinoma and prostatic intraepithelial neoplasia-association with increased expression of Polo-like kinase-1

BACKGROUND: Cyclooxygenases (COX) as well as Polo-like kinases (PLK) are involved in proliferation and cell cycle regulation and have been suggested for preventive and therapeutic approaches in prostate carcinoma. METHODS: In this study, we studied expression and prognostic impact of COX-2 in invasive prostate carcinoma, prostatic intraepithelial neoplasia (PIN), atrophic glands, and normal prostatic glands, and investigated the association between COX-2 and PLK-1. RESULTS: We observed a positivity for COX-2 in 72.1% of PIN and in 44.7% of prostate carcinomas with an overexpression of COX-2 in prostate cancer and PIN compared to benign prostatic tissue (P < 0.0005). Furthermore, we observed a strong correlation between expression of PLK-1 and COX-2 (P < 0.0005). CONCLUSIONS: To our knowledge, this is the first report of a correlation between COX-2 and PLK-1 in a malignant tumor. COX-2 and PLK-1 may be interesting targets for new molecular therapies in prostate cancer.     

Inhibition of SULT2B1b expression alters effects of 3beta-hydroxysteroids on cell proliferation and steroid hormone receptor expression in human LNCaP prostate cancer cells

BACKGROUND: Sulfation is an important steroid inactivation in human tissues. Sulfotransferase (SULT) 2B1b selectively conjugates 3beta-hydroxysteroids and is expressed in epithelial cells of normal and cancerous prostate tissues. Dehydroepiandrosterone (DHEA) and Delta(5)-androstenediol (Delta(5)-Adiol) sulfation prevents their conversion to more potent androgens and estrogens in tissues although both compounds may also be biologically active. METHODS: SULT2B1b expression and activity were inhibited >85% in human LNCaP prostate adenocarcinoma cells using short interference RNA (siRNA). The effects of treating control and SULT2B1b-deficient LNCaP cells with DHEA, Delta(5)-Adiol, and 5alpha-androstane-3beta-17beta-diol (Anstane-diol) on cellular proliferation, estrogen receptors (ERs), androgen receptor (AR), and prostate specific antigen protein levels were examined. RESULTS: Physiological concentrations of DHEA and Delta(5)-Adiol increased proliferation of control cells and the proliferative effects were significantly increased in SULT2B1b-siRNA cells. DHEA, but not Delta(5)-Adiol increased AR levels at concentrations >/=1,000 nM in SULT2B1b-siRNA cells but not in control LNCaP cells. ER-alpha levels were not affected with any of the compounds tested. Physiological concentrations of DHEA and Delta(5)-A-diol decreased ER-beta levels in control cells and had significantly greater effects in SULT2B1b-siRNA cells. In contrast, Anstane-diol had no effect on AR or ER-alpha levels but induced more elevation of ER-beta levels in SULT2B1b-siRNA cells at concentrations >/=1,000 nM. CONCLUSIONS: SULT2B1b is involved in regulating prostate cell responsiveness to DHEA and Delta(5)-Adiol. Inhibition of SULT2B1b increased cell proliferation and ER-beta repression after treatment with physiological levels of DHEA and Delta(5)-Adiol indicating that SULT2B1b has an inhibitory effect on DHEA and Delta(5)-Adiol activity.