Serotonin synthesis and metabolism-related molecules in a human prostate cancer cell line.

Prostate cancer is one of the most common tumors in males and its incidence is steadily increasing worldwide. Serotonin or 5-hydroxytryptamine (5-HT) is a well-known neurotransmitter that mediates a wide variety of physiological effects. An increase in the number of 5-HT-releasing neuroendocrine (NE) cells has been correlated with tumor progression. However, it is particularly unclear whether released 5-HT or the release of 5-HT has a role in tumor cell growth. We hypothesized that 5-HT synthesis and metabolism in NE cells regulate the growth of prostate cancer cells. In the present study, 5-HT was found to play a role as a cell growth factor in prostate cancer cells. Moreover, the pharmacological inhibition of 5-HT synthesis and metabolism interrupted the growth of prostate cancer cells. To confirm the existence of 5-HT in prostate cancer cells, we performed ELISA, HPLC, RT-PCR and immunohistochemical analyses. A high expression of tryptophan hydroxylase (TPH-1), dopa decarboxylase (DDC) and monoamine oxidase A (MAO-A) was noted in the prostate cancer cells when compared with normal prostate cells. Previous studies showed that 5-HT stimulated the proliferation of prostate cancer cells mediated by 5-HT receptors 5-HTR1A and R1B. However, cell proliferation was significantly inhibited when siRNA for both DDC and TPH-1 was transfected to the cells. Consequently, we propose that the secretion system of prostate NE cells capable of 5-HT synthesis and metabolism plays a significant role in prostate tumor generation and progression. These findings provide crucial clues for the development of potential pharmacotherapeutics to slow prostate tumor progression.

Angiogenesis in renal cell carcinoma: the role of tumor-associated macrophages.

OBJECTIVE: To explore vascularity and associated molecules in renal cell carcinoma (RCC) and to study their correlations to disease outcome. METHODS: Tissue samples from 51 Japanese patients with renal cell carcinoma (RCC) were obtained between November 1997 and August 2000. Pyrimidine nucleoside phosphorylase and vascular endothelial growth factor (VEGF) levels of RCC and normal kidney tissue were determined by enzyme-linked immunosorbent assay. Microvessel density (MVD) was measured by immunohistochemistry using anti-factor-VIII-related antigen and CD34. The number of infiltrating tumor-associated macrophages (TAM) was measured by immunohistochemistry using anti-CD68 antibody. RESULTS: Pyrimidine nucleoside phosphorylase and VEGF levels were significantly higher in RCC than in normal kidney tissue. The VEGF level was higher in more progressive (high grade, larger or symptomatic) RCC. Although MVD as determined by the factor VIII level was higher in larger tumors, MVD determined by CD34 was higher in low-grade and low-stage tumors. Patients with symptoms, large tumor or high stage showed higher numbers of TAM. VEGF level and TAM were significantly higher in patients with recurrence than in those without recurrence. In univariate analysis, VEGF, TAM and CD34 tumor grade and stage were identified as prognostic factors. Moreover, TAM was the only independent prognostic factor by multivariate analysis. Among these parameters, only TAM and MVD as determined by factor VIII showed significant correlations. CONCLUSION: TAM and VEGF are substantially involved in tumor progression of RCC. As the TAM count is well correlated to the MVD, the main mechanism of tumor progression by TAM might be angiogenesis.

Leiomyoma of the seminal vesicle.

We report a case of leiomyoma of the seminal vesicle in a 74-year-old man who presented with left hemilumbago. Computed tomography and magnetic resonance imaging revealed a mass containing coarse calcification and low signal intensity areas on T1- and T2-weighted images. The clinical features of previously reported cases of leiomyoma of the seminal vesicle are presented, including those of the present case. There remains a lack of consensus regarding surgical resection of leiomyoma of the seminal vesicle.

Bacillus Calmette-Guérin cell-wall skeleton enhances the killing activity of cytotoxic lymphocyte-activated human dendritic cells transduced with the prostate-specific antigen gene.

UNLABELLED: To determine whether dendritic cells (DC) transduced with the prostate-specific antigen (PSA) gene can induce PSA-specific cytotoxic lymphocytes (CTL) against prostate cancer cells, and whether bacillus Calmette-Guérin (BCG) cell-wall skeleton (CWS) can enhance the maturation of DC-PSA and the killing activity of subsequently induced PSA-specific CTL. MATERIALS AND METHODS; We generated an adenovirus encoding the PSA gene (AxCA-PSA) using the cosmid-terminal protein complex method. DC were infected with AxCA-PSA using the centrifugal method. The ability of CTL to lyse target cells expressing PSA, i.e the PSA-positive prostate cancer cell line, LNCap, and PSA-transduced autologous phytohaemagglutinin (PHA) blasts expressing PSA, was assessed using the 51Cr-release assay. The maturation of DC-PSA stimulated by BCG-CWS was assayed by flow cytometry. The cytotoxic activity enhanced by BCG-CWS was assessed by the 51Cr-release assay. RESULTS: DC-PSA induced PSA-specific CTL with 85% cytotoxic activity against LNCaP (effector: target ratio, E:T, of 50:1). However, the cytotoxic activity against PSA-negative cells was very low. Anti-CD8 and anti-major histocompatibility (MHC) class I antibodies blocked PSA-specific cytotoxicity. The PSA-specific killing was reproducible against autologous PHA blast cells expressing PSA, independently of human leukocyte antigen haplotype. Furthermore, the combination of DC-PSA with BCG-CWS remarkably enhanced the PSA-specific cytotoxicity against PHA blasts expressing PSA (15-30% at an E:T ratio of 50:1). CONCLUSION: These findings suggest that DC-PSA can induce MHC class I-restricted PSA-specific CD8+ CTL responses and that DC-PSA matured by BCG-CWS enhance PSA-specific cytotoxicity. The combination of DC-PSA with BCG-CWS might be a useful approach for treating advanced prostate cancer.

Expression of Epstein-Barr virus in renal cell carcinoma.

There have been few studies regarding the etiology of renal cell carcinoma. To examine the possible involvement of Epstein-Barr virus (EBV) in this disease, 9 renal cell carcinoma (RCC), 2 nephroblastoma (Wilms' tumor) and 2 RCC cell lines were subjected to mRNA in situ hybridization and indirect immunofluorescence staining. Messenger RNA in situ hybridization using BamHIW, EBNA LP, EBNA 2 and EBER1 probes of EBV revealed signals in all the examined samples, although some samples showed weak signals using the EBNA LP probe. Indirect immunofluorescence staining using anti-EBNA LP, anti-EBNA2, anti-LMP1 and anti-BZLF1 antibodies showed definitive fluorescence. PCR also revealed EBV DNA in all 8 RCC specimens including 7 cases other than hybridization and fluorescence. EBV infected all the RCC and nephroblastoma irrespective of the histological or clinical stage. On the other hand, EBV expression was stronger in papillary and clear cell-type RCC than chromophobe cell-type, as well as being stronger in the higher grades of RCC. These results suggest that the expression of EBV may be involved in the pathogenesis of RCC and nephroblastoma.

[Preoperative parameters, including percent of positive biopsy cores, in predicting pathological findings after radical prostatectomy].

OBJECTIVES: We investigated whether preoperative parameters predict pathological stage at radical prostatectomy for patients with clinically localized prostatic cancer. MATERIALS AND METHODS: We studied a total of 160 men with clinically localized prostatic cancer (less than or equal to clinical T2) who underwent radical rertropubic prostatectomy at Wakayama Medical University. Clinical Ts patients are not included in this study. Preoperative parameters include patient age, Body Mass Index, preoperative serum PSA value, biopsy Gleason score, clinical stage, the percent of positive biopsy cores (%PosBx) and the percent of positive biopsy cores on the dominant side (%DomPosBx). Univariate and multivariate analysis were performed to examine the prognostic significance of these preoperative parameters. Significant independent factors were combined to create a table to predict pathologically organ confined disease. RESULTS: Univariate analysis showed preoperative serum PSA value (p< 0.001), biopsy Gleason score (p =0.001), clinical stage (p = 0.026), %PosBx (p= 0.002) and %DomPosBx (p=0.003) were significantly related to the pathological stage. On multivariate analysis, serum PSA value (p< 0.01), biopsy Gleason score (p<0.05) and %DomPosBx (p<0.05) were significant independent predictors of pathological stage. CONCLUSION: We provide two model combinations using preoperative clinical factors, one is a combination of serum PSA and biopsy Gleason score and the other is a combination of serum PSA and %DomPosBx, which define a new preoperative model for predicting pathological organ confined prostatic cancer. These combinations are useful and provide important information for urologists to determine the appropriate treatment strategy for clinically localized prostatic cancer.

Intravesical instillation therapy with bacillus Calmette-Guérin for superficial bladder cancer: study of the mechanism of bacillus Calmette-Guérin immunotherapy.

AIM: In order to clarify the initial step of the mechanism by which bacillus Calmette-Guérin (BCG) exhibits antitumor activity via the immune response induced in the bladder submucosa after intravesical BCG therapy for human bladder cancer, various cytokines secreted in the urine after BCG instillation were measured. METHODS: After transurethral resection of bladder cancer, a 6-week course of BCG instillation was performed. At the first and sixth weeks' dosings, spontaneously excreted urine was collected before and 4, 8, and 24 h after BCG instillation. The urinary cytokines were determined by Sandwich enzyme-linked immunosorbent assay using monoclonal antibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF), tumor necrosis factor (TNF)-alpha, granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-1beta, IL-8, interferon (IFN)-gamma, and IL-12. RESULTS: After the BCG therapy, various cytokines, such as GM-CSF, TNF-alpha, G-CSF, IL-1beta, IL-8, IFN-gamma, and IL-12 were secreted, comprising the immune response cascade. The mean urinary excretions of GM-CSF and TNF-alpha 4 h after the sixth week's instillation were significantly higher than the pre-instillation levels. There were no significant increases in the urinary IFN-gamma or IL-12 levels between 4 and 24 h after the sixth week's instillation. The TNF-alpha level 4 h after the sixth week's instillation had a strong tendency towards the absence of recurrence, with a mean follow-up of 54.1 months. The Kaplan-Meier curve showed the 2, 5, and 10-year recurrence-free survival rates were 72.4%, 65.8%, and 56.4%, respectively. CONCLUSIONS: We suggested that the urinary levels of TNF-alpha might be essential in antitumor activity after BCG therapy and might play an important role in the prevention of bladder tumor recurrence.

[Efficacy of intravesical bacillus Calmette-Guerin for carcinoma in situ of bladder].

Three months after an initial 6-week course ofintravesical bacillus Calmette-Guerin (BCG) given between January 1990 and March 2005, 94 (90%) out of 104 patients with carcinoma in situ (CIS) of the bladder achieved a complete response (CR). The 5- and 10-year recurrence-free rates were 67 and 60%, respectively (median follow-up 42 months). Three months after a second course ofintravesical BCG given to 23 patients who failed the initial induction course for CIS was evaluated. Of these, 96% achieved a CR, and the 5- and 10-year recurrence-free rates were 56 and 28%,respectively (median follow-up 23 months). Only one patient who received a second course of BCG therapy showed disease progression. Two of the 4 patients with BCG-refractory CIS of the bladder achieved CR after intravesical gemcitabine therapy and maintained a tumor-free status beyond 6 months. Five of the 16 patients showing disease progression had upper urinary tract cancer, 4 had recurrent or muscle invasive bladder cancer, 6 had prostatic involvement of CIS, and one patient had urethral recurrence. Three of the 16 patients died. Bladder preservation was achieved in 97 of the 104 patients, although 7 patients ultimately underwent radical cystectomy and urinary diversion for aggressive disease. In conclusion, some patients may be managed safely by repeated endoscopic resection and intravesical therapy with cystectomy postponed until objective evidence of progression exists.

[The recurrence of urothelial carcinoma in situ at the fossa navicularis of the urethra and the glans penis arising eight years after transurethral resection of a bladder tumor to treat superficial bladder cancer].

A 63-year-old man underwent transurethral resection of a bladder tumor to treat superficial bladder cancer in 1995. Histological examination showed urothelial carcinoma, G2>G3 with carcinoma in situ (CIS) at the bladder neck. He underwent postoperative intravesical bacillus Calmette-Guerin (BCG) therapy. In June, 2003, he complained of rubor of his external urethral meatus and visited our clinic. Biopsies at the external urethral meatus and the fossa navicularis of the urethra showed CIS. Radiological examinations, cystourethroscopy and multiple biopsies from other sites of urothelium, including bladder and urethral mucosa, did not reveal any other malignancies. Thereafter, partial penectomy and bilateral inguinal lymphadenectomy were performed. Histological examinations showed CIS at the urethral mucosa of the fossa navicularis and the skin of the glans penis. Postoperative urine cytologies were negative.

Sustained prophylactic effect of intravesical bacille Calmette-Guérin for superficial bladder cancer: a smoothed hazard analysis in a randomized prospective study.

OBJECTIVES: A previous meta-analysis had revealed that intravesical chemotherapy was effective in reducing the recurrence of superficial bladder cancer only in the early phase, the phase thought to be caused by tumor cell implantation and/or residual tumor cells. To ascertain the sustained prophylactic effect of intravesical bacille Calmette-Guérin (BCG) after transurethral resection of bladder tumor (TURBT), we compared the estimation of the duration of the effect with that of doxorubicin. METHODS: Eighty eligible patients with superficial bladder cancer (Stage Ta or T1, grade 1 or 2) were included. Patients were randomly allocated into two groups: the BCG group (six weekly instillations of 80 mg BCG [Tokyo 172 strain]) and the doxorubicin group (17 instillations of 20 mg doxorubicin). A comparison between the smoothed hazards of tumor recurrence was performed using a kernel function method. RESULTS: All 80 patients (40 each in the BCG and doxorubicin groups) were compared. The median follow-up period was 667 days (range 64 to 1607). The risk of recurrence was significantly lower in the BCG group than in the doxorubicin group (P = 0.017, log-rank test). A smoothed hazard curve depicting the reduced risk of recurrence in the BCG group suggested that BCG is not only efficacious in the early phase of recurrence (up to 500 days after TURBT), but also in the late phase, and the latter is thought to include second primary tumors (new tumors). CONCLUSIONS: BCG instillation may prevent tumor recurrence caused by both tumor cell implantation and second primary tumors.

[Inflammatory pseudotumor of the prostate: a case report].

We report a rare case of inflammatory pseudotumor of the prostate. A 42-year-old man with a history of hematospermia and chronic prostatitis presented with difficulty in voiding. Cystoscopy demonstrated a large non-papillary tumor occupying the prostatic urethra along with two bladder stones. Magnetic resonance imaging (MRI) demonstrated a 7-cm prostatic mass protruding toward the bladder and the rectum. Transrectal biopsy of the prostate demonstrated a fibrous lesion containing inflammatory cells without evidence of malignancy. We performed transurethral resection of the prostatic lesion to release the bladder outlet obstruction, followed by cystolithotripsy. Histopathological examination of the surgical specimen demonstrated a benign fibromuscular lesion with spindle cell proliferation, leading to a diagnosis of inflammatory pseudotumor. Postoperatively, the patient voided normally without any signs of recurrence on follow-up at five months. Inflammatory pseudotumor is an unusual benign lesion of unknown etiology. Only 10 previous cases of the disease involving the prostate have been reported in English and Japanese literature. Prostatic involvement of inflammatory pseudotumor may show a presentation similar to malignant prostatic sarcoma. Thus, accurate identification of this benign process is important in order to avoid unnecessary radical surgery.

[Carcinoma in situ of the bladder involving the prostate with an unusual invasive pattern following BCG therapy: a case report].

We report a case of carcinoma in situ (CIS) of the bladder involving the prostate with an unusual invasive pattern following Bacillus Calmette Guerin (BCG) therapy. A 41-year-old man achieved complete response after a course of intravesical instillation of BCG for diffuse CIS of the bladder. Two years later, urine cytology became positive. We performed random biopsy of the bladder and urethra three times and examined the bilateral upper urinary tract with retrograde pyelography and split urine cytology. However, none of these examinations revealed any malignant features, leading to a suspicion that the prostate was the recurrent site. Transrectal needle biopsy of the prostate revealed urothelial carcinoma (UC) at the transition between bladder and prostate. Transurethral biopsy of the prostatic urethra also detected UC in a core of the bladder neck only. Under a diagnosis of UC involving the prostate, we performed total cystectomy with ileal conduit diversion. Histopathological findings of the surgical specimen showed prostatic stromal invasion of the tumor. In this case, CIS at the bladder neck might directly and silently invade the prostatic stroma, thus transurethral biopsy contributed little to the diganosis. We recommend transrectal needle biopsy of the prostate as well as TUR biopsy in such rare cases.

Contrast-enhanced ultrasonography in the diagnosis of solid renal tumors.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of contrast-enhanced ultrasonography (CEUS) in the diagnosis of solid renal tumors. METHODS: Twenty-nine patients with solid tumors detected on gray scale ultrasonography underwent resection for suspected renal malignancy. Findings of arterial phase contrast computed tomography (CT) and CEUS were compared for each diagnosis. RESULTS: Histopathologic examination of resected lesions showed malignancy in 26 patients (clear cell carcinoma, n = 18; papillary renal cell carcinoma, n = 6; collecting duct carcinoma, n = 1; and infiltrative urothelial carcinoma, n = 1) and benign tumors in 3 patients (oncocytoma, n = 2; and angiomyolipoma, n = 1). Contrast CT failed to show tumor blood flow in 5 of 29 patients, whereas CEUS showed this in all patients. Positive predictive values of CEUS and contrast CT in the diagnosis of renal malignancy were 100% and 82.8%, respectively. Among clear cell carcinomas, hypervascularity was observed on contrast CT in 16 of 18 patients and on CEUS in 17 of 18 patients. On the basis of hypervascularity, diagnostic sensitivity values for clear cell carcinoma were 94.4% for CEUS and 88.9% for contrast CT, whereas specificity values were 45.5% for CEUS and 72.7% for contrast CT. Among papillary cell carcinomas, contrast CT showed avascular lesions in 4 of 6 patients. However, CEUS showed blood flow in these lesions, leading to diagnosis of hypovascular renal tumors. CONCLUSIONS: Contrast-enhanced ultrasonography was more sensitive for detecting slight tumor blood flow than contrast CT and was useful in preoperatively diagnosing malignant hypovascular renal tumors but was less so for hypervascular renal tumors.

[Treatment of Bacillus Calmette-Guerin refractory superficial bladder cancer: further intravesical therapy].

We here report our clinical experience with salvage therapy for patients with bacillus Calmette-Guerin (BCG)-refractory superficial bladder cancer and discuss current approaches to the disease, especially focusing on bladder preservation. First, we evaluated the efficacy of an initial 6-week course of intravesical BCG in 93 patients with carcinoma in situ (CIS) of the bladder. Of these, 91% achieved a complete response (CR) at the evaluation at 3 months. The 2- and 5-year recurrence-free rates were 71 and 67%, respectively (mean follow-up 39 months). These results support the intravesical BCG as a first-line therapy for CIS. Next, we assessed the efficacy of a second course of intravesical BCG for 16 patients who failed the initial induction course for CIS. Of these, 94% achieved CR at the evaluation at 3-month, and the 2- and 5-year recurrence-free rates were 62 and 46%, respectively (mean follow-up 28 months). None of the patients who received a second course had disease progression. Thus, a second course of BCG therapy seems to be a reasonable option for CIS patients failing the initial course. We also report our initial experience with intravesical gemcitabine therapy for 3 patients with BCG-refractory CIS of the bladder and 1 patient with recurrent multiple tumors. Gemcitabine (1500 mg in 100 ml saline) was given in the bladder for 1 hour twice weekly for a total of 12 treatments. The treatment was associated with minimal bladder irritation and systemic absorption, and was well tolerated except in a 90-year-old man who discontinued therapy because of grade 2 toxicity. Two patients achieved CR and maintained a tumor-free status beyond 14 months, suggesting that the intravesical gemcitabine is a promising salvage therapy for BCG-refractory superficial bladder cancer.

[Radical cystectomy for invasive bladder carcinoma in patients 75 years old or older].

Between 1995 and 2004, 43 patients underwent radical cystectomy and urinary diversion for the treatment of invasive bladder cancer at our institution. Of these patients, seven who were 75 years old or older, were considered elderly. Survival and treatment outcome of these patients were compared to younger counterparts stratified into three groups by age at diagnosis (12 patients younger than 64, 12 patients 65 to 69 years, and 12 patients 70 to 74 years). Preoperative morbidity was encountered in 57% of the elderly patients, and 42% of the elderly patients had two or more complications. There was one operative death (14%) among the elderly patients but no such deaths in the 3 younger groups. The postoperative complication rate for patients age 75 years or older was 86%, compared to 75% for patients younger than 64, 75% for those age 65 to 69 and 83% for those age 70-74. The prevalence did not differ significantly between the older and youger patients. There were no cancer deaths among the elderly patients, but 8 of the 36 younger patients died of cancer. The cancer-specific 5-year survival rate was 100% at 34 months in the elderly population. These findings suggest that radical cystectomy and urinary diversion is a relatively safe procedure and a curative operation is worth attempting in elderly patients with invasive bladder cancer, if they are in generally good health.

[Pyoderma gangrenosum of the penis presenting as Fournier's gangrene: a case report].

We report a case of pyoderma gangrenosum of the penis presenting as Fournier's gangrene. A 77-year-old man who had undergone radiotherapy for localized prostate cancer 16 month earlier, presented with penile pain and fever. Symptoms began with erythema and induration on the dorsal surface of the penile shaft followed by spontaneous purulent drainage with severe pain. Magnetic resonance imaging was unremarkable except for swelling of the penile skin. Biopsy of the ulcerative penile lesion demonstrated a nonspecific inflammation without vasculitis or malignancy. Despite broad-spectrum antibiotics and debridement, the penile lesion extended and new satellite lesions developed as pustules on the glans. Since cultures were negative for aerobic and anaerobic bacteria, a course of intravenous prednisolone was then initiated at 100 mg/day. Within 24 hours the temperature normalized, progression of the penile lesions stopped and became convalescent. The steroid was then tapered and discontinued. The penile lesions healed slowly during the subsequent 1-month period. Based on the clinical course and histopathological findings as well as exclusion of other ulcerative conditions, a diagnosis of pyoderma gangrenosum was made. Penile involvement of this non-infectious ulcerating skin disease has rarely been reported. Pyoderma gangrenosum affecting the penile skin, such as that in present case, may show a similar presentation as Fournier's gangrene. Prompt differential diagnosis is mandatory since effective management for each processes is markedly different.

[Future perspective on the prevention of nephrolithiasis].

Renal stone formation has been explained by the physicochemical theory; i.e., nucleation, growth and aggregation of crystals in the urine. Current medical prevention is based on this theory and seeks to modulate promoters and inhibitors of stone formation. Recent studies have identified increasing numbers of macromolecular inhibitors such as glycosaminoglycans, bikunin, osteopontin and urinary prothrombin F1. These appear to be more important than low-molecular inhibitors like citrate. On the other hand, many investigators have focused on the role of tubular epithelial cells in stone formation. While crystal retention in the nephron has been considered necessary for stone formation, we and others have found that calcium oxalate crystals can bind to renal epithelial cells. Moreover, available evidence suggests that oxalate and/or calcium oxalate crystals can damage renal epithelial cells and enhance crystal binding. Concurrently, oxalate exposure induces genes coding macromolecular inhibitors, which are supposed to be a protective mechanism against stone formation. Thus, understanding of the mechanisms involved in kidney stone formation could lead to new therapeutic approaches to preventing stone recurrence. However, clinical application of the prophylactic approaches proposed here awaits further progress in basic research using rapidly growing new technologies. Application of the DNA microarray technique to the rat stone model may provide a clue to understanding stone forming process at the genetic level. In addition, case-control association analysis using single nucleotide polymorphism as a marker may be useful for detecting susceptibility genes in patients with calcium stone disease.

Down-regulation of drs mRNA in human prostate carcinomas.

We have previously reported that the drs gene has the ability to suppress transformation by v-src and v-K-ras in the rat cell line F2808. We have also shown that the expression of drs mRNA is markedly reduced in a variety of human cancer cell lines, suggesting that down-regulation of drs mRNA is correlated with the development of human cancers. To clarify the role of the drs gene in prostate carcinogenesis, we examined the expression of the drs gene in 3 normal prostate, 13 prostate carcinoma, 5 benign prostate hyperplasia (BPH), and 2 prostatic intraepithelial neoplasia (PIN) tissue specimens by in situ hybridization and in 3 prostate carcinoma cell lines (PC3, LNCaP, and DU145) and 2 BPH tissues by Northern blot analysis. Furthermore, the deletion, and rearrangement of the drs gene were analyzed by Southern blot analysis. The drs mRNA was significantly expressed in normal prostate and BPH tissues, whereas it was markedly down-regulated in prostate carcinoma tissues and prostate carcinoma cell lines. In 2 tissues from PIN, drs mRNA was weakly expressed. There were no differences between prostate carcinoma cell lines and BPH tissues in terms of their banding patterns of Southern blot analysis. These results indicate that down-regulation of drs mRNA is closely correlated with development of prostate carcinoma, suggesting a tumor-suppressor function of the drs gene in this cancer.