Faculty Bibliography

To elucidate the mechanism of androgen-dependent cellular proliferation in prostate cancer, androgen-dependent alterations of individual cell cycle regulatory proteins in the androgen-sensitive prostate cancer cell line LNCaP were evaluated. LNCaP cells were deprived of androgens by culture in steroid-depleted media for 5 days, which resulted in the maximal accumulation of cells in G(0)/G(1) phase of the cell cycle. The mitogenic concentration of the synthetic androgen R1881 was established as 0.1 nM using cell proliferation assay. Protein and mRNA levels of particular cyclins, cyclin-dependent kinases (Cdks), cyclin-dependent kinase inhibitors (Ckis), and the retinoblastoma proteins (Rb) were assessed. Androgen stimulation resulted in a post-transcriptional reduction in Rb protein levels, an increase in Rb phosphorylation at serine 780 and an accumulation of high molecular weight Rb protein species. Androgen stimulation also induced the expression of the Cdk2 and Cdk1 as well as their regulatory partners, cyclin A and cyclin B, resulting in a corresponding increase in cyclin A/Cdk2 activity in vitro. Pulse-chase showed decreased Rb protein stability in androgen-treated LNCaP cells. Collectively, our findings suggest a novel mechanism of androgen-dependent prostate cancer growth in which androgen stimulation results in decreased Rb protein expression in LNCaP cells. The observation of decreased Rb protein stability in the setting of increased phosphorylation supports the concept of phosphorylation mediated protein degradation. We propose that the observed reduction in Rb protein level occurs through Rb degradation via the ubiquitin/proteasome pathway, and is preceded by selective Rb phosphorylation by cyclin A/Cdk2 and cyclin B/Cdk1

PURPOSE: We determine whether site specific labeling of sextant prostate biopsy cores predicts the site of extracapsular extension in a radical prostatectomy specimen, thereby justifying increased cost of pathological evaluation. MATERIALS AND METHODS: Between January 1994 and December 1997, 407 radical prostatectomies were performed at our institution by a single surgeon (H. L.). Surgical specimens showing extracapsular extension were examined by a single pathologist (J. M.) to identify the site of extension. Several different methods of submitting transrectal ultrasound guided biopsy cores were used since the majority of cases did not undergo biopsy at our institution. In 243 cases sextant biopsies were labeled right versus left. Of these cases 103 specimen cores were individually labeled. The ability of the positive biopsy core location to predict the location of extracapsular extension in the surgical specimen was determined. Univariate and multivariate logistic regression analyses were performed to assess the ability of biopsy core characteristics, including Gleason score, percentage of cancer in the core, core location and number of positive cores in the specimen, to predict the site of extracapsular extension. A similar analysis was performed for the 243 cases with right versus left core labeling. RESULTS: The positive predictive value was 8.9+/-2.2% for a single positive core to identify the location of extracapsular extension correctly in the individually labeled core cases. The absence of cancer in a sextant biopsy had a negative predictive value of 96.9+/-1.4%. The overall sensitivity was 59.4+/-3.8% for a positive biopsy core. In the right versus left core cases the positive predictive value was 12.9+/-3.0% with a sensitivity of 85.1+/-3.2%. In an individual core Gleason score 8 or greater and/or cancer in more than 50% of tissue enhanced the positive predictive value but not to a clinically useful level. Multivariate logistic regression identified Gleason score, number of positive ipsilateral cores and base position of the positive biopsy as the most predictive variables for the site of extracapsular extension. CONCLUSIONS: When submitting biopsy specimens by individually labeled core or right versus left core, the positive predictive value of an individual positive core for the location of extracapsular extension is not sufficient to guide the surgical decision to spare or excise a neurovascular bundle. Therefore, the clinical information provided by individually labeled or right versus left core labeling does not justify the increased associated costs

PURPOSE: Although transitional cell carcinoma of the bladder (TCC) metastasizes frequently with devastating consequences, no marker has been available to monitor this process. Uroplakins are a group of specific markers for normal urothelium and are continuously expressed by the majority of TCCs. Detection of uroplakin-positive cells in the circulation would be a strong indication of hematogenous dissemination of tumor cells in patients with TCC. MATERIALS AND METHODS: Total RNAs were extracted from peripheral blood of 60 patients with TCC (50 non-metastatic and 10 metastatic) and 10 healthy controls, reverse-transcribed and subjected to polymerase chain reaction amplification (RT-PCR) using oligonucleotide primers of human uroplakin II gene. A uroplakin-expressing human bladder cancer cell line (RT4) was used as a positive control to establish the sensitivity of the RT-PCR assay. RESULTS: We showed that the PCR-amplification of the mRNA encoding uroplakin II (UPII), a 15-kDa urothelium-specific marker, constitutes a highly sensitive and specific assay for detecting 100% of transitional cell carcinoma tissue, and that this assay can detect a single bladder cancer cell in a 5-ml. blood sample. UPII mRNA was detected in the blood samples of 2 patients with metastatic bladder cancer without chemotherapy and 1 out of 8 such patients with chemotherapy, but not in those of 50 non-metastatic patients or normal controls. CONCLUSIONS: Uroplakin II is a highly specific marker for human TCC and the detection of uroplakin II in the peripheral blood is associated with metastatic spread of bladder cancer cells. The specific and sensitive detection of uroplakin II provides a useful adjunct for detecting bladder cancer metastasis, staging, and monitoring chemotherapeutic response

Prostate cancer is the most common neoplasm in men and a significant cause of mortality in affected patients. Despite significant advances, current methods of treatment are effective only in the absence of metastatic disease. Gene therapy offers a renewed hope of using the differential characteristics of normal and malignant tissue in constructing treatment strategies. Several clinical trials in prostate cancer gene therapy are currently under way, using immunomodulatory genes, anti-oncogenes, tumor suppressor genes and suicide genes. A continued understanding of the etiological mechanisms involved in the establishment and progression of prostate cancer, along with advances in gene therapy technology, should make gene therapy for prostate cancer therapeutically valuable in the future