Faculty Bibliography

We investigated the role of alterations of HDM2, the human homologue of murine mdm2, in the tumorigenesis and progression of cutaneous melanoma. A well-characterized cohort of 172 cases representing different points in the spectrum of melanocyte transformation (16 dysplastic nevi, 11 melanomas in situ, 107 invasive primaries, and 38 metastatic lesions), as well as 11 human melanoma cell lines were examined by immunohistochemistry and Western blotting for HDM2 protein expression, and by either Southern blotting (SB) or fluorescence in situ hybridization for HDM2 gene amplification. HDM2 overexpression, defined as >20% tumor cells showing nuclear immunoreactivity, was observed in 1 of 16 (6%) dysplastic nevi, 3 of 11 (27%) melanomas in situ, and 81 of 145 (56%) invasive primary and metastatic melanomas. Comparable frequencies of HDM2 overexpression were observed among invasive primary cases with differing tumor thicknesses as well as among the metastatic cases: 21 of 40 (53%) at < or =1.5 mm; 31 of 50 (62%) at 1.6-3.9 mm; 10 of 17 (58%) at >4 mm; and 19 of 38 (50%) metastases. HDM2 amplification was observed in 1 of 88 (1%) primary cases using fluorescence in situ hybridization, and in 0 of 12 (0%) metastatic cases that overexpressed HDM2 using SB. Melanoma cell lines expressed HDM2 protein, but there was no evidence of amplification by SB. Our data suggest that HDM2 protein overexpression is common in invasive and metastatic melanoma. Observing HDM2 overexpression in noninvasive melanoma suggests that expression of this oncogene may play an early role in melanocyte transformation. HDM2 amplification occurs infrequently, and other mechanisms that up-regulate HDM2 expression are under investigation

PURPOSE: Amplification of HER-2/neu gene and overexpression of its encoded product, the p185neu (HER-2/neu) tyrosine kinase membrane receptor, have been associated with tumor progression in certain neoplasms. We conducted this study to investigate patterns of HER-2/neu protein expression in prostate cancer, analyzing different points in the natural and treated history of the disease. EXPERIMENTAL DESIGN: Radical prostatectomy cases (83) and 20 metastatic lesions were studied for the association between HER-2/neu protein overexpression detected by immunohistochemistry and clinicopathological parameters, including time to prostate-specific antigen (PSA) relapse. RESULTS: HER-2/neu protein overexpression, defined as complete membrane staining in >10% of tumor cells using the Food and Drug Administration-approved Dako kit, was found in 9 of 45 (20%) of evaluable hormone naive primary tumors and 23 of 34 (67%) primary tumors after androgen-deprivation therapy (P = 0.0001). Of the 20 metastatic lesions, positivity was noted in 16 (80%) of the cases. On univariate analysis, HER-2/neu overexpression was associated with pretreatment PSA (P = 0.011) and time to PSA relapse (P = 0.02). After controlling for pretreatment PSA, the association between hormone treatment and HER-2/neu was still observed. No association was found between HER-2/neu overexpression and Gleason score, capsular invasion, and tumor proliferative index determined by Ki67. CONCLUSIONS: These data suggest that there is significant HER-2/neu overexpression in primary tumors that persist after androgen deprivation. It also emphasizes the importance of characterizing tumors at determined points in the natural or treated history of prostate cancer when targeting treatment to specific biological processes

Cyclin D1 is a key regulator of the G1 phase progression of the cell cycle. There is increasing evidence that deregulated cyclin D1 expression is implicated in tumorigenesis and tumor progression in certain neoplasms. Recently, it has been reported that cyclin D1 overexpression might be related to the evolution of androgen-independent disease in prostate cancer. This study was conducted to investigate patterns of cyclin D1 expression in prostate cancer samples representing different points in the natural history and treatment evolution of the disease. Association with clinical outcomes was also explored. Using immunohistochemistry, 86 radical prostatectomy specimens (53 naive and 33 after androgen deprivation) and 22 androgen-independent bone metastases were studied. We examined the difference in cyclin D1 expression in primary versus metastatic cases. In addition, we examined the association in primary cases between cyclin D1 expression and clinicopathological parameters of poor clinical outcome, including time to prostate-specific antigen relapse and Ki67 proliferative index. Cyclin D1-positive phenotype, defined as identification of positive immunoreactivity in the nuclei of > or =20% of tumor cells, was observed in 10 of 86 (11%) primary cases compared with 15 of 22 (68%) androgen-independent bone metastases (P = 0.001). There was no correlation between cyclin D1 overexpression and either Gleason score, neo-adjuvant hormone treatment, or prostate-specific antigen relapse We observed a statistical association between cyclin D1 overexpression and high Ki67 proliferative index, defined as > or =20% of positive tumor cells (P = 0.02). These data support the hypothesis that cyclin D1 overexpression may represent an oncogenic event in androgen-independent metastatic prostate cancer to the bone

The evaluation of new therapies in prostate cancer requires unique end points for agents with diverse mechanisms of action. Because retinoic acid may have a confounding effect on prostate-specific antigen, we incorporated a pathological end point into the outcome assessment of two sequential clinical trials using all-trans-retinoic acid (ATRA) and the combination of 13-cis-retinoic acid and IFN-2a (cRA inverted question markIFN). Pre- and posttherapy tumor biopsy specimens were studied for histological changes, apoptosis (terminal deoxynucleotidyl transferase-mediated nick end labeling assay), and proliferation index (Ki67). Prostate-specific membrane antigen (PSMA) expression was also evaluated using two different monoclonal antibodies to its intracellular domain (Cytogen 7E11 and Hybritech PM2). Fourteen patients with androgen-independent disease were treated with ATRA (50 mg/m2 p.o. every 8 h daily) and 16 androgen-independent and 4 androgen-dependent patients were treated with cRA inverted question markIFN (10 mg/kg/day cRA plus 3, 6, or 9 million units daily IFN). Both therapies were well tolerated, with fatigue and cheilitis being the most common adverse events. Clinical activity, assessed by radiographs and serum prostate-specific antigen, was minimal, and the majority of patients progressed within 3 months. One patient with androgen-dependent disease had prolonged stabilization for >1 year. The majority of cases (95%) showed no gross histological changes and no difference in apoptotic or proliferative indices. Increased PSMA immunoreactivity was seen in seven of nine (78%) cases using PM2 antibody and in two of nine (22%) cases using the 7E11 antibody. Although antitumor effects were modest, the results suggest a role for retinoids in modulating the expression of PSMA on prostate cancer cells

To determine the potential role of p53 inactivation in prostate cancer, we studied a well characterized cohort of 86 patients treated with radical prostatectomy. We analyzed patterns of p53, mdm2, and p21/WAF1 expression by immunohistochemistry. Results were then correlated with clinicopathological parameters of poor outcome, including time to PSA relapse. In addition, data were also correlated with proliferative index, as assessed by Ki67 antigen detection. p53-positive phenotype, defined as identification of nuclear immunoreactivity in > 20% of tumor cells, was observed in 6 of 86 cases (7%). An association was observed between p53-positive phenotype and decreased time to PSA relapse (P < 0.01). mdm2-positive phenotype, defined as > or = 20% of tumor cells displaying nuclear immunoreactivity, was observed in 28 of 86 cases (32.5%). mdm-2-positive phenotype was found to be associated with advanced stage (P = 0.009). p21-positive phenotype, defined as > 5% of tumor cells with nuclear immunoreactivity, was observed in 28 of 86 cases (32.5%). An association was observed between p21-positive phenotype and high Ki67 proliferative index (P = 0.002). Patients with p21-positive phenotype had a significant association with decreased time to PSA relapse (P = 0.0165). In addition, a significant association was found between p21-positive phenotype and coexpression of mdm2 (P < 0.01). Forty-three of 86 cases (50%) were found to have one or more alterations, and patients with any alteration were found to have a higher rate of PSA relapse (P < 0.01). It is our hypothesis that a pathway of prostate cancer progression involves p53 inactivation caused by mdm2 overexpression and that p21 transactivation in this setting is due to an alternative signaling system, rather than through a p53-dependent mechanism

The present study was performed to detect circulating prostatic carcinoma (PC) cells using a novel three-step immunobead reverse transcriptase (RT) polymerase chain reaction (PCR) assay for prostatic specific membrane antigen (PSMA) messenger RNA (mRNA). The sensitivity and specificity of this technique was assessed and the incidence of immunobead RT-PCR positivity correlated with progressive metastatic disease and serum prostatic specific antigen (PSA) levels. Fifty peripheral blood (PB) samples from 46 patients with PC were incubated with magnetic beads coated with Ber-EP4 antibody directed against the human epithelial antigen a membrane antigen widely expressed by epithelial cells. The epithelial cell-enriched magnetic fraction was then subjected to mRNA isolation using oligo-deoxythymidine (dT) magnetic beads. Nested RT-PCR for PSMA was performed on the mRNA oligo-dT complex and the identity of the RT-PCR products was confirmed by Southern blotting. Twenty-one PB samples from 8 control subjects without PC were also evaluated. Three-step immunobead PSMA RT-PCR was able to detect one PC cell per 1 mL of PB. The positivity rate of the RT-PCR assay was significantly higher (11 of 25; 44%) in patients with metastatic tumor than in patients with non-metastatic disease (1 of 21; 5%) (P = 0.003). In patients with metastatic PC, RT-PCR positivity was much higher in patients with progressive disease (10 of 13; 77%) than in patients with responding or stable disease (1 of 12; 8%) (P = 0.001). There was a statistically significant correlation between immunobead PSMA PCR positivity and high levels of serum PSA (P = 0.005). All control subjects without PC tested negative for PSMA PCR. The three-step immunobead RT-PCR for PSMA can detect circulating PC cells with high specificity and sensitivity. Preliminary data show a strong correlation between immunobead PCR positivity, the presence of progressive metastatic disease, and high levels of serum PSA

Metabolic imaging with positron emission tomography (PET) for the staging and monitoring of treatment response has important implications in clinical oncology. The choice of radiotracer is likely to be critically important. The objective of our study was to compare the pharmacokinetics of C-11-methionine with FDG in a group of androgen independent patients with metastatic prostate cancer, to determine the differential metabolism of the two tracers, and to determine the optimal time of imaging after injection in treated and untreated patients. A total of 29 dynamic scans (19 pretreatment and 10 posttreatment) were performed in 10 patients with progressive or new lesions on bone scans (index lesions). A total of 13 index lesions were identified in baseline scans. Patients were infused with 370 MBq C-11-methionine on the couch and 32 dynamic images acquired over 60 minutes. After at least 5 half-lives of C-11, patients were then dynamically imaged (15 frames) for 45 minutes with FDG. Index lesions demonstrated both C-11-methionine (13/13) and FDG uptake (12/13). The plateau of methionine uptake in tumor was reached by 10 minutes, and thereafter remained constant. FDG tumor uptake was slower and for some patients continued to rise beyond 45 minutes. The clearance of blood activity for C-11-methionine was more rapid than FDG and the plateau was 10 and 45 minutes respectively. In 5 patients scanned after therapy, 4 responded to treatment, which was reflected by a corresponding decrease in C-11-methionine and FDG tumor uptake. No change was observed in the relative shape of the uptake curves however, between the C-11-methionine and the FDG uptake, either in the 4 who responded to treatment or for one patient who did not respond. The SUV of C-11-methionine was significantly higher than for FDG (P <.008). Both C-11-methionine and FDG are taken up in index lesions in patients with progressive prostate cancer. The advantages of C-11-methionine over FDG are the higher tumor to blood ratio, the more rapid tumor uptake allowing earlier imaging, and a flatter plateau rendering lesion activity on whole body images more uniform and less susceptible to gradual change than FDG. This indicates the feasibility of whole body PET imaging with decay corrected C-11-methionine. Additional studies are planned to define optimal imaging times after different therapies in comparison to FDG and bone scans

The INK4A gene maps to the 9p21 region and was initially described [M. Serrano et al., Nature (Lond.), 366: 704-707, 1993; A. Kamb et al., Science (Washington DC), 264: 436-440, 1994] as encoding a 148-amino-acid protein termed p16. The p16 protein associates exclusively with Cdk4 and Cdk6, inhibiting their complexation with D-type cyclins and the consequent phosphorylation of pRb. This contributes to cell cycle arrest. The purpose of the present study was to evaluate patterns of p16 expression in a well-characterized cohort of prostatic adenocarcinomas while exploring potential associations between alterations of p16 and clinicopathological variables. Normal and malignant tissues from 88 patients with prostate carcinoma were examined. In situ hybridization and immunohistochemistry assays were used to determine the status of the INK4A exon 1alpha transcripts and levels of p16 protein, respectively. Associations between altered patterns of expression and clinicopathological variables, including pretreatment prostate-specific antigen (PSA) level, Gleason grade, pathological stage, and hormonal status, were evaluated using the Mantel-Haenszel chi2 test. Biochemical (PSA) relapse after surgery was evaluated using the Kaplan-Meier method and the log-rank test. Levels of p16 expression and INK4A exon 1alpha transcripts in normal prostate and benign hyperplastic tissues were undetectable. However, p16 nuclear overexpression was observed in 38 (43%) prostate carcinomas, whereas the remaining 50 (57%) cases showed undetectable p16 levels. Overexpression of p16 protein was found to correlate with increased INK4A exon 1alpha transcripts. Moreover, p16 overexpression was associated with a higher pretreatment PSA level (P = 0.018), the use of neoadjuvant androgen ablation (P = 0.001), and a sooner time to PSA relapse after radical prostatectomy (P = 0.002). These data suggest that p16 overexpression is associated with tumor recurrence and a poor clinical course in patients with prostate cancer

BACKGROUND: The p27KIP1 gene, whose protein product is a negative regulator of the cell cycle, is a potential tumor suppressor gene; however, no tumor-specific mutations of this gene have been found in humans. This study was undertaken to identify and to assess potential alterations of p27KIP1 gene expression in patients with benign prostatic hyperplasia (BPH) and patients with prostate cancer. METHODS: We analyzed 130 prostate carcinomas from primary and metastatic sites, as well as prostate samples from normal subjects and from patients with BPH. Immunohistochemistry and in situ hybridization were used to determine the levels of expression and the microanatomical localization of p27 protein and messenger RNA (mRNA), respectively. Immunoblotting and immunodepletion assays were performed on a subset of the prostate tumors. Associations between alterations in p27KIP1 expression and clinicopathologic variables were evaluated with a nonparametric test. The Kaplan-Meier method and the logrank test were used to compare disease-relapse-free survival. Prostate tissues of p27Kip1 null (i.e., knock-out) and wild-type mice were also evaluated. RESULTS: Normal human prostate tissue exhibited abundant amounts of p27 protein and high levels of p27KIP1 mRNA in both epithelial cells and stromal cells. However, p27 protein and p27KIP1 mRNA were almost undetectable in epithelial cells and stromal cells of BPH lesions. Furthermore, p27Kip1 null mice developed enlarged (hyperplastic) prostate glands. In contrast to BPH, prostate carcinomas were found to contain abundant p27KIP1 mRNA but either high or low to undetectable levels of p27 protein. Primary prostate carcinomas expressing lower levels of p27 protein appeared to be biologically more aggressive (two-sided P = .019 [Cox regression analysis]). CONCLUSIONS/IMPLICATIONS: On the basis of these results, we infer that loss of p27Kip1 expression in the human prostate may be causally linked to BPH and that BPH is not a precursor to prostate cancer

Uroplakins (UPs) are integral membrane proteins that are synthesized as the major differentiation products of mammalian urothelium. We have cloned the human UP-II gene and localized it on chromosome 11q23. A survey of 50 transitional cell carcinomas (TCCs) revealed a UP-II polymorphism but no tumor-specific mutations. Immunohistochemical staining using rabbit antisera against a synthetic peptide of UP-II and against total UPs showed UP reactivity in 39.5% (17 of 43 cases) of conventional TCCs, 12.8% (5 of 39) of bilharzial-related TCCs, and 2.7% (1 of 36) of bilharzial-related squamous cell carcinomas (SCCs). The finding that fewer bilharzial TCCs express UPs than conventional TCCs (12.8 versus 40%) raised the possibility that the former are heterogeneous, expressing SCC features to varying degrees. Our data strongly support the hypothesis that urothelium can undergo at least three pathways of differentiation: (a) urothelium-type pathway; (b) epidermis-type pathway; and (c) glandular-type pathway, characterized by the production of UPs, K1/K10 keratins, and secreted glycoproteins, respectively. Vitamin A deficiency and mesenchymal factors may play a role in determining the relative contributions of these pathways to urothelial differentiation as well as to the formation of TCC, SCC, and adenocarcinoma, or a mixture thereof