Faculty Bibliography

Our purpose was to determine the clinical relevance of the detection of circulating tumor cells (CTCs) expressing urothelial and epithelial markers in bladder cancer patients. Sixty-two patients who presented to Memorial Sloan-Kettering Cancer Center between July 2000 and September 2001 were studied. Peripheral blood was tested by nested RT-PCR assay for uroplakins (UPs) Ia, Ib, II and III as well as for epidermal growth factor receptor (EGFR). We determined the sensitivity and specificity of each individual marker and the combinations of UPIa/UPII and UPIb/UPIII. The latter strategy was based on our data, which showed that UPIa and UPIb form heterodimers with UPII and UPIII, respectively. Forty patients had clinically advanced bladder cancer and 22 had no evidence of disease at the time of assay. Eight of the 22 patients recurred during the follow-up period. All 8 patients were positive at presentation for UPIa/UPII. The combination of UPIa/UPII provided the best sensitivity (75%) of detecting CTCs, with a specificity of 50%. The combination of UPIb/UPIII was the most specific (79%) but had modest sensitivity (31%). Detection of EGFR-positive cells alone and in combination with UPs was inferior to that for UPIa/UPII. Combinations of urothelial markers are superior to single urothelial or epithelial markers in detecting CTCs in bladder cancer patients. Further efforts are under way to confirm the potential predictive value of these markers in a prospectively designed study of a larger cohort of patients.

PURPOSE: Neutral endopeptidase (NEP) is a cell-surface peptidase that inactivates neuropeptide growth factors implicated in prostate cancer progression. The clinical significance of decreased NEP expression observed in prostate cancer is unclear. We investigated whether decreased NEP expression in localized prostate cancers is associated with prostate-specific antigen (PSA) relapse after radical prostatectomy. EXPERIMENTAL DESIGN: NEP expression patterns were examined by immunohistochemistry in 223 men, who underwent radical prostatectomy between 1990 and 2000 at the Veterans Administration Medical Center (New York, NY) with available representative tissues and adequate follow up. We also examined whether hypermethylation of the NEP promoter contributes to down-regulation of NEP protein expression in a subset of patients that showed decreased NEP expression (n = 22). RESULTS: Three patterns of NEP expression were observed: (a) membranous expression similar to benign prostate epithelium (n = 82; 37%); (b) complete loss of NEP expression in prostate cancer compared with adjacent benign prostate glands (n = 105; 47%); and (c) heterogeneous NEP expression (n = 36; 16%). In a multivariate analysis, complete loss of NEP expression was associated with PSA relapse after controlling for grade, stage, pretreatment PSA, and race simultaneously (hazard ratio, 1.99; 95% confidence interval, 1.13-3.52; two-sided chi(2) P = 0.017). In addition, DNA hypermethylation of the NEP promoter was frequently (73%) identified in a subset of 22 of cases that showed decreased NEP expression. CONCLUSION: Our data suggest that decreased NEP expression might contribute to progression of localized prostate cancer after surgery. Data also suggest that methylation is an important mechanism of NEP protein silencing. Larger prospective studies are required for confirmation

PURPOSE: The protein encoded by N-myc downstream-regulated gene 1 (NDRG1) is a recently discovered protein whose transcription is induced by androgens and hypoxia. We hypothesized that NDRG1 expression patterns might reveal a biological basis for the disparity of clinical outcome of prostate cancer patients with different ethnic backgrounds. EXPERIMENTAL DESIGN: Patients who underwent radical prostatectomy between 1990 and 2000 at Veterans Administration Medical Center of New York were examined. We studied 223 cases, including 157 African Americans and 66 Caucasians (T2, n = 144; >/=T3, n = 79; Gleason <7, n = 122; >/=7, n = 101). Three patterns of NDRG1 expression were identified in prostate cancer: (a) intense, predominately membranous staining similar to benign prostatic epithelium; (b) intense, nucleocytoplasmic localization; and (c) low or undetectable expression. We then examined the correlations between patients' clinicopathological parameters and different NDRG1 expression patterns. RESULTS: In this study of patients with equal access to care, African-American ethnic origin was an independent predictor of prostate-specific antigen recurrence (P < 0.05). We also observed a significant correlation between different patterns of NDRG1 expression and ethnic origin. Pattern 2 was less frequent in African Americans (21% versus 38%), whereas the reverse was observed for pattern 3 (60% in African Americans versus 44% in Caucasians; P = 0.03). This association remained significant after controlling for both grade and stage simultaneously (P = 0.02). CONCLUSIONS: Our data suggest that different NDRG1 expression patterns reflect differences in the response of prostatic epithelium to hypoxia and androgens in African-American compared with Caucasian patients. Further studies are needed to determine the contribution of NDRG1 to the disparity in clinical outcome observed between the two groups

We examined mutations in BRAF exons 11 and 15 and N-RAS exons 2 and 3, in 77 metastatic melanoma cases and 11 melanoma cell lines. Significant differences in the mutation rates observed at different metastatic sites could not be detected. The most frequent mutation, the V599E amino acid substitution in BRAF exon 15, was observed in 31 of 77 (40%) tissues and 5 of 11 (45%) cell lines. Tandem base-pair substitutions encoding V599R and V599K amino acid changes were observed in two cases. Novel findings with respect to melanoma include a cell line possessing a 2 base-pair substitution in BRAF exon 11 and a case harboring mutations in both BRAF exon 11 and N-RAS exon 3. Our data show that BRAF mutation is common in melanoma metastases, regardless of their site, that mutations include both exons 11 and 15, and suggest that anti-RAS/RAF strategies may be effective in metastatic melanoma patients

PURPOSE: The purpose is to investigate the clinical relevance of altered patterns of p27 and Skp2 expression in African-American patients with localized prostate cancer. The abundance of p27, an inhibitor of cell proliferation, is controlled by Skp2-dependent proteolysis. EXPERIMENTAL DESIGN: A well-characterized cohort of 162 African-Americans who underwent radical prostatectomy at the Veterans Affairs Medical Center of New York between 1990 and 2000 was studied. We analyzed p27 and Skp2 expression by immunohistochemistry. Altered expression of p27 (defined as <40% tumor cells expressing the protein) and Skp2 (defined as > or ==' BORDER='0'>20% tumor cells expressing the protein) were correlated with clinicopathological parameters and time to prostate-specific antigen (PSA) recurrence. RESULTS: Altered expression of p27 and Skp2 was observed in 112 of 162 (69.1%) and 93 of 162 (57.4%) cases, respectively. Inverse patterns of Skp2 and p27 protein expression were seen in 87 of 162 (53.7%) cases. A marginally significant association was found between Skp2 overexpression and extracapsular extension (P = 0.065). Moreover, patients with Skp2 overexpression had a 2.77 years decreased median time to PSA recurrence compared with patients with low Skp2 expression; however, the difference was not statistically significant. In multivariate analysis, only tumor grade and stage independently predicted PSA recurrence in this cohort. CONCLUSIONS: Our data suggest a role for Skp2 overexpression in prostate cancer pathogenesis that might not be exclusively related to p27 degradation. More studies are needed to determine the mechanistic role of Skp2 in prostate cancer

Overexpression of the oncogene HDM2 is observed in a substantial proportion of melanomas, including noninvasive and thin lesions, suggesting that HDM2 overexpression may be an early event in melanocyte transformation. To determine the role of HDM2 in the clinical progression of melanoma, we examined whether its expression was associated with patient survival. From November 1972 through November 1982, 134 patients with melanoma who participated in the New York University Melanoma Cooperative Group were studied, if representative tissues and follow-up were available. HDM2 protein expression was assessed immunohistochemically. Unexpectedly, we observed that HDM2 overexpression was statistically significantly associated with improved disease-free survival (relative risk [RR] = 0.47, 95% confidence interval [CI] = 0.24 to 0.89; two-sided chi(2) P =.021) and overall survival (RR = 0.55, 95% CI = 0.33 to 0.94; two-sided chi(2) P =.027) in multivariable analysis. HDM2 overexpression appears to be an independent predictor of survival for patients with primary melanoma; however, larger prospective studies are required for validation