Ribonuclear foci at the neuromuscular junction in myotonic dystrophy type 1.

In myotonic dystrophy type 1 (DM1) the muscle fibers express RNA containing an expanded CUG repeat (CUG(exp)). The CUG(exp) RNA is retained in the nucleus, forming ribonuclear foci. Splicing factors in the muscleblind (MBNL) family are sequestered in ribonuclear foci, resulting in abnormal regulation of alternative splicing. In extrajunctional nuclei, these effects on splicing regulation lead to reduced chloride conductance and altered insulin receptor signaling. Here we show that CUG(exp) RNA is also expressed in subsynaptic nuclei of muscle fibers and in motor neurons in DM1, causing sequestration of MBNL1 protein in both locations. In a transgenic mouse model, expression of CUG(exp) RNA at high levels in extrajunctional nuclei replicates many features of DM1, but the toxic RNA is poorly expressed in subsynaptic nuclei and the mice fail to develop denervation-like features of DM1 myopathology. Our findings indicate that subsynaptic nuclei and motor neurons are at risk for DM1-induced spliceopathy, which may affect function or stability of the neuromuscular junction.

A preoperative nomogram for disease recurrence following radical prostatectomy for prostate cancer.

BACKGROUND: Few published studies have combined clinical prognostic factors into risk profiles that can be used to predict the likelihood of recurrence or metastatic progression in patients following treatment of prostate cancer. We developed a nomogram that allows prediction of disease recurrence through use of preoperative clinical factors for patients with clinically localized prostate cancer who are candidates for treatment with a radical prostatectomy. METHODS: By use of Cox proportional hazards regression analysis, we modeled the clinical data and disease follow-up for 983 men with clinically localized prostate cancer whom we intended to treat with a radical prostatectomy. Clinical data included pretreatment serum prostate-specific antigen levels, biopsy Gleason scores, and clinical stage. Treatment failure was recorded when there was clinical evidence of disease recurrence, a rising serum prostate-specific antigen level (two measurements of 0.4 ng/mL or greater and rising), or initiation of adjuvant therapy. Validation was performed on a separate sample of 168 men, also from our institution. RESULTS: Treatment failure (i.e., cancer recurrence) was noted in 196 of the 983 men, and the patients without failure had a median follow-up of 30 months (range, 1-146 months). The 5-year probability of freedom from failure for the cohort was 73% (95% confidence interval = 69%-76%). The predictions from the nomogram appeared accurate and discriminating, with a validation sample area under the receiver operating characteristic curve (i.e., comparison of the predicted probability with the actual outcome) of 0.79. CONCLUSIONS: A nomogram has been developed that can be used to predict the 5-year probability of treatment failure among men with clinically localized prostate cancer treated with radical prostatectomy.

DNA ploidy by image analysis of individual foci of prostate cancer: a preliminary report.

The malignant potential of an individual focus of prostate cancer is difficult to determine. The established pathological features associated with malignant behavior include tumor volume, grade, and invasiveness (local extension or metastasis). We used nuclear image analysis to determine the DNA ploidy value of each cancer in a series of 30 radical prostatectomy specimens from patients with early stage prostate cancer in order to further explore the malignant potential of each separate focus of cancer. The volume, grade, invasiveness (extracapsular extension or seminal vesicle invasion), and zone of origin of each of the 63 separate cancers were determined. The DNA ploidy histogram of 200 cancer cells was compared with 50 normal epithelial nuclei on the same Feulgen-stained tissue sections. Sixty % of the cancers were diploid, and 40% were nondiploid. Ploidy correlated with volume and grade. All cancers less than 0.02 cm3 were diploid; 26% of foci 0.02 to 2.0 cm3 and 82% of foci greater than 2.0 cm3 were nondiploid. There were 16 cancers of transition zone origin ranging in size from 0.02 to 12.1 cm3 and only one (7.3 cm3) was nondiploid. There were 47 cancers of peripheral zone origin (range, 0.01 to 18.98) and 24 (51%) were nondiploid. Eight of the 24 nondiploid cancers were small (less than 1.0 cm3), and two were only 0.03 cm3. We conclude that some very small prostate cancers are nondiploid and that progression of prostate cancer is not a function of volume alone, whereby tumors only acquire full malignant potential at large volumes. Cancers of peripheral zone origin acquire a nondiploid cell population at a smaller volume than do cancers of transition zone origin, further supporting a fundamental difference between cancers arising in these zones.

Caveolin-1 expression in clinically confined human prostate cancer: a novel prognostic marker.

We demonstrated previously elevated caveolin-1 expression in metastatic mouse and human prostate cancer cells both in vitro and in vivo. In this study, we analyzed its prognostic value for progression of clinically confined human prostate cancer. Immunohistochemical staining with a caveolin-1-specific antibody was performed on routinely processed paraffin sections from 189 radical prostatectomy specimens. Caveolin-1 immunoreactivity was evaluated in association with patients' age, race, preoperative prostate-specific antigen, clinical stage, and pathological features including Gleason score, extraprostatic extension, status of surgical margins, and time to disease progression after surgery. Positive caveolin-1 immunostaining was detected in 47 of the 189 cancers (25%) and correlated positively with Gleason score, positive surgical margin, as well as lymph node involvement (P = 0.0071, 0.0267, and 0.0399, respectively). In lymph node-negative cancers (n = 162), caveolin-1 immunoreactivity predicts a shorter time to disease progression after surgery (P = 0.0033, univariate analysis). Multivariate analyses that included caveolin-1 and other prognostic pathological markers identified positive caveolin-1 immunostaining as an independent predictor for time to disease progression (P = 0.0186). Thus, our study establishes caveolin-1 as a novel prognostic marker for clinically confined human prostate cancer.

Reduced infiltration of tumor-associated macrophages in human prostate cancer: association with cancer progression.

Tumor-associated macrophages (TAMs) are highly active immune effector cells that may either positively or negatively regulate the growth of various malignant cells, depending on the biological context. However, the role of TAMs in human prostate cancer progression is unclear. TAMs were immunohistochemically labeled using a monoclonal (CD68) antibody in radical prostatectomy specimens derived from 81 prostate cancer patients. CD68-positive cells were counted with the aid of a microscope and expressed as macrophage index (MphiI), including TAMs/mm2 total tumor tissue (MphiItotal), TAMs/mm2 tumor stroma (MphiIstroma), and TAMs/mm2 cancer cell area (MphiIcancer). MphiIs were analyzed in association with patients' clinical and pathological stage, recurrence status, and histological grade of the cancer. There were significant inverse relationships between MphiItotal and MphiIstroma and clinical stage (P = 0.016 and P = 0.006, respectively). Reduced MphiItotal was also associated with the presence of positive lymph nodes (P = 0.010). Interestingly, although all of the MphiIs differed between Gleason score groups, only MphiIcancer was positively associated with Gleason score. Univariate analysis of MphiItotal and multivariate analysis of MphiItotal with specific pathological markers revealed that MphiItotal was an independent predictor for disease-free survival after surgery (Cox proportional hazard model, P = 0.044 and P = 0.007, respectively). For patients with high MphiItotal (> or = 185.8, the mean MphiItotal value), the disease-free probability 5 years after surgery was 0.75, which was significantly higher than for those with low MphiItotal (0.31, P = 0.0008). Additional immunohistochemical studies that evaluated cytotoxicity-related biomarkers in stroma-associated mononuclear cells suggested reduced functional activities in highly aggressive prostate cancer compared with less aggressive disease. Our results indicate that reduced MphiItotal is a novel prognostic marker for prostate cancer.

Reduced lysyl oxidase messenger RNA levels in experimental and human prostate cancer.

To identify genes associated with prostate cancer progression, we developed a strategy involving the use of differential display PCR and a panel of genetically matched primary tumor- and metastasis-derived mouse prostate cancer cell lines. We analyzed sequences that were differentially stimulated by transforming growth factor-beta1 in primary tumor-versus metastasis-derived cell lines, based on our previous studies indicating that acquisition of differential responses to this growth factor could result in phenotypic traits that facilitate tumor metastasis from specific cell clones within the primary tumor. Using this system, we isolated and sequenced a cDNA fragment that encoded mouse lysyl oxidase (LO) and was induced by transforming growth factor-beta1 in primary tumor but not in metastasis-derived cells. Northern blotting analysis revealed increased LO expression in a panel of primary tumor cell lines but significantly reduced or nondetectable expression in their matched metastatic counterparts. Further in situ hybridization analysis revealed LO expression in normal mouse prostate epithelium but, in most cases, progressive loss of expression in primary prostate cancer and associated metastatic lesions. Importantly, in situ hybridization studies of normal human prostate and prostate malignancies revealed a similar loss of expression during progression to metastasis. The progressive loss of LO expression during prostate cancer progression provides information that may increase our understanding of the mechanisms that underlie this disease. In addition, LO may provide a useful molecular marker and/or establish a novel therapeutic target for prostate cancer.

Detection of metastatic prostate cancer using a splice variant-specific reverse transcriptase-polymerase chain reaction assay for human glandular kallikrein.

We developed a highly sensitive splice variant-specific reverse transcriptase-PCR (RT-PCR) assay for human glandular kallikrein (hK2) mRNA and tested its ability to detect metastatic disease in men with clinically localized prostate cancer. An RT-PCR assay using primers spanning intron IV and including a significant portion of the 3' untranslated region of the hKLK2 gene, with maximum nonhomology to both hK1 and hK3, was developed. The limit of detection of the assay was five copies of hK2 cDNA and one LNCaP cell in 10(9) lymphoblasts. RT-PCR-hK2 was performed on preoperative peripheral blood specimens from 228 consecutive radical prostatectomy patients as well as 7 metastatic prostate cancer patients and 14 healthy men without prostate cancer. This new RT-PCR-hK2 assay amplifies two distinct fragments. The larger fragment (hK2-U) is approximately 680 bp in length and corresponds to the amplified product of a previously reported splice variant in the splice donor site of intron IV in the hKLK2 gene. The smaller fragment (hK2-L) is approximately 643 bp in length and corresponds to the amplified product of the native hK2 mRNA. Whereas the RT-PCR-hK2-L assay was positive in 71% of our patients with metastatic prostate cancer, 14% of healthy control men also tested positive. By univariate (P = 0.028) and multivariate (P = 0.0269) analysis, which controlled for preoperative PSA, clinical stage, and biopsy Gleason score, RT-PCR-hK2-L status added prognostic information to the prediction of lymph node-positive disease. We have developed a new RT-PCR assay which demonstrates a high sensitivity for detecting hK2 mRNA. Preoperative RT-PCR-hK2-L status helps predict pathological lymph node positivity in patients with clinically localized prostate cancer.

A precursor form of prostate-specific antigen is more highly elevated in prostate cancer compared with benign transition zone prostate tissue.

Prostate-specific antigen (PSA) is a widely used serum marker for prostate cancer (PCa), but in the critical diagnostic range of 4-10 ng/ml it has limited specificity for distinguishing early PCa from benign prostatic hyperplasia (BPH). PSA in serum is comprised of a variety of both "free" and "complexed" forms that have been used to improve the specificity of PSA for prostate cancer detection. We previously reported that pro PSA (pPSA), the zymogen or precursor form of PSA, is a component of free PSA in the serum of PCa patients. In the current study, we examined prostate tissues to understand the origin and specificity of pPSA. PSA was immuno-affinity purified from matched sets of prostate tissues including peripheral zone cancer (PZ-C); peripheral zone noncancer; and benign tissue from the transition zone (TZ), the primary site of BPH within the prostate. We found that pPSA is differentially elevated in PZ-C, but is largely undetectable in TZ. N-terminal sequencing revealed that the pPSA was comprised primarily of [-2]pPSA and minor levels of [-4]pPSA, containing pro leader peptides of 2 and 4 amino acids, respectively. The median value of pPSA was 3% in PZ-C and 0% (undetectable) in TZ (P < 0.0026). No pPSA was detected in 13 of 18 transition zone specimens (72%), but only 2 of the 18 matched cancer specimens (11%) contained no measurable pPSA. These results demonstrate that pPSA is more highly correlated with prostate cancer than with BPH. The pPSA in serum may represent a more cancer-specific form of PSA that could help distinguish prostate cancer from BPH.

Age-related radical-induced DNA damage is linked to prostate cancer.

We measured concentrations and ratios of mutagenic (8-OH) lesions to putatively nonmutagenic formamidopyrimidine (Fapy) lesions of adenine (Ade) and guanine (Gua) to elucidate radical (.OH)-induced changes in DNA of normal, normal from cancer, and cancer tissues of the prostate. The relationship between the lesions was expressed using the mathematical model log(10)[(8-OH-Ade + 8-OH-Gua)/(FapyAde + FapyGua)]. Logistic regression analysis of the log ratios for DNA of normal and cancer tissues discriminated between the two tissue groups with high sensitivity and specificity. Correlation analysis of log ratios for normal prostates revealed a highly significant increase in the proportion of mutagenic base lesions with age. Data from correlation analysis of the log ratios for normal tissues from cancer were consistent with an age-dependent, dose-response relationship. The slopes for both correlations intersected at approximately 61 years, an age when prostate cancer incidence is known to rise sharply. The age-related increase in the proportion of.OH-induced mutagenic base lesions is likely a significant factor in prostate cancer development.

15S-Hydroxyeicosatetraenoic acid activates peroxisome proliferator-activated receptor gamma and inhibits proliferation in PC3 prostate carcinoma cells.

15-Lipoxygenase (15-LOX)-2 is expressed in benign prostate secretory cells and benign prostate produces 15S-hydroxyeicosatetraenoic acid (15S-HETE) from exogenous arachidonic acid (AA). In contrast, 15S-LOX-2 and 15S-HETE formation are reduced in prostate carcinoma (Pca). The mechanisms whereby reduced 15-LOX-2 may contribute to Pca development or progression are not known. We investigated the expression of peroxisome proliferator-activated receptor (PPAR) gamma in benign and malignant prostate tissues and the ability of 15S-HETE to activate PPARgamma-dependent transcription and modulate proliferation of the Pca cell line PC3. In contrast to benign prostate and similar to most Pca tissues, 15-LOX-2 mRNA was not detected in PC3 cells, and they did not produce detectable 15-HETE from [14C]AA. By reverse transcription-PCR, PPARgamma mRNA was present in 18 of 18 benign and 9 of 9 tumor specimens. The PPARgamma ligand BRL 49653 and 15S-HETE caused a dose-dependent inhibition of PC3 proliferation in a 14-day soft agar colony-forming assay (IC50 of 3 and 30 microM, respectively). 15S-HETE (10 microM) caused greater inhibition than 10 microM 15R-HETE. At 3 days, BRL 49653 and 15S-HETE caused a slight increase in cells in G0-G1 and a corresponding decrease in cells in S phase. In PC3 cells transiently transfected with a luciferase reporter linked to a PPAR response element, 1 microM BRL 49653 and 10 microM 15S-HETE caused approximately threefold and greater than twofold induction of PPAR-dependent transcription, respectively. By quantitative real-time reverse transcription-PCR and Northern analysis, 3-day treatment with BRL 49653 and 15S-HETE caused a reduction of PPARgamma expression but a marked up-regulation of the PPAR response element containing adipocyte type fatty acid binding protein. These results support the hypothesis that 15-LOX-2-derived 15S-HETE may constitute an endogenous ligand for PPARgamma in the prostate and that loss of this pathway by reduced expression of 15-LOX-2 may contribute to increased proliferation and reduced differentiation in prostate carcinoma.

Induction of human Cdc37 in prostate cancer correlates with the ability of targeted Cdc37 expression to promote prostatic hyperplasia.

The Cdc37 gene encodes a 50 kDa protein which targets intrinsically unstable oncoprotein kinases such as Cdk4, Raf-1, and src to the molecular chaperone Hsp90. This activity is thought to play an important role in the establishment of signaling pathways controlling cell proliferation. The budding yeast Cdc37 homolog is required for cell division and mammalian Cdc37 is expressed in proliferative zones during embryonic development and in adult tissues, consistent with a positive role in proliferation. Here we report that human prostatic tumors, neoplasias and certain pre-malignant lesions display increased Cdc37 expression, suggesting an important and early role for Cdc37 in prostatic transformation. To test the consequences of increased Cdc37 levels, transgenic mice expressing Cdc37 in the prostate were generated. These mice displayed a wide range of growth-related abnormalities including prostatic epithelial cell hyperplasia and dysplasia. These data suggest that the expression of Cdc37 may promote inappropriate proliferation and may be an important early step in the development of human prostate cancer.

Postoperative nomogram for disease recurrence after radical prostatectomy for prostate cancer.

PURPOSE: Although models exist that place patients into discrete groups at various risks for disease recurrence after surgery for prostate cancer, we know of no published work that combines pathologic factors to predict an individual's probability of disease recurrence. Because clinical stage and biopsy Gleason grade only approximate pathologic stage and Gleason grade in the prostatectomy specimen, prediction of prognosis should be more accurate when postoperative information is added to preoperative variables. Therefore, we developed a postoperative nomogram that allows more accurate prediction of probability for disease recurrence for patients who have received radical prostatectomy as treatment for prostate cancer, compared with the preoperative nomogram we previously published. PATIENTS AND METHODS: By Cox proportional hazards regression analysis, we modeled the clinical and pathologic data and disease follow-up for 996 men with clinical stage T1a-T3c NXM0 prostate cancer who were treated with radical prostatectomy by a single surgeon at our institution. Prognostic variables included pretreatment serum prostate-specific antigen level, specimen Gleason sum, prostatic capsular invasion, surgical margin status, seminal vesicle invasion, and lymph node status. Treatment failure was recorded when there was either clinical evidence of disease recurrence, a rising serum prostate-specific antigen level (two measurements of 0.4 ng/mL or greater and rising), or initiation of adjuvant therapy. Validation was performed on this set of men and a separate sample of 322 men from five other surgeons' practices from our institution. RESULTS: Cancer recurrence was noted in 189 of the 996 men, and the recurrence-free group had a median follow-up period of 37 months (range, 1 to 168 months). The 7-year recurrence-free probability for the cohort was 73% (95% confidence interval, 68% to 76%). The predictions from the nomogram appeared to be accurate and discriminating, with a validation sample area under the receiver operating characteristic curve (ie, a comparison of the predicted probability with the actual outcome) of 0.89. CONCLUSION: A postoperative nomogram has been developed that can be used to predict the 7-year probability of disease recurrence among men treated with radical prostatectomy.

Differential expression of nuclear retinoid receptors in normal and malignant prostates.

PURPOSE: To determine (1) whether nuclear retinoic acid receptors (RARs) and retinoid X receptors (RXRs) are differentially expressed in normal and in cancerous human prostate tissues and (2) whether oral fenretinide therapy impacts the expression of these receptors in prostate cancer. PATIENTS AND METHODS: In situ hybridization with antisense riboprobes was used to probe for RAR and RXR transcripts in prostate tissues in a two-phased study: (1) expression of retinoid receptors in eight normal prostates was compared with their expression in 10 randomly picked radical prostatectomy specimens (group A); (2) expression of retinoid receptors was determined in 22 radical prostatectomy specimens from participants in a clinical study (group B). Twelve patients received oral fenretinide 200 mg/d, and 10 received placebo pills for 28 days before surgery. RESULTS: RARalpha, RARgamma, RXRalpha, and RXRgamma mRNAs were detected in most normal and cancerous prostates. In group A, RARbeta mRNA was expressed in only four of 10 malignant prostates but was present in seven of eight benign prostates (P =.05). RXRbeta mRNA was expressed in four of eight benign prostates and in zero of 10 malignant prostates (P =.023). In group B prostates, RARbeta and RXRbeta mRNAs were markedly reduced in all cancers and in the adjacent, nonmalignant tissue. There were no differences between receptor expression in the fenretinide-treated group and the placebo group. CONCLUSION: RARbeta and RXRbeta mRNAs are selectively lost in both prostate cancer and adjacent morphologically normal prostatic tissue, supporting the concept of a field of carcinogenesis. One month of oral fenretinide (200 mg/d) did not influence the expression of retinoid receptors in prostate cancer.

Prediction of response to salvage radiation therapy in patients with prostate cancer recurrence after radical prostatectomy.

PURPOSE: To identify factors predictive of local recurrence as defined by a complete response to salvage radiation therapy in patients whose disease recurs after radical prostatectomy. PATIENTS AND METHODS: Ninety-five patients with recurrence after radical prostatectomy who were evaluated by prostatic fossa biopsies, and a subset of 49 of these patients treated with radiation for control of presumed or biopsy-proven local recurrence, were studied. RESULTS: Biopsies were positive in 40 (42%) of the 95 biopsied patients. Multivariate analysis revealed that prebiopsy prostate-specific antigen (PSA) level, postrecurrence PSA doubling time, and positive digital rectal examination (DRE) of the prostatic fossa were all statistically significant predictors of a positive biopsy. For the 49 patients subsequently treated with salvage radiation therapy, the overall actuarial 3- and 5-year PSA relapse-free probabilities were 43% and 24%, respectively. Univariate analysis showed no differences in the PSA relapse-free probabilities associated with any pathologic features of the radical prostatectomy specimen, biopsy confirmation of local recurrence, or DRE of the prostatic fossa. In multivariate analysis, controlling for all other variables, preradiation PSA and postrecurrence PSA doubling time measured before radiation were the only statistically significant predictors of outcome. CONCLUSION: DRE of the prostatic fossa, prebiopsy PSA, and postrecurrence PSA doubling time predict which patients will have biopsy-proven local recurrence. However, response to salvage radiation therapy is associated with postrecurrence PSA doubling time and with preradiation PSA level only. DRE of the prostatic fossa and biopsy confirmation of local recurrence are not associated with salvage radiation outcome.

Preoperative plasma levels of transforming growth factor beta(1) (TGF-beta(1)) strongly predict progression in patients undergoing radical prostatectomy.

PURPOSE: Elevated local and circulating levels of transforming growth factor beta(1) (TGF-beta(1)) have been associated with prostate cancer invasion and metastasis. We tested the hypothesis that preoperative plasma TGF-beta(1) levels would independently predict cancer stage and prognosis in patients who undergo radical prostatectomy. PATIENTS AND METHODS: The study group consisted of 120 consecutive patients who underwent radical prostatectomy for clinically localized prostate cancer (median follow-up, 53.8 months). Preoperative plasma levels of TGF-beta(1) were measured and correlated with pathologic parameters and clinical outcomes. TGF-beta(1) levels also were measured in 44 healthy men without cancer, in 19 men with prostate cancer metastatic to regional lymph nodes, and in 10 men with prostate cancer metastatic to bone. RESULTS: Plasma TGF-beta(1) levels in patients with lymph node metastases (14.2 +/- 2.6 ng/mL) and bone metastases (15.5 +/- 2.4 ng/mL) were higher than those in radical prostatectomy patients (5.2 +/- 1.3 ng/mL) and healthy subjects (4.5 +/- 1.2 ng/mL) (P <.001). In a preoperative analysis, preoperative plasma TGF-beta(1) level and biopsy Gleason sum both were predictors of organ-confined disease (P =.006 and P =.006, respectively) and PSA progression (P <.001 and P =.021, respectively). In a postoperative multivariate analysis, preoperative plasma TGF-beta(1) level, pathologic Gleason sum, and surgical margin status were predictors of PSA progression (P =.020,P =.020, and P =.022, respectively). In patients who progressed, preoperative plasma TGF-beta(1) levels were higher in those with presumed distant compared with local-only failure (P =.019). CONCLUSION: Plasma TGF-beta(1) levels are markedly elevated in men with prostate cancer metastatic to regional lymph nodes and bone. In men without clinical or pathologic evidence of metastases, the preoperative plasma TGF-beta(1) level is a strong predictor of biochemical progression after surgery, presumably because of an association with occult metastatic disease present at the time of radical prostatectomy.

The emerging role of the PI3-K-Akt pathway in prostate cancer progression.

The PI3-K-Akt pathway plays a central role in the development and progression of prostate cancer and other malignancies. We review original studies and summarize relevant sections of previous reviews concerning the relationships between abnormalities in the PI3-K-Akt pathway and prostate cancer progression. We discuss laboratory and clinical data that indicate gene perturbation and dysregulation of PI3-K-Akt pathway is common in prostate cancer and other malignancies. We further discuss the critical role of the PI3-K-Akt pathway in the oncogenic signaling network and provide examples that establish the PI3-K-Akt pathway as a focal point for the future development of informative biomarkers and effective therapies for prostate cancer.

Elevated caveolin-1 levels in African-American versus white-American prostate cancer.

Clinical studies suggest that African-American (AA) prostate cancer patients manifest a more aggressive form of the disease compared with white prostate cancer patients. However, the biological underpinnings of this potential difference remain unresolved. To address this issue, we used specific quantitative immunostaining protocols to determine whether a panel of biomarkers related to apoptosis including caveolin-1, bcl-2, p53, and c-myc were differentially expressed in AA versus white prostate cancer patients with similar clinical and pathological characteristics. We further attempted to correlate biomarker positivity with proliferation-related markers including Ki-67 labeling index and apoptotic index. Interestingly, our results indicated that only the incidence of caveolin-1 staining was significantly different between these two ethnic/racial groups of prostate cancer patients. The incidence of caveolin-1 staining in white patients was 17% compared with 39% in AA patients (P = 0.0048; Fisher's exact test). In addition, the percentage of caveolin-1-positive prostate cancer cells was also higher in moderately differentiated (Gleason score 6) prostate cancer patients in AA versus whites. Because caveolin-1 has been shown previously to demonstrate antiapoptotic activities in prostate cancer cells, our results suggest that differences in caveolin-1 expression may in part underlie the apparent differences in the clinical virulence of this disease in AA versus white prostate cancer patients.

Decreased expression of transforming growth factor beta receptor type I is associated with poor prognosis in bladder transitional cell carcinoma patients.

Transforming growth factor (TGF) beta, a potent growth inhibitor of proliferation in most cells, usually exerts its effects through an interaction with membrane receptors, type I (TbetaR-I) and type II (TbetaR-II). In the present study, the expression of TGF-beta receptors was correlated with tumor grade, pathological stage, and probability of progression and survival in patients with bladder transitional cell carcinoma (TCC). To this end, immunohistochemistry was carried out in specimens obtained from 59 patients who underwent either radical cystectomy or transurethral resection of bladder tumor. Among these patients, 18 (30.5 %) had loss of TbetaR-I expression, whereas 27 (44.0%) had loss of TbetaR-II expression. There was a correlation between the loss of expression of TbetaR-I and TbetaR-II and the tumor grade (P = 0.041 and P = 0.026, respectively). In addition, both pathological and lymph node status also were associated with the loss of TbetaR-I and TbetaR-II expression (P = 0.025 and P = 0.004, respectively). Interestingly though, only the loss of expression of TbetaR-I was associated with an increased probability of tumor progression and a decreased probability of survival (P = 0.0046 and P = 0.0022, respectively). These results suggest that the status of TbetaR-I expression may be a potential prognostic marker in patients with bladder TCC.

Association of p53 mutations with metastatic prostate cancer.

In prostate cancer, mutation of the p53 tumor suppressor gene has been associated with locally advanced disease and hormone-resistant disease that is predominantly localized to bone. However, little is known regarding the status of the p53 gene in metastatic prostate cancer that has not been treated with hormonal manipulation. We evaluated formalin-fixed, paraffin-embedded malignant tissues from 86 patients with various stages of prostate cancer, including pathologically confined, locally advanced, and metastatic disease, to detect abnormal p53 nuclear protein accumulation using immunohistochemistry. No abnormal p53 immunostaining was detected in 18 patients with prostate cancer confined to the gland. Two tumors from 21 patients with locally advanced disease (extracapsular extension and/or seminal vesicle invasion) had abnormal nuclear p53 accumulation, and a mutation in exon 7 of the p53 gene was detected in tumor DNA from one patient using single-strand conformation polymorphism-direct sequencing analysis. Of the remaining 47 patients studied in whom tissues from the prostate gland and a metastatic site (44 lymph node, 2 bone, and 1 lung) were available, only 3 had received hormonal therapy prior to obtaining metastatic tissue. In four patients both primary and metastatic tumors demonstrated accumulation of p53 protein, whereas seven additional patients exhibited p53 accumulation only at the metastatic site. In three patients the metastatic tumors harbored missense single-base substitutions in exon 5, as detected using single-strand conformation polymorphism-direct sequencing. These results indicate that p53 abnormalities are associated with lymph node metastases derived from prostate cancer patients that had not undergone hormonal therapy.

Clustered p53 immunostaining: a novel pattern associated with prostate cancer progression.

Abnormal p53 protein accumulation is typically defined as present when greater than 5 or 10% of cancer cells stain positively. We present a novel approach whereby immunopositivity is defined when 15 or more cells within a 300 x 400-micrometer(2) field exhibit p53 protein accumulation; a feature that we have called "clustered" staining. We assessed p53 immunostaining of moderately differentiated, clinically localized prostate cancers derived from two patient groups: those without cancer recurrence 5 years after radical prostatectomy, and those in whom cancer had recurred following radical prostatectomy. Clustered p53 immunopositivity was present in 10 (63%) of 16 patients in the recurrent group and in only 7 (21%) of 33 in the nonrecurrent group. Clustered p53 staining was clearly associated with cancer recurrence (P < 0.01). This refinement of a commonly used assay may help define the biological aggressiveness of a cancer.