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Mark A Rubin

Publications and source records attributed to Mark A Rubin.

At least 19 recordsLinked to original sources
PubMed2026

Reversing-or Rewiring-Lineage Plasticity? Lessons from EZH2 Loss in Prostate Cancer.

Enhancer of zeste homolog 2 (EZH2) inhibitors have been proposed to counteract lineage plasticity (LP) in prostate cancer and thereby resensitize tumors to androgen receptor (AR) inhibition. In this issue of Cancer Research, Jacobi and colleagues provide new mechanistic insights into EZH2 biology across prostate cancer progression using a genetically engineered mouse model that recapitulates the transition toward a neuroendocrine (NE) phenotype. Unexpectedly, genetic deletion of Ezh2 did not reverse LP but instead promoted the diversification of transcription factor (TF) programs driving NE differentiation. In particular, the loss of EZH2 activated members of the KLF TF family, which contributed to this transcriptional diversification. Moreover, EZH2 deletion altered the chromatin-binding landscape of AR, redirecting it toward KLF-associated genomic sites. Collectively, these results refine our understanding of EZH2 function in prostate cancer: Rather than simply reversing LP, EZH2 loss rewires transcriptional networks and reshapes the AR cistrome. These findings are timely given the growing number of clinical trials testing EZH2 inhibitors in metastatic prostate cancer and highlight the need to define when and how to deploy EZH2 inhibition to exploit its effects on tumor lineage dynamics. See related article by Jacobi et al., p. 889.

Male↗
PubMed2025

A double-negative prostate cancer subtype is vulnerable to SWI/SNF-targeting degrader molecules.

Proteolysis targeting chimera (PROTAC) therapies degrading SWI/SNF ATPases offer a novel approach to interfere with androgen receptor (AR) signaling in AR-dependent castration-resistant prostate cancer (CRPC-AR). To explore the utility of SWI/SNF therapy beyond AR-sensitive CRPC, we investigated SWI/SNF-targeting agents in AR-negative CRPC. SWI/SNF targeting PROTAC treatment of cell lines and organoid models reduced the viability of not only CRPC-AR but also WNT-signaling dependent AR-negative CRPC (CRPC-WNT). The CRPC-WNT subgroup represents 11% of around 400,000 cases of CRPC worldwide who die yearly of CRPC. We discovered that SWI/SNF ATPase SMARCA4 depletion interfered with the master transcriptional regulator TCF7L2 (TCF4) in CRPC-WNT. Functionally, TCF7L2 maintains proliferation via the MAPK signaling axis in this subtype of CRPC. These data suggest a mechanistic rationale for interventions that perturb the DNA binding of the pro-proliferative TCF7L2 transcription factor (TF) and/or direct MAPK signaling inhibition in the CRPC-WNT subclass of advanced prostate cancer.

Journal Article↗
PubMed2003

Effects of raf kinase inhibitor protein expression on suppression of prostate cancer metastasis.

BACKGROUND: Raf kinase inhibitor protein (RKIP), an inhibitor of Raf-mediated activation of mitogen-activated protein/extracellular signal-regulated kinase kinase (MEK), is expressed at lower levels in human C4-2B metastatic prostate cancer cells than in the parental non-metastatic LNCaP prostate cancer cells from which they were derived. We examined whether RKIP functions as a suppressor of metastasis. METHODS: Immunohistochemistry was used to detect RKIP expression in clinical samples of primary prostate cancer and prostate cancer metastases. LNCaP and C4-2B cells were stably transfected with plasmids that constitutively expressed antisense and sense RKIP cDNA, respectively, or with empty vector. Assays of cell proliferation, soft-agar colony formation, and in vitro cell invasion were used to examine the malignant phenotypes of the transfected cells. An orthotopic murine model was used to examine the effect of expressing RKIP in C4-2B cells on the development of spontaneous metastasis. RESULTS: Clinical samples of primary prostate cancer had detectable RKIP expression, whereas clinical samples of prostate cancer metastases did not. There were no differences in the in vitro proliferation rate or colony-forming ability between the control vector-transfected and sense RKIP vector-transfected C4-2B cells or between the control vector-transfected and the antisense RKIP vector-transfected LNCaP cells. Overexpression of RKIP in C4-2B cells was associated with decreased in vitro cell invasion, decreased development of lung metastases in vivo, and decreased vascular invasion in the primary tumor but did not affect primary tumor growth in mice. CONCLUSIONS: RKIP does not influence the tumorigenic properties of human prostate cancer cells. It appears to be a novel and clinically relevant suppressor of metastasis that may function by decreasing vascular invasion.

Aged↗
PubMed2003

Expression of CXCR4 and CXCL12 (SDF-1) in human prostate cancers (PCa) in vivo.

Human prostate cancers (PCa) express great variability in their ability to metastasize to bone. The identification of molecules associated with aggressive phenotypes will help to define PCa subsets and will ultimately lead to better treatment strategies. The chemokine stromal-derived factor-1 (SDF-1 or CXCL12) and its receptor CXCR4 are now known to modulate the migration and survival of an increasing array of normal and malignant cell types including breast, pancreatic cancers, glioblastomas, and others. The present investigation extends our previous investigations by determining the expression of CXCR4 and CXCL12 in humans using high-density tissue microarrays constructed from clinical samples obtained from a cohort of over 600 patients. These data demonstrate that CXCR4 protein expression is significantly elevated in localized and metastastic cancers. At the RNA level, human PCa tumors also express CXCR4 and message, but overall, they were not significantly different suggesting post-transcriptional regulation of the receptor plays a major role in regulating protein expression. Similar observations were made for CXCL12 message, but in this case more CXCL12 message was expressed by metastastic lesions as compared to normal tissues. PCa cell lines also express CXCL12 mRNA, and regulate mRNA expression in response to CXCL12 and secrete biologically active protein. Furthermore, neutralizing antibody to CXCL12 decreased the proliferation of bone homing LNCaP C4-2B and PC3 metastastic tumor cells. These investigations provide important new information pertaining to the molecular basis of how tumors may 'home' to bone, and the mechanisms that may account for their growth in selected end organs.

Adult↗
PubMed2003

Multiplex biomarker approach for determining risk of prostate-specific antigen-defined recurrence of prostate cancer.

BACKGROUND: Molecular signatures in cancer tissue may be useful for diagnosis and are associated with survival. We used results from high-density tissue microarrays (TMAs) to define combinations of candidate biomarkers associated with the rate of prostate cancer progression after radical prostatectomy that could identify patients at high risk for recurrence. METHODS: Fourteen candidate biomarkers for prostate cancer for which antibodies are available included hepsin, pim-1 kinase, E-cadherin (ECAD; cell adhesion molecule), alpha-methylacyl-coenzyme A racemase, and EZH2 (enhancer of zeste homolog 2, a transcriptional repressor). TMAs containing more than 2000 tumor samples from 259 patients who underwent radical prostatectomy for localized prostate cancer were studied with these antibodies. Immunohistochemistry results were evaluated in conjunction with clinical parameters associated with prostate cancer progression, including tumor stage, Gleason score, and prostate-specific antigen (PSA) level. Recurrence was defined as a postsurgery PSA level of more than 0.2 ng/mL. All statistical tests were two-sided. RESULTS: Moderate or strong expression of EZH2 coupled with at most moderate expression of ECAD (i.e., a positive EZH2:ECAD status) was the biomarker combination that was most strongly associated with the recurrence of prostate cancer. EZH2:ECAD status was statistically significantly associated with prostate cancer recurrence in a training set of 103 patients (relative risk [RR] = 2.52, 95% confidence interval [CI] = 1.09 to 5.81; P =.021), in a validation set of 80 patients (RR = 3.72, 95% CI = 1.27 to 10.91; P =.009), and in the combined set of 183 patients (RR = 2.96, 95% CI = 1.56 to 5.61; P<.001). EZH2:ECAD status was statistically significantly associated with disease recurrence even after adjusting for clinical parameters, such as tumor stage, Gleason score, and PSA level (hazard ratio = 3.19, 95% CI = 1.50 to 6.77; P =.003). CONCLUSION: EZH2:ECAD status was statistically significantly associated with prostate cancer recurrence after radical prostatectomy and may be useful in defining a cohort of high-risk patients.

Adult↗
PubMed2003

Haploinsufficiency and reduced expression of genes localized to the 8p chromosomal region in human prostate tumors.

Cytogenetic and molecular studies have suggested that deletion or rearrangement of sequences that map to the short arm of chromosome 8 may be permissive for tumorigenesis in several organ systems, and in human prostate tumors in particular. In this study, we hypothesized that genes deleted for one copy and localized to the 8p chromosomal region may be transcriptionally down-regulated or ablated in affected human prostate tumor tissues. To test this hypothesis, we used cDNA microarray analysis to determine the transcriptional profiles for 259 transcribed sequences mapping to the 8p chromosomal region for seven human prostate tumor xenografts, completely characterized for numerical and structural alterations on chromosome 8, and five normal human prostate tissues. These experiments identified 33 genes differentially expressed between normal and malignant prostate tissues, the majority of which (28/33, 85%) were transcriptionally down-regulated in malignant compared to normal human prostate tissues. These findings, that haploinsufficiency and transcriptional down-regulation for genes mapping to 8p are largely coincident in human prostate tumors, should provide a powerful tool for the identification of tumor-suppressor genes associated with human prostate cancer initiation and progression.

Alleles↗
PubMed2003

Dysregulation of the annexin family protein family is associated with prostate cancer progression.

Hormone refractory prostate cancer (PCa) is invariably lethal despite aggressive clinical treatment strategies. Detection strategies are needed to identify aggressive PCa before it becomes widely disseminated. Recently, two studies identified annexin 1 and 7 as potential biomarkers in the development of PCa progression. The annexins are a group of calcium-binding structural proteins that may play a role in the regulation of membrane trafficking, cellular adhesion, and cell signaling. Therefore the goal of this study is to simultaneously characterize the multiple members of the annexin family of genes in advanced PCa. Prostate samples from men with advanced hormone refractory PCa were compared to samples of hormone-naïve PCa and noncancerous prostate tissue. Samples from 15 patients with advanced hormone refractory PCa were used. To examine the annexin family, gene expression profiles from 21 noncancerous prostate tissues, 16 clinically localized PCas, and 20 hormone refractory PCa samples were used. By cDNA microarray analysis, annexins 1, 2, 4, 7, and 11 were significantly decreased in hormone refractory PCa when compared to localized hormone-naïve PCa with 2.2-, 1.5-, 1.3-, 1.4-, and 1.8-fold decreases, respectively (all P values <0.05). Interstudy validation of annexin family transcript expression was performed by meta-analysis of three other published prostate profiling studies. High-density tissue microarrays were used to validate a subset of annexins at the protein level by immunohistochemistry. Tissue microarray analysis revealed a significant decrease in protein expression for annexins 1, 2, 4, 7, and 11 in hormone refractory PCa as compared to localized PCa with 1.68-, 2.46-, 2.52-, and 3.01-fold decreases, respectively (Kruskal Wallis test, all P values P < 0.05). However, no significant differences were detected between the clinically localized PCa and noncancerous prostate tissues. These findings suggest that down-regulation of several members of the annexin family may contribute to PCa tumorigenesis. Annexins 1, 2, 4, 7, and 11 may play a role in tumor progression through distinct mechanisms or, alternatively, they may have redundant tumor suppressor activities. This study also suggests that a meta-analysis of existing gene expression data is useful in confirming findings from individual studies. Finally, down-regulation of several annexin family members may play a role in the development of the lethal PCa phenotype.

Adult↗
PubMed2003

Evaluation of the interobserver reproducibility of Gleason grading of prostatic adenocarcinoma using tissue microarrays.

The Gleason system is the internationally recognized standard for grading prostate cancer, due mainly to its strong prognostic capability. However, interobserver reproducibility is variable in the community setting. Herein we present a novel approach to evaluating Gleason grading among pathologists using high-density tissue microarrays (TMAs). A CD-ROM containing 537 different TMA spot images of 0.6-mm diameter was sent to 10 genitourinary pathologists in France. The pathologists were expected to score each TMA spot based on their experience evaluating standard prostate biopsies, transurethral resections, and prostatectomy samples. There was no consensus meeting beforehand to agree on how the group would apply the Gleason grading system for this project. Percentage of agreement and kappa value were used to assess the level of agreement. A short questionnaire was sent to assess pathologists' opinion on this new approach to evaluating Gleason grading. An average of 311 images were analyzed (range, 104 to 537; median, 256.5). Four of the pathologists evaluated all 537 images and assigned Gleason grades to 149 images with an overall kappa for interobserver agreement for the exact score between 0.31 and 0.52 and between 0.45 to 0.69 if 3 Gleason categories (</=6, 7, and >7) were used. When 2 categories were considered (</=7 or >7), kappa ranged from 0.58 to 0.83. All pathologists analyzed 104 images. Similar results were obtained with an agreement between 0.28 and 0.54 for the 3 Gleason categories. After finishing this test, 90% of genitourinary pathologists considered this approach useful for resident training and 90% for pathology teaching. We conclude that a Gleason score can be easily assigned to each TMA spot of a 0.6-mm-diameter prostate cancer sample. These data also indicated that using TMA spot images may be a good approach for teaching the Gleason grading system due to the small area of tissue.

Adenocarcinoma↗
PubMed2003

Basal cell cocktail (34betaE12 + p63) improves the detection of prostate basal cells.

Antibodies against high molecular weight cytokeratin (34betaE12) and p63 are frequently used basal cell markers to aid in the diagnosis of prostate cancer (Pca). Absence of a basal cell marker in an atypical lesion histologically suspicious for cancer supports a diagnosis of Pca. However, absence of basal cells demonstrable by basal cell immunohistochemistry (IHC) is not always conclusive for PCa. Some benign prostatic lesions may have inconspicuous or even lack basal cell lining focally. Technical factors such as tissue fixation and antigen retrieval techniques may also make the detection of basal cells difficult. Improving the sensitivity of current basal cell markers is critical if these tests are being used to help make diagnostic decisions in conjunction with standard histology. In this study, we test the hypothesis that that inclusion of both 34betaE12 and p63 in the same IHC reaction (basal cell cocktail) is advantageous over either marker used alone. One thousand three hundred fifty glands from 9 trans-urethral resectioned of prostate specimens with benign prostatic hypertrophy were used to study the immunostaining intensity and pattern for 34betaE12, p63, and the basal cell cocktail. Basal cell marker expression was scored as strong, moderate, weak, or negative. Basal cell staining was considered complete if 75% of the gland's circumference was positive for the basal cell marker and partial if <25% of the circumference was stained. The mean staining intensity and variance were calculated for 34betaE12, p63, and the basal cell cocktail. A paired test was used to evaluate whether the overall basal cell staining was significantly different between 34betaE12, p63, and the basal cell cocktail. F-test was used to assess the variances for 34betaE12, p63, and the basal cell cocktail. A high-density tissue microarray (TMA) comprising prostate tissue from 103 tumors from men with clinically localized Pca and a separate TMA comprising metastatic hormone-refractory Pca samples from 23 rapid autopsy cases were used to study the aberrant expression of 34betaE12 and p63 in clinically localized and poorly differentiated Pca. The prostate glands in transition zone have variable basal cell staining intensity and pattern with 34betaE12, p63, or the cocktail. Histologically, benign glands lack basal cell lining in 2%, 6%, and 2% of glands with cocktail, 34betaE12, and p63 staining, respectively. The staining variance for the cocktail is significantly smaller than that for 34betaE12 (0.0100 vs 0.1559, p = 0.0008). It is also smaller than that for p63, although a statistical significance has not been reached (0.0100 vs 0.0345, p = 0.099). The basal cell cocktail stains the basal cell layers more intensely than either 34betaE12 or p63 alone, with complete and partial strong basal cell staining in 93% and 1% of benign glands, compared with 55% and 4% with 34betaE12 and 81% and 1% with p63. Complete and partial weak staining is seen in 0% and 0% of benign glands with basal cell cocktail, compared with 8% and 7% with 34betaE12 and 4% and 1% with p63 (p = 0.007 and 0.014 for cocktail vs 34betaE12 and cocktail vs p63, respectively). A total of 2.8% clinically localized Pca had positive 34betaE12 staining and 0.3% had positive p63 staining. Five (22%) of the metastatic Pca is positive for 34betaE12. However, none had p63 expression. The basal cell cocktail had a staining pattern identical to that of 34betaE12. IHC of the prostatic glands from the transition zone is subjected to staining variability that results in frequent variable and occasional negative basal cell staining in histologically benign glands; 34betaE12 is most susceptible, and basal cell cocktail is least susceptible to such variability. Basal cell cocktail not only increases the sensitivity of the basal cell detection, but also reduces the staining variability and therefore renders the basal cell immunostaining more consistent. We recommend this basal cell cocktail for routine Pca diagnostic work-up.

Biomarkers, Tumor↗
PubMed2003

Beta-catenin-related anomalies in apoptosis-resistant and hormone-refractory prostate cancer cells.

PURPOSE: beta-Catenin is a critical end component of the wnt signaling pathway that regulates cell growth, apoptosis, and migratory behavior in response to intercellular adhesion molecules. The aim of this study was to evaluate abnormalities of beta-catenin protein expression, subcellular localization, and activity in an in vitro model of acquired apoptosis-resistance in cultured PC cells and in primary human prostate cancers (PrCa). EXPERIMENTAL DESIGN: Apoptosis-resistant human prostate cancer cell line variants were derived from parental LNCaP cells by repeated brief exposure to apoptotic stimuli. The derivative and parental cells were analyzed for beta-catenin expression and intracellular localization using cell fractionation and Western blotting procedures. Endogenous transcriptional activity from the TCF/LEF-1 response element was also studied in these variants after transfection with a beta-catenin sensitive reporter plasmid. Finally, beta-catenin protein expression and intracellular localization were evaluated on 212 patients [122 localized PrCa and 90 hormone-refractory (HRPC) PrCa specimens by immunohistochemistry]. RESULTS: Western blot analysis showed that the intracellular partitioning of beta-catenin was shifted from the membrane fraction in parental cells to the cytoplasmic/nuclear fractions of the apoptosis-resistant cell lines. Coordinately, transcriptional activity from a TCF/LEF-promoted reporter plasmid was increased significantly in the apoptosis-resistant lines. In the primary prostate tumors analyzed, cytoplasmic and/or nuclear beta-catenin expression was correlated statistically with the HRPC status and Gleason score. In the group of localized PrCa, abnormal beta-catenin expression tended to be associated with a higher Gleason score and with pT3 disease. No mutation was found in patients with HRPC and abnormal beta-catenin expression. CONCLUSION: These data suggest that anomalies of beta-catenin expression occur in PrCa and that these anomalies are associated with disease progression, especially to the therapeutic-resistant state.

Adult↗
PubMed2002

The role of calpain in the proteolytic cleavage of E-cadherin in prostate and mammary epithelial cells.

The E-cadherin protein mediates Ca(2+)-dependent interepithelial adhesion. Association of E-cadherin with the catenin family of proteins is critical for the maintenance of a functional adhesive complex. We have identified a novel truncated E-cadherin species of 100-kDa (E-cad(100)) in prostate and mammary epithelial cells. E-cad(100) was generated by treatment of cells with ionomycin or TPA. Cell-permeable calpain inhibitors prevented E-cad(100) induction by ionomycin. Immunoblotting for spectrin and mu-calpain confirmed calpain activation in response to ionomycin treatment. Both the mu- and m-isoforms of calpain efficiently generated E-cad(100) in vitro. The E-cad(100) fragment was unable to bind to beta-catenin, gamma-catenin, and p120, suggesting that this cleavage event would disrupt the E-cadherin adhesion complex. Mutational analysis localized the calpain cleavage site to the cytosolic domain upstream of the beta- and gamma-catenin binding motifs of E-cadherin. Because E-cadherin is inactivated in many adenocarcinomas we hypothesized that calpain may play a role in prostate tumorigenesis. A prostate cDNA microarray data base was analyzed for calpain expression in which it was found that m-calpain was up-regulated in localized prostate cancer, and to an even higher degree in metastatic prostate cancer compared with normal prostate tissue. Furthermore, we examined the cleavage of E-cadherin in prostate cancer specimens and found that E-cad(100) accumulated in both localized and metastatic prostate tumors, supporting the cDNA microarray data. These findings demonstrate a novel mechanism by which E-cadherin is functionally inactivated through calpain-mediated proteolysis and suggests that E-cadherin is targeted by calpain during the tumorigenic progression of prostate cancer.

Amino Acid Sequence↗
PubMed2002

The polycomb group protein EZH2 is involved in progression of prostate cancer.

Prostate cancer is a leading cause of cancer-related death in males and is second only to lung cancer. Although effective surgical and radiation treatments exist for clinically localized prostate cancer, metastatic prostate cancer remains essentially incurable. Here we show, through gene expression profiling, that the polycomb group protein enhancer of zeste homolog 2 (EZH2) is overexpressed in hormone-refractory, metastatic prostate cancer. Small interfering RNA (siRNA) duplexes targeted against EZH2 reduce the amounts of EZH2 protein present in prostate cells and also inhibit cell proliferation in vitro. Ectopic expression of EZH2 in prostate cells induces transcriptional repression of a specific cohort of genes. Gene silencing mediated by EZH2 requires the SET domain and is attenuated by inhibiting histone deacetylase activity. Amounts of both EZH2 messenger RNA and EZH2 protein are increased in metastatic prostate cancer; in addition, clinically localized prostate cancers that express higher concentrations of EZH2 show a poorer prognosis. Thus, dysregulated expression of EZH2 may be involved in the progression of prostate cancer, as well as being a marker that distinguishes indolent prostate cancer from those at risk of lethal progression.

Biomarkers, Tumor↗
PubMed2002

Expression profiling of human renal carcinomas with functional taxonomic analysis.

BACKGROUND: Molecular characterization has contributed to the understanding of the inception, progression, treatment and prognosis of cancer. Nucleic acid array-based technologies extend molecular characterization of tumors to thousands of gene products. To effectively discriminate between tumor sub-types, reliable laboratory techniques and analytic methods are required. RESULTS: We derived mRNA expression profiles from 21 human tissue samples (eight normal kidneys and 13 kidney tumors) and two pooled samples using the Affymetrix GeneChip platform. A panel of ten clustering algorithms combined with four data pre-processing methods identified a consensus cluster dendrogram in 18 of 40 analyses and of these 16 used a logarithmic transformation. Within the consensus dendrogram the expression profiles of the samples grouped according to tissue type; clear cell and chromophobe carcinomas displayed distinctly different gene expression patterns. By using a rigorous statistical selection based method we identified 355 genes that showed significant (p < 0.001) gene expression changes in clear cell renal carcinomas compared to normal kidney. These genes were classified with a tool to conceptualize expression patterns called "Functional Taxonomy". Each tumor type had a distinct "signature," with a high number of genes in the categories of Metabolism, Signal Transduction, and Cellular and Matrix Organization and Adhesion. CONCLUSIONS: Affymetrix GeneChip profiling differentiated clear cell and chromophobe carcinomas from one another and from normal kidney cortex. Clustering methods that used logarithmic transformation of data sets produced dendrograms consistent with the sample biology. Functional taxonomy provided a practical approach to the interpretation of gene expression data.

Adenocarcinoma, Clear Cell↗
PubMed2002

Meta-analysis of microarrays: interstudy validation of gene expression profiles reveals pathway dysregulation in prostate cancer.

The increasing availability and maturity of DNA microarray technology has led to an explosion of cancer profiling studies. To extract maximum value from the accumulating mass of publicly available cancer gene expression data, methods are needed to evaluate, integrate, and intervalidate multiple datasets. Here we demonstrate a statistical model for performing meta-analysis of independent microarray datasets. Implementation of this model revealed that four prostate cancer gene expression datasets shared significantly similar results, independent of the method and technology used (i.e., spotted cDNA versus oligonucleotide). This interstudy cross-validation approach generated a cohort of genes that were consistently and significantly dysregulated in prostate cancer. Bioinformatic investigation of these genes revealed a synchronous network of transcriptional regulation in the polyamine and purine biosynthesis pathways. Beyond the specific implications for prostate cancer, this work establishes a much-needed model for the evaluation, cross-validation, and comparison of multiple cancer profiling studies.

Adenosine Monophosphate↗
PubMed2002

Prostate stem cell antigen as therapy target: tissue expression and in vivo efficacy of an immunoconjugate.

We conducted an expression analysis of prostate stem cell antigen (PSCA)in normal urogenital tissues, benign prostatic hyperplasia (n = 21), prostatic intraepithelial neoplasia (n = 33), and primary (n = 137) and metastatic (n = 42) prostate adenocarcinoma, using isotopic in situ hybridization on tissue microarrays. In normal prostate, we observe PSCA expression in the terminally differentiated, secretory epithelium; strong expression was also seen in normal urothelium. Forty-eight percent of primary and 64% of metastatic prostatic adenocarcinomas expressed PSCA RNA. Our studies did not confirm a positive correlation between level of PSCA RNA expression and high Gleason grade. We characterized monoclonal anti-PSCA antibodies that recognize PSCA expressed on the surface of live cells, are efficiently internalized after antigen recognition, and kill tumor cells in vitro in an antigen-specific fashion upon conjugation with maytansinoid. Unconjugated anti-PSCA antibodies demonstrated efficacy against PSCA-positive tumors by delaying progressive tumor growth in vivo. Maytansinoid-conjugated antibodies caused complete regression of established tumors in a large proportion of animals. Our results strongly suggest that maytansinoid-conjugated anti-PSCA monoclonal antibodies should be evaluated as a therapeutic modality for patients with advanced prostate cancer.

Adenocarcinoma↗
PubMed2002

alpha-Methylacyl coenzyme A racemase as a tissue biomarker for prostate cancer.

CONTEXT: Molecular profiling of prostate cancer has led to the identification of candidate biomarkers and regulatory genes. Discoveries from these genome-scale approaches may have applicability in the analysis of diagnostic prostate specimens. OBJECTIVES: To determine the expression and clinical utility of alpha-methylacyl coenzyme A racemase (AMACR), a gene identified as being overexpressed in prostate cancer by global profiling strategies. DESIGN: Four gene expression data sets from independent DNA microarray analyses were examined to identify genes expressed in prostate cancer (n = 128 specimens). A lead candidate gene, AMACR, was validated at the transcript level by reverse transcriptase polymerase chain reaction (RT-PCR) and at the protein level by immunoblot and immunohistochemical analysis. AMACR levels were examined using prostate cancer tissue microarrays in 342 samples representing different stages of prostate cancer progression. Protein expression was characterized as negative (score = 1), weak (2), moderate (3), or strong (4). Clinical utility of AMACR was evaluated using 94 prostate needle biopsy specimens. MAIN OUTCOME MEASURES: Messenger RNA transcript and protein levels of AMACR; sensitivity and specificity of AMACR as a tissue biomarker for prostate cancer in needle biopsy specimens. RESULTS: Three of 4 independent DNA microarray analyses (n = 128 specimens) revealed significant overexpression of AMACR in prostate cancer (P<.001). AMACR up-regulation in prostate cancer was confirmed by both RT-PCR and immunoblot analysis. Immunohistochemical analysis demonstrated an increased expression of AMACR in malignant prostate epithelia relative to benign epithelia. Tissue microarrays to assess AMACR expression in specimens consisting of benign prostate (n = 108 samples), atrophic prostate (n = 26), prostatic intraepithelial neoplasia (n = 75), localized prostate cancer (n = 116), and metastatic prostate cancer (n = 17) demonstrated mean AMACR protein staining intensity of 1.31 (95% confidence interval, 1.23-1.40), 2.33 (95% CI, 2.13-2.52), 2.67 (95% CI, 2.52-2.81), 3.20 (95% CI, 3.10-3.28), and 2.50 (95% CI, 2.20-2.80), respectively (P<.001). Pairwise comparisons demonstrated significant differences in staining intensity between clinically localized prostate cancer compared with benign prostate tissue, with mean expression scores of 3.2 and 1.3, respectively (mean difference, 1.9; 95% CI, 1.7-2.1; P<.001). Using moderate or strong staining intensity as positive (score = 3 or 4), evaluation of AMACR protein expression in 94 prostate needle biopsy specimens demonstrated 97% sensitivity and 100% specificity for detecting prostate cancer. CONCLUSIONS: AMACR was shown to be overexpressed in prostate cancer using independent experimental methods and prostate cancer specimens. AMACR may be useful in the interpretation of prostate needle biopsy specimens that are diagnostically challenging.

Biomarkers, Tumor↗
PubMed2002

Diagnosis of melanoma aspirates on ThinPrep: the University of Michigan experience.

The purpose of this study was to compare the cytologic features of melanoma fine-needle aspirates (FNAs) prepared by ThinPrep (TP) with those in conventional smears (CS) and to identify any diagnostic pitfalls. Fifty-one aspirates diagnosed as melanoma were obtained, 36 of which were prepared by both TP and CS. The preparations were evaluated for cellularity, cell aggregates, cellular appearance, melanin pigment, cytoplasmic, and nuclear features. Categorical data were analyzed by the chi-square test and continuous data by the Wilcoxin-signed rank test. Correlation was determined by Spearman's test for bivariate correlations (rho). Good correlation between the two methods was identified for the following features: cellularity, cell type, bi/multinucleated cells, cytoplasmic features, NC ratio, and presence of macronucleoli. TP exhibits coarser chromatin compared to CS (P = 0.005). Six of 36 CS contained large cellular groups; none of the TP contained them (P = 0.018). Twenty-five of 36 CS contained intranuclear inclusions as opposed to 12/36 TP (P < 0.001). The number of inclusions was significantly reduced on TP. The amount of intracellular melanin was the same with both techniques. Background melanin was markedly reduced on TP except when either trapped by fibrin or attached to cellular clusters (P = 0.006). Background blood was also markedly reduced on TP (P < 0.005). In summary, the cytological features of TP and CS for FNA evaluation of melanoma correlate well; however, one needs to be aware of the cytologic alterations introduced by TP. TP is a sufficient preparation method in the diagnosis of melanoma FNA aspirates when performed by clinicians. It is also a useful adjunct in bloody or low-cellular aspirates, where it tends to reduce the background blood and concentrate the cells.

Adult↗