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Mark A Rubin

Publications and source records attributed to Mark A Rubin.

At least 91 records · Page 5Linked to original sources
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

Diagnostic usefulness of monoclonal antibody P504S in the workup of atypical prostatic glandular proliferations.

We stained 37 prostate needle biopsies and 3 transurethral resections (TURP) containing atypical foci and 20 morphologically unequivocal prostate cancer biopsies, including 4 with foamy features, with P504S. Of 20 biopsies with unequivocal cancer, 18 showed variable P504S staining (sensitivity, 90%); 1 minute cancer and 1 foamy cancer lacked P504S staining. Of 40 cases with atypical foci (biopsies, 37; TURP, 3), 9 were diagnosed as high-grade prostatic intraepithelial neoplasia (HGPIN), 2 were excluded, and 29 had foci of atypical small glandular proliferation. Of these 29 cases, 7 were highly suggestive of cancer, 2 of which lacked P504S staining. In 22 cases with benign atypical foci, 11 were diagnosed as postatrophic hyperplasia (none expressed P504S) and 7 as atypical adenomatous hyperplasia (AAH; 1 showed focal weak P504S staining). Of 9 HGPIN specimens, 8 showed predominantly diffuse, moderate P504S staining. P504S has slightly lower sensitivity for detection of prostate cancer than found previously. Heterogeneous expression patterns may explain negativity in some biopsy specimens with minute cancer. In atypical small glandular proliferations, diffuse positive P504S staining in atypical glands strongly supports a cancer diagnosis, but negative staining does not exclude it. P504S seems to have low sensitivity for detecting foamy prostate cancer. Most HGPINs show diffuse moderate P504S staining. AAH may show focal P504S staining. We recommend using P504S along with morphologic examination and conventional basal cell markers.

Antibodies, Monoclonal↗
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↗
PubMed2002

APC/CTNNB1 (beta-catenin) pathway alterations in human prostate cancers.

Genetic alterations serve as beacons for the involvement of specific pathways in tumorigenesis. It was previously shown that 5% of prostate tumors harbor CTNNB1 mutations, suggesting that this tumor type may involve a deregulated APC/CTNNB1 pathway. To explore this possibility further, we searched for mutations in genes implicated in this pathway in 22 samples that included cell lines, xenografts, and primary tumors. We identified seven alterations: two in CTNNB1, three in APC, and two in hTRCP1 (also known as BTRC) which controls the degradation of CTNNB1. Alterations in the CTNNB1 regulatory domain, APC, and hTRCP1 were mutually exclusive, consistent with their equivalent effects on CTNNB1 stability. These results suggest that CTNNB1 signaling plays a critical role in the development of a significant fraction of prostate cancers. Moreover, they provide the first evidence that hTRCP1 plays a role in human neoplasia.

Animals↗
PubMed2002

alpha-Methylacyl-CoA racemase: expression levels of this novel cancer biomarker depend on tumor differentiation.

alpha-Methylacyl-CoA racemase (AMACR) has previously been shown to be a highly sensitive marker for colorectal and clinically localized prostate cancer (PCa). However, AMACR expression was down-regulated at the transcript and protein level in hormone-refractory metastatic PCa, suggesting a hormone-dependent expression of AMACR. To further explore the hypothesis that AMACR is hormone regulated and plays a role in PCa progression AMACR protein expression was characterized in a broad range of PCa samples treated with variable amounts and lengths of exogenous anti-androgens. Analysis included standard slides and high-density tissue microarrays. AMACR protein expression was significantly increased in localized hormone-naive PCa as compared to benign (P < 0.001). Mean AMACR expression was lower in tissue samples from patients who had received neoadjuvant hormone treatment but still higher compared to hormone-refractory metastases. The hormone-sensitive tumor cell line, LNCaP, demonstrated stronger AMACR expression by Western blot analysis than the poorly differentiated cell lines DU-145 and PC-3. AMACR protein expression in cells after exposure to anti-androgen treatment was unchanged, whereas prostate-specific antigen, known to be androgen-regulated, demonstrated decreased protein expression. Surprisingly, this data suggests that AMACR expression is not regulated by androgens. Examination of colorectal cancer, which is not hormone regulated, demonstrated high levels of AMACR expression in well to moderately differentiated tumors and weak expression in anaplastic colorectal cancers. Taken together, these data suggest that AMACR expression is not hormone-dependent but may in fact be a marker of tumor differentiation.

Biomarkers, Tumor↗
PubMed2002

Changes in differential gene expression because of warm ischemia time of radical prostatectomy specimens.

The expression of thousands of genes can be monitored simultaneously using cDNA microarray technology. This technology is being used to understand the complexity of human disease. One significant technical concern regards potential alterations in gene expression because of the effect of tissue ischemia. This study evaluates the increase in the differential gene expression because of tissue processing time. To evaluate differential gene expression because of ischemia time, prostate samples were divided into five time points (0, 0.5, 1, 3, and 5 hours). Each time point consisted of a homogeneous mixture of 12 to 15 prostate tissue cubes (5 mm(3)). These tissues were maintained at room temperature until at the assigned time point the tissue was placed in OCT, flash frozen in liquid nitrogen, and stored at -80 degrees C until RNA extraction. RNA from each time point was hybridized against an aliquot of 0 time point RNA from the same prostate. Four prostate glands were used in parallel studies. M-A plots were graphed to compare variability between time point sample hybridizations. Statistical Analysis of Microarray software was used to identify genes overexpressed at the 1-hour time point versus the 0-hour time with statistically significance. Microarray analysis revealed only a small percentage of genes (<0.6%) from more than 9000 to demonstrate overexpression at the 1-hour time point. Among the 41 statistically significant named overexpressed genes at the 1-hour time point were early growth response 1 (EGR1), jun B proto-oncogene (jun B), jun D proto-oncogene (jun D), and activating transcription factor 3 (ATF3). Genes previously associated with prostate cancer did not have significantly altered expression with ischemia time. Increased EGR1 protein expression was confirmed by Western blot analysis. Microarray technology has opened the possibility of evaluating the expression of a multitude of genes simultaneously, however, the interpretation of this complex data needs to be assessed circumspectly using refined statistical methods. Because RNA expression represents the tissue response to insults such as ischemia, and is also sensitive to degradation, investigators need be mindful of confounding artifacts secondary to tissue processing. All attempts should be made to process tissue rapidly to ensure that the microarray gene profile accurately represents the state of the cells and confirmatory studies should be performed using alternative methods (eg, Northern blot analysis, Western blot, immunohistochemistry).

Artifacts↗
PubMed2002

Characterization of RhoC expression in benign and malignant breast disease: a potential new marker for small breast carcinomas with metastatic ability.

The most important factor in predicting outcome in patients with early breast cancer is the stage of the disease. There is no robust marker capable of identifying invasive carcinomas that despite their small size have a high metastatic potential, and that would benefit from more aggressive treatment. RhoC-GTPase is a member of the Ras-superfamily and is involved in cell polarity and motility. We hypothesized that RhoC expression would be a good marker to identify breast cancer patients with high risk of developing metastases, and that it would be a prognostic marker useful in the clinic. We developed a specific anti-RhoC antibody and studied archival breast tissues that comprise a broad spectrum of breast disease. One hundred eighty-two specimens from 164 patients were used. Immunohistochemistry was performed on formalin-fixed tissues. Staining intensity was graded 0 to 3+ (0 to 1+ was considered negative and 2 to 3+ was considered positive). RhoC was not expressed in any of the normal, fibrocystic changes, atypical hyperplasia, or ductal carcinoma in situ, but was expressed in 36 of 118 invasive carcinomas and strongly correlated with tumor stage (P = 0.01). RhoC had high specificity (88%) in detecting invasive carcinomas with metastatic potential. Of the invasive carcinomas smaller than 1 cm, RhoC was highly specific in detecting tumors that developed metastases. RhoC expression was associated with negative progesterone receptor and HER-2/neu overexpression. We characterized RhoC expression in human breast tissues. RhoC is specifically expressed in invasive breast carcinomas capable of metastasizing, and it may be clinically useful in patients with tumors smaller than 1 cm to guide treatment.

Animals↗