Alpha-methylacyl CoA racemase (P504S): overview and potential uses in diagnostic pathology as applied to prostate needle biopsies

Diagnostic Accuracy of Alpha-Methylacyl-CoA Racemase Immunohistochemical Expression for the Diagnosis of Ovarian and Endometrial Clear Cell Carcinomas

Background & Objective

Clear cell carcinoma (CCC) is an uncommon histopathologic subtype of ovarian and endometrial carcinoma. Due to the morphologic overlapping with other subtypes of ovarian and endometrial carcinomas, an accurate diagnosis is crucial.

Methods

In this study, 31 cases of ovarian clear cell carcinoma (OCCC), 28 endometrial clear cell carcinoma (ECCC), and 80 non-CCC subtypes (33 high-grade serous carcinomas of the ovary, 2 low-grade serous carcinomas, 10 ovarian endometrioid, 3 serous carcinomas and 29 endometrioid carcinomas of the endometrium) were investigated for immunohistochemical expression of AMACR. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for the distinction of OCCC and ECCC from other histopathologic subtypes were calculated.

Results

Positive AMACR staining was seen in 18 OCCCs (58%) and 10 ECCCs (35.7%). In the non-clear cell group, 44 cases of ovarian (98%) and 25 cases of endometrial carcinoma (78%) showed negative results. Only one case of ovarian endometrioid carcinoma and 7 cases (22%) of endometrial endometrioid carcinomas revealed a positive reaction (P<0.05). Collectively, sensitivity, specificity, PPV, and NPV of AMACR expression, for the diagnosis of OCCC were calculated as 58%, 98%, 94.7%, and 77.2%, respectively. The sensitivity, specificity, PPV, and NPV were shown to be as 35.7%, 78.1%, 58.8%, and 58.1%, respectively in the endometrium.

Conclusion

AMACR may be a highly specific immunohistochemical marker for the distinction of serous and clear cell carcinoma. A small percentage of endometrioid carcinoma may show positive staining. The sensitivity of this marker may not be higher than the other well-known Napsin-A IHC marker.

Downregulation of miR-99b-5p and Upregulation of Nuclear mTOR Cooperatively Promotes the Tumor Aggressiveness and Drug Resistance in African American Prostate Cancer

Mammalian target of rapamycin (mTOR) regulates various fundamental cellular events including cell proliferation, protein synthesis, metabolism, apoptosis, and autophagy. Tumor suppressive miR-99b-5p has been implicated in regulating PI3K/AKT/mTOR signaling in a variety of types of cancer. Our previous study suggested the reciprocal miR-99b-5p/MTOR (downregulated/upregulated) pairing as a key microRNA-mRNA regulatory component involved in the prostate cancer (PCa) disparities. In this study, we further validated the expression profiles of mTOR and miR-99b-5p in the PCa, colon, breast, and lung cancer specimens and cell lines. The immunohistochemistry (IHC), immunofluorescence, Western blot, and RT-qPCR assays have confirmed that mTOR is upregulated while miR-99b-5p is downregulated in different patient cohorts and a panel of cancer cell lines. Intriguingly, elevated nuclear mTOR expression was observed in African American PCa and other advanced cancers. Transfection of the miR-99b-5p mimic resulted in a significant reduction in nuclear mTOR and androgen receptor (AR), while a slight/moderate to no decrease in cytoplasmic mTOR and AR in PCa and other cancer cells, suggesting that miR-99b-5p inhibits mTOR and AR expression and their nuclear translocation. Moreover, overexpression of miR-99b-5p targets/inhibits AR-mTOR axis, subsequently initiating cell apoptosis and sensitizing docetaxel-induced cytotoxicity in various cancers. In conclusion, our data suggest that reciprocal miR-99b-5p/nuclear mTOR pairing may be a more precise diagnostic/prognostic biomarker for aggressive PCa, than miR-99b-5p/MTOR pairing or mTOR alone. Targeting the AR-mTOR axis using miR-99b-5p has also been suggested as a novel therapeutic strategy to induce apoptosis and overcome chemoresistance in aggressive PCa.

Circ_0076305 facilitates prostate cancer development via sponging miR-411-5p and regulating PGK1

Abnormal expression of circular RNA (circRNA) is tightly linked to cancer progression. In this study, we aimed to investigate the biological role of circ_0076305 in prostate cancer (PCa). RT-qPCR was utilized to examine circ_0076305, microRNA-411-5p (miR-411-5p) and phosphoglycerate kinase 1 (PGK1) expression in PCa tissues and cells. CCK-8 assay, EdU assay, wound-healing assay and flow cytometry were executed to investigate the regulatory function of circ_0076305 on the proliferation, migration and apoptosis of PCa cells. Western blot (WB) assay was applied for measuring the protein levels. The effect of circ_0076305 on cellular glycolysis was examined using commercial kits. RNA immunoprecipitation (RIP) and dual-luciferase reporter assays were conducted for confirming the association between miR-411-5p and circ_0076305 or PGK1. The role of circ_0076305 in vivo was detected via establishing mice xenograft model. Circ_0076305 was highly expressed in PCa. Circ_0076305 silencing could repress cell growth, migration and glycolysis while triggered apoptosis in PCa cells. MiR-411-5p was targeted by circ_0076305, and miR-411-5p suppression counteracted the influence of circ_0076305 silencing in PCa cells. Additionally, miR-411-5p directly targeted PGK1, and miR-411-5p upregulation restrained PCa cell malignant behaviours via reducing PGK1. Mechanically, circ_0076305 sponged miR-411-5p to affect PGK1 expression. Importantly, circ_0076305 interference inhibited tumour growth in vivo. Circ_0076305 served as a novel oncogene PCa progression through regulation of miR-411-5p/PGK1 axis.

[Verumontanum mucosal hyperplasia as a differential diagnosis of a local recurrence following radical prostatectomy]

Verumontanum mucosal gland hyperplasia (VMGH) is a benign microacinar proliferative lesion, which occurs exclusively in the verumontanum and the posterior urethra and is one of the lesions that may be confused with a low-risk adenocarcinoma of the prostate gland.We present the case of a 72-year-old male patient who underwent radical prostatectomy due to an adenocarcinoma of the prostate gland (pT2c pN0 cM0 R0, Gleason Score: 3 + 3 = 6). Five years after the operation, we sonographically detected a 3x2 cm large tumour in the prostate bed. While our first assumption was a PSA-negative local recurrence following radical prostatectomy, a comprehensive histological examination along with the clinical evaluation led us to the diagnosis of a VMGH. VMGH is a less well-known differential diagnosis of PSA-negative local recurrence following radical prostatectomy, whose clinical manifestation should be presented.

Molecular profiling of radical prostatectomy tissue from patients with no sign of progression identifies ERG as the strongest independent predictor of recurrence

BACKGROUND

As a major cause of morbidity and mortality among men, prostate cancer is a heterogenous disease, with a vast heterogeneity in the biology of the disease and in clinical outcome. While it often runs an indolent course, local progression or metastasis may eventually develop, even among patients considered "low risk" at diagnosis. Therefore, biomarkers that can discriminate aggressive from indolent disease at an early stage would greatly benefit patients. We hypothesized that tissue specimens from early stage prostate cancers may harbor predictive signatures for disease progression.

METHODS

We used a cohort of radical prostatectomy patients with longitudinal follow-up, who had tumors with low grade and stage that revealed no signs of future disease progression at surgery. During the follow-up period, some patients either remained indolent (non-BCR) or progressed to biochemical recurrence (BCR). Total RNA was extracted from tumor, and adjacent normal epithelium of formalin-fixed-paraffin-embedded (FFPE) specimens. Differential gene expression in tumors, and in tumor versus normal tissues between BCR and non-BCR patients were analyzed by NanoString using a customized CodeSet of 151 probes.

RESULTS

After controlling for false discovery rates, we identified a panel of eight genes (ERG, GGT1, HDAC1, KLK2, MYO6, PLA2G7, BICD1 and CACNAID) that distinguished BCR from non-BCR patients. We found a clear association of ERG expression with non-BCR, which was further corroborated by quantitative RT-PCR and immunohistochemistry assays.

CONCLUSIONS

Our results identified ERG as the strongest predictor for BCR and showed that potential prognostic prostate cancer biomarkers can be identified from FFPE tumor specimens.

Prostate-specific markers to identify rare prostate cancer cells in liquid biopsies

Despite improvements in early detection and advances in treatment, patients with prostate cancer continue to die from their disease. Minimal residual disease after primary definitive treatment can lead to relapse and distant metastases, and increasing evidence suggests that circulating tumour cells (CTCs) and bone marrow-derived disseminated tumour cells (BM-DTCs) can offer clinically relevant biological insights into prostate cancer dissemination and metastasis. Using epithelial markers to accurately detect CTCs and BM-DTCs is associated with difficulties, and prostate-specific markers are needed for the detection of these cells using rare cell assays. Putative prostate-specific markers have been identified, and an optimized strategy for staining rare cancer cells from liquid biopsies using these markers is required. The ideal prostate-specific marker will be expressed on every CTC or BM-DTC throughout disease progression (giving high sensitivity) and will not be expressed on non-prostate-cancer cells in the sample (giving high specificity). Some markers might not be specific enough to the prostate to be used as individual markers of prostate cancer cells, whereas others could be truly prostate-specific and would make ideal markers for use in rare cell assays. The goal of future studies is to use sensitive and specific prostate markers to consistently and reliably identify rare cancer cells.

LXRs, SHP, and FXR in Prostate Cancer: Enemies or Ménage à Quatre With AR?

Androgens and androgen receptor (AR, NR3C4) clearly play a crucial role in prostate cancer progression. Besides, the link between metabolic disorders and the risk of developing a prostate cancer has been emerging these last years. Interestingly, “lipid” nuclear receptors such as LXRα/NR1H3 and LXRβ/NR1H2 (as well as FXRα/NR1H4 and SHP/NR0B2) have been described to decrease the lipid metabolism, while AR increases it. Moreover, these former orphan nuclear receptors can regulate androgen levels and modulate AR activity. Thus, it is not surprising to find such receptors involved in the physiology of prostate. This review is focused on the roles of liver X receptors (LXRs), farnesoid X receptor (FXR), and small heterodimeric partner (SHP) in prostate physiology and their capabilities to interfere with the androgen-regulated pathways by modulating the levels of active androgen within the prostate. By the use of prostate cancer cell lines, mice deficient for these nuclear receptors and human tissue libraries, several authors have pointed out the putative possibility to pharmacologically target these receptors. These data open a new field of research for the development of new drugs that could overcome the castration resistance in prostate cancer, a usual phenomenon in patients.

Extracellular Citrate Affects Critical Elements of Cancer Cell Metabolism and Supports Cancer Development In Vivo

Glycolysis and fatty acid synthesis are highly active in cancer cells through cytosolic citrate metabolism, with intracellular citrate primarily derived from either glucose or glutamine via the tricarboxylic acid cycle. We show here that extracellular citrate is supplied to cancer cells through a plasma membrane-specific variant of the mitochondrial citrate transporter (pmCiC). Metabolomic analysis revealed that citrate uptake broadly affected cancer cell metabolism through citrate-dependent metabolic pathways. Treatment with gluconate specifically blocked pmCiC and decreased tumor growth in murine xenografts of human pancreatic cancer. This treatment altered metabolism within tumors, including fatty acid metabolism. High expression of pmCiC was associated with invasion and advanced tumor stage across many human cancers. These findings support the exploration of extracellular citrate transport as a novel potential target for cancer therapy.Significance: Uptake of extracellular citrate through pmCiC can be blocked with gluconate to reduce tumor growth and to alter metabolic characteristics of tumor tissue. Cancer Res; 78(10); 2513-23. ©2018 AACR.

AMACR overexpression acts as a negative prognostic factor in oral squamous cell carcinoma

Background: Alpha-methylacyl-CoA racemase (AMACR) is a key enzyme responsible for the metabolism of branched-chain fatty acids. It has been found to be an important prognostic factor in numerous types of cancers. This study was aimed to investigate the expression of AMACR and its prognostic significance in patients with oral squamous cell carcinoma (SCC). Methods: Analysis of publicly available microarray data of oral SCC revealed that AMACR was significantly upregulated in tumor tissue compared with normal mucosa. We further assessed the protein expression of AMACR in 164 patients with oral SCC by immunohistochemistry. The prognostic impact of AMACR expression and its association with various clinicopathological parameters were statistically analyzed. Results: AMACR overexpression was significantly associated with advanced tumor status (P=0.001), advanced nodal status (P=0.036), increased vascular invasion (P=0.026) and increased perineural invasion (P=0.004). Patients with high expression level of AMACR had significantly worse disease-specific survival (DSS), distant metastasis-free survival (DMFS) and local recurrence-free survival (LRFS) (all P<0.0001). In multivariate analysis, AMACR overexpression was also an independent negative prognostic factor for DSS (hazard ratio [HR]: 4.410, 95% confidence interval [CI]: 2.285-8.511, P<0.001), DMFS (HR: 5.157, 95% CI: 2.756-9.651, P<0.001) and LRFS (HR: 4.462, 95% CI: 2.429-8.198, P<0.001). Conclusions: High expression of AMACR was not only a key adverse prognostic factor but also a potential therapeutic target in oral SCC.

Reactivation of androgen receptor-regulated lipid biosynthesis drives the progression of castration-resistant prostate cancer

Androgen receptor (AR) is a transcriptional activator that, in prostate cells, stimulates gene expression required for various cellular functions, including metabolisms and proliferation. AR signaling is also essential for the development of hormone-dependent prostate cancer (PCa) and its activity can be blocked by androgen-deprivation therapies (ADTs). Although PCa patients initially respond well to ADTs, the cancer inevitably relapses and progresses to lethal castration-resistant prostate cancer (CRPC). Although AR activity is generally restored in CRPC despite the castrate level of androgens, it is unclear whether AR signaling is significantly reprogrammed. In this study, we examined the AR cistrome in a PCa cell line-derived CRPC model using integrated bioinformatical analyses. Significantly, we found that the AR cistrome is largely retained in the CRPC stage. In particular, AR-mediated lipid biosynthesis is highly conserved and reactivated during the progression to CRPC, and increased level of lipid synthesis is associated with poor prognosis. The restoration of lipid biosynthetic pathways is partially due to the increased expression of AR splice variants. Blocking lipid/cholesterol synthesis in AR variants-expressing CRPC cell line and xenograft models markedly reduces tumor growth through inhibition of mTOR pathway. Silencing the expression of a fatty acid elongase, ELOVL7, also leads to the regression of CRPC xenograft tumors. These results demonstrate the importance of reactivation of AR-regulated lipid biosynthetic pathways in driving CRPC progression, and suggest that ADTs may be therapeutically enhanced by blocking lipid biosynthetic pathways.

Cell type specific gene expression analysis of prostate needle biopsies resolves tumor tissue heterogeneity

A lack of cell surface markers for the specific identification, isolation and subsequent analysis of living prostate tumor cells hampers progress in the field. Specific characterization of tumor cells and their microenvironment in a multi-parameter molecular assay could significantly improve prognostic accuracy for the heterogeneous prostate tumor tissue. Novel functionalized gold-nano particles allow fluorescence-based detection of absolute mRNA expression levels in living cells by fluorescent activated flow cytometry (FACS). We use of this technique to separate prostate tumor and benign cells in human prostate needle biopsies based on the expression levels of the tumor marker alpha-methylacyl-CoA racemase (AMACR). We combined RNA and protein detection of living cells by FACS to gate for epithelial cell adhesion molecule (EPCAM) positive tumor and benign cells, EPCAM/CD45 double negative mesenchymal cells and CD45 positive infiltrating lymphocytes. EPCAM positive epithelial cells were further sub-gated into AMACR high and low expressing cells. Two hundred cells from each population and several biopsies from the same patient were analyzed using a multiplexed gene expression profile to generate a cell type resolved profile of the specimen. This technique provides the basis for the clinical evaluation of cell type resolved gene expression profiles as pre-therapeutic prognostic markers for prostate cancer.

A cross sectional study of p504s, CD133, and Twist expression in the esophageal metaplasia dysplasia adenocarcinoma sequence

The incidence of esophageal adenocarcinoma has increased dramatically over recent years and Barrett's esophagus is considered the most established risk factor for its development. Endoscopic surveillance of Barrett's esophagus is therefore recommended but hinges on histological interpretation of randomly taken biopsies which is poorly reproducible. The use of biomarkers presents an opportunity to improve our ability to risk-stratify these patients.We examined three biomarkers namely p504s, CD133, and Twist in the setting of Barrett's esophagus, low-grade dysplasia, and esophageal adenocarcinoma to evaluate differential expression between benign, dysplastic, and malignant Barrett's tissue in an exploratory cross-sectional study. Twenty-five cases each of Barrett's esophagus, low-grade dysplasia, and esophageal adenocarcinoma were included along-with 25 cases of esophagectomy resections for Barrett's adenocarcinoma. The biomarkers were immunostained on automated Ventana(®) immunostainer. The biopsies were assessed for biomarker expression by two independent observers. Granular cytoplasmic staining of p504s was observed in dysplastic Barrett's biopsies and esophageal adenocarcinoma but not in Barrett's esophagus. Apical and membranous CD133 expression was also observed in dysplastic Barrett's and esophageal adenocarcinoma. Nuclear Twist expression was seen predominantly in stromal cells. There was increased p504s expression in dysplastic Barrett's esophagus and esophageal adenocarcinoma compared with controls. CD133 expression was detected for the first time in esophageal adenocarcinoma and dysplastic Barrett's esophagus. Twist expression was not convincing enough to be labeled as Barrett's biomarker. p504s and CD133 have the potential to differentiate benign from malignant Barrett's tissue in this exploratory study. Their validity should be established in prospective longitudinal studies.

The Application of Immunohistochemical Biomarkers in Urologic Surgical Pathology

Context

Tumors of the genitourinary tract can be diagnostically challenging, particularly in core biopsies and cystoscopic biopsies with limited material. Immunohistochemistry is a valuable tool to use when morphology alone is insufficient for diagnosis.

Objectives

To review tumors and benign lesions of the kidney, urinary bladder, prostate gland, testis, and paratesticular structures with an emphasis on difficult differential diagnoses, as well as staining patterns in normal tissue. Recommended immunohistochemical stain panels are discussed that can assist in the diagnostic workup.

Data Sources

Review of current literature.

Conclusions

Immunohistochemistry is a valuable tool, assisting in the diagnosis of problematic tumors and benign lesions of the genitourinary tract.

α-Methylacyl-CoA racemase (AMACR) serves as a prognostic biomarker for the early recurrence/metastasis of HCC

AIMS

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide, and it is still lacking effective prognostic biomarkers so far. Previous results of the iTRAQ-based quantitative proteomics study (iTRAQ-2DLC-MS/MS) have shown that α-methylacyl-CoA racemase (AMACR) might be a promising prognostic biomarker for the early recurrence/metastasis of hepatocellular carcinoma (HCC). Here a large-scale cohort clinical study was performed to evaluate its prognostic potential.

METHODS

HCC samples from patients (n=158) were used for the construction of tissue microarray. The expression level of AMACR was determined by immunohistochemical staining. A large-scale cohort clinical study between the expression of AMACR and some major clinical parameter has been performed to assess the prognostic potential of AMACR for the early recurrence/metastasis of HCC.

RESULTS

Some important clinical parameters such as α-fetoprotein, tumour numbers, dissemination to regional lymph nodes, tumour capsule and portal vein tumour thrombosis are significantly associated with the low expression of AMACR. The expression of AMACR was an independent factor for the survival of patients with HCC. The median survival time was 17 months in the low-expression group compared with 45 months in the high-expression group.

CONCLUSIONS

This study reveals that the AMACR might be a potential prognostic marker for predicting early recurrence/metastasis of HCC after hepatectomy.

Selection of aptamers for fluorescent detection of alpha-methylacyl-CoA racemase by single-bead SELEX

This paper first reports DNA aptamers and a fluorescent enzyme-linked aptamer assay (ELAA) targeting alpha-methylacyl-CoA racemase (AMACR), an emerging prostate cancer biomarker. The aptamers were in vitro selected using a new single-bead SELEX approach, which was rapid and consumed only ca. 45 ng AMACR. Before SELEX, silane chemistry was used to prepare epoxide-functionalized glass microbeads (EGBs, 500 μm in size and manipulated by tweezers) for AMACR coating. Recombinant AMACR was also prepared. During SELEX, the ligand evolution was assured by a differential real-time quantitative PCR assay. After SELEX, the aptamers were identified by the alignment analysis and 2nd structure prediction from the selected, cloned sequences. The circular dichroism (CD) analysis revealed that the aptamers formed stable B-form, stem-loop conformations. The fluorescent ELAA method confirmed the nM-level affinity and high specificity of the aptamers against AMACR. Finally, an aptamer-based fluorescent AMACR assay was demonstrated. The assay featured a wide dynamic range (from 10(-1) to 10(3) nM of AMACR), a low detection limit of 0.44 nM (19.5 ng/mL), and high AMACR specificity and is promising for clinical AMACR diagnostics.

α-Methylacyl-CoA racemase (P504S) is a useful marker for the differential diagnosis of solid pseudopapillary neoplasm of the pancreas

The differential diagnosis of solid pseudopapillary neoplasm (SPN) from some other nonductal pancreatic tumors may be difficult because of similarities in morphological features. Therefore, immunohistochemical staining is frequently necessary. α-Methylacyl-CoA racemase (AMACR) is a diagnostically useful marker for prostatic cancer and papillary renal cell carcinoma. The aim of this study was to investigate AMACR as a new immunohistochemical marker to differentiate SPNs from other nonductal pancreatic tumors. We investigated immunohistochemical staining for AMACR in 26 SPNs, 21 pancreatic neuroendocrine tumors, and 7 acinar cell carcinomas. All cases of SPN showed granular cytoplasmic expression of AMACR, whereas all cases of pancreatic neuroendocrine tumors and acinar cell carcinomas were negative for this immunohistochemical marker. Hence, our findings demonstrate for the first time that AMACR is a useful immunohistochemical marker for the differential diagnosis of SPNs.

When is prostate cancer really cancer?

Several investigators have challenged the idea that low-grade cancers are a cause for concern, suggesting that the term cancer should not be applied to these tumors. This article reviews the defining features of cancer, and the diagnostic and prognostic classification systems currently used for prostate cancer. Logical, morphologic, and molecular evidence is presented to show that low-grade prostate cancers are correctly classified as cancer. The authors suggest, however, that 6 out of 10 on an aggressiveness scale is inappropriate for indolent cancer, and that a proposed reinterpretation of Gleason grading categories is a more logical way to address overtreatment.

Alpha methylacyl-CoA racemase (AMACR) in prostate adenocarcinomas from Japanese patients: is AMACR a "race"-dependent marker?

BACKGROUND

Alpha methylacyl-CoA racemase (AMACR) is a useful diagnostic marker for prostate adenocarcinoma. However, its usefulness has not been fully validated in Japanese patients. The aim of this study was to evaluate the diagnostic utility of AMACR in prostate needle biopsy examination in Japanese patients.

METHODS

A total of 119 prospective consecutive prostate needle biopsy specimens (680 cores) obtained from Japanese patients were examined. Sixty patients had adenocarcinoma (adenocarcinoma, 160 cores; benign, 204 cores), 14 patients had high-grade prostatic intraepithelial neoplasia (HGPIN; 19 cores), and 45 patients did not have any neoplastic lesions (297 cores). AMACR expression was scored semi-quantitatively as 0 (no expression), 1+ (partial and/or weak expression), or 2+ (strong, circumferential expression). The number of positively stained glands was counted.

RESULTS

2+ AMACR expression was observed in 70.1% of adenocarcinoma cases and in 52.6% of HGPIN cases. Of the adenocarcinoma cases showing 2+ AMACR expression, 34.8% demonstrated a heterogeneous expression pattern, with 1-75% of AMACR-positive glands. Three hundred eighty-five of the benign glands with an adenocarcinoma component showed 2+ AMACR expression (35 cases, 94 cores). 2+ AMACR expression was observed in 67 non-neoplastic benign glands (9 cases, 19 cores).

CONCLUSIONS

The sensitivity and specificity of AMACR for the diagnosis of prostate adenocarcinoma and benign glands in Japanese patients are lower than those previously reported in Western countries. Pathologists should be cautious while interpreting AMACR expression pattern in Japanese patients.

Comparative analysis of three- and two-antibody cocktails to AMACR and basal cell markers for the immunohistochemical diagnosis of prostate carcinoma

Background

Immunohistochemistry using antibody cocktails against basal cell specific and cancer-associated markers is important in the diagnosis of prostate carcinoma in needle biopsies. We compared the usefulness for detecting prostate carcinoma of a three-marker cocktail of antibodies to α-methylacyl-CoA racemase (AMACR), p63 and cytokeratin (CK) 5 with a traditional two-marker cocktail of AMACR and p63.

Methods

Sixty-six prostate needle biopsies were analysed prospectively. Serial sections were immunostained with the two- and three- antibody cocktails. Blinded slides were assessed individually by two pathologists and sensitivity, specificity and kappa statistics were calculated.

Results

Both antibody cocktails contributed to the detection of prostate carcinoma in needle biopsies. There was an acceptable level of agreement between the pathologists for both the cocktails. Sensitivity was similar for one pathologist comparing both the cocktails (76.4% and 75.7%), but was slightly lower comparing the three-antibody with the two-antibody cocktail for the other pathologist (66.6% vs. 77.4%, respectively). Higher specificity values of 90.3% were achieved by both pathologists using three-antibody as compared with two-antibody cocktails (68.7% and 71.8%).

Conclusions

Antibody cocktails are important in diagnosing prostate carcinoma in needle biopsies. Adding an extra basal cell marker to the traditional two-antibody cocktail improves the specificity of detecting prostate carcinoma in limited needle biopsy material, and should be considered for routine diagnostic use.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2492231327330327

α-Methylacyl-CoA racemase spliced variants and their expression in normal and malignant prostate tissues

OBJECTIVES

To evaluate the possibility of using α-methylacyl-CoA racemase (AMACR) variants to improve the specificity of prostate cancer (CaP) detection. AMACR has been used as a diagnostic biomarker for CaP and is now a standard biomarker for needle biopsy specimens with ambiguous lesions.

METHODS

We used in silico analysis and molecular cloning to discover new AMACR variants and quantitative reverse transcription-polymerase chain reaction (RT-PCR) to measure the transcript levels of AMACR and its variants in 4 prostate cell lines and in 23 pairs of CaP and adjacent normal tissue.

RESULTS

We found 4 novel variants, IAs, IBL, IBLd, and IBLi. Transcript levels of most AMACR variants were significantly upregulated in CaP compared with its adjacent normal counterparts. A variants, the functional variants based on bioinformatic analysis, showed levels of transcript expression in CaP in this order: IA≫IAd=IIA≫IIAs>IAs. In contrast, the expression of the B variants, which appear to be nonfunctional due to the absence of exon 3, was lower than that of the A variants. IB was the most abundant form of B variant; and expression of IIB was negligible. More important, the difference between levels of variant IA, IAd, IIA, IIAs, IB, and IBLi in CaP and normal tissue was significantly higher than the difference in levels of total AMACR.

CONCLUSIONS

Our data suggest that AMACR variants have better power than total AMACR in discriminating between CaP and adjacent normal tissue. These findings may be useful for the development of future diagnostic assays.

AMACR is not applicable as a diagnostic tool in hepatocellular carcinoma

Alpha-methylacyl coenzyme A racemase (AMACR or P504S) is a mitochondrial and peroxisomal protein present in a variety of human cells. Demonstration of increased expression is used diagnostically in prostatic adenocarcinoma. AMACR is also produced by normal hepatocytes and it has been postulated that the demonstration of AMACR expression or its pattern of distribution is useful in the diagnosis of hepatocellular carcinoma (HCC) (Jiang et al., Hum Pathol 2003;34, Guzman et al., Appl Immunohistochem Mol Morphol 2006;14, Li et al., J Exp Clin Cancer Res 2008;27). The aim of the present study was to evaluate whether immunohistochemical staining for AMACR can be used in a routine histopathologic setting. Immunohistochemical staining for AMACR was performed on paraffin-embedded tissue from livers resected for HCC during 1980-2006 at Rigshospitalet, Copenhagen, Denmark (n = 44). Tumor sections as well as surrounding non-neoplastic tissues were studied. In both tumor and non-tumor tissues, intracellular localization and staining pattern were assessed and the staining intensity of AMACR was graded. The fraction of stained tumor cells was not significantly different from that of stained non-tumor cells in the same patients (p = 0.97). A significantly lower staining intensity was observed in clear cell areas (p = 0.005), but the AMACR expression did not correlate with the HCC type and could not distinguish neoplastic from non-neoplastic liver cells. AMACR is not applicable as a tool in the histopathologic diagnosis of HCC.

Reliability of the 34βE12, keratin 5/6, p63, bcl-2, and AMACR in the diagnosis of prostate carcinoma

OBJECTIVE

In this study, we aimed to investigate which basal cell marker should be used with α-methylacyl coenzyme A racemase (AMACR) to increase diagnostic accuracy in the diagnosis of prostate carcinoma.

MATERIALS AND METHODS

A total of 98 cases of prostate biopsy, comprising 65 cases with prostate adenocarcinoma and 33 cases without adenocarcinoma, were included in this study. Prostate-specific antigen (PSA) serum levels before biopsies were obtained. The number of cores with malignant glands and Gleason scores for each case were determined. Paraffin sections were stained immunohistochemically with 34βE12, keratin 5/6, p63, bcl-2, and AMACR.

RESULTS

According to staining pattern, extensiveness, and intensity of basal cell markers in benign glands, 34βE12 gave the best results. As negative markers for prostate adenocarcinoma, the best markers were p63 and 34βE12. According to the AUC values in ROC curves for both extensiveness and intensity, the arrangement from the best to the worst was 34βE12, p63, bcl-2, and keratin 5/6. The 34βE12 had the best sensitivity and specificity values (95% and 98%, respectively). Staining extensiveness and intensity of keratin 5/6 in malignant glands, and those of bcl-2 in benign glands had statistically significant positive correlation with serum PSA levels. Even though AMACR is a negative marker for benignity, some of the benign glands also had positive immune reaction with AMACR. However, AMACR positivity was usually focal and weak. Nevertheless, intensively stained subjects were also present. No correlation was present between AMACR and basal cell markers.

CONCLUSIONS

As a result, we suggest that keratin 5/6 and bcl-2 should not be used to identify benign glands in prostate biopsy since they show high positivity in malignant glands and high negativity in benign glands. 34βE12 should be the first choice as a basal cell marker. p63 can be used together with 34βE12, but it may not give additional diagnostic information. When we evaluated the correlation of basal cell markers, we did not find any complementary staining results among basal cell markers. Our study showed that 34βE12 is the most appropriate negative marker to combine with AMACR as a positive marker for the diagnosis of prostate adenocarcinoma.

Alpha-methylacyl-CoA racemase expression is upregulated in gastric adenocarcinoma: a study of 249 cases

Alpha-methylacyl-CoA racemase (AMACR [P504S]) is a mitochondrial and peroxisomal enzyme involved in beta-oxidation of dietary branched-chain fatty acids and their derivatives. Recent studies showed that AMACR is expressed in several neoplasms, including prostate and colon cancer. However, AMACR expression in gastric neoplasms has yet to be thoroughly investigated. Because AMACR overexpression in human solid tumors is a potential target for cancer treatment, we aimed to evaluate the expression of AMACR in a large cohort of patients with gastric adenocarcinoma. The study evaluated 249 primary gastric adenocarcinomas by immunohistochemistry. Nonneoplastic gastric tissue samples from various sites (antrum, body, fundus, and pylorus) were also examined. The immunopositivity of each sample was graded on a scale from 0 to 3 (0, no expression; 1, weak expression, 2, intermediate expression; 3, strong expression). We observed AMACR expression in 141 tumor cases: 44, 47, and 50 cases had weak, intermediate, and strong expression, respectively. Both intestinal and signet ring cell adenocarcinoma cases had overexpression of AMACR, however intestinal adenocarcinoma had significantly higher expression than did signet ring cell adenocarcinoma (p<0.05). Nonneoplastic gastric mucosa did not show AMACR expression. The results of our study demonstrate that AMACR expression is upregulated in gastric cancer, and suggest that further prospective studies to explore the potential role of AMACR as a therapeutic target for gastric cancer are warranted.

[New markers in prostate biopsies]

The use of serum prostate-specific antigen screening to facilitate early detection of prostate cancer has resulted in a dramatic increase in the number of prostate needle core biopsies which pathologists must examine. This has been accompanied by a strong increase in the number of biopsies with ambiguous lesions, and an unequivocal diagnosis of malignancy is difficult to render, especially in the case of limited foci or in small atypical acinar lesions. When assessing small foci of atypical glands upon needle biopsy, the pathologist searches for differences between the benign glands and atypical glands in terms of usual morphological features and in such cases, immunohistochemical stains for basal cell markers such as 34betaE12 antibody or antibodies directed against cytokeratin 5 and 6 and more recently p63 may be a useful adjuvant to identify basal cells which are typically present in benign glands but absent in prostatic carcinoma. However several benign mimickers of prostate carcinoma, including atrophy, atypical adenomatous hyperplasia, nephrogenic adenoma can stain negatively with these antibodies and thus a negative basal cell marker immunostain alone does not exclude a diagnosis of benignancy. Alpha-methyl-coenzyme-A-racemase (AMACR) a new sensitive marker of prostate carcinoma, can be useful in confirming ambiguous lesion suspected for malignancy. Although, as with any immunohistochemical studies, problems exist in terms of both sensitivity and specificity. The aim of this review is to describe the histological features of prostatic carcinoma in case of small focus, and discuss the application of these new prostatic markers in the light of the current literature to highlight the best practice guidelines.

Alpha-methylacyl-CoA racemase--an 'obscure' metabolic enzyme takes centre stage

Branched-chain lipids are important components of the human diet and are used as drug molecules, e.g. ibuprofen. Owing to the presence of methyl groups on their carbon chains, they cannot be metabolized in mitochondria, and instead are processed and degraded in peroxisomes. Several different oxidative degradation pathways for these lipids are known, including alpha-oxidation, beta-oxidation, and omega-oxidation. Dietary branched-chain lipids (especially phytanic acid) have attracted much attention in recent years, due to their link with prostate, breast, colon and other cancers as well as their role in neurological disease. A central role in all the metabolic pathways is played by alpha-methylacyl-CoA racemase (AMACR), which regulates metabolism of these lipids and drugs. AMACR catalyses the chiral inversion of a diverse number of 2-methyl acids (as their CoA esters), and regulates the entry of branched-chain lipids into the peroxisomal and mitochondrial beta-oxidation pathways. This review brings together advances in the different disciplines, and considers new research in both the metabolism of branched-chain lipids and their role in cancer, with particular emphasis on the crucial role played by AMACR. These recent advances enable new preventative and treatment strategies for cancer.

The role of tissue microarrays in prostate cancer biomarker discovery

Tissue microarrays (TMAs) offer the potential to rapidly translate genomics and basic science research findings to practical clinical application. This is particularly true in the field of cancer biomarker research, where TMAs can be used for candidate biomarker validation and association with patient clinical, pathologic, and outcomes parameters. In this review, we examine the effect of TMA use on prostate cancer biomarker research, focusing on the types of TMAs that have been used, and the biomarkers that have been examined. The results demonstrate that TMAs have been very effective in screening candidate biomarkers for subsequent, extended evaluation in large patient populations. In addition, the use of TMAs in multiple biomarker series allows for the statistical analysis of sets of biomarkers as diagnostic or prognostic tests. The processes used here can be applied to any tumor type to improve patient diagnosis, prognosis, and treatment response prediction.

Alpha-methylacyl CoA racemase in pulmonary adenocarcinoma, squamous cell carcinoma, and neuroendocrine tumors: expression and survival analysis

CONTEXT

Alpha-methylacyl CoA racemase (AMACR) is an oxidative enzyme involved in isomeric transformation of fatty acids entering the beta-oxidation pathway. AMACR serves as a useful marker in establishing a diagnosis of prostatic malignancy; however, limited information is available in regard to its presence in pulmonary neoplasms.

OBJECTIVE

To investigate AMACR expression within a spectrum of lung carcinomas and its correlation with patients' survival.

DESIGN

Four hundred seventy-seven pulmonary carcinomas, including 150 squamous cell carcinomas, 150 adenocarcinomas, 46 typical carcinoids, 31 atypical carcinoids, 28 large cell neuroendocrine carcinomas, and 72 small cell carcinomas, were studied immunohistochemically using tissue microarray-based samples.

RESULTS

Overall, pulmonary tumors were positive for AMACR in a significant percentage (47%) of cases. Among tumor types, 22% of squamous cell carcinoma, 56% of adenocarcinoma, 72% of typical carcinoid, 52% of atypical carcinoid, 70% of large cell neuroendocrine carcinoma, and 51% of small cell lung carcinoma were positive for AMACR. Furthermore, the Kaplan-Meier analysis revealed that the patients with AMACR-positive small cell carcinoma had better survival (19% vs 5% after 5 years, P = .04) than patients with AMACR-negative tumors. Such survival advantage was seen for patients with stage I-II (P = .01) but not stage III-IV small cell carcinomas (P = .58).

CONCLUSIONS

These results indicate that, similar to prostate cancer, the overexpression of AMACR frequently occurs in pulmonary carcinomas. Additionally, its positive correlation with outcome of stage I-II small cell lung carcinoma warrants further investigation of the AMACR role in the prognosis of this tumor.

Is triple immunostaining with 34betaE12, p63, and racemase in prostate cancer advantageous? A tissue microarray study

This study aimed to determine the usefulness of a combination of 3 immunohistochemical markers, 34/betaE12, p63 and alpha-methylacyl coenzyme A racemase (AMACR), for the diagnosis of prostate cancer using tissue microarrays (TMAs) constructed from 91 archival radical prostatectomy specimens derived from the Pathology Department files of Singapore General Hospital, Singapore. Triple immunostaining using a cocktail of these 3 antibodies was performed on TMA sections using the streptavidin-biotin method. When compared with immunohistochemical staining using the individual antibodies, we found that the triple cocktail allowed improved evaluation of basal cells in benign glands, and AMACR allowed simultaneous corroboration of malignant prostatic glands in the same section. We achieved a specificity of 100% with the triple cocktail, and sensitivity was acceptable, at 93.8%. In comparison, specificity and sensitivity of the individual antibodies were 95.5% and 97.3%, 93.3% and 93.8%, 97.0% and 95.6% for p63, 34betaE12, and AMACR, respectively. The triple cocktail offers a cost-effective way of evaluating abnormal prostatic glandular foci, in addition to maximizing the use of small tissue samples from prostatic needle biopsies.

Alpha-methylacyl-CoA racemase (AMACR/P504S) can distinguish hepatocellular carcinoma and dysplastic hepatocytes from benign nondysplastic hepatocytes

Immunohistochemical staining with alpha-methylacyl-CoA racemase AMACR (P504S) has been described in a number of normal tissues and was found to be useful for detecting malignancies including hepatocellular carcinoma (HCC). Our aim was to determine whether AMACR is differentially expressed in benign nondysplastic liver tissue, hepatocellular dysplasia, and HCC. The study material consisted of paraffin blocks containing primary HCC and surrounding liver tissue from 20 patients who underwent hepatectomy at the time of liver transplantation. Immunohistochemical stains were performed with anti-AMACR by standard methods. Staining features were characterized on the basis of the pattern and distribution of reactivity. A positive AMACR immunostain was defined as either finely stippled or coarsely granular in pattern, in a diffuse or parabasal cytoplasmic distribution. A negative AMACR immunostain was defined as absence of reactivity. Anti-AMACR immunostains were positive in malignant, dysplastic, and benign nondyplastic hepatocytes in all cases. The staining pattern was the same in malignant and dysplastic hepatocytes. It consisted of coarsely granular reactivity in a parabasal or diffuse cytoplasmic distribution. In contrast, benign nondysplastic hepatocytes were distinguished by weak, finely stippled diffuse cytoplasmic staining. Malignant and dysplastic hepatocytes showed an identical pattern of immunostaining for AMACR that was distinct from benign hepatocytes. Prospective studies are needed to determine whether staining for AMACR can distinguish HCC or dysplasia in cytologic and small histologic specimens.

Kinetic fluorescence reverse transcriptase-polymerase chain reaction for alpha-methylacyl CoA racemase distinguishes prostate cancer from benign lesions

BACKGROUND

High-throughput gene expression profiling has recently shown that the mRNA for alpha-methylacyl CoA racemase (AMACR or P504S) is overexpressed in prostate carcinomas (PCa). Several immunohistochemical studies have reported the usefulness of anti-AMACR/P504S for detecting prostate cancer over the full range of prostate specimens encountered in surgical pathology. We tested real-time reverse transcriptase-polymerase chain reaction (RT-PCR) for specific and sensitive detection of AMACR transcripts as a supplementary measure for discriminating between malignant and benign lesions in prostatic tissues.

METHODS

Total RNA was isolated from snap-frozen chips in 55 cases of benign prostatic hyperplasia (BPH) and from frozen sections in 57 prostatectomy cases. The latter were analyzed by an uropathologist (J.K.) and found to contain at least 50% malignant epithelia. Relative quantification of AMACR transcripts was performed by RT-PCR using hybridization probes for detection and PBGD for normalization.

RESULTS

Normalized AMACR transcript levels showed an average 3.75-fold increase in 57 prostate carcinomas cases when compared to 55 cases of BPH (p<0.0001). A 85.6% specificity and 64.9% sensitivity can be achieved if the cutoff is set at 12.95. AMACR expression levels among PCa cases were not statistically associated with the tumor and lymph node stage, the grading, the surgical margins, the Gleason score or progression.

DISCUSSION

The present study demonstrates the usefulness of quantitative AMACR-mRNA transcript detection in prostatic tissues as an alternative to immunological staining techniques. Since the latter clearly predominate in the laboratory routine, PCR-based detection of AMACR has the potential to gain widespread acceptance as a suitable future tool for monitoring prostate cancer patients.

Diagnostic utility of a p63/alpha-methyl coenzyme A racemase (p504s) cocktail in ambiguous lesions of the prostate upon needle biopsy

OBJECTIVE

To investigate the potential utility of a new combined immunostaining technique for diagnosing prostate cancer from histological analysis of needle biopsy specimens.

MATERIALS AND METHODS

Tissue was immunostained with a combination of antibodies against a basal cell marker (p63), and an enzyme commonly overexpressed in prostate cancer (p504s), on 63 small prostate cancer foci (<1 mm) and 109 cases of ambiguous lesions observed in needle biopsies.

RESULTS

After p63/p504s immunostaining, 93% of the ambiguous lesions (102/109) were classified. The final diagnoses retained were: 92 prostate cancers, seven atypical small acinar proliferations suspected of being malignant but undiagnosed, 21 prostatic intraepithelial neoplasia, five atypical adenomatous hyperplasia, and 36 atrophic benign mimickers of cancer.

CONCLUSIONS

Combining p504s as a positive marker for prostate cancer and p63 as a negative marker might improve diagnostic performance, sensitivity and specificity, and lead to fewer false-negative results. This simple immunostaining procedure should reduce the percentage of residual ambiguous lesions and the need for additional biopsies.

Virtual microscopy in prostate histopathology: simultaneous viewing of biopsies stained sequentially with hematoxylin and eosin, and alpha-methylacyl-coenzyme A racemase/p63 immunohistochemistry

PURPOSE

Histopathological diagnosis of small focus carcinomas in prostatic needle biopsies is often assisted by IHC. To make a definitive diagnosis the pathologist must compare IHC findings with hematoxylin and eosin stained tissue morphology. We introduce what is to our knowledge a new application of virtual microscopy, in which hematoxylin and eosin, and IHC stains done sequentially on the same microscope slide can be simultaneously displayed and compared on a computer screen.

MATERIALS AND METHODS

A total of 30 hematoxylin and eosin stained prostatic needle biopsies were scanned with a computer controlled microscope. The slides were destained and then immunostained with a cocktail of AMACR and p63 antibodies, which labels the nuclei of nonmalignant basal cells (p63) and the cytoplasm of neoplastic glandular cells suspicious for malignancy (AMACR). The slides were then scanned again and the pairs of virtual slides were aligned for synchronized viewing.

RESULTS

The presented technique was found helpful when suspicious lesions were small and when examining the immunoprofile of specimens was warranted, in addition to examining hematoxylin and eosin stained tissue morphology. The usefulness of our approach based on virtual microscopy can be evaluated on the website , which also serves as an educational tool for self-learning the correlation between hematoxylin and eosin stained tissue morphology, and AMACR/p63 IHC in prostate biopsies.

CONCLUSIONS

The technology for simultaneously viewing sequentially hematoxylin and eosin and IHC stained prostate biopsies can be readily used for educational purposes, as exemplified by our website, and along with the availability of rapid virtual slide scanners it can also be used for clinical diagnostics.

Routine immunohistochemical staining for high-molecular weight cytokeratin 34-beta and alpha-methylacyl CoA racemase (P504S) in postirradiation prostate biopsies

A total of 43 cases of postirradiation prostate cores were assessed in an attempt to determine if routine use of alpha-methylacyl-CoA racemase (AMACR) in conjunction with high-molecular weight cytokeratin (HMWCK) would increase the recognition of carcinoma in postirradiation prostate biopsies. We concluded that in most cases the addition of AMACR in conjunction with HMWCK does not increase the recognition of prostatic adenocarcinoma, however it is supportive in nature. In one case the use of AMACR highlighted the extent of the adenocarcinoma which otherwise would have been designated as atypical small acinar proliferation (ASAP). Further evaluation is required to assess the significance of a diagnosis of atypical small acinar proliferation in postirradiation prostate biopsies.

Utility of alpha-methylacyl coenzyme A racemase (p504s antibody) as a diagnostic immunohistochemical marker for cancer

Alpha-methylacyl-coenzyme A racemase (AMACR; P504S) is a mitochondrial and peroxisomal enzyme involved in the metabolism of branched-chain fatty acid and bile acid intermediates. Recently, AMACR has been demonstrated to be overexpressed in localized and metastatic prostate cancer and in high-grade prostatic intraepithelial neoplasia but not in normal prostatic glands, suggesting that it may be an important tumor marker. This study examines AMACR expression in a variety of human cancers to assess its viability as a tumor marker in the clinical setting. Two hundred sixty-three cancers from different sites were examined in three multitumor tissue micro arrays, which included two or three tissue cores (1.0 mm in diameter) from each neoplastic and normal tissue specimen. Cancers studied included breast (94 cases), prostate (38), lung (28), endometrium (27), colon (29), ovary (26), and melanoma (21). Normal tissues in the microarray were prostate (15), lung (6), endometrium (5), colon (4), ovary (2), and skin (3). Sections were immunostained, after prior pressure cooker antigen retrieval, using rabbit monoclonal AMACR antibody (1:40) (Zeta Corp, Sierra Madre, CA) and horseradish peroxidase-labeled polymer conjugated secondary antibody (Envision, Dako, Carpinteria, CA). A section of prostate cancer and prostatic intraepithelial neoplasia was used as positive control. Protein expression was scored as negative, weak (faint cytoplasmic or granular apical staining), moderate (diffuse granular cytoplasmic stain), and strong (diffuse intense cytoplasmic stain). Only moderate and strong staining was considered as positive staining, based on prior work. AMACR protein overexpression was found in several cancers, including prostate (34/38 [89.5%]), colon (13/29 [44.8%]), lung (4/28 [14.3%]), melanoma (2/21 [9.5%]), endometrium (2/27 [7.4%]), and breast (3/94 [3.2%]). None of the ovarian cancers (26 cases) demonstrated AMACR overexpression. AMACR expression was not present in any of the normal tissues nor in benign prostatic tissue associated with prostate carcinomas. This study suggests that AMACR is potentially an important tumor marker, particularly for prostate and colon cancer. It may be a useful adjunct to an immunohistochemical panel employed in the differential diagnosis of colon versus ovarian and breast carcinoma; the latter two infrequently express AMACR.

Alpha-methylacyl-CoA racemase (AMACR/P504S) protein expression in urothelial carcinoma of the upper urinary tract correlates with tumour progression

Alpha-methylacyl-CoA racemase (AMACR/P504S) is a useful biomarker of prostate cancer. We evaluated the expression of AMACR in upper urinary tract urothelial carcinomas with respect to associations with tumour stage, grade and metastasis-free survival. A total of 268 tumours were investigated immunohistochemically using a tissue microarray technique. AMACR expression was noted in 127 of 261 (48.7%) evaluated tumours and was associated with high tumour stage [58 of 139 (41.7%) pTa/pT1 vs. 69 of 122 (56.6%) pT2-pT4, P=0.019] and high tumour grade [44 of 137 (32.1%) low vs. 83 of 124 (66.9%) high grade, P<0.001]. In addition, AMACR expression was associated with the presence of tumour necrosis (P<0.001) and marked stromal desmoplasia (P=0.0026). This correlation indicates that increased AMACR expression might be related to hypoxia-induced changes in cancer cell metabolism, such as increased dependence on fatty acid oxidation for energy generation. Progressive disease was observed in 73 of 183 (39.9%) patients with solitary invasive carcinomas and was associated with AMACR expression (P=0.017). Multivariate analysis, however, proved only pT-stage >1 (P<0.001) and high tumour grade (P<0.001) to be independent predictors of patient outcome. In conclusion, AMACR expression correlated with advanced tumour stage and grade and may serve as an additional prognostic indicator in upper urinary tract urothelial cancer.

Kleine suspekte Prostataläsionen

Punch biopsies have been taken from the prostate with increasing frequency in recent years, with a resulting increase in the number of diagnoses made. To check the diagnosis of "small two- or three-gland carcinoma" we prepared new H and E sections and, when the atypical glands were no longer available, also performed immunohistochemical analyses in 1,041 cases referred to our uropathology consultation service, comparing the diagnoses supplied by the referring doctors with the final diagnoses. In 61.6 of these cases histology confirmed the diagnosis of adenocarcinoma of the prostate; the diagnosis recorded when the basal cell marker was absent and the tumour marker P504S was strongly expressed was atypical microglandular proliferation or suspected carcinoma. Previous diagnoses of prostatic carcinoma were confirmed in 99% of cases. In this way we also confirmed a further 27.9% of cases of prostate carcinoma in the grey area of diagnoses endorsed "suggestive" or "suspected". The patients concerned were thus spared multiple screening biopsies and were assigned for definitive treatment.

Construction of tissue microarrays from prostate needle biopsy specimens

Needle biopsies are taken as standard diagnostic specimens for many cancers, but no technique exists for the high-throughput analysis of multiple individual immunohistochemical (IHC) markers using these samples. Here we present a simple and highly reliable technique for constructing tissue microarrays (TMAs) from prostatic needle biopsies. Serial sectioning of the TMAs, called 'Checkerboard TMAs', facilitated expression analysis of multiple proteins using IHC markers. In total, 100% of the analysed biopsies within the TMA both preserved their antigenicity and maintained their morphology. Checkerboard TMAs will allow the use of needle biopsies (i) alongside other tissue specimens (trans-urethral resection of prostates and prostatectomies in the case of prostate cancer) in clinical correlation studies when searching for new prognostic markers, and (ii) in a diagnostic context for assessing expression of multiple proteins in cancers from patients prior to treatment.

Diagnostic utility of immunohistochemistry in morphologically difficult prostate cancer: review of current literature

Varma M & Jasani B (2005) Histopathology47, 1-16 Diagnostic utility of immunohistochemistry in morphologically difficult prostate cancer: review of current literatureImmunohistochemistry is widely used to distinguish prostate cancer from benign mimics and to establish the prostatic origin of poorly differentiated carcinoma. We critically review the recent advances in prostate cancer immunohistochemistry, including the introduction of newer basal cell markers such as p63 and the discovery of the overexpression of alpha-methylacyl coenzyme A racemase (AMACR) in prostate cancer. The description of newer urothelial markers to aid the distinction of prostate cancer from urothelial carcinoma is also presented together with refinements in the quality control of PSA and PSAP immunostaining. Although AMACR is a useful immunohistochemical marker for prostate cancer, it has significant limitations. These limitations are discussed and the need for interpreting AMACR immunoreactivity in the appropriate morphological context and in conjunction with basal call markers is emphasized. We also describe the utility of an immunohistochemical panel composed of PSA, PSAP and high molecular weight cytokeratin for distinguishing poorly differentiated prostate cancer from high-grade urothelial carcinoma. A morphological differential diagnosis based selection of immunohistochemical markers is highlighted as a novel approach in the diagnosis of prostate cancer in routine surgical pathology practice.

Molecular pathology of prostate cancer

The molecular pathology of prostate cancer is complex; not only are multiple genes involved in its pathogenesis, but additional environmental factors such as diet and inflammation are also involved. The exhaustive research into prostate cancer to date has demonstrated a complex interaction of multiple genes and environmental factors, some of which may be more important in individual prostate cancer cases. This is an exciting era, with the emergence of new investigative tools such as DNA microarray technology and the application of the field of proteomics to the study of human cancers. Knowledge of genetic changes underlying the initiation, development, and progression of prostate cancer is accumulating rapidly. With increasing knowledge, it may be possible to distinguish indolent from aggressive prostate tumours by molecular fingerprinting. This review discusses the most consistently reported molecular pathological findings in hereditary and sporadic prostate cancer, together with new concepts and technologies.

Differential Expression of α-Methylacyl Coenzyme A Racemase in Adenocarcinomas of the Small and Large Intestines

Alpha-methylacyl coenzyme A racemase (AMACR), a novel immunomarker for prostatic adenocarcinoma, has recently been shown to be expressed in a number of malignancies including colorectal adenocarcinoma. In the current study, 59 surgically resected primary small intestinal adenocarcinomas (34 ampullary and 25 non-ampullary) were immunohistochemically examined for AMACR expression and compared with 66 colorectal adenocarcinomas (including 24 secondary tumors involving the small intestine by direct extension or metastasis). The results show that no AMACR immunoreactivity was detected in normal-appearing small and large intestinal mucosa. While 41 of 66 (62%) colorectal adenocarcinomas exhibited a variable degree of cytoplasmic staining, only 1 of 25 (4%) non-ampullary and 2 of 34 (6%) ampullary small intestinal adenocarcinomas showed positive AMACR immunoreactivity (P < 0.0001). Interestingly, AMACR appeared to be less frequently expressed in mucinous or poorly differentiated colorectal adenocarcinomas when compared with non-mucinous or better-differentiated counterparts, suggesting an association with microsatellite instability status. These results extend our previous observations that small intestinal adenocarcinomas differ markedly from colorectal adenocarcinomas despite their morphologic similarity. The different AMACR expression patterns may not only provide an additional diagnostic tool in the distinction between adenocarcinomas of the small and large intestinal origins but may also shed light on further understanding of intestinal tumorigenesis.

Alpha-methylacyl-CoA racemase (AMACR) expression in normal prostatic glands and high-grade prostatic intraepithelial neoplasia (HGPIN): association with diagnosis of prostate cancer

BACKGROUND

Alpha-methylacyl-CoA racemase (AMACR) is strongly expressed in prostate cancer with variable expression in high-grade prostatic intraepithelial neoplasia (HGPIN) and low expression in normal prostate. We examined whether AMACR expression in HGPIN and normal tissue was associated with subsequent diagnosis of cancer or proximity to a cancer focus.

METHODS

Needle core biopsies from 45 patients with isolated HGPIN, 12 radical prostatectomy (RP) specimens with prostatic carcinoma and 6 cystoprostatectomies without prostatic carcinoma were immunostained for AMACR. Among patients with HGPIN, 23 (cases) showed cancer on a later biopsy and 22 (controls) had no cancer with at least 3 consecutive negative biopsies.

RESULTS

In the biopsy set, the mean AMACR expression per gland in the normal compartment of the cases (0.29) was significantly higher than the controls (0.21) (P = 0.0006). In the RP set, normal glands near a cancer focus had higher mean AMACR expression than those that were distant (P = 0.0006). There was no difference within the HGPIN compartment between cases and controls in the biopsies, or between near and distant glands in the RP set. Mean AMACR staining of normal glands in the cystoprostatectomy specimens was significantly lower than in normal glands in close proximity to a cancer focus.

CONCLUSIONS

Higher expression of AMACR in normal glands near a focus of cancer, as well as in the subjects eventually showing cancer, suggests a possible field effect in prostatic carcinogenesis. AMACR expression in normal glands therefore might be a useful predictor for repeat biopsy outcomes or as an intermediate endpoint in chemoprevention studies.

Immunohistochemistry in diagnostic surgical pathology of the prostate

Immunohistochemistry (IHC) can play an important role in diagnostic surgical pathology of the prostate. Basal cell markers, such as the 34betaE12 antibody and antibodies directed against cytokeratin 5 and 6 or p63, are very useful for demonstration of basal cells as their presence argues against a diagnosis of invasive prostatic carcinoma (PC). However, several benign mimickers of PC, including atrophy, atypical adenomatous hyperplasia (AAH), nephrogenic adenoma, and mesonephric hyperplasia, can stain negatively with these markers, and thus, a negative basal cell marker immunostain alone does not exclude a diagnosis of benignancy. Although there are examples in the literature of high grade PC that stain focally with some of the basal cell markers, these cases are usually readily diagnosed based on H&E appearances and are unlikely to be confused with these benign mimickers. Alpha-methylacyl-coenzyme-A racemase (AMACR) is a sensitive marker of PC (except for a few uncommon variants: atrophic, foamy gland, and pseudohyperplastic variants), and its detection by immunohistochemical staining in atypical prostatic lesions can be very useful in confirming an impression of adenocarcinoma. AMACR expression can also be identified in high grade prostatic intraepithelial neoplasia (PIN), prostatic atrophy, AAH, and benign prostatic glands, and accordingly, a diagnosis of PC should not be based solely on a positive AMACR immunostain, especially when the luminal staining is weak and/or noncircumferential. The use of AMACR/basal cell antibody cocktails has been found to greatly facilitate the distinction between PC and its benign mimickers, especially when only limited tissue is available for staining. Prostate specific antigen (PSA) and prostate specific acid phosphatase (PSAP) are both quite sensitive and fairly specific markers of PC (there are a few nonprostatic tumors that can express one or both), and are both very helpful in establishing or confirming the diagnosis of PC when the differential diagnosis includes other tumors that can involve the prostate such as urinary bladder urothelial carcinoma. 34betaE12, p63, thrombomodulin, and uroplakin III are additional urothelial associated markers useful in this differential diagnosis. CDX2 and villin are useful markers to diagnostically separate colonic adenocarcinoma from PC. AMACR positivity and negative basal cell marker reactions are useful to confirm the presence of residual PC after hormonal or radiation therapy. Pan-cytokeratin, PSA, and PSAP can also highlight subtle infiltrates of PC with hormonal or radiation therapy effect. PSA and PSAP immunohistochemical stains are valuable in confirming metastatic carcinoma as being of prostatic origin and should always be utilized in the diagnostic evaluation of metastatic adenocarcinoma of unknown primary origin in males.

Diagnostic utility of a p63/alpha-methyl-CoA-racemase (p504s) cocktail in atypical foci in the prostate

Prostatic needle biopsy is the preferred method for diagnosing early prostate cancer, providing specific information. In cases of histological cancer mimics, a diagnosis of atypical small acinar proliferation suspected of but not diagnosed as malignancy can be made. In such cases, and in small focus carcinomas, pathologists use 34betaE12, cytokeratin (CK) 5/6 or p63 immunostaining to label basal cells, and alpha-methylacyl-CoA racemase (AMACR/p504s) immunostaining as a positive prostate cancer marker on two distinct slides. However, in cases of small foci, ambiguous lesions might disappear. The purpose of our study was to improve the sensitivity of a cocktail of two antibodies (p63/p504s) with a sample incubation on 260 prostatic specimens, in order to help make a decision in conjunction with standard histology and CK 5/6 immunostaining. We tested 101 small focus prostatic cancers, 104 atypical small acinar proliferation, 19 high-grade prostatic intraepithelial neoplasia, two atypical adenomatous hyperplasia and 34 benign mimics of cancer. After p63/p504s immunostaining, the final diagnoses retained were as follows: 154 prostatic cancers, 14 atypical small acinar proliferation, 30 high-grade prostatic intraepithelial neoplasia, three atypical adenomatous hyperplasia and 62 benign mimics of cancer. To differentiate malignant from benign lesions, we used the criteria of greater sensitivity to p504s/p63 (95%) than to CK 5/6 (57%) or p63 (86%), and higher specificity for p504s/p63 (95%) than for CK 5/6 (88%) or p63 (81%). With the p504s/p63 cocktail, 89% of the ambiguous lesions were classified vs 53% for CK 5/6. Combined use of the two antibodies, one (p504s) as a positive marker and the other (p63) as a negative marker, with a simple immunostaining procedure, may improve diagnostic performance, sensitivity and specificity, leading to a reduction in the risk of false negatives; this technique in cases of atypical small acinar proliferation should reduce the percentage of residual ambiguous lesions and the need for additional biopsies.

A mouse model for α-methylacyl-CoA racemase deficiency: adjustment of bile acid synthesis and intolerance to dietary methyl-branched lipids

alpha-Methylacyl-CoA racemase (Amacr) deficiency in humans leads to sensory motor neuronal and liver abnormalities. The disorder is recessively inherited and caused by mutations in the AMACR gene, which encodes Amacr, an enzyme presumed to be essential for bile acid synthesis and to participate in the degradation of methyl-branched fatty acids. To generate a model to study the pathophysiology in Amacr deficiency we inactivated the mouse Amacr gene. As per human Amacr deficiency, the Amacr(-/-) mice showed accumulation (44-fold) of C27 bile acid precursors and decreased (over 50%) primary (C24) bile acids in bile, serum and liver, however the Amacr(-/-) mice were clinically symptomless. Real-time quantitative PCR analysis showed that, among other responses, the level of mRNA for peroxisomal multifunctional enzyme type 1 (pMFE-1) was increased 3-fold in Amacr(-/-) mice. This enzyme can be placed, together with CYP3A11 and CYP46A1, to make an Amacr-independent pathway for the generation of C24 bile acids. Exposure of Amacr(-/-) mice to a diet supplemented with phytol, a source for branched-chain fatty acids, triggered the development of a disease state with liver manifestations, redefining the physiological significance of Amacr. Amacr is indispensable for the detoxification of dietary methyl-branched lipids and, although it contributes normally to bile acid synthesis from cholesterol, the putative pMFE-1-mediated cholesterol degradation can provide for generation of bile acids, allowing survival without Amacr. Based upon our mouse model, we propose elimination of phytol from the diet of patients suffering from Amacr deficiency.