Alpha-methylacyl-CoA racemase (AMACR) in fine-needle aspiration specimens of prostate lesions

Diagnostic utility of a-methylacyl COA racemase in prostate cancer of the Iranian population

Background:

Considering the great variations in the reported prevalence of prostate cancer across the world possibly due to different genetic and environmental backgrounds, we aimed to determine the expression pattern and the diagnostic utility of α-methylacyl coenzyme A racemase (AMACR) among Iranian patients with prostate adenocarcinoma.

Materials and Methods:

In this cross-sectional study, formalin-fixed paraffin-embedded tissues of 58 patients with a definitive pathologic diagnosis of prostatic adenocarcinoma were evaluated. The expression of AMACR, intensity, and extensity of its staining was determined in selected samples by immunohistochemical technique.

Results:

AMACR expression was significantly higher in neoplastic compared to normal tissue (P < 0.05). The expression of AMACR was significantly associated with the age of the patients (P = 0.04). The intensity of the staining was associated with the grade of the prostate adenocarcinoma (P = 0.04). There was no significant relationship between AMACR expression and perineural invasion. The sensitivity, specificity, positive predictive value, and negative predictive value of AMACR were 90%, 96%, 96%, and 90%, respectively.

Conclusion:

Findings from our study indicate that AMACR could be used as a diagnostic tool for the diagnosis of prostate adenocarcinoma. However, due to false-positive staining in the mimicker of prostatic adenocarcinoma, it is recommended to use it in combination with basal cell markers.

Diagnostic Value of Cytokeratin 34 beta E12 (Ck34βE12) and α-Methylacyl-CoA racemase (AMACR) Immunohistochemical Expression in Prostatic Lesions

Background & Objective

Some prostatic lesions contain small suspicious foci for prostatic carcinoma in which the morphological features are equivocal. Two immunohistochemical markers namely, cytokeratin 34 beta E12 (Ck34βE12) and α-Methylacyl-CoA racemase (AMACR), were evaluated in these lesions for a definitive diagnosis and avoiding misdiagnosis or overdiagnosis of prostatic carcinoma.

Methods

A total of 90 paraffin embedded blocks of prostatic tissue were selected and categorized into three groups as follows: 50 cases of benign prostatic hyperplasia (BPH), 20 cases of prostatic carcinoma, and 20 cases of benign prostatic lesions with suspicious foci labeled as ASAP (atypical small acinar proliferation) that occupy not more than 5% of the lesion. These cases were revised for histopathological diagnosis and stained with two immunohistochemical markers: Ck34βE12 and AMACR.

Results

While 92.9% of BPH were positive for Ck34βE12, 96% of prostatic carcinoma were negative for this marker (P=0.0001). Regarding AMACR, 92.9% of BPH cases were negative, but 92% of prostatic carcinoma cases were positive for this marker (P=0.0001). Out of 20 cases of BPH, 15 cases containing suspicious foci showed Ck34βE12+/AMACR- (diagnosis: benign), but 5 cases were Ck34βE12-/AMACR+, for which the diagnosis changed to prostatic carcinoma (P=0.04).

Conclusion

Immunohistochemical staining with Ck34βE12 and AMACR improved the diagnostic performance and increased confidence level for establishing definite diagnosis in cases with suspicious foci, in which the morphological features were equivocal. This could help to avoid misdiagnosis or overdiagnosis of prostatic carcinoma that would eventually improve the management of the patient and subsequently the prognosis.

High alpha-methylacyl-CoA racemase (AMACR) is associated with ERG expression and with adverse clinical outcome in patients with localized prostate cancer

Alpha-methylacyl-CoA racemase (AMACR) is a well-characterized marker extensively utilized in prostate cancer (PCA) diagnosis. However, the prognostic value of AMACR expression and its relation to TMPRSS2-ERG gene rearrangement as one of the most common molecular alterations in PCA is not fully explored. AMACR expression was investigated in a cohort of 218 men with localized PCA treated by radical prostatectomy and correlated with ERG and various clinical and pathological parameters. In vitro studies assessed AMACR changes to ERG knockdown and other related genes. In addition, bioinformatics validated the significance of AMACR/ERG expression and assessed relevant genetic signatures in relation to AMACR/ERG expression. AMACR expression was significantly associated with disease progression and with ERG (p ∼0). Seventeen percent of cancer foci showed negative/weak AMACR expression while being ERG positive. High AMACR expression was significantly associated with positive surgical margins (p = 0.01), specifically in tumors with lower Gleason score <7, with ∼95 % exhibiting positive surgical margin (p = 0.008). High AMACR showed marginal association with PSA biochemical recurrence (BCR) (p = 0.06) which was slightly more pronounced in ERG-positive tumors (p = 0.04). This was validated in other public cohorts. However, in this cohort, the association with BCR was not statistically significant in multivariate analysis (p = 0.09). Using in vitro cellular models, AMACR messenger RNA (mRNA) expression, but not protein levels, showed an association with ERG expression. We report for the first time a significant association between AMACR and ERG with prognostic implication. Patients with high AMACR/ERG-positive PCA may be at higher risk for disease progression, and additional studies in larger cohorts are needed to confirm the above findings. Functional studies investigating the molecular pathways connecting AMACR and ERG may provide an additional insight into PCA progression pathways.

Diagnostic usefulness of the cytological study of the transport buffer in transrectal prostate core biopsies

BACKGROUND

To evaluate the diagnostic usefulness of the cytological study of the transport buffer in the diagnosis of prostate adenocarcinoma in transrectal core biopsies.

METHODS

A total of 256 consecutively biopsied patients have been included in the analysis, 100 of them diagnosed of prostate adenocarcinoma. The procedure included the cytological analysis of the transport buffer and conventional histology. Cytological evaluation was performed in a blind way by the same pathologist.

RESULTS

Overall sensitivity, specificity, and positive and negative predictive values to detect malignancy in the cytological slides were 54%, 98%, 94% and 76%, respectively. When restricted the analysis to cases with Gleason score higher than 8, sensitivity and negative predictive value increased to 85% and 97%, respectively. Similarly, when the analysis focused exclusively to cases with more than 5mm of cancer in the biopsy, sensitivity and positive predictive value increased to 66% and 96%, respectively.

CONCLUSIONS

This study shows that whilst specificity was maintained in 98%, sensitivity, and positive and negative predictive values significantly improved in high grade and high volume adenocarcinomas. Our findings confirm that the cytological study of the transport buffer may complement the histology in the diagnosis of prostate adenocarcinoma.

A-methylacyl-CoA racemase (AMACR) and prostate-cancer risk: a meta-analysis of 4,385 participants

Background

Alpha-methylacyl-CoA racemase (AMACR) is a mitochondrial and peroxisomal enzyme that is overexpressed in prostate cancer. The aim of this study was to confirm and expand the findings that the PCa risk increased in men associated with AMACR expression across various geographic regions.

Methods

A systematic search of databases was carried out and other relevant articles were also identified. Then the meta-analyses were conducted according to the standard guidelines.

Results

A total of 22 studies with 4,385 participants were included on the basis of inclusion criteria. AMACR by IHC was significantly associated with increased diagnosis of PCa (OR = 76.08; 95% CI, 25.53–226.68; P<0.00001). Subgroup-analysis showed that findings didn’t substantially change when only Caucasians or Asians (OR = 51.23; 95% CI, 19.41–135.24; P<0.00001) were considered. Expression of AMACR by PCR in relation to PCa risk suggested that AMACR was associated with PCa (OR = 33.60; 95% CI, 4.67–241.77; P<0.00001). There was also no significant publication bias observed.

Conclusions

Our findings provide further evidences that the expression of AMACR contribute to PCa risk. AMACR protein overexpression was found in prostate cancers, low expression in any of the normal tissues or in benign prostatic tissue. AMACR is potentially an important prostate tumor marker.

Cancer biomarker discovery: the entropic hallmark

Background

It is a commonly accepted belief that cancer cells modify their transcriptional state during the progression of the disease. We propose that the progression of cancer cells towards malignant phenotypes can be efficiently tracked using high-throughput technologies that follow the gradual changes observed in the gene expression profiles by employing Shannon's mathematical theory of communication. Methods based on Information Theory can then quantify the divergence of cancer cells' transcriptional profiles from those of normally appearing cells of the originating tissues. The relevance of the proposed methods can be evaluated using microarray datasets available in the public domain but the method is in principle applicable to other high-throughput methods.

Methodology/Principal Findings

Using melanoma and prostate cancer datasets we illustrate how it is possible to employ Shannon Entropy and the Jensen-Shannon divergence to trace the transcriptional changes progression of the disease. We establish how the variations of these two measures correlate with established biomarkers of cancer progression. The Information Theory measures allow us to identify novel biomarkers for both progressive and relatively more sudden transcriptional changes leading to malignant phenotypes. At the same time, the methodology was able to validate a large number of genes and processes that seem to be implicated in the progression of melanoma and prostate cancer.

Conclusions/Significance

We thus present a quantitative guiding rule, a new unifying hallmark of cancer: the cancer cell's transcriptome changes lead to measurable observed transitions of Normalized Shannon Entropy values (as measured by high-througput technologies). At the same time, tumor cells increment their divergence from the normal tissue profile increasing their disorder via creation of states that we might not directly measure. This unifying hallmark allows, via the the Jensen-Shannon divergence, to identify the arrow of time of the processes from the gene expression profiles, and helps to map the phenotypical and molecular hallmarks of specific cancer subtypes. The deep mathematical basis of the approach allows us to suggest that this principle is, hopefully, of general applicability for other diseases.