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

Nuclear translocation of Atox1 potentiates activin A-induced cell migration and colony formation in colon cancer

Background

Colorectal cancer remains a deadly cancer due to metastatic disease. To understand the molecular mechanisms of metastasis in colon cancer, we investigated whether the copper chaperone antioxidant-1 (Atox1) protein plays a role in this process. Recent findings indicate that Atox1 protein has transcription factor activities and plays a vital role in cell proliferation in cancer cells. However, the role of Atox1 in metastasis has not been examined.

Methods

Atox1 expression was determined by immunofluorescence in a tissue microarray generated from a spectrum of CRC patients. Subcellular fractionation of colon cancer cell lines SW480 and SW620 cells was used to examine the cellular location of Atox1 in the face of activin A, a cytokine that stimulates colon cancer metastasis. Atox1 expression was genetically manipulated and cellular migration measured through trans-well assay and proliferation measured by colony formation assays.

Results

Here we demonstrate that in patients with metastatic colon cancer, there is a significant increase in the expression of nuclear Atox1. Interestingly, the metastatic CRC cell line SW620 has increased nuclear localization of Atox1 compared to its related non-metastatic cell line SW480. Further, inhibition of endogenous Atox1 by siRNA in SW620 decreased colony formation and reactive oxygen species generation via decreased expression of Atox1 targets cyclin D1 and NADPH oxidase subunit p47 phox, respectively. Additionally, overexpression of nuclear-targeted but not copper binding domain-mutated Atox1 in SW480 cells increased colony formation and cell migration that was further augmented by activin A stimulation, a known enhancer of colon cancer metastasis.

Conclusions

Our findings suggest that nuclear Atox1 might be a new therapeutic target as well as a new biomarker for metastatic colorectal cancer.

NFkB is essential for activin-induced colorectal cancer migration via upregulation of PI3K-MDM2 pathway

Colorectal cancer (CRC) remains a common and deadly cancer due to metastatic disease. Activin and TGFB (TGFβ) signaling are growth suppressive pathways that exert non-canonical pro-metastatic effects late in CRC carcinogenesis. We have recently shown that activin downregulates p21 via ubiquitination and degradation associated with enhanced cellular migration independent of SMADs. To investigate the mechanism of metastatic activin signaling, we examined activated NFkB signaling and activin ligand expression in CRC patient samples and found a strong correlation. We hypothesize that activation of the E3 ubiquitin ligase MDM2 by NFkB leads to p21 degradation in response to activin treatment. To dissect the link between activin and pro-carcinogenic NFkB signaling and downstream targets, we found that activin but not TGFB induced activation of NFkB leading to increased MDM2 ubiquitin ligase via PI3K. Further, overexpression of wild type p65 NFkB increased MDM2 expression while the NFkB inhibitors NEMO-binding domain (NBD) and Bay11-7082 blocked the activin-induced increase in MDM2. In conclusion, in colon cancer cell migration, activin utilizes NFkB to induce MDM2 activity leading to the degradation of p21 in a PI3K dependent mechanism. This provides new mechanistic knowledge linking activin and NFkB signaling in advanced colon cancer which is applicable to targeted therapeutic interventions.

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.

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.

Role of alpha methylacyl-coenzyme A racemase in differentiating hepatocellular carcinoma from dysplastic and nondysplastic liver cell lesions

Distinction of hepatocellular carcinoma (HCC) from liver cell dysplasia (LCD) is one of the problems faced by pathologists. In spite of various methods claimed to differentiate between these 2 lesions, no reliable marker is available until now. The aim of the study was to assess the value of alpha methylacyl-coenzyme A (COA) racemase (AMACR) in distinguishing HCC from LCD. Formalin-fixed, paraffin-embedded tissue sections from 30 HCCs and 30 nonneoplastic liver tissues (12 dysplastic and 18 nondysplastic lesions) were immunostained for AMACR. Staining intensity was interpreted as low (negative, mild) and high expressions (moderate, marked). Alpha methylacyl-COA racemase showed high expression in 21 (70%) of 30 HCCs and 7 (58.3%) of 12 LCDs. All 18 nondysplastic lesions revealed low AMACR expression. The percentage of high AMACR expression was significantly more in HCC and LCD as compared with nondysplastic lesions (P = .001 in each). There was no significant difference in AMACR expression between HCC and LCD. Furthermore, the pattern of AMACR immunostaining was coarsely granular cytoplasmic positivity in HCC as well as LCD in comparison with the weak finely granular in nondysplastic lesions. Alpha methylacyl-COA racemase cannot discriminate HCC from LCD, although it can separate HCC and LCD from nondysplastic lesions.

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.

Clear cell adenocarcinoma of urinary bladder and urethra: another urinary tract lesion immunoreactive for P504S

CONTEXT

Clear cell carcinoma of the urinary bladder/ urethra is a rare tumor histologically resembling the neoplasms in the female genital tract. Adequate characterization of this tumor has been hampered by its rarity. alpha-Methylacyl-CoA racemase (AMACR)/P504S has been reported to be positive in prostatic adenocarcinoma, papillary renal cell carcinoma, and gastrointestinal neoplasmas; however, it has never been studied in clear cell carcinoma of the lower urinary tract.

OBJECTIVE

To investigate the immunohistochemical staining profile in 4 primary clear cell carcinomas of the urinary tract, including P504S, which has not been previously evaluated in these tumors.

DESIGN

Four cases of clear cell adenocarcinoma were retrieved from our archives: 2 cases from the urinary bladder (one each from a man and a woman) and 2 cases from the urethra (both from women, 1 in a diverticulum). Immunohistochemistry performed on the cases were P504S, K903, cytokeratin (CK) 7, CK20, CA 125, and p63.

RESULTS

We found that clear cell carcinomas had a distinct immunoreactive profile: strongly positive for P504S, K903, and CK7, and negative for p63. Two cases were also positive for CA 125 and CK20.

CONCLUSION

The immunohistochemical profile of clear cell carcinomas shares some similarity to conventional urothelial carcinoma; however, it deviates from those tumors in being positive for P504S and negative for p63. This staining profile may suggest a nonurothelial origin for these tumors, may serve as a useful tool in the differential diagnosis of this tumor, and may reflect its etiology. Because similar expression of P504S is also seen in nephrogenic adenomas, this marker should not be used to differentiate nephrogenic adenomas from clear cell adenocarcinomas.

Significance of overexpression of alpha methylacyl-coenzyme A racemase in hepatocellular carcinoma

BACKGROUND

alpha-Methylacyl-CoA racemase (AMACR), an immunomarker for prostatic adenocarcinoma, has been shown to be expressed in a variety of other neoplasms. This study aims to evaluate immunohistochemical expression of the AMACR in neoplastic and nonneoplastic liver lesions, and assess its value in the diagnosis of hepatocellular carcinoma (HCC).

METHODS

Formalin-fixed paraffin-embedded tissue sections of 51 HCC (14 well, 22 moderately and 15 poorly differentiated), 9 hepatocellular adenoma (HCA), 48 cirrhotic nodules (CN) and 16 normal liver tissues (NLT) were immunostained for AMACR.

RESULTS

Expression of AMACR is significantly enhanced in HCC tissue compared with non-HCC tissue. High expression of AMACR was found in 82% of HCC including 86% of well-differentiated HCC. In contrast, only 11% of HCA, 13% of CN and 6% of NLT showed high expression for AMACR. Clinicopathological evaluation showed a significant correlation between AMACR expression and venous invasion and capsular invasion by HCC.

CONCLUSION

Our results suggest that AMACR staining may serve as a useful marker for the differential diagnosis of well-differentiated HCC from HCA. Increased AMACR expression and its association with tumor venous invasion suggest that AMACR may play a role in HCC development and progression.