Immunoreactivity to monoclonal antibody, Hep Par 1, in human hepatocellular carcinomas according to histopathological grade and histological pattern

Phenotype-dependent production of des-γ-carboxy prothrombin in hepatocellular carcinoma

BACKGROUND

Des-γ-carboxy prothrombin (DCP) is an established tumor marker for hepatocellular carcinoma (HCC), but the precise mechanism of its production remains unknown. We have recently demonstrated that cytoskeletal rearrangement during the phenotypic changes involved in epithelial mesenchymal transition (EMT) plays a crucial role in DCP production through the impairment of vitamin K uptake. However, DCP production in long-lasting severe hypoxic conditions with nutrient deprivation-such as transarterial embolization-remains unknown.

METHODS

We examined the effects of long-lasting hypoxia with nutrient deprivation, as well as the constitutive expression of hypoxia-inducible factor (HIF)-1α, on EMT status, DCP production, and protein synthesis in human hepatoma cell lines by enzyme-linked immunosorbent assay, immunofluorescent studies, and western blotting. Immunohistochemistry findings for DCP, anti-hepatocyte paraffin 1 (Hep Par 1), and vimentin were examined using human resected HCC samples.

RESULTS

Both severe hypoxia with nutrient deprivation and HIF-1α transfection led to the cessation of DCP production, by attenuating protein synthesis through the hypophosphorylation of mammalian target of rapamycin and its effector proteins, indicative of a further phenotypic shift involving impaired liver-specific protein synthesis. In immunohistochemistry, the distribution of DCP- and Hep Par 1-positive HCC cells was mostly similar and vimentin-positive HCC cells were frequently observed in the areas that were negative for Hep Par 1 and/or DCP.

CONCLUSIONS

HCC cells produce DCP when they undergo mild phenotypic changes. However, when HCC cells adopt mesenchymal properties they lose their capacity for protein synthesis, and the production of DCP is attenuated. Building upon our previous works, it appears that DCP could be a unique tumor marker that reflects the stepwise phenotypic changes of HCC.

Gadoxetate disodium-enhanced hepatobiliary phase MRI of hepatocellular carcinoma: correlation with histological characteristics

OBJECTIVE

The purpose of this study was to assess whether gadoxetate disodium-enhanced hepatobiliary phase MRI could predict the histologic factors of hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

Fifty-three HCCs histopathologically proved by surgery in 51 patients were evaluated retrospectively. All patients underwent gadoxetate disodium-enhanced MRI before surgical resection. The differences in contrast enhancement ratio of the lesions and differences in contrast-to-noise ratio (CNR) among the histologic grades of HCC were compared by using the Kruskal-Wallis test. The Spearman method was used to determine the correlations among contrast enhancement ratio, CNR, cell density ratio, and positivity for anti-hepatocyte antibody, keratin 7, and keratin 19.

RESULTS

Of 53 HCCs, 50 showed low signal intensity on hepatobiliary phase images, whereas three HCCs were hyperintense on hepatobiliary phase images compared with surrounding hepatic parenchyma. Although well-differentiated HCCs tended to show higher contrast enhancement, there was no statistical significance between contrast enhancement ratio of the tumors and histologic grade (p = 0.414). No significant difference was observed between CNR and histologic grade (p = 0.965). The contrast enhancement ratios of the tumors were significantly lower in the keratin 19-positive group than in the keratin 19-negative group (p = 0.015). There was no significant correlation among contrast enhancement ratio, anti-hepatocyte antibody positivity, cell density ratio, and keratin 7 positivity (p > 0.05).

CONCLUSION

The contrast enhancement ratio and CNR of HCCs were not correlated with histologic grades. The contrast enhancement ratio was significantly lower in keratin 19-positive HCCs.

The antigen for Hep Par 1 antibody is the urea cycle enzyme carbamoyl phosphate synthetase 1

Hepatocyte paraffin 1 (Hep Par 1), a murine monoclonal antibody, is widely used in surgical pathology practice to determine the hepatocellular origin of neoplasms. However, identity of the antigen for Hep Par 1 is unknown. The aim of this study was to characterize the Hep Par 1 antigen. To identify the antigen, immunoprecipitation was used to isolate the protein from human liver tissue, and a distinct protein band was detected at approximately 165 kDa. The protein band was also present in small intestinal tissue, but was not present in several other non-liver tissues nor in three human hepatocellular carcinoma cell lines, Huh-7, HepG2, and LH86. The protein was purified and analyzed by mass spectrometry. It was identified as carbamoyl phosphate synthetase 1 (CPS1). CPS1 is a rate-limiting enzyme in urea cycle and is located in mitochondria. We demonstrated that hepatoid tumors (gastric and yolk sac) were immunoreactive with both Hep Par 1 antibody and anti-CPS1 antibody, further confirming the results of mass spectrometric analysis. We found that the three human hepatocellular carcinoma cell lines do not express either CPS1 RNA or protein. We confirmed that the gene was present in these cell lines, suggesting that suppression of CPS1 expression occurs at the transcriptional level. This finding may have relevance to liver carcinogenesis, since poorly differentiated hepatocellular carcinomas exhibit poor to absent immunoreactivity to Hep Par 1. In conclusion, we have identified the antigen for Hep Par 1 antibody as a urea cycle enzyme CPS1. Our results should encourage further investigation of potential role that CPS1 expression plays in liver pathobiology and carcinogenesis.

Diagnostic utility of immunohistochemistry in hepatocellular carcinoma, its variants and their mimics

Hepatocellular carcinoma (HCC) is known for its histomorphologic heterogeneity. Immunohistochemistry (IHC) can help in the comparative morphologic evaluation of HCC, its variants and their mimics. Some of these diagnostic challenges can be attributed to (i) the variety of neoplasms that can arise from the hepatic stem cell lineage; (ii) the spectrum of well-differentiated hepatocellular nodular lesions; (iii) the liver being a target for metastases with some of these histologic entities mimicking variants of HCC or actually arising in the liver; and (iv) the limitations of serum alpha-fetoprotein (AFP). The role of IHC is in the distinction of benign hepatocellular nodules from reactive hepatocytes; WD-HCC from benign hepatocellular nodules; poorly differentiated HCC from cholangiocarcinoma and metastases; and determination of histogenesis of malignant tumor; and of primary site of origin of malignant tumor. A panel of antibodies has more discriminant value. AFP expression usually indicates malignancy in a hepatocellular nodule and hepatocytic histogenesis of a malignancy. Polyclonal carcinoembryonic antigen (pCEA) and CD10 stain bile canaliculi in better-differentiated HCC. HepPar1 is generally accepted as a hepatocytic marker. However, not all HCC stain uniformly and not all HepPar1-positive tumors are of hepatocytic origin or arise in the liver. Mature hepatocytes and hepatocellular nodules stain with CAM 5.2, CK 8, and 18 but not with CK 7, 19, 20, or AE1/AE3. Biliary epithelium expresses CK 7 and 19. CD 34 highlights sinusoidal capillarization. AFP, pCEA/CD10, and CD34 are useful for ascertainment of malignancy in hepatocellular nodules; HepPar1 and cytokeratins to be included if histogenesis is the issue. IHC results should be interpreted in the larger context of the case.

DNA end binding activity and Ku70/80 heterodimer expression in human colorectal tumor

AIM: To determine the DNA binding activity and protein levels of the Ku70/80 heterodimer, the functional mediator of the NHEJ activity, in human colorectal carcinogenesis.

METHODS: The Ku70/80 DNA-binding activity was determined by electrophoretic mobility shift assays in 20 colon adenoma and 15 colorectal cancer samples as well as matched normal colonic tissues. Nuclear and cytoplasmic protein expression was determined by immunohistochemistry and Western blot analysis.

RESULTS: A statistically significant difference was found in both adenomas and carcinomas as compared to matched normal colonic mucosa (P<0.00). However, changes in binding activity were not homogenous with approximately 50% of the tumors showing a clear increase in the binding activity, 30% displaying a modest increase and 15% showing a decrease of the activity. Tumors, with increased DNA-binding activity, also showed a statistically significant increase in Ku70 and Ku86 nuclear expression, as determined by Western blot and immunohistochemical analyses (P<0.001). Cytoplasmic protein expression was found in pathological samples, but not in normal tissues either from tumor patients or from healthy subjects.

CONCLUSION: Overall, our DNA-binding activity and protein level are consistent with a substantial activation of the NHEJ pathway in colorectal tumors. Since the NHEJ is an error prone mechanism, its abnormal activation can result in chromosomal instability and ultimately lead to tumorigenesis.

Elevated hepatocyte paraffin 1 and neprilysin expression in hepatocellular carcinoma are correlated with longer survival

Hepatocyte paraffin 1 (Hep Par 1) and neprilysin (CD10) are well-known markers of hepatocellular carcinoma (HCC). To assess their potential prognostic role, we conducted a retrospective analysis of 97 formalin-fixed and paraffin-embedded HCC from patients treated by surgery with curative intent, using standard immunohistochemical procedures and semiquantitative analysis. Strong Hep Par 1 expression and canalicular CD10 staining pattern were significantly correlated with smaller tumor size (p=0.007 and 0.04, respectively). On univariate analysis, longer overall survival was observed in patients with strong Hep Par 1 expression (p=0.0005) and in patients with a CD10can staining pattern (p=0.02). On multivariate analysis, the combined immunohistochemical score (CIS) obtained by addition of Hep Par 1 and CD10can scores and subtraction of cytoplasmic CD10 score was retained as the single most important prognostic factor (p=0.001). Patients with a CIS <4 had a 3.5-fold increased risk of death, as compared to those with a CIS >or=4. In conclusion, strong Hep Par 1 expression, presence of CD10can labeling, and absence of CD10cyt staining are favorable prognostic factors in HCC, which can be easily combined into a single immunohistochemical score for routine clinical use.

The value of Cdx2 immunostaining in differentiating primary ovarian carcinomas from colonic carcinomas metastatic to the ovaries

Histologic differentiation of primary ovarian carcinoma from colonic carcinoma metastatic to the ovary may be difficult. Cytokeratin 7 (CK7) and cytokeratin 20 (CK20) immunostaining is usually used, but these markers lack specificity for ovarian and intestinal epithelium, and overlapping results have been reported. Cdx2 is a transcription factor whose expression in normal tissues is limited to the intestinal epithelium. It is also expressed in the vast majority of colonic carcinomas and in a sizeable proportion of cases of gastric, pancreatobiliary, and ovarian mucinous carcinomas. We evaluated Cdx2, CK7, and CK20 expression in 50 ovarian carcinomas (15 serous, 20 mucinous, and 15 endometrioid), 15 colonic carcinomas metastatic to the ovaries, and 20 primary colonic carcinomas. The extent (1-25%/1+, 26-75%/2+, >75%/3+) and intensity (weak/1+, strong/2+) of staining were recorded semiquantitatively. All primary and metastatic colonic carcinomas had diffuse (3+) strong Cdx2 reactivity. All serous and endometrioid tumors were Cdx2 negative, whereas mucinous carcinomas had 1+ or 2+ immunoreactivity. All ovarian carcinomas had strong diffuse CK7 staining, whereas all colonic carcinomas were negative for CK7. CK20 stained diffusely and strongly all primary and metastatic colonic carcinomas and was 1+ or 2+ in all mucinous carcinomas, in 67% of serous carcinomas, and in 33% of endometrioid carcinomas. In conclusion, 1) Cdx2 is a highly sensitive (100%) marker for colonic carcinoma metastatic to the ovary; 2) Cdx2 is more specific than CK20 as it is not expressed by serous and endometrioid carcinomas; and 3) a limited panel of Cdx2 and CK7 helps in distinguishing colonic carcinomas metastatic to the ovaries (Cdx2+/CK7-) from primary ovarian serous (Cdx2-/CK7+), endometrioid (Cdx2-/CK7+), and mucinous (Cdx2+/CK7+) carcinomas.

Cutaneous metastasis of hepatocellular carcinoma diagnosed with hepatocyte paraffin (Hep Par 1) antibody immunohistochemistry

Cutaneous metastases from hepatocellular carcinomas are rare, and their diagnosis may be difficult on histological grounds. We report a case of metastatic hepatocellular carcinoma to the skin that was confirmed immunohistochemically by the expression of a hepatomitochondria-specific antigen detectable on paraffin-embedded sections (Hep Par 1).

A novel diagnostic marker, p28GANK distinguishes hepatocellular carcinoma from potential mimics

PURPOSE

To investigate the sensitivity, specificity, and spatial distribution of the product of p28 gene (p28(GANK) protein) in human hepatocellular carcinoma (HCC) and nonhepatocellular carcinomas in relation to immunostaining with Cytokeratin 18 (CK18), alpha-fetoprotein (AFP), and Hepatocyte paraffin 1 (HepPar1).

METHOD

In this retrospective study, formalin-fixed paraffin-embedded tissues from 24 HCCs, five intrahepatic cholangiocarcinomas (ICC), five combined hepatocellular cholangiocarcinomas (C-HCC-CC) and mine metastatic hepatic carcinomas (MHC) were immunostained for p28(GANK) as well as CK18, AFP and HepPar1. Only cases with more intensified staining in carcinoma contrast to the adjacent liver tissues were accepted as positive.

RESULT

In HCC, p28(GANK) was expressed restrictively in hepatocytes of both para-lesion and carcinoma liver tissues, while absent in the bile duct epithelial cells, Kupffer cells, and other interstitial cells. The positive staining of p28(GANK) was noted in 16 (66.7%) specimens of HCC and three (60.0%) specimens of C-HCC-CC, and no specific lesion staining was found in all tested specimens of ICC and MHC. Sensitivity and specificity for hepatocyte-originated carcinoma were, respectively, 65.5% and 100% for p28(GANK), 79.3% and 85.2% for CK18, 20.7% and 100% for AFP, 79.3% and 92.0% for HepPar1.

CONCLUSION

The hepatocytic staining for p28(GANK) is clearly useful in differentiating hepatocyte-originated carcinoma from non-HCC. p28(GANK) may be used as an ancillary marker for the diagnosis of HCC.

Hep Par 1 expression in carcinoma of the cervix: implications for diagnosis and prognosis

AIMS

To determine the frequency and pattern of Hep Par 1 expression in cervical carcinomas of various histological types and to correlate expression with prognostic parameters.

METHODS

Twenty nine cervical carcinomas were analysed for tumour type, hepatoid and neuroendocrine differentiation, and vascular invasion. A semiquantitative analysis was performed for Hep Par 1, alpha fetoprotein, chromogranin, and synaptophysin immunoreactivity.

RESULTS

Hep Par 1 expression was seen in seven of the 29 cervical carcinomas (three of seven adenocarcinomas, one of 17 squamous cell carcinomas, one of two adenocarcinomas with adenocarcinoma in situ, one of two adenocarcinomas in situ, and one of one large cell neuroendocrine carcinoma with adenocarcinoma in situ). Normal looking endocervical epithelium was also positive in one case. Cases expressing Hep Par 1, with or without neuroendocrine coexpression, were associated with a higher rate of vascular invasion and a worse prognosis. Three of the five cases expressing neuroendocrine markers also coexpressed Hep Par 1.

CONCLUSIONS

Hep Par 1 expression in carcinoma of the cervix is not uncommon and is present in a variety of histological types. Expression of this marker appears to be associated with more aggressive biological behaviour and a worse prognosis. The uterine cervix is another site that may express Hep Par 1 and hence the use of this antibody in situations of diagnostic difficulty, especially involving lesions within the liver, have to be coupled with the knowledge of the range of tissues it may stain.

The diagnostic value of hepatocyte paraffin antibody 1 in differentiating hepatocellular neoplasms from nonhepatic tumors: a review

Hepatocyte paraffin-1 (HepPar-1) is a recently developed monoclonal antibody that appears to identify an antigen unique to hepatocellular mitochondria. This article reviews the use of this new antibody in the differential diagnosis of primary hepatocellular neoplasms, cholangiocarcinomas, and carcinomas metastatic to the liver. Hepatocyte paraffin-1 appears to be the most sensitive and specific positive marker of hepatocellular differentiation, but like any immunohistochemical marker, should be interpreted only in the context of the overall clinicopathologic picture and as part of a panel of antibodies.

Hep Par 1 in gastric and bowel carcinomas: an immunohistochemical study

AIMS

Hep Par 1 has been described as a specific marker of hepatocellular differentiation and its immunohistochemical use has been suggested as a helpful tool for hepatocellular carcinoma (HCC) diagnosis. Most metastatic liver tumours come from the gastrointestinal tract and usually can be distinguished from HCC only through histology. We evaluated by immunohistochemistry the specificity of Hep Par 1, studying the presence of the epitope that reacts with Hep Par 1 in primary gastric and colorectal cancers.

METHODS

A series of 39 cases of primary gastric and 18 cases of colorectal carcinoma were selected. Twenty-six of the 39 gastric carcinomas were of the intestinal type, six of the diffuse type, three of the mixed type and five had hepatoid differentiation. Two of the 18 colorectal adenocarcinomas were well differentiated, 14 moderately differentiated, one poorly differentiated and one was of the mucinous type. Five-microm sections were stained by immunohistochemistry using Hep Par 1 as primary antibody.

RESULTS

Immunohistochemical staining was observed in 26 gastric carcinomas (69%) and nine large bowel carcinomas (50%). Fifteen of the 26 positive-stained gastric cancers were of intestinal type, four of diffuse type and two of mixed type cases. All of the five hepatoid type cases stained positively. Two of the nine positively stained colorectal cancers were well differentiated, six were moderately differentiated and one was a mucinous type adenocarcinoma. The staining pattern was cytoplasmic and granular as described in benign and malignant hepatocytes. The percentage of immunostained cells was graded as follows: 0 (no staining); 1 (>0-5%); 2 (> 5-50%); 3 (> 50%). Of the 26 positive gastric tumours, 13 showed a staining score of 1, eight scored 2, and five scored 3. Four of the nine positive intestinal carcinomas showed a staining score of 1, and five scored 2.

CONCLUSIONS

Our results show that Hep Par 1 is a highly sensitive marker of hepatocellular differentiation as demonstrated by the expression in gastric tumours with hepatoid histotype. However, the frequent reaction with neoplastic cells of gastric and bowel carcinomas shows a low grade of specificity of this antibody.