Immunological approach to hepatocellular carcinoma

Labyrinthin: A distinct pan-adenocarcinoma diagnostic and immunotherapeutic tumor specific antigen

Structural analysis and detection of optimal cell surface localization of labyrinthin, a pan-adenocarcinoma target, was studied with respect to adenocarcinoma specificity vs. normal and non-adenocarcinoma cells. Patient-derived tissue microarray immunohistochemistry (IHC) was performed on 729 commercially prepared tissue blocks of lung, colon, breast, pancreas, prostate, and ovary cancers combined, plus a National Cancer Institute (NCI) tissue microarray derived from another 236 cases. The results confirmed that anti-labyrinthin mouse monoclonal MCA 44-3A6 antibody recognized adenocarcinomas, but not normal or non-adenocarcinoma cancer cells. The consensus of multiple topology analysis programs on labyrinthin (255 amino acids) estimate a type II cell membrane associated protein with an N-terminus signal peptide. However, because the labyrinthin sequence is enveloped within the 758 amino acids of the intracellular aspartyl/asparaginyl beta-hydroxylase (ASPH), a purported tumor associated antigen, standard IHC methods that permeabilize cells can expose common epitopes. To circumvent antibody cross-reactivity, cell surface labyrinthin was distinguished from intracellular ASPH by FACS analysis of permeabilized vs non-permeabilized cells. All permeabilized normal, adeno-and non-adenocarcinoma cells produced a strong MCA 44-3A6 binding signal, likely reflecting co-recognition of intracellular ASPH proteins along with internalized labyrinthin, but in non-permeabilized cells only adenocarcinoma cells were positive for labyrinthin. Confocal microscopy confirmed the FACS results. Labyrinthin as a functional cell-surface marker was suggested when: 1) WI-38 normal lung fibroblasts transfected with labyrinthin sense cDNA displayed a cancerous phenotype; 2) antisense transfection of A549 human lung adenocarcinoma cells appeared more normal; and 3) MCA44-3A6 suppressed A549 cell proliferation. Collectively, the data indicate that labyrinthin is a unique, promising adenocarcinoma tumor-specific antigen and therapeutic target. The study also raises a controversial issue on the extent, specificity, and usefulness of ASPH as an adenocarcinoma tumor-associated antigen.

Recent advances in research on aspartate β-hydroxylase (ASPH) in pancreatic cancer: A brief update

Pancreatic cancer (PC) is a highly aggressive tumor, often difficult to diagnose and treat. Aspartate β-hydroxylase (ASPH) is a type II transmembrane protein and the member of α-ketoglutarate-dependent dioxygenase family, found to be overexpressed in different cancer types, including PC. ASPH appears to be involved in the regulation of proliferation, invasion and metastasis of PC cells through multiple signaling pathways, suggesting its role as a tumor biomarker and therapeutic target. In this review, we briefly summarize the possible mechanisms of action of ASPH in PC and recent progress in the therapeutic approaches targeting ASPH.

Identification of Tumor Antigen AF20 as Glycosylated Transferrin Receptor 1 in Complex with Heat Shock Protein 90 and/or Transporting ATPase

We previously isolated AF20, a murine monoclonal antibody that recognizes a cell surface glycoprotein of approximately 90-110 kDa. The AF20 antigen is specifically expressed in human hepatoma and colon cancer cell lines, and thus could serve as a cancer biomarker. To uncover the molecular identity of the AF20 antigen, a combination of ion-exchange chromatography, immunoprecipitation, and SDS-polyacrylamide gel electrophoresis was employed to purify the AF20 antigen followed by trypsin digestion and mass spectrometry. Surprisingly, three host proteins were thus purified from human hepatoma and colon cancer cell lines: transferrin receptor 1 (TFR1), heat shock protein 90 (HSP90), and Na+/K+ ATPase or Mg++ ATPase. Co-immunoprecipitation followed by Western blot analysis confirmed interaction among the three proteins. However, only the cDNA encoding TFR1 conferred strong cell surface staining by the AF20 antibody following its transient transfection into a cell line lacking endogenous AF20. In support of the molecular identity of AF20 as TFR1, diferric but not iron-free transferrin could prevent AF20 antigen-antibody interaction during immunoprecipitation. Moreover, very similar patterns of AF20 and TFR1 overexpression was documented in colon cancer tissues. In conclusion, AF20 is glycosylated TFR1. This finding could explain the molecular structure of AF20, its cell surface localization, as well as overexpression in cancer cells. Glycosylated TFR1 should serve as a usefulness target for anti-cancer therapy, or a vehicle for delivery of anti-tumor drugs with high affinity and specificity. The biological significance of the complex formation between TFR1, HSP90, and/or transporting ATPase warrants further investigation.

Overexpression of aspartyl-(asparaginyl)-beta-hydroxylase in hepatocellular carcinoma is associated with worse surgical outcome

The association between the overexpression of aspartyl-(asparaginyl)-beta-hydroxylase (AAH) and the invasiveness of hepatocellular carcinoma (HCC) in vitro has been reported. However, the prognostic value of AAH expression in HCC remains unclear. The purpose of this study was to investigate the relationship between AAH expression, tumor recurrence, and patient survival. We identified AAH as the most overexpressed gene in HCC by way of complementary DNA microarray hybridization. A prospective study of 233 patients undergoing curative resection indicated that AAH expression was an independent factor affecting recurrence (hazard ratio [HR] 3.161, 95% confidence interval [CI] 2.115-4.724, P < 0.001) and survival (HR 2.712, 95% CI 1.734-4.241, P < 0.001). Patients with AAH overexpression had a poorer prognosis than those with AAH underexpression (P < 0.001 for both recurrence and survival). In Barcelona Clinic Liver Cancer stage A patients with AAH overexpression or underexpression, the tumor recurrence and survival rates were also statistically different (45% and 85% versus16% and 33% in 1- and 3-year cumulative recurrence rates, respectively; 73% and 37% versus 90% and 80% in 1- and 3-year survival rates, respectively; P < 0.001 for both). Furthermore, in stage A patients with tumors measuring < or =5 cm in diameter, the time to recurrence was 26.7 +/- 1.6 versus 51.9 +/- 2.8 months, and the 1- and 3- year survival rates were 97% and 52% versus 100% and 90% in AAH overexpression and underexpression patients, respectively (P < 0.001 for both).

CONCLUSION

AAH overexpression in HCC is strongly correlated with worse surgical outcome, and this molecule likely provides a more precise prognostic predictor in early stage HCCs.

Prognostic value of aspartyl (asparaginyl)-beta-hydroxylase/humbug expression in non-small cell lung carcinoma

Despite improvements in the detection and use of biomarkers, including epidermal growth factor receptor, ERCC1, and p16, the 5-year survival rate with non-small cell lung cancer remains at 15%. This suggests that additional biomarkers are needed to better prognosticate clinical course and guide therapeutic approaches. Previous studies showed that increased levels of aspartyl (asparaginyl)-beta-hydroxylase and a highly related molecule, humbug, correlate with clinical course and survival with hepatic, biliary, pancreatic, and colon carcinomas. We now characterize the prognostic use of aspartyl (asparaginyl)-beta-hydroxylase/humbug immunoreactivity in different subtypes of non-small cell lung cancer. Tissue microarrays including 375 paraffin-embedded non-small cell lung cancers (195 adenocarcinomas; 18 bronchioloalveolar carcinomas; 113 squamous cell carcinomas; and 49 large cell carcinomas) were immunostained with FB50 monoclonal antibody, which recognizes human aspartyl (asparaginyl)-beta-hydroxylase/humbug. Immunoreactivity (intensity and distribution) in neoplastic cells were scored under code, and data were subjected to univariate and Cox multivariate analyses, adjusting for age, stage, and treatment. High levels of FB50 immunoreactivity were more often detected in adenocarcinomas (28% for adenocarcinoma, 17% for bronchioloalveolar carcinoma), compared with squamous cell carcinomas (10%) and large cell carcinomas (10%). Univariate analysis demonstrated inverse relationships between intensity of FB50 immunoreactivity and survival with squamous cell carcinoma (P = .004), and a strong trend with respect to large cell carcinoma (P = .057). Cox multivariate test showed that FB50 immunoreactivity (P = .025), clinical stage (P = .029), and tumor size (P = .0001) were all independent predictors of survival with squamous cell carcinoma. High levels of FB50 immunohistochemical staining correlate with poor prognosis in non-small cell lung cancer, particularly squamous cell carcinoma subtype. Therefore, FB50 immunoreactivity may be useful in defining patient subsets that are likely to benefit from adjuvant therapy.

Molecular therapy and prevention of liver diseases

Molecular analyses have become an integral part of biomedical research as well as clinical medicine. The definition of the molecular and genetic basis of many human diseases has led to a better understanding of their pathogenesis and has in addition offered new perspectives for their diagnosis, therapy and prevention. Genetically, liver diseases can be classified as hereditary monogenic, acquired monogenic, complex genetic and diseases. Based on this classification, gene therapy is based on six concepts: gene repair, gene substitution, cell therapy, block of gene expression or function, DNA vaccination as well as gene augmentation. While recent developments are promising, various delivery, targeting and safety issues need to be addressed before gene therapy will enter clinical practice. In the future, molecular diagnosis and therapy liver diseases will be part of our patient management and complement existing diagnostic, therapeutic and preventive strategies.

Prognostic value of humbug gene overexpression in stage II colon cancer

Overexpression of aspartyl (asparaginyl) beta-hydroxylase (AAH) has been demonstrated in hepatocellular carcinoma, cholangiocarcinoma, and pancreatic carcinoma. AAH has an important role in regulating cell motility and invasiveness. Humbug is a truncated homolog of AAH, with a role in calcium regulation. The present study examines the prognostic use of AAH and humbug gene expression in stage II colon cancer. One hundred thirty cases of TNM stage II colon carcinoma were retrieved from the Rhode Island Hospital pathology archives. Tissue microarrays were immunostained with the FB50 and 15C7 monoclonal antibodies generated to recombinant AAH. However, FB50 also recognizes humbug. In addition, AAH and humbug expression was analyzed in samples of colon cancer and adjacent normal mucosa by real-time quantitative reverse transcriptase-polymerase chain reaction. Humbug (FB50) expression was localized to the tumor cytoplasm, whereas normal colonic epithelium did not exhibit significant immunoreactivity. Humbug staining was detected in 85% of the neoplasms, 23% of which stained strongly. Strong humbug immunoreactivity positively correlated with nuclear grade (P = .006) and inversely with survival (P = .027). In contrast to humbug, AAH (15C7) immunoreactivity was seen in normal and neoplastic epithelium. There was no correlation between AAH immunoreactivity and tumor grade, or survival. Correspondingly, reverse transcriptase-polymerase chain reaction studies demonstrated up-regulation of humbug but not AAH in 95% of colon carcinomas relative to adjacent colon cancer-free mucosa (P < .0001). This study demonstrates that high levels of humbug immunoreactivity in colon carcinomas correlate with histologic grade and tumor behavior, suggesting that humbug can serve as a prognostic biomarker of TNM stage II colon cancers. In addition, molecular studies demonstrated that the increased levels of FB50 detected were due to humbug, as opposed to AAH overexpression.

Aspartyl-asparagyl beta hydroxylase over-expression in human hepatoma is linked to activation of insulin-like growth factor and notch signaling mechanisms

Aspartyl-(asparagyl)-beta-hydroxylase (AAH) is overexpressed in various malignant neoplasms, including hepatocellular carcinomas (HCCs). The upstream regulation of AAH and its functional role in Notch-mediated signaling and motility in HCC cells was accessed. The mRNA transcript levels of AAH, insulin receptor substrate (IRS), insulin and insulin-like growth factor (IGF) receptors and polypeptides, Notch, Jagged, and HES were measured in 15 paired samples of HCC and adjacent HCC-free human liver biopsy specimens using real-time quantitative RT-PCR and Western blot analysis. Overexpression of AAH was detected in 87% of the HCC relative to the paired HCC-free liver tissue. IRS-1, IRS-2, and IRS-4 were each overexpressed in 80% of the HCC samples, and IGF-I and IGF-2 receptors were overexpressed in 40% and 100% of the HCCs, respectively. All HCC samples had relatively increased levels of Notch-1 and HES-1 gene expression. Overexpression of AAH led to increased levels of Notch, and co-immunoprecipitation experiments demonstrated a direct interaction between AAH and Notch as well as its ligand Jagged. In conclusion, contributions to the malignant phenotype of HCC is due to activation of IGF-I and IGF-II signaling that results in over-expression of both AAH and Notch. The functional role of AAH in relation to cell motility has been linked to increased activation of the Notch signaling pathway.

Aspartyl-(asparaginyl)-beta-hydroxylase regulates hepatocellular carcinoma invasiveness

BACKGROUND/AIMS

We measured aspartyl (asparaginyl)-beta-hydroxylase (AAH) gene expression in human hepatocelluar carcinoma and surrounding uninvolved liver at both the mRNA and protein level and examined the regulation and function of this enzyme.

METHODS

Since growth of HCC is mediated by signaling through the insulin-receptor substrate, type 1 (IRS-1), we examined-if AAH is a downstream gene regulated by insulin and IGF-1 in HCC cells. In addition, IRS-1 regulation of AAH was examined in a transgenic (Tg) mouse model in which the human (h) IRS-1 gene was over-expressed in the liver, and an in vitro model in which a C-terminus truncated dominant-negative hIRS-1 cDNA (hIRS-DeltaC) was over-expressed in FOCUS HCC cells. The direct effects of AAH on motility and invasiveness were examined in AAH-transfected HepG2 cells.

RESULTS

Insulin and IGF-1 stimulation increased AAH mRNA and protein expression and motility in FOCUS and Hep-G2 cells. These effects were mediated by signaling through the Erk MAPK and PI3 kinase-Akt pathways. Over-expression of hIRS-1 resulted in high levels of AAH in Tg mouse livers, while over-expression of hIRS-DeltaC reduced AAH expression, motility, and invasiveness in FOCUS cells. Finally, over-expression of AAH significantly increased motility and invasiveness in HepG2 cells, whereas siRNA inhibition of AAH expression significantly reduced directional motility in FOCUS cells.

CONCLUSIONS

The results suggest that enhanced AAH gene activity is a common feature of human HCC and growth factor signaling through IRS-1 regulates AAH expression and increases motility and invasion of HCC cells. Therefore, AAH may represent an important target for regulating tumor growth in vivo.

Clinicopathological correlates of aspartyl (asparaginyl) beta-hydroxylase over-expression in cholangiocarcinoma

Aspartyl (asparaginyl) beta-hydroxylase (AAH) expression in surgically resected intrahepatic cholangiocarcinoma significantly correlated with tumor size, growth type, differentiation, vascular invasion, and prognosis after surgery. AAH may have a role in regulating invasive or metastatic tumor cell growth of human intrahepatic cholangiocarcinoma.

BACKGROUND

Recent studies demonstrated increased expression of the AAH gene in the majority of cholangiocarcinomas. The present study was undertaken to determine the relationship between high or low levels of AAH expression and the clinical course of intrahepatic cholangiocarcinoma (ICC).

METHODS

AAH expression was examined in 50 surgically resected primary ICCs, 12 samples of normal liver, and 12 cases of primary sclerosing cholangitis (PSC). The sections were evaluated by immunohistochemical staining with the FB-50 monoclonal antibody to human AAH protein. The sections were examined under code and graded for relative levels of AAH immunoreactivity. The results were analyzed with respect to multiple clinical and histopathological variables to determine correlates of AAH expression in ICCs.

RESULTS

Forty-six of the 50 (92%) ICCs had AAH immunoreactivity, whereas the 12 normal liver and 12 PSC specimens were AAH negative. In the ICC specimens, the highest levels of AAH immunoreactivity were detected at the infiltrating margins that interfaced with uninvolved liver tissue, and the lowest levels occurred in the central portions of the tumors. Multivariate analysis demonstrated that high levels of AAH expression were correlated with tumor size (P < 0.05), infiltrative growth pattern (P < 0.01), aggressive histological grade (P < 0.01), vascular invasion (P < 0.05), and poor prognosis (P < 0.05).

CONCLUSIONS

These findings suggest that AAH has an important role in regulating invasive or metastatic tumor cell growth of human ICC, and that high levels of AAH expression correlate with poor prognosis.

Human aspartyl (asparaginyl) beta-hydroxylase monoclonal antibodies: potential biomarkers for pancreatic carcinoma

INTRODUCTION

Pancreatic adenocarcinoma is among the top 10 leading causes of death due to cancer in the United States. The lack of reliable and sensitive biomarkers for this disease makes it difficult to render an early diagnosis.

AIMS

To evaluate carcinoma-associated monoclonal antibodies (MoAbs), including AF-20, SF-25, and FB-50, for their binding specificity to pancreatic adenocarcinoma relative to normal pancreatic tissue. In addition, binding of the Th9 MoAb to human Reg 1 protein was studied because of its potential role in cell growth.

METHODOLOGY

Adjacent histologic sections were immunostained with each of the MoAbs and graded on a scale of 0 to 4+, corresponding to the relative distribution and intensity of immunoreactivity within the tumor and normal adjacent tissue.

RESULTS

Intense levels (grade 3 or 4) of FB50 immunoreactivity were detected in 19 of 19 tumors but not in normal adjacent pancreatic tissue. In addition, increased levels of FB50 immunoreactivity were detected in at least 75% of the tumor cells in 18 of the 19 cases. SF-25 immunoreactivity similarly distinguished pancreatic adenocarcinoma from normal pancreas in 14 of 19 cases. In contrast, AF20 immunoreactivity was detected in 6 of 19 pancreatic adenocarcinomas, and for the most part, the labeling was focal and of a low level. TH9 immunoreactivity was detected in 5 of 19 tumors but also in normal as well as inflamed adjacent pancreatic tissue.

CONCLUSION

These results suggest that the FB50 and SF25 MoAbs represent excellent potential biomarkers of pancreatic adenocarcinoma and could be configured in an immunoassay for detecting pancreatic adenocarcinoma cells in biologic fluids.

Oncogenic signal transduction and therapeutic strategy for hepatocellular carcinoma

Discoveries of oncogenic signaling molecules lead to the comprehension of molecular mechanisms of tumor progression, as well as to the development of novel therapeutic tools for hepatocellular carcinoma. We have identified critical functions of intracellular signals transmitted from insulin-like growth factor and Wnt oncoprotein in carcinogenesis. The insulin-like growth factor system activates a number of signaling cascades resulting not only in hepatic mitogenesis, but also in cell survival. The secreted oncoprotein Wnt transforms beta-catenin potentials as a component of cell adhesion complexes with cadherins, into a transcription factor in the nucleus. Here, the important role of such signal transduction is reviewed, and we emphasize its control as a promising approach for the treatment of hepatocellular carcinoma.