Comparative Immunohistochemical Analysis of Clinicopathological Subgroups in Hepatocellular Carcinomas from Japan and Indonesia.

Background: Standardized pathological evaluation based on immunohistochemical (IHC) analysis could improve hepatocellular carcinoma (HCC) diagnoses worldwide. We evaluated differences in clinicopathological subgroups in HCCs from two academic institutions in Tokyo-Japan, and Jakarta-Indonesia. Methods: Clinicopathological parameters and molecular expression patterns were evaluated in 35 HCCs from Indonesia and 41 HCCs from Japan. IHC analysis of biliary/stem cell (B/S) markers (cytokeratin 19, sal-like protein 4, epithelial cell adhesion molecule) and Wnt/ß-catenin (W/B) signaling-related molecules (ß-catenin, glutamine synthetase) could determine the IHC-based subgroups. For immuno-subtypes categorization, CD3/CD79α double immunohistochemistry was done to evaluate the infiltration of T and B cells. CD34 staining allowed identification of vessels that encapsulated tumor clusters (VETC). Results: Indonesian HCC patients were mostly <60 years old (66%) with a hepatitis B virus (HBV) background (82%), in contrast to Japanese HCC patients (8% and 19%, respectively, both P < 0.001). In comparison with Japanese, Indonesian cases more frequently had >5 cm tumor size (74% vs 23%, P = 0.001), poor differentiation (40% vs 24%), portal vein invasion (80% vs 61%), and α-fetoprotein levels >500 ng/ml (45% vs 13%, P = 0.005). No significant differences were found in the proportions of B/S, W/B, and -/- subgroups from both countries. No immune-high tumors were observed among Indonesian cases, and immune-low tumors (66%) were more common than in Japanese cases (54%). VETC-positive tumors in Indonesia were significantly more common (29%), and most were in the HBV (90%) and -/- subgroups (90%), whereas Japanese VETC cases (10%, P = 0.030) were nonviral (100%) and W/B subgroups (75%). Conclusion: IHC-based analysis more precisely reflected the clinicopathological differences of HCCs in Japan and Indonesia. These findings provide new insights into standardization attempts and HCC heterogeneity among countries.

Immunovascular classification of HCC reflects reciprocal interaction between immune and angiogenic tumor microenvironments.

BACKGROUND AND AIMS: Immune cells and tumor vessels constitute important elements in tumor tissue; however, their detailed relationship in human tumors, including HCC, is still largely unknown. Consequently, we expanded our previous study on the immune microenvironment of HCC and analyzed the relationship among the immune microenvironment, inflammatory/angiostatic factor expression, angiogenic factor expression, and tumor vessel findings, including vessels encapsulating tumor clusters (VETC) and macrotrabecular-massive (MTM) patterns. APPROACH AND RESULTS: We classified HCC into four distinct immunovascular subtypes (immune-high/angiostatic [IH/AS], immune-mid/angio-mid [IM/AM], immune-low/angiogenic [IL/AG], and immune-low/angio-low [IL/AL]). IH/AS, IM/AM, and IL/AG subtypes were associated with decreasing lymphocytic infiltration and increasing angiogenic factor expression and VETC/MTM positivity, reflecting their reciprocal interaction in the tumor microenvironment of HCC. IL/AG subtype was further characterized by CTNNB1 mutation and activation of Wnt/ß-catenin pathway. IL/AL subtype was not associated with increased lymphocyte infiltration or angiogenic factor expression. Prognostically, IH/AS subtype and VETC/MTM positivity were independently significant in two independent cohorts. Increased angiogenic factor expression was not necessarily associated with VETC/MTM positivity and poor prognosis, especially when inflammatory/angiostatic milieu coexisted around tumor vessels. These results may provide insights on the therapeutic effects of immunotherapy, antiangiogenic therapies, and their combinations. The potential of evaluating the immunovascular microenvironment in predicting the clinical effect of these therapies in nonresectable HCC needs to be analyzed in the future study. CONCLUSIONS: HCC can be classified into four distinct immunovascular subtypes (IH/AS, IM/AM, IL/AG, and IL/AL) that reflect the reciprocal interaction between the antitumor immune microenvironment and tumor angiogenesis. In addition to its clinicopathological significance, immunovascular classification may also provide pathological insights on the therapeutic effect of immunotherapy, antiangiogenic therapy, and their combination.

Telomerase reverse transcriptase (TERT) promoter mutation correlated with intratumoral heterogeneity in hepatocellular carcinoma.

Telomerase reverse transcriptase (TERT) promoter mutations are frequently observed in hepatocellular carcinoma (HCC); however, the impact of TERT promoter mutations (TPMs) on clinical features and morphological patterns in HCC remains unresolved. Using DNA extracted from 97 HCCs, correlations between TPM status and both the clinical features of HCC and the immunohistochemically-based subgroups were evaluated. Morphological tumor patterns were semi-quantitatively analyzed using hematoxylin and eosin-stained slides of the whole tumor cross-sectional area. The percentages of tumor area occupied by early, well, moderate and poor histological patterns were calculated as a homogeneity index. TPMs were observed in 53 of 97 (55%) HCCs and were significantly associated with older age (P = 0.018) and HCV-related background (P = 0.048). The biliary/stem cell marker-positive subgroup was less likely to have TPMs (29%) compared to the Wnt/ß-catenin signaling marker-positive subgroup (60%). In contrast to TPM-negative HCCs, TPM-positive HCCs clearly exhibited intratumoral morphological heterogeneity (0.800 ± 0.117 vs 0.927 ± 0.096, P < 0.0001), characterized by two or more heterogeneous histological patterns (P < 0.0001) and had more well or early differentiated histological patterns (P = 0.024). Our findings showed that intratumoral heterogeneity was strongly related to TPM-positive HCCs, which established novel roles of TPMs, and may improve our understanding particularly about HCC development and diagnosis.

Precision pathology analysis of the development and progression of hepatocellular carcinoma: Implication for precision diagnosis of hepatocellular carcinoma.

Outcomes for patients with hepatocellular carcinoma (HCC) remain poor because the condition is often unresponsive to the available treatments. Consequently, the early and precise diagnosis of HCC is crucial to achieve improvements in prognosis. For patients with chronic liver disease, the assessment of liver fibrosis is also important to ascertain both the staging of fibrosis and the risk of HCC occurrence. Early HCC was first described in 1991 in Japan and was defined internationally in 2009. As the concept of early HCC spread, the multistage hepatocarcinogenesis process became accepted. Consequently, improvements in imaging technology made the early diagnosis of HCC possible. At present, the most appropriate therapeutic strategy for HCC is determined using an integrated staging system that assesses the tumor burden, the degree of liver dysfunction and the patient performance status; however, pathological and molecular features are not taken into account. The recent introduction of several new therapeutic agents will change the treatment strategy for HCC. Against this background, HCC subclassification based on tumor cellular and microenvironmental characteristics will become increasingly important. In this review, we give an overview of how pathological analysis contributes to understanding the development and progression of HCC and establishing a precision diagnosis of HCC.

Quantitative assessment of liver fibrosis reveals a nonlinear association with fibrosis stage in nonalcoholic fatty liver disease.

Accurate staging of liver fibrosis is crucial to guide therapeutic decisions for patients with nonalcoholic fatty liver disease (NAFLD). Digital image analysis has emerged as a promising tool for quantitative assessment of fibrosis in chronic liver diseases. We sought to determine the relationship of histologic fibrosis stage with fiber amounts quantified in liver biopsy specimens for the better understanding of NAFLD progression. We measured area ratios of collagen and elastin fibers in Elastica van Gieson-stained biopsy tissues from 289 patients with NAFLD from four hospitals using an automated computational method and examined their correlations with Brunt's fibrosis stage. As a secondary analysis, we performed multivariable logistic regression analysis to assess the associations of the combined area ratios of collagen and elastin with noninvasive fibrosis markers. The combined fiber area ratios correlated strongly with Brunt's stage (Spearman correlation coefficient, 0.78; P < 0.0001), but this relationship was nonlinear (P = 0.007) with striking differences between stage 4 (median area ratios, 12.3%) and stages 0-3 (2.1%, 2.8%, 4.3%, and 4.8%, respectively). Elastin accumulation was common in areas of thick bridging fibrosis and thickened venous walls but not in areas of perisinusoidal fibrosis. The highest tertile of the combined fiber area ratios was associated with the fibrosis-4 index and serum type IV collagen 7s domain (7s collagen) levels, whereas the upper two tertiles of the fiber amounts significantly associated with body mass index, aspartate aminotransferase, and 7s collagen in the multivariable analysis. Conclusion: Quantitative fibrosis assessment reveals a nonlinear relationship between fibrosis stage and fiber amount, with a marked difference between stage 4 and stage 3 and much smaller differences among stages 0-3, suggesting a heterogeneity in disease severity within NAFLD-related cirrhosis. (Hepatology Communications 2018;2:58-68).

Overexpression of adenylate cyclase-associated protein 2 is a novel prognostic marker in malignant melanoma.

Malignant melanoma is one of the lethal malignant tumors worldwide. Previously we reported that adenylate cyclase-associated protein 2 (CAP2), which is a well-conserved actin regulator, was overexpressed in hepatocellular carcinoma; however, CAP2 expression in other clinical cancers remains unclear. The aim of the current study was to clarify the clinicopathological significance of CAP2 overexpression in malignant melanoma. Immunohistochemical analyses revealed that many melanoma cells exhibited diffuse cytoplasmic expression of CAP2, whereas no normal melanocytes showed detectable immunostaining for CAP2. A high level of CAP2 expression was seen in 14 of 50 melanomas and was significantly correlated with greater tumor thickness and nodular melanoma subtypes. In addition, a high level of CAP2 expression was associated with poor overall survival in univariate and multivariate analyses. For 13 patients, samples of primary and metastatic melanoma tissue were available: four patients exhibited higher levels of CAP2 expression in metastatic tumor compared to the primary site, whereas no patient showed lower levels of CAP2 expression in metastatic melanomas. Our findings show that CAP2 overexpression is a novel prognostic marker in malignant melanoma and that CAP2 expression seems to increase stepwise during tumor progression, suggesting the involvement of CAP2 in the aggressive behavior of malignant melanoma.

OATP1B3 expression is strongly associated with Wnt/ß-catenin signalling and represents the transporter of gadoxetic acid in hepatocellular carcinoma.

BACKGROUND & AIMS: In the current era of emerging molecular targeted drugs, it is necessary to identify before treatment the specific subclass to which a tumour belongs. Gadoxetic acid is a liver-specific contrast agent that is preferentially taken up by hepatocytes. Therefore, gadoxetic acid-enhanced magnetic resonance imaging (EOB-MRI) should provide precise molecular information about hepatocellular carcinomas (HCCs). The aim of this study was to investigate the transporters of gadoxetic acid in HCC comprehensively and to analyse the molecular regulatory mechanism of such transporters. METHODS: Expression levels of transporters, transcriptional factors and Wnt target genes in clinical samples were examined by quantitative real-time reverse transcription polymerase chain reaction and immunohistochemistry. LiCl treatment of the HCC cell line KYN-2 was conducted in vitro to assess the effects of Wnt signalling activity. RESULTS: Comprehensive analyses of transporter mRNAs and protein expressions revealed that the organic anion transporting polypeptide 1B3 (OATP1B3) had the strongest correlation with tumour enhancement in hepatobiliary-phase images of EOB-MRI. Association analysis with OATP1B3 expression revealed significant correlation with the expression of Wnt/ß-catenin target genes. Further, LiCl treatment induced OATP1B3 mRNA expression in KYN-2 cells, indicating a strong association between OATP1B3 expression and Wnt/ß-catenin signalling. The sensitivity and specificity to predict Wnt/ß-catenin-activated HCC using tumour enhancement in EOB-MRI were 78.9% and 81.7%, respectively. CONCLUSIONS: OATP1B3 was confirmed as the most important transporter mediating HCC enhancement in EOB-MRI. OATP1B3 expression showed a strong association with the expression of Wnt/ß-catenin target genes, therefore, OATP1B3-upregulated HCC likely represents a specific subclass of Wnt/ß-catenin-activated HCC.

Upregulated SMAD3 promotes epithelial-mesenchymal transition and predicts poor prognosis in pancreatic ductal adenocarcinoma.

In pancreatic ductal adenocarcinoma (PDAC), features of epithelial-mesenchymal transition (EMT) are often seen in tumor tissue, and such features correlate with poor prognosis. Solitary infiltration of tumor cells represents a morphological phenotype of EMT, and we previously reported that a high degree of solitary cell infiltration correlates with EMT-like features, including reduced E-cadherin and elevated vimentin levels. Using solitary cell infiltration to evaluate the degree of EMT, gene-expression profiling of 12 PDAC xenografts was performed, and SMAD3 was identified as an EMT-related gene. Immunohistochemistry using clinical specimens (n=113) showed that SMAD3 accumulated in the nuclei of tumor cells, but was not detected in most epithelial cells in the pancreatic duct. Moreover, SMAD3 upregulation correlated with malignant characteristics, such as higher tumor grade and lymph node metastasis, as well as with EMT-like features. SMAD4, which plays a key role in transforming growth factor-ß (TGF-ß) signaling, is inactivated in approximately half of PDAC cases. In this study, the nuclear accumulation of SMAD3 was immunohistochemically detected even in SMAD4-negative cases. SMAD3 knockdown resulted in upregulated E-cadherin, downregulated vimentin, and reduced cell motility in pancreatic cancer cells regardless of SMAD4 status. In addition, TGF-ß-treatment resulted in EMT induction in cells carrying wild-type SMAD4, and EMT was suppressed by SMAD3 knockdown. Patients with upregulated SMAD3 and a high degree of solitary cell infiltration had shorter times to recurrence and shorter survival times after surgery, and multivariate analysis showed that both factors were independent prognostic factors linked to unfavorable outcomes. These findings suggest that SMAD3 in PDAC is involved in the promotion of malignant potential through EMT induction in tumor cells regardless of SMAD4 status and serves as a potential biomarker of poor prognosis.

Presence of primary cilia in cancer cells correlates with prognosis of pancreatic ductal adenocarcinoma.

Primary cilia are microtubule-based organelles that protrude from basal bodies and are involved in cell differentiation, sensory functions, and planar cell polarity. Although there are many studies examining the roles of primary cilia in the fields of embryology and physiology, few such studies have been carried out in the field of oncology, and the role of primary cilia in cancer cells is poorly understood. In this study, we identified primary cilia by immunofluorescence analysis in which primary cilia were visualized as green rods labeled with anti-acetylated α-tubulin adjacent to basal bodies detected as red dots labeled with anti-γ-tubulin. Primary cilia were found in human pancreatic cancer cell lines and in cancer cells in 25 of 100 pancreatic ductal carcinoma patients. In the clinical samples, most primary cilia in cancer tissue were observed in areas showing well-differentiated glandular structures. Patients whose cancers were primary cilia positive had a higher frequency of lymph node metastasis than those whose cancers were primary cilia negative (P = .016). Univariate analysis demonstrated that tumor size (P = .009), tumor grade (P = .001), lymph node metastasis (P = .008), and the presence of primary cilia (P = .002) correlated with overall survival. Multivariate analysis found that tumor grade (P < .001) and the presence of primary cilia (P = .001) were independent prognostic indicators. In conclusion, we showed that pancreatic cancer cells can form primary cilia and that the presence of primary cilia is significantly associated with the prognosis of pancreatic ductal adenocarcinoma.

Overexpression of Leucine-Rich Repeat-Containing G Protein-Coupled Receptor 5 (LGR5) Represents a Typical Wnt/ß-Catenin Pathway-Activated Hepatocellular Carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the most common and most frequently lethal cancers worldwide. Although many advances have been made in the analysis of multistage hepatocarcinogenesis, we still lack information to guide adequate clinical management options for HCC. A large number of genetic alterations occur during hepatocarcinogenesis, and many genetic studies have indicated that one of the most frequently mutated oncogenes found in HCC is ß-catenin. SUMMARY: Molecular subclassification of HCC based on gene expression signatures has identified a typical hepatocyte-like subclass of HCC harboring ß-catenin mutations; this subclass is characterized by better histological differentiation and a less aggressive nature. We previously identified overexpression of the leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5), also known as GPR49, in HCC with ß-catenin mutations. LGR5 has been indicated as one of the downstream target genes of the Wnt signaling pathway; however, the functional role of LGR5 in cancer is largely unknown. We demonstrated that HCC cells transfected with LGR5 exhibited higher colony forming activity and were more resistant to a cytotoxic drug than the control HCC cells were. Overexpression of LGR5 also retarded cell migration. LGR5-transfected HCC cells formed nodule-type tumors in the livers of immunodeficient mice, whereas control cells formed more invasive tumors. Results of our recent research suggest that aberrant expression of LGR5 could regulate the epithelial cell phenotype and promotes HCC cell survival. HCC cells overexpressing LGR5 seem to represent a typical phenotype of a less aggressive HCC. KEY MESSAGES: Recent efforts on the molecular classification of HCC have led us to new strategies for dealing with HCC. These specific signatures may predict the risk of recurrence or the patient survival rate, which affect the outlook and may suggest treatment strategies for HCC patients.

Involvement of hepatocellular carcinoma biomarker, cyclase-associated protein 2 in zebrafish body development and cancer progression.

Cyclase-associated protein 2 (CAP2) is a conserved protein that is found up-regulated in hepatocellular carcinoma (HCC). By using zebrafish, combined with HCC cell lines, we further investigated the role of CAP2. The zebrafish CAP2 sequence was 60% identical to human CAP2 with 77% homology in the C-terminal actin-binding domain, and 58% in the N-terminal cyclase-binding domain. CAP2 expression was observed during zebrafish development and was preferentially expressed in the skeletal muscle and heart. Knockdown using two different morpholinos against CAP2 resulted in a short-body morphant zebrafish phenotype with pericardial edema. CAP2 was observed co-localized with actin in zebrafish skeletal muscle, and in the leading edge of lamellipodium in HCC cell lines. CAP2 silencing resulted in a defect in lamellipodium formation and decreased cell motility in HCC cell lines. Strongly positive expression of CAP2 was observed in 10 of 16 (63%) poorly, 30 of 68 (44%) moderately, and 2 of 21 (10%) well differentiated HCC. CAP2 expression was significantly associated with tumor size, poor differentiation, portal vein invasion, and intrahepatic metastasis. Our results indicate that an important conserved function of CAP2 in higher vertebrates may be associated with the process of skeletal muscle development. CAP2 also played an important role in enhancing cell motility, which may promote a more invasive behavior in the progression of HCC. These findings highlight the link between development and cancer.

Leucine-rich repeat-containing G protein-coupled receptor 5 regulates epithelial cell phenotype and survival of hepatocellular carcinoma cells.

The leucine-rich repeat containing G protein-coupled receptor 5 (LGR5), also known as GPR49, is a seven-transmembrane receptor that is expressed in stem cells of the intestinal crypts and hair follicles of mice. LGR5 is overexpressed in some types of human cancer, and is one of the target genes of the Wnt signaling pathway. To explore the function of LGR5 in cancer cells, stable hepatocellular carcinoma (HCC) cell lines expressing FLAG-tagged LGR5 were established. Overexpression of LGR5 resulted in changes in cell shape from an extended flat (mesenchymal) phenotype to a round aggregated (stem cell-like) phenotype. Cells transfected with LGR5 showed higher colony forming activity, and were more resistant to a cytotoxic drug than cells transfected with empty vector. Overexpression of LGR5 inhibited cell motility. LGR5-transfected cells formed nodule type tumors in the livers of immunodeficient mice, whereas empty vector-transfected cells formed more invasive tumors. Down-regulation of LGR5 changed the morphology of HCC cells from the aggregated phenotype to an extended spindle phenotype, and cell motility was increased. This is the first study reporting the functional role of LGR5 in the biology of HCC cells, and the results suggest that aberrant expression of LGR5 regulates epithelial cell phenotype and survival.

Identification by differential tissue proteome analysis of talin-1 as a novel molecular marker of progression of hepatocellular carcinoma.

OBJECTIVE: Hepatocellular carcinoma (HCC) is characterized by a multistage process of tumor progression. This study addressed its molecular features to identify novel protein candidates involved in HCC progression. METHODS: Using liquid chromatography-tandem mass spectrometry, proteomes of 4 early HCCs and 4 non-HCC tissues derived from 2 cases of liver transplant surgery were compared with respect to the separation profiles of their tryptic peptides. Immunohistochemistry was performed on 106 HCC nodules to confirm the results of the proteomic analysis. RESULTS: Statistical analysis of the profiles selected the peptide peaks differentiating HCC from non-HCC. A database search of the tandem mass spectrometry data from those peptide peaks identified 61 proteins, including a cytoskeletal protein, talin-1, as upregulated in HCC. Talin-1 expression levels in HCC nodules were significantly associated with the dedifferentiation of HCC (p = 0.001). A follow-up survey of the examined clinical cases revealed a correlation between talin-1 upregulation and a shorter time to recurrence after resection (p = 0.039), which may be related to the higher rate of portal vein invasion in HCCs with talin-1 up-regulation (p = 0.029). CONCLUSIONS: Proteomic analysis led to identification of talin-1 as a promising HCC marker. Talin-1 upregulation is associated with HCC progression and may serve as a prognostic marker.

Molecular diagnosis of multistage hepatocarcinogenesis.

Human hepatocellular carcinoma is recognized as a good model for multistage carcinogenesis, as the malignant steps from chronic liver disease through to advanced human hepatocellular carcinoma are relatively clear. We address the activation of different molecular pathways during hepatocarcinogenesis that is especially useful in the diagnosis of pathological multistage human hepatocellular carcinoma. In chronic liver disease, the gene-expression signature as well as the degree of liver fibrosis could help us to predict the development of human hepatocellular carcinoma or survival outcome after treatment for human hepatocellular carcinoma. Several genes, such as HSP70, CAP2 and GPC3, have been identified as potential biomarkers for early human hepatocellular carcinoma. Classical oncogenes or tumor suppressor genes, such as beta-catenin and p53, are mutated during the progression from early to advanced human hepatocellular carcinoma. Also, the presence of hepatoblastic feature like CK19 in advanced human hepatocellular carcinoma can be used as a predictor of aggressive human hepatocellular carcinoma. Although many advances have been made in the diagnosis of multistage hepatocarcinogenesis, we still need further useful markers to more precisely evaluate each step of hepatocarcinogenesis for better treatment choices, and that will promote future molecular-targeted therapy.

Reduced transforming growth factor-beta receptor II expression in hepatocellular carcinoma correlates with intrahepatic metastasis.

Hepatocellular carcinoma (HCC) occurs mainly in the liver associated with chronic hepatitis and hepatic cirrhosis as a result of prolonged viral infection. Transforming growth factor-beta (TGF-beta) induces the fibrosis in hepatic cirrhosis, although it is also an inhibitor of hepatocyte proliferation. To understand the role of TGF-beta signaling in HCC progression, we analyzed gene expression in HCC cells in relation to TGF-beta signaling using a two-way clustering algorithm. By the analysis, five HCC cell lines were classified into two groups according to their metastatic capacity. TGF-beta receptor II (TGFBR2) was downregulated in metastatic cells, which did not show a response to TGF-beta. Immunohistochemistry demonstrated clear membrane distribution of TGFBR2 in noncancerous hepatocytes, whereas reduced TGFBR2 expression was observed in 34 of 136 HCCs. In clinical cases, reduced TGFBR2 expression correlated with larger tumor size (P<0.001), poor differentiation (P<0.001), portal vein invasion (P=0.002), intrahepatic metastasis (IM) (P<0.001), and shorter recurrence-free survival (P=0.022). In conclusion, reduced TGFBR2 expression was associated with aggressive features of HCC such as IM, and may represent an immunohistochemical biomarker to detect aggressive HCC.

Molecular pathology in early hepatocarcinogenesis.

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors characterized by an obvious multistage process of tumor development. Remarkable progress in diagnostic imaging has led to the discovery of small equivocal lesions, now widely recognized as dysplastic nodule, or early HCC. Early HCC is considered a key step in HCC development and progression. However, the molecular pathology involved in early hepatocarcinogenesis remains unclear due to a lack of corresponding experimental models, difficulty in obtaining fresh samples, and an inconsistency in diagnostic criteria. With gene expression profiling, we have currently identified the overexpression of heat-shock protein 70 and cyclase-associated protein 2 as early HCC signatures. We also recently identified the overexpression of the stemness gene Bmi-1 in early HCC. This overexpression was subsequently found to correlate with ATP-binding cassette transporter B1 expression. These findings give new insight into the mechanism of early hepatocarcinogenesis. Nevertheless, further analysis is still necessary to carefully evaluate the roles of these molecular pathology candidates in early hepatocarcinogenesis.

Bmi-1 gene is upregulated in early-stage hepatocellular carcinoma and correlates with ATP-binding cassette transporter B1 expression.

Overexpression of "stemness gene"Bmi-1 has been identified in some solid tumors. We investigated Bmi-1 expression in hepatocellular carcinoma (HCC) and ATP-binding cassette transporter B1 (ABCB1) as a new potential target for Bmi-1. Bmi-1 was highly expressed in HCC cell lines and the most well differentiated cell line, KIM-1, showed the highest expression. Immunohistochemical, immunocytochemical, and immunoelectron microscopic analysis showed the Bmi-1 protein as having a high intensity of small dots within the nucleus which reflected concentrated sites of Bmi-1 repressive activity. Clear "dot-pattern" staining was observed in 24 of 37 (65%) well differentiated HCC (including 13 of 21 early nodules [62%]), in 32 of 71 (45%) moderately differentiated HCC, and 7 of 14 (50%) poorly differentiated HCC. A similar expression was not observed in non-cancerous background regions. High Bmi-1 expression was observed in the early and well differentiated HCC. Furthermore, overexpression and suppression of Bmi-1 was followed by a respective increase and decrease in ABCB1 expression. As with Bmi-1, high ABCB1 expression was also observed in the early and well differentiated HCC. A strong correlation between ABCB1 and Bmi-1 mRNA expression was seen in HCC cell lines and clinical samples (Pearson's correlation coefficient 0.95 and 0.90, respectively). The Bmi-1 gene is upregulated in HCC, and in particular is highly expressed in early and well differentiated HCC. The fact that this expression correlated with that of ABCB1 suggests a new regulation target for Bmi-1, and gives new insight into early hepatocarcinogenesis mechanisms and potential targets for future HCC treatment.

Candidate molecular markers for histological diagnosis of early hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. HCC occurs mainly in chronically diseased livers, e.g. following hepatitis B and C infection. These high-risk patients are closely followed up, and increasing numbers of small equivocal lesions are detected by imaging diagnosis. They are now widely recognized as precursor or early-stage HCCs and are classified as dysplastic nodule or early HCC. These lesions lack typical imaging and histology of ordinary HCC and do not show elevated serum markers of alpha-fetoprotein and PIVKA-II, for example. Molecular analysis of these lesions would help to develop molecular markers for objective histological diagnosis of early HCC and possibly new serum markers for early detection of HCC. It has been reported that HSP70, CAP2, glypican 3 and glutamine synthetase could serve as molecular markers for early HCC. Further analysis is expected to evaluate their usefulness in routine pathological diagnosis including biopsy diagnosis and also as serum markers for early detection of HCC.