Masaaki Takamura

Reduced NKG2D ligand expression in hepatocellular carcinoma correlates with early recurrence

BACKGROUND & AIMSnThe activating receptor natural killer group 2, member D (NKG2D) and its ligands play a crucial role in immune response to tumors. NKG2D ligand expression in tumors has been shown to be associated with tumor eradication and superior patient survival, but the involvement of NKG2D ligands in the immune response against hepatocellular carcinoma (HCC) still remains to be elucidated.nnnMETHODSnWe investigated the expression of NKG2D ligands in HCC tissues collected from 54 patients and HCC cell lines. We also examined the proteasome expression and the effect of inhibition of proteasome activity on NKG2D ligand expression in HCC tissues and cell lines.nnnRESULTSnIn dysplastic nodules (DN), well-differentiated (well-HCC), and moderately-differentiated HCCs (mod-HCC), UL16-binding protein (ULBP) 1 was expressed predominantly in tumor cells, but not in poorly-differentiated HCCs (poor-HCC). Remarkably, recurrence-free survival of patients with ULBP1-negative HCC was significantly shorter than that of patients with ULBP1-positive HCC (p=0.006). Cox regression analysis revealed that loss of ULBP1 expression was an independent predictor of early recurrence (p=0.008). We confirmed that ULBP1 was expressed in the well- and mod-HCC cell lines, but not in the poor-HCC cell line KYN-2. However, inhibition of proteasome activity resulted in significant up-regulation of ULBP1 expression in KYN-2. Moreover, we found that 20S proteasome expression was more abundant in KYN-2 than that in the well- and mod-HCC cell lines.nnnCONCLUSIONSnULBP1 is prevalently expressed in DN to mod-HCC, but loss of its expression correlates with tumor progression and early recurrence.

Hepatocellular carcinoma with progenitor cell features distinguishable by the hepatic stem/progenitor cell marker NCAM

We analyzed hepatocellular carcinoma (HCC) with progenitor cell features using hepatic stem/progenitor cell marker neural cell adhesion molecule (NCAM). Approximately 8.3% of the operated HCC cases expressed NCAM, and 22.3% of the HCC patients had soluble NCAM levels >1000ng/ml (the highly soluble NCAM group). Soluble NCAM status was a significant independent factor predictive of long-term survival in patients with HCC, and high levels of soluble NCAM were significantly related to intrahepatic metastasis. The 140-kDa NCAM isoform was specifically detected in the highly soluble NCAM group of HCC patients andits related signals are potential drug targets for NCAM+ HCC.

Autoantibodies in primary biliary cirrhosis: recent progress in research on the pathogenetic and clinical significance.

Primary biliary cirrhosis (PBC) is a chronic progressive cholestatic liver disease characterized by immune-mediated destruction of the small- and medium-sized intrahepatic bile ducts and the presence of antimitochondrial antibodies (AMA) in the serum. AMA are detected in over 90% of patients with PBC, whereas their prevalence in the general population is extremely low, varying from 0.16% to 1%. Previous studies have shown that the unique characteristics of biliary epithelial cells undergoing apoptosis may result in a highly direct and very specific immune response to mitochondrial autoantigens. Moreover, recent studies have demonstrated that serum from AMA-positive PBC patients is reactive with a number of xenobiotic modified E2 subunits of the pyruvate dehydrogenase complex, which is not observed in the serum of normal individuals. These findings indicate that chemicals originating from the environment may be associated with a breakdown in the tolerance to mitochondrial autoantigens. While it is currently generally accepted that AMA are the most specific serological markers of PBC, more than 60 autoantibodies have been investigated in patients with PBC, and some have previously been considered specific to other autoimmune diseases. This review covers the recent progress in research on the pathogenetic and clinical significance of important autoantibodies in PBC. Determining the pathogenic role of those autoantibodies in PBC remains a priority of basic and clinical research.

Clinical significance of cell cycle inhibitors in hepatocellular carcinoma

It is well accepted that cell cycle regulators are strongly implicated in the progression of cancer development. p16 and p27 are potent cyclin-dependent kinase (CDK) inhibitors involved in G1 phase progression, and are regarded as adverse prognostic biomarkers for various types of cancers. It has been reported that the main mechanism for p16 inactivation is aberrant DNA methylation, while p27 is exclusively inactivated by proteasome-mediated protein degradation. We have found that p27 is decreased in around half of hepatocellular carcinomas (HCCs), and in some cases p27 is inactivated by inappropriate interaction with cyclin D1/CDK4 complexes. In such cases, p16 is concomitantly inactivated through DNA methylation. Taking into consideration the complex interaction between p16 and p27, a comprehensive analysis including p16 and p27 would be useful for predicting the prognosis of HCC patients.

Increased Susceptibility to Severe Chronic Liver Damage in CXCR4 Conditional Knock-Out Mice

BackgroundThe chemokine SDF-1 and its receptor CXCR4 are essential for the proper functioning of multiple organs. In the liver, cholangiocytes and hepatic progenitor cells (HPCs) are the main cells that produce SDF-1, and SDF-1 is thought to be essential for HPC-stimulated liver regeneration.AimsIn this study, CXCR4 conditionally targeted mice were used to analyze the role of SDF-1 in chronically damaged liver.MethodsChronic liver damage was induced in MxCre CXCR4f/null mice and the control MxCre CXCR4f/wt mice by CCl4. Serum markers were analyzed to assess liver function and damage, the number of cytokeratin-positive cells as a measure of HPCs, and the extent of liver fibrosis. Additional parameters relating to liver damage, such as markers of HPCs, liver function, MMPs, and TIMPs were measured by real-time PCR.ResultsSerum ALT was significantly higher in MxCre CXCR4f/null mice than MxCre CXCR4f/wt mice. The number of cytokeratin-positive cells and the area of fibrosis were also increased in the MxCre CXCR4f/null mice. The expression of mRNAs for several markers related to hepatic damage and regeneration was also increased in the liver of MxCre CXCR4f/null mice, including primitive HPC marker prominin-1, MMP9, TNF-α, and α-SMA.ConclusionsMxCre CXCR4f/null mice were susceptible to severe chronic liver damage, suggesting that SDF-1-CXCR4 signals are important for liver regeneration and preventing the progression of liver disease. Modulation of SDF-1 may therefore be a promising treatment strategy for patients with chronic liver disease.

Involvement of liver-intestine cadherin in cancer progression

Cadherins constitute a superfamily of Ca2+-dependent cell adhesion molecules that play critical roles in the maintenance of tissue structure and morphogenesis. Their dysregulation is commonly observed in a variety of cancers. Liver-intestine cadherin (LI-cadherin), which was so named in view of its sole expression in the liver and intestine of the rat, is a structurally unique member of the cadherin superfamily, possessing seven cadherin repeats within the extracellular cadherin domain and only 25 amino acids in the cytoplasmic domain. Its adhesive property does not require any interaction with cytoplasmic components such as catenins, and it responds to small changes in extracellular Ca2+ below the physiological plasma concentration. In humans, the distribution of LI-cadherin is limited to the duodenum, jejunum, ileum, colon, and part of the pancreatic duct. Data accumulated from studies of the biological characteristics of LI-cadherin have shown that it plays an important role in the pathophysiology of human cancers. Here, we review recent information about LI-cadherin and its implications for cancer progression.

Presence of antibodies against self human leukocyte antigen class II molecules in autoimmune hepatitis.

Autoimmune hepatitis (AIH) can arise de novo after liver transplantation (LT) for non-autoimmune liver diseases. Considering the identical features of de novo AIH after LT and classical AIH, as well as the importance of anti-human leukocyte antigen (HLA) antibodies in graft rejection, we investigated the presence of circulating anti-HLA class II antibodies in the sera of 35 patients with AIH, 30 patients with primary biliary cirrhosis (PBC), and 30 healthy donors using fluorescent dye-impregnated beads bound to HLA molecules. We then investigated the allele specificity of the antibodies and identified the HLA alleles in each patient using DNA-based HLA typing. We also examined HLA class II expression in liver samples using immunohistochemistry. Anti-HLA class II antibodies were detected significantly more frequently in the patients with AIH (88.1%) than in the patients with PBC (33.3%) or in the healthy donors (13.3%) (both P <0.01). We confirmed that the anti-HLA class II antibodies in the AIH patients showed specificity for several HLA class II alleles, including self HLA class II alleles. Moreover, positive reactivity with anti-self HLA class II antibodies was associated with higher serum transaminase levels. In conclusion, we demonstrated, for the first time, that antibodies against self HLA class II alleles were detectable in patients with AIH. Our results suggest that an antibody-mediated immune response against HLA class II molecules on hepatocytes may be involved in the pathogenesis or acceleration of liver injury in AIH.

Alteration of p53-binding protein 1 expression as a risk factor for local recurrence in patients undergoing resection for extrahepatic cholangiocarcinoma

P53-binding protein 1 (53BP1) is an early DNA damage response-protein that is rapidly recruited to sites of DNA double-strand breaks. The presence of 53BP1 nuclear foci can be considered as a cytologic marker for endogenous double-strand breaks reflecting genomic instability. This study aimed to clarify the early DNA damage response mediated by 53BP1 in tumor specimens of ductal resection margins and to elucidate its predictive value for clinically evident local recurrence at ductal stumps in 110 patients undergoing resection for extrahepatic cholangiocarcinoma. The ductal resection margin status was classified as negative (85 patients), positive with carcinoma in situ (14 patients), or positive with invasive carcinoma (11 patients). The nuclear staining pattern of 53BP1 was evaluated by immunofluorescence. TUNEL analysis was used to calculate apoptotic index. Ductal margin status was the only independent risk factor for local recurrence (P=0.001). The cumulative probability of local recurrence at 5 years was 10%, 40% and 100% in patients with negative ductal margins, positive with carcinoma in situ and positive with invasive carcinoma, respectively (P<0.001). Of the 14 tumor specimens of carcinoma in situ, 10 showed diffuse localization of 53BP1 in nuclei (53BP1 inactivation) and 4 showed discrete nuclear foci of 53BP1 (53BP1 activation). All 11 tumor specimens of invasive carcinoma showed 53BP1 inactivation. Apoptotic index was markedly decreased in tumor specimens with 53BP1 inactivation compared to those with 53BP1 activation (median index, 0% vs. 22%; P<0.001). Among 14 patients with residual carcinoma in situ, the cumulative probability of local recurrence was significantly higher in patients with 53BP1 inactivation than in patients with 53BP1 activation (60% vs. 0% at 5 years; P=0.020). In conclusion, after resection for extrahepatic cholangiocarcinoma, clinically evident local recurrence at ductal stumps is closely associated with 53BP1 inactivation and decreased apoptosis.

Phase I study of miriplatin combined with transarterial chemotherapy using CDDP powder in patients with hepatocellular carcinoma

BackgroundThere is no standard therapeutic procedure for the hepatocellular carcinoma (HCC) in patients with poor hepatic reserve function. With the approval of newly developed chemotherapeutic agent of miriplatin, we have firstly conducted the phase I study of CDDP powder (DDP-H) and miriplatin combination therapy and reported its safety and efficacy for treating unresectable HCC in such cases. To determine the maximum tolerated dose (MTD) and dose-limiting toxicity (DLT) for the combination of transarterial oily chemoembolization (TOCE) and transarterial chemotherapy (TAC) using miriplatin and DDP-H for treating unresectable hepatocellular carcinoma (HCC).MethodsTransarterial chemotherapy using DDP-H was performed through the proper hepatic artery targeting the HCC nodules by increasing the dose of DDP-H (35–65u2009mg/m2) followed by targeting the HCC nodules by transarterial oily chemoembolization with miriplatin.ResultsA total of nine patients were enrolled in this study and no DLT was observed with any dose of DDP-H in all cases in whom 80u2009mg (median, 18–120) miriplatin was administered. An anti-tumour efficacy rating for partial response was obtained in one patient, while a total of four patients (among eight evaluated) showed stable disease response, leading to 62.5% of disease control rate. The pharmacokinetic results showed no further increase in plasma platinum concentration following miriplatin administration.ConclusionOur results suggest that a combination of DDP-H and miriplatin can be safely administered up to their respective MTD for treating HCC.Trial registrationThis study was registered with the University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR000003541).

Ribonucleotide reductase M1 expression in intrahepatic cholangiocarcinoma.

BACKGROUND/AIMSnRibonucleotide reductase M1 (RRM1) is a key molecule for gemcitabine resistance. This study evaluated the immunohistochemical expression of RRM1 in resected specimens of intrahepatic cholangiocarcinoma (ICC) and investigated the efficacy of gemcitabine-based neoadjuvant chemotherapy in relation to RRM1 expression in tumors.nnnMETHODOLOGYnA retrospective analysis was conducted on 34 consecutive Japanese patients who underwent resection of ICC. Of the 34 patients, 2 were treated with neoadjuvant chemotherapy consisting of gemcitabine 800mg/m2 every 2 weeks to address extrahepatic tumor extension. Expression of RRM1 in tumor specimens was assessed using immunohistochemistry and was classified as either positive or negative.nnnRESULTSnRRM1-positive expression was detected in 19/34 (56%) tumor specimens. Two patients were treated with gemcitabine-based neoadjuvant chemotherapy; one had a tumor specimen showing RRM1-positive expression and showed a 14% tumor reduction rate (stable disease); another patient had a tumor showing RRM1-negative expression and showed a 68% tumor reduction rate (partial response). Surgical procedures planned before administration of neoadjuvant chemotherapy were performed in both patients.nnnCONCLUSIONSnNeoadjuvant chemotherapy with gemcitabine for locally advanced ICC was well tolerated and did not impair planned surgical resections. Tumor expression of RRM1 may determine the efficacy of gemcitabine-based chemotherapy for patients with ICC.