Gadoxetic acid-enhanced MR imaging is the most useful imaging technique for evaluating small HCC, including early HCC.

Hepatocellular carcinoma (HCC) is one of the most common fatal cancers worldwide. Hepatitis B virus and hepatitis C virus infections, exposure to aflatoxin, and excessive intake of alcohol have been identified as major risk factors. However, the molecular mechanisms underlying their development are still poorly understood. Recently, beta-catenin, one of the key components of the Wnt signaling pathway, has been found to be mutated in about 20% of HCCs, suggesting a role of the Wnt pathway in their development. In this study, we examined beta-catenin and APC mutations in 22 HCCs associated with HCV infection, using single-strand conformation polymorphism (SSCP) followed by direct DNA sequencing. beta-Catenin mutations were found in nine (41%) cases, but no APC mutations were found. beta-Catenin immunohistochemistry revealed nuclear accumulation of beta-catenin protein in all nine tumors with a beta-catenin mutation and two additional tumors without a mutation. These results suggest that activation of the Wnt signaling pathway by beta-catenin mutation contributes significantly to the hepatocellular carcinogenesis associated with HCV infection.

Major etiologic factors associated with human hepatocellular carcinomas (HCCs) include infection with hepatitis C (HCV) and hepatitis B virus (HBV), excess alcohol intake and aflatoxin B 1 exposure. While the G3 T p53 mutation at codon 249 has been identified as a genetic hallmark of HCC caused by aflatoxin B 1 , the genetic profile associated with other etiologic factors appears to be less distinctive. In our study, we screened HCCs resulting from HCV infection (51 cases), HBV infection (26 cases) or excess alcohol intake (23 cases) for alterations in genes involved in the RB1 pathway (p16 INK4a , p15 INK4b , RB1, CDK4 and cyclin D1), the p53 pathway (p53, p14 ARF and MDM2) and the Wnt pathway (␤-catenin, APC). Alterations of the RB1 pathway, mainly p16 INK4a methylation, loss of RB1 expression and cyclin D1 amplification, were most common (69 -100% of cases). There was a significant correlation between loss of RB1 expression and RB1 methylation. All 24 HCCs with RB1 promoter methylation lacked RB1 expression, while none of the 67 cases with RB1 expression exhibited RB1 methylation (p < 0.0001), suggesting that promoter methylation is a major mechanism of loss of RB1 expression in HCCs. Alterations of the p53 pathway consisted mostly of p53 mutations or p14 ARF promoter methylation (20 -48%). Mutations of the p53 gene were found at a similar frequency (13-15%) in all etiologic groups, without any consistent base change or hot spot. Mutations of ␤-catenin were found in 13-31% of cases, while no APC mutations were detected in any of the HCCs analyzed. With the exception of only 3 of 39 cases (8%), cyclin D1 amplification and ␤-catenin mutations were mutually exclusive, supporting the view that cyclin D1 is a target of the Wnt signaling pathway. Overall, the RB1, p53 and Wnt pathways were commonly affected in HCCs of different etiology, probably reflecting common pathogenetic mechanisms, i.e., chronic liver injury and cirrhosis, but tumors associated with alcoholism had more frequent alterations in the RB1 and p53 pathways than those caused by HCV infection.Key words: hepatocellular carcinoma; p53; RB1; cyclin D1; ␤-catenin; HCV; HBV; alcohol Hepatocellular carcinoma (HCC) is the most common histologic type of primary liver cancer, and also one of the most frequent human malignant neoplasms. 1 In developed countries, the majority of HCCs develop in patients with chronic infection with hepatitis C (HCV) or hepatitis B virus (HBV), or in patients who had excess alcohol consumption, while in sub-Saharan Africa and parts of China, exposure to aflatoxin B 1 is a major etiologic factor alongside coexisting chronic HBV infection. 2,3 HCV is a single-stranded, positive-sense RNA virus that lacks the capability to integrate into the human genome. However, the core protein of HCV can promote cell growth by repressing transcriptional activity of the p53 promoter. 4 Transgenic mice overexpressing HCV core protein develop HCCs. 5 As with HBV infection, HCV infection results in chronic hepatic inflammation, degeneration and nec...

SummaryInterleukin 10 (IL-10) is a cytokine with a variety of reported effects including inhibition of monocyte major histocompatibility complex (MHC) class II-dependent antigen presentation, type 1 helper T cell cytokine production, and inhibition of T cell proliferation. Herein we report the effect of IL-10 pretreatment on antigen presentation to tumor-and allo-specific CD8 + cytotoxic T lymphocytes (CTL). Prior incubation of human melanoma cells with recombinant IL-10 (rlL-10) for 48-72 h resulted in a dose-dependent, up to 100% inhibition, of autologous CTL-mediated, HLA-A2.1-restricted, tumor-specific lysis. Allo-specific CTL cytotoxicity against Epstein-Barr virus-transformed lymphoblastoid cell lines (LCL) was also inhibited, demonstrating a protective effect also on lymphoid calls. In contrast, IL-10 pretreatment of allogeneic LCL or K562 targets had either no effect or slightly enhanced cytotoxic activity mediated by freshly isolated or IL-2-activated natural killer cells. Flow cytometric analysis with monoclonal antibodies against HLA-A2, or nonpolymorphic determinants of MHC class I proteins, revealed a 20-50% reduction in call-surface expression, whereas intercellular adhesion molecules 1, and 2, and lymphocyte function-associated antigen 3 levels were not affected. In addition, relative to untreated target cells, IL-10 pretreated tumor ceils were unaltered in their capacity to affect CTL-mediated lysis by cold target inhibition, demonstrating that the effect of IL-10 is unrelated to the initial binding of CTL to their targets. These results are compatible with an effect of IL-10 on the MHC class I antigen presentation pathway, and suggest a novel mechanism of immune tolerance, based on escape from CTL-mediated tumor and allo-transplant rejection. I L-10 was discovered because of its ability to suppress cytokine expression by type 1 helper T cells (Thl) and NK cells (1). More recently, it has been shown to have pleitropic immunosuppressive effects. In vitro, IL-10 also blocks monocytedependent T cell proliferation (2), inhibits monocyte class II MHC expression (3), the upregulation of B7 on monocytes (4), and monocyte-associated production of nitric oxide and killing of parasites (5).IL-IO is produced by a variety of cell types, including T cells, B cells, and macrophages (6, 7). Higher levels of human IL-10 were produced by Th2 than Thl clones (8), and several human carcinoma lines, freshly isolated tumor biopsies, patient serum, and ascites fluid express or contain IL-10 (9-11). These observations suggest that the presence of IL-IO may be a common feature of several types of human tumors-a finding of potential importance regarding adverse effects on the host immune response.In view of these findings, and since there is evidence suggesting that tumors can be rejected by infiltrating CTL, we analyzed the effect that IL-10 pretreatment of tumors had on their sensitivity to MHC class I-restricted CTL. Our results show that pretreated melanoma and human B cell lines were impervious to otherwise lethal C...

T cells from mice bearing an experimental colon carcinoma, and from patients with colorectal and renal carcinomas, have atypical T-cell receptors (TCR). In the present study, further characterization of modulations in CD3- and CD16-associated zeta chain in peripheral blood lymphocytes (PBL) and tumor-infiltrating lymphocytes (TIL) from colorectal carcinomas was performed. Relative to PBL, the percentage of natural killer (NK) cells among fresh TIL was reduced, while a higher proportion of T cells expressing HLA-DR was found. As previously reported, we found significantly reduced levels of the CD3- and CD16-associated zeta chain in TIL and, to a lesser extent, also in patients' PBL. Levels of zeta chain in T and NK cells from non-cancerous colorectal tissue from patients were lower than in PBL but higher than in TIL, with a direct relationship between levels of this signal-transducing molecule and the distance from the tumor. In addition, zeta levels correlated with the Dukes' stage of the disease, since PBL from patients with lymph-node involvement or distant organ metastases (Dukes' stages C and D) had significantly less CD3 zeta than patients with localized disease (stages A and B). Patients' T cells also had decreased levels of cell-surface and cytoplasmic CD3 epsilon. We also observed reduced levels of the TCR accessory molecules CD4 and CD8, mainly on TIL but to a lesser extent also on patients' PBL. Biochemical analysis of anti-CD3 epsilon-immunoprecipitated TCR complexes demonstrated that the CD3 complex was not associated with the zeta chain, either on TIL or on PBL or on lymphocytes from non-cancerous colon tissue, suggesting a defect in the assembly of the TCR complex. Following several days of in vitro culture with recombinant interleukin-2 and phytohemagglutinin, anti-CD3 or anti-CD2 monoclonal antibodies (MAbs), levels of CD3 zeta chain as well as of cell surface CD3 epsilon were normalized. Our findings suggest an abnormal expression as well as assembly of several different signal-transducing molecules of T cells and NK cells, which correlate with the stage of the disease in patients with colorectal carcinomas.