No abstract

Primary hepatocellular carcinoma (HCC) is one of the most common malignancies and has the fourth highest mortality rate worldwide. The major risk factors, including chronic infections with the hepatitis B or C virus, are exposure to dietary aflatoxin B1(AFB1), vinyl chloride, or alcohol consumption. Southern China and sub‐Saharan Africa have the highest dietary AFB1 exposure, making it and hepatitis B virus (HBV) the major causes of cancer mortality in these geographic areas. Recent studies have discovered genetic and epigenetic changes involved in the molecular pathogenesis of HCC, including somatic mutations in the p53 tumor suppressor gene (TP53). AFB1 induces typical G:C to T:A transversions at the third base in codon 249 of p53. Chronic active hepatitis B and C (HCV) infection, and further inflammatory and oxyradical disorders including Wilson disease (WD) or hemochromatosis, generate reactive oxygen/nitrogen species that can damage DNA and mutate the p53 gene. The X gene of HBV (HBx) is the most common open reading frame integrated into the host genome in HCC. The integrated HBx is frequently mutated and has a diminished ability to function as a transcriptional cotransactivator and to activate the NF‐kappa B pathway. However, the mutant HBx proteins still retain their ability to bind to and abrogate p53‐mediated apoptosis. In summary, both viruses and chemicals are implicated in the etiology and molecular pathogenesis of HCC. The resultant molecular changes in the ras and Wnt signal‐transduction pathways, and the p53 and Rb tumor suppressor pathways significantly contribute to liver carcinogenesis. Hum Mutat 21:201–216, 2003. Published 2003 Wiley‐Liss, Inc.

Background Hepatocellular carcinoma (HCC) is a typical inflammation-associated cancer, but may also provoke antitumour immune responses whose significance and underlying mechanisms are incompletely understood. Objective To characterise immune responses in the diethylnitrosamine (DEN)-liver cancer mouse model. Design Tumour development and immune cell functions upon DEN treatment were compared between C57BL/6 wild-type (WT), chemokine scavenging receptor D6-deficient, B cell- (Igh6), CD4 T cell- (MHC-II) and T-/B cell-deficient (Rag1) mice. Relevance for human HCC was tested by comparing gene array results from 139 HCC tissues. Results The induction of premalignant lesions after 24 weeks and of HCC-like tumours after 42 weeks by DEN in mice was accompanied by significant leucocyte infiltration in the liver and upregulation of distinct intrahepatic chemokines (CCL2, CCL5, CXCL9). Macrophages and CD8 (cytotoxic) T cells were most prominently enriched in tumour-bearing livers, similar to samples from human HCC. Myeloid-derived suppressor cells (MDSC) increased in extrahepatic compartments of DEN-treated mice (bone marrow, spleen). The contribution of immune cell subsets for DEN-induced hepatocarcinogenesis was functionally dissected. In D6−/− mice, which lack the chemokine scavenging receptor D6, hepatic macrophage infiltration was significantly increased, but tumour formation and progression did not differ from that of WT mice. In contrast, progression of hepatic tumours (numbers, diameters, tumour load) was strikingly enhanced in T-/B cell-deficient Rag1−/− mice upon DEN treatment. When mice deficient for B cells (Igh6−/−, µMT) or major histocompatibility complex II were used, the data indicated that T cells prevent initial tumour formation, while B cells critically limit growth of established tumours. Accordingly, in tumour-bearing mice antibody production against liver-related model antigen was enhanced, indicating tumour-associated B cell activation. In agreement, T and B cell pathways were differentially regulated in gene array analyses from 139 human HCC tissues and significantly associated with patients’ survival. Conclusions Distinct axes of the adaptive immune system, which are also prognostic in human HCC, actively suppress DEN-induced hepatocarcinogenesis by controlling tumour formation and progression.

One essential immunoregulatory function of heat shock protein (HSP) is activation of the innate immune system. We investigated the activation of human monocytes and monocyte-derived dendritic cells (DC) by recombinant human HSP60, human inducible HSP72, and preparations of human gp96 and HSP70 under stringent conditions, in the absence of serum and with highly purified monocytes. HSP60 induced human DC maturation and activated human DC to secrete proinflammatory cytokines. HSP72 induced DC maturation to a lesser extent, but activated human monocytes and immature DC as efficiently as HSP60 to release proinflammatory cytokines. The independence of the effects of HSP60 and HSP72 from endotoxin or another copurifying bacterial component was shown by the resistance of these effects to polymyxin B, their sensitivity to heat treatment, the inactivity of endotoxin controls at concentrations up to 100-fold above the endotoxin contents of the HSP, and the inactivity of a recombinant control protein. Preparations of HSP70, which consisted mainly of the constitutively expressed HSP73, induced only marginal cytokine release from monocytes. The gp96 preparations did not have significant effects on human monocytes and monocyte-derived DC, indicating that these human APC populations were not susceptible to gp96 signaling under the stringent conditions applied in this study. The biological activities of gp96 and HSP70 preparations were confirmed by their peptide binding activity. These findings show that HSP can differ considerably in the capacity to activate monocyte-derived APC under certain conditions and underline the potential of HSP60 and HSP72 as activation signals for the innate immune system.

Activation of the p53 network plays a central role in the inflammatory stress response associated with ulcerative colitis and may modulate cancer risk in patients afflicted with this chronic disease. Here, we describe the gene expression profiles associated with four microenvironmental components of the inflammatory response (NO .

We investigated the downstream mechanisms by which chemotherapeutic drugs elicit apoptosis in hepatocellular carcinoma (HCC). Genomic signatures of HCC cell lines treated with different chemotherapeutic drugs were obtained. Analyses of apoptosis pathways were performed and RNA interference was used to evaluate the role of the p53 family. Endogenous p53, p63 and p73 were upregulated in response to DNA damage by chemotherapeutic drugs. Blocking p53 family function led to chemoresistance in HCC. Stimulation and blocking experiments of the CD95-, the TNF-and the TRAIL-receptor systems revealed that cytotoxic drugs, via the p53 family members as transactivators, can trigger expression of each of these death receptors and consequently sensitize HCC cells toward apoptosis. Furthermore, our findings demonstrate a link between chemotherapy, the p53 family and the mitochondrial apoptosis pathway in HCC. Chemotherapeutic treatment induces expression of proapoptotic Bcl-2 family members like Bax and BCL2L11 and the expression of Apaf1, BNIP1, Pdcd8 and RAD. Thus, upon DNA damage, p53, p63 and p73 promote apoptosis via the extrinsic and the intrinsic signaling pathway. In addition, not only proapoptotic genes were upregulated, but also genes known to exert antiapoptotic functions. Bleomycininduced upregulation of BCL-XL/BCLXL1 and MDM2 suggests that it is the ratio of proapoptotic and antiapoptotic proteins that regulates the apoptosis response of HCC cells toward chemotherapy, thereby playing a decisive role between treatment sensitivity vs. drug resistance. The clinical importance of these data is evidenced by our finding that the bleomycin target gene signature can predict the prognosis of patients suffering from HCC.Inactivation of tumor suppressor genes or activation of protooncogenes can lead to clonal outgrowth and tumor progression. These oncogenic events evolve as important determinants in the response of human tumors to commonly used DNA damaging agents. 1 Many anticancer agents induce DNA damage as part of their mechanism of tumor cytotoxicity. DNA damage activates p53, which in turn induces the expression of proteins that halt the cell-division cycle to allow for DNA repair. 2,3 Activation of p53 can also initiate programs of cell death (apoptosis) or permanent growth arrest (senescence) if the DNA damage is severe. [4][5][6][7][8][9][10][11][12][13] Furthermore, the recent identification and characterization of the p53/p63/p73 network provides evidence of a tight link between developmental processes and tumorigenesis. 14-16 p63 and p73 are not only important for normal development and differentiation, but are also implicated in tumorigenesis and the response to chemo-or radiotherapies. [17][18][19][20] The p53 family genes, p53, p63 and p73, produce multiple isoforms that vary in composition of the NH 2 -and C-termini. Isoforms of the p53 family can interact with each other and form a complicated network. The dominant-negative (DN) isoforms can oppose the transactivation capabilities of the full length (TA) prot...

Supplementary data are available at Bioinformatics online.

Multiple activations of individual genes during embryonic liver and HCC development have repeatedly prompted speculations about conserved embryonic signatures driving cancer development. Recently, the emerging discussion on cancer stem cells and the appreciation that generally tumors may develop from progenitor cells of diverse stages of cellular differentiation has shed increasing light on the overlapping genetic signatures between embryonic liver development and HCC. However there is still a lack of systematic studies investigating this area. We therefore performed a comprehensive analysis of differentially regulated genetic signaling pathways in embryonic and liver cancer development and investigated their biological relevance.Genetic signaling pathways were investigated on several publically available genome wide microarray experiments on liver development and HCC. Differentially expressed genes were investigated for pathway enrichment or underrepresentation compared to KEGG annotated pathways by Fisher exact evaluation. The comparative analysis of enrichment and under representation of differentially regulated genes in liver development and HCC demonstrated a significant overlap between multiple pathways. Most strikingly we demonstrated a significant overlap not only in pathways expected to be relevant to both conditions such as cell cycle or apoptosis but also metabolic pathways associated with carbohydrate and lipid metabolism. Furthermore, we demonstrated the clinical significance of these findings as unsupervised clustering of HCC patients on the basis of these metabolic pathways displayed significant differences in survival.These results indicate that liver development and liver cancer share similar alterations in multiple genetic signaling pathways. Several pathways with markedly similar patterns of enrichment or underrepresentation of various regulated genes between liver development and HCC are of prognostic relevance in HCC. In particular, the metabolic pathways were identified as novel prognostically relevant players in HCC development.