Dysregulation of growth factors and their receptors is central to human hepatocellular carcinoma (HCC). We previously demonstrated that the Frizzled-7 membrane receptor mediating the Wnt signalling can activate the b-catenin pathway and promotes malignancy in human hepatitis B virus-related HCCs. Expression patterns of all the 10 Frizzled receptors, and their extracellular soluble autoparacrine regulators (19 Wnt activators and 4 sFRP inhibitors) were assessed by real-time RT -PCR in 62 human HCC of different etiologies and their matched peritumorous areas. Immunostaining was performed to localise Frizzled on cell types in liver tissues. Regulation of three known Frizzled-dependent pathways (b-catenin, protein kinase C, and C-Jun NH 2 -terminal kinase) was measured in tissues by western blot. We found that eight Frizzled-potentially activating events were pleiotropically dysregulated in 95% HCC and 68% peritumours as compared to normal livers (upregulations of Frizzled-3/6/7 and Wnt3/4/5a, or downregulation of sFRP1/5), accumulating gradually with severity of fibrosis in peritumours and loss of differentiation status in tumours. The hepatocytes supported the Wnt/Frizzled signalling since specifically overexpressing Frizzled receptors in liver tissues. Dysregulation of the eight Frizzled-potentially activating events was associated with differential activation of the three known Frizzled-dependent pathways. This study provides an extensive analysis of the Wnt/Frizzled receptor elements and reveals that the dysregulation may be one of the most common and earliest events described thus far during hepatocarcinogenesis.

In cancer patients, plasma often contains mutant DNA released by cancer cells. We have assessed the significance of plasma DNA mutations for subsequent cancer development in healthy subjects in a large longitudinal prospective study. The European Prospective Investigation into Cancer and Nutrition study was analyzed with a nested case-control design. Cases were nonsmokers or ex-smokers for >10 years and newly diagnosed with lung, bladder, or upper aerodigestive tract cancers or leukemia accrued after a median follow-up of 6.3 years. Controls were matched 2:1 for follow-up, age, sex, area of recruitment, and smoking status. KRAS2 mutations were detected by mutant-enriched PCR and sequencing (n = 1,098). TP53 mutations were detected by denaturing high-performance liquid chromatography, temporal temperature gradient electrophoresis, and sequencing (n = 550). KRAS2 or TP53 mutations were detected in 13 of 1,098 (1.2%) and 20 of 550 (3.6%) subjects, respectively, 16 of whom developed cancer on average after 18.3 months of follow-up. Among 137 subjects who developed bladder cancer, 5 had KRAS2 mutations [odds ratio (OR), 4.25; 95% confidence interval (95% CI), 1.27-14.15] and 7 had TP53 mutations (OR, 1.81; 95% CI, 0.66-4.97). There was a nonsignificant trend for association between TP53 mutations and bulky adducts in lymphocyte DNA (OR, 2.78; 95% CI,. This is the first report of TP53 or KRAS2 mutations in the plasma of healthy subjects in a prospective study, suggesting that KRAS2 mutation is detectable ahead of bladder cancer diagnosis. TP53 mutation may be associated with environmental exposures. These observations have implications for monitoring early steps of carcinogenesis. (Cancer Res 2006; 66(13): 6871-6)

Hepatocellular carcinoma (HCC) may develop according to two major pathways, one involving HBV infection and TP53 mutation and the other characterized by HCV infection and CTNNB1 mutation. We have investigated HBV/HCV infections and TP53/CTNNB1 mutations in 26 HCC patients from Thailand. HBV DNA (genotype B or C) was detected in 19 (73%) of the cases, including 5 occult infections and 3 coinfections with HCV. TP53 and CTNNB1 mutations were not mutually exclusive, and most of TP53 mutations were R249S, suggesting a significant impact of aflatoxin-induced mutagenesis in HCC development.

No abstract