Interleukin-6 (IL-6) may play a role in the pathogenesis of hepatocellular carcinoma (HCC). Recently, it was reported in mouse models that estrogen-mediated inhibition of IL-6 production explains the gender disparity in HCC. We conducted a retrospective cohort study to examine whether this hypothesis is applicable to human HCC. We enrolled 330 patients with chronic hepatitis C whose serum samples were collected between January 1994 and December 2002. Serum IL-6 concentrations were measured and patients were divided into three groups according to IL-6 levels: low, middle, and high. We evaluated the association between serum IL-6 levels and the risk of subsequent HCC development, including subgroup analysis on each gender. During the follow-up period (mean 9.0 yr), HCC developed in 126 patients. The incidence rates differed significantly among the three groups (p 5 0.015), increasing in accordance with serum IL-6 levels. However, unexpectedly, this tendency was significant only in female patients. In a multivariate analysis, higher serum IL-6 level was an independent risk factor for HCC development in female patients, with a hazard ratio of 1.61. Although female patients showed a weak negative correlation between serum IL-6 levels and estradiol levels, the lower risk of HCC in female patients cannot be fully explained by estrogen-mediated inhibition of IL-6 production. In conclusion, higher serum IL-6 level was an independent risk factor for HCC development in female but not male chronic hepatitis C patients. Measurement of serum IL-6 levels may provide useful information for predicting future HCC development in female chronic hepatitis C patients. ' 2009 UICC

Significance The precise roles of E-cadherin in the liver and liver carcinogenesis are still unknown. Here we show that mice lacking E-cadherin in the liver develop spontaneous periportal inflammation via an impaired intrahepatic biliary network, as well as periductal fibrosis, which resembles primary sclerosing cholangitis. Inducible gene knockout studies identified E-cadherin loss in biliary epithelial cells as a causal factor of cholangitis induction, and dysregulated E-cadherin expression was also seen in patients with primary sclerosing cholangitis. E-cadherin loss also significantly accelerates genetically and chemically engineered liver cancer through epithelial–mesenchymal transition, up-regulation of stem cell markers, and ERK activation. Thus, E-cadherin plays critical roles in maintaining homeostasis and suppressing carcinogenesis in the liver.

The carcinogenic mechanism of extrahepatic cholangiocarcinoma (ECC) is unclear, due at least in part to the lack of an appropriate mouse model. Because human studies have reported frequent genetic alterations in the Ras-and TGFβ/SMAD-signaling pathways in ECC, mice with tamoxifen-inducible, duct-cell-specific Kras activation and a TGFβ receptor type 2 (TGFβR2) deletion were first generated by crossing LSL-Kras G12D , Tgfbr2 flox/flox , and K19 CreERT mice (KT-K19 CreERT ). However, KT-K19 CreERT mice showed only mild hyperplasia of biliary epithelial cells (BECs) in the extrahepatic bile duct (EHBD) and died within 7 wk, probably a result of lung adenocarcinomas. Next, to analyze the additional effect of E-cadherin loss, KT-K19 CreERT mice were crossed with CDH1 flox/flox mice (KTC-K19 CreERT ). Surprisingly, KTC-K19 CreERT mice exhibited a markedly thickened EHBD wall accompanied by a swollen gallbladder within 4 wk after tamoxifen administration. Histologically, invasive periductal infiltrating-type ECC with lymphatic metastasis was observed. Time-course analysis of EHBD revealed that recombined BECs lining the bile duct lumen detached due to E-cadherin loss, whereas recombined cells could survive in the peribiliary glands (PBGs), which are considered a BEC stem-cell niche. Detached dying BECs released high levels of IL-33, as determined by microarray analysis using biliary organoids, and stimulated inflammation and a regenerative response by PBGs, leading eventually to ECC development. Cell lineage tracing suggested PBGs as the cellular origin of ECC. IL-33 cooperated with Kras and TGFβR2 mutations in the development of ECC, and anti-IL-33 treatment suppressed ECC development significantly. Thus, this mouse model provided insight into the carcinogenic mechanisms, cellular origin, and potential therapeutic targets of ECC.extrahepatic cholangiocarcinoma | IL-33 | organoid | ILC2 | amphiregulin

Mitogen-activated protein kinase (MAPK) pathways regulate multiple cellular functions and are highly active in many types of human cancers. Apoptosis signal-regulating kinase 1 (ASK1) is an upstream MAPK involved in apoptosis, inflammation, and carcinogenesis. This study investigated the role of ASK1 in the development of gastric cancer. In human gastric cancer specimens, we observed increased ASK1 expression, compared to nontumor epithelium. Using a chemically induced murine gastric tumorigenesis model, we observed increased tumor ASK1 expression, and ASK1 knockout mice had both fewer and smaller tumors than wild-type (WT) mice. ASK1 siRNA inhibited cell proliferation through the accumulation of cells in G1 phase of the cell cycle, and reduced cyclin D1 expression in gastric cancer cells, whereas these effects were uncommon in other cancer cells. ASK1 overexpression induced the transcription of cyclin D1, through AP-1 activation, and ASK1 levels were regulated by cyclin D1, via the Rb-E2F pathway. Exogenous ASK1 induced cyclin D1 expression, followed by elevated expression of endogenous ASK1. These results indicate an autoregulatory mechanism of ASK1 in the development of gastric cancer. Targeting this positive feedback loop, ASK1 may present a potential therapeutic target for the treatment of advanced gastric cancer. JNK | c-JunG astric cancer (GC) is a common cancer worldwide, associated with a high mortality despite its declining incidence in recent decades. Smoking, salted or smoked foods, and Helicobacter pylori appear to be major environmental inducers of GC (1-3). Although the role of H. pylori in causing mucosal effects has been investigated, which molecular signal(s) initiate the program of irreversible transformation remain unclear, and thus molecular targeting therapies for GC have not been well established.Mitogen-activated protein kinase (MAPK) pathways are important for the development of gastric tumorigenesis (4). Apoptosis signal-regulating kinase 1 (ASK1) is a ubiquitously expressed MAPK kinase kinase (MAP3K), activated by various stress stimuli, including reactive oxygen species (ROS), TNF-α, and LPS (5-7). ASK1 activates the JNK and p38 signaling pathways and is required for both oxidative stress and cytokine-induced apoptosis (5). Furthermore, ASK1 affects multiple cellular functions, including survival, differentiation, and the innate immune response (5,7,8) and has been reported to be involved in the pathogenesis of various human diseases, including neurodegenerative (9), cardiovascular (10), and inflammatory diseases (11,12). Additionally, ASK1 has been shown to participate in both colon (12) and skin (13) tumorigenesis through the regulation of inflammation and apoptosis. However, no reported study has demonstrated a role for ASK1 in gastric tumorigenesis.In this study, we examined the role of ASK1 in gastric tumorigenesis using both human GC samples and ASK1-deficient (ASK1 −/− ) mice. We demonstrated that ASK1 is important for gastric tumorigenesis through the regulation of cyclin D1 e...

Interleukin-6 (IL-6) is a pleiotropic cytokine that affects various functions, including tumor development. Although the importance of IL-6 in gastric cancer has been documented in experimental and clinical studies, the mechanism by which IL-6 promotes gastric cancer remains unclear. In this study, we investigated the role of IL-6 in the epithelial–stromal interaction in gastric tumorigenesis. Immunohistochemical analysis of human gastritis, gastric adenoma, and gastric cancer tissues revealed that IL-6 was frequently detected in the stroma. IL-6–positive cells in the stroma showed positive staining for the fibroblast marker α-smooth muscle actin, suggesting that stromal fibroblasts produce IL-6. We compared IL-6 knockout (IL-6−/−) mice with wild-type (WT) mice in a model of gastric tumorigenesis induced by the chemical carcinogen N-methyl-N-nitrosourea. The stromal fibroblasts expressed IL-6 in tumors from WT mice. Gastric tumorigenesis was attenuated in IL-6−/− mice, compared with WT mice. Impaired tumor development in IL-6−/− mice was correlated with the decreased activation of STAT3, a factor associated with gastric cancer cell proliferation. In vitro, when gastric cancer cell line was co-cultured with primary human gastric fibroblast, STAT3–related genes including COX-2 and iNOS were induced in gastric cancer cells and this response was attenuated with neutralizing anti-IL-6 receptor antibody. IL-6 production from fibroblasts was increased when fibroblasts were cultured in the presence of gastric cancer cell–conditioned media. IL-6 production from fibroblasts was suppressed by an interleukin-1 (IL-1) receptor antagonist and siRNA inhibition of IL-1α in the fibroblasts. IL-1α mRNA and protein were increased in fibroblast lysate, suggesting that cell-associated IL-1α in fibroblasts may be involved. Our results suggest the importance of IL-6 mediated stromal-epithelial cell interaction in gastric tumorigenesis.