Mutations in the PIK3CA gene, which encodes the p110A catalytic subunit of phosphatidylinositol 3-kinase (PI3K), have been reported in human cancers, including colorectal cancer. Most of the mutations cluster at hotspots within the helical and kinase domains. Whereas H1047R, one of the hotspot mutants, is reported to have elevated lipid kinase activity, the functional consequences of other mutations have not been examined. In this study, we examined the effects of colon cancer-associated PIK3CA mutations on the lipid kinase activity in vitro, activation of the downstream targets Akt and p70S6K in vivo and NIH 3T3-transforming ability. Of eight mutations examined, all showed increased lipid kinase activity compared with wild-type p110A. All the mutants strongly activated Akt and p70S6K compared with wild-type p110A as determined by immunoblotting using phospho-specific antibodies. These mutants also induced morphologic changes, loss of contact inhibition, and anchorage-independent growth of NIH 3T3 cells. The hotspot mutations examined in this study, E542K, E545K, and H1047R, all had high enzymatic and transforming activities. These results show that almost all the colon cancer-associated PIK3CA mutations are functionally active so that they are likely to be involved in carcinogenesis. (Cancer Res 2005; 65(11): 4562-7)

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Purpose: Nuclear factor nB (NF-nB) is an important transcription factor in various biological processes. Constitutive NF-nB activation has been noted in many tumors, including colorectal cancers. However, the precise role of this activation in colorectal cancer is unclear. Experimental Design: Constitutive NF-nB activation was evaluated in colorectal cancer tissues and cell lines. To inhibit NF-nB activation, we established cancer cells with stable knockdown of InB kinase g (NF-nB essential modulator), which is the regulatory subunit of the InB kinase complex, by RNA interference. Cell growth and apoptosis were evaluated in wild-type cells (WT) and knocked-down cells (KD). Microarray and protein array analysis were also done. To determine involvement of angiogenesis, human umbilical vein endothelial cells were used. By s.c. transplantation of the cells into nude mice, tumor sizes, vascularity, and chemodrug sensitivity were analyzed. Results: Constitutive NF-nB activation was observed in 40% of colorectal cancer tissues and 67% of cell lines. Cell proliferation was not different between WT and KD in vitro, whereas apoptosis mediated by tumor necrosis factor-a and 5-fluorouracil were increased in KD. Several angiogenic chemokines were decreased in KD. Human umbilical vein endothelial cells incubated in WT supernatant showed more branch points than in KD, suggesting that constitutive NF-nB activation was involved in angiogenesis. Subcutaneous tumor expansion was suppressed to 23% in KD, and vessels were also decreased. By 5-fluoruracil treatment, tumor expansion was suppressed to a greater extent in KD (to 6%) than in WT (to 50%). Conclusion: NF-nB inhibition may represent a potent treatment modality in colorectal cancer, especially in cases with constitutive NF-nB activation.Colorectal cancer is the second leading cause of cancer-related death in industrialized nations (1). The development of colorectal cancer results from the sequential accumulation of activating mutations in oncogenes, such as ras, and mutations, truncations, or deletions in the coding sequences of several tumor suppressor genes, including p53 and adenomatous polyposis coli (APC; ref. 2).Over the last decade, there has been a great deal of progress in the development of new therapies for the treatment of colorectal cancer. The cytotoxic chemotherapy drug 5-fluorouracil (FU) was reformulated, and two new drugs, oxaliplatin and irinotecan, have been investigated as adjunctive therapies. In addition, targeted therapies, including monoclonal antibodies against vascular endothelial growth factor (VEGF; bevacizumab) and the epidermal growth factor receptor (cetuximab), are now standard treatments for metastatic colorectal carcinoma (3, 4). However, many cases show tolerance of such treatments (3, 4). Therefore, it is necessary to develop new approaches to replace or complement current therapies.Nuclear factor nB (NF-nB) transcription factors are key regulators of innate immune responses, inflammation, and cell survival (5), and are assembled...

In obesity-driven and NASH-driven HCC, metabolic reprogramming mediated by the downregulation of CPT2 enables HCC cells to escape lipotoxicity and promotes hepatocarcinogenesis.

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...

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