Project description:Gene-expression profiles of liver and hepatocellular carcinoma induced by diethylnitrosamine (DEN) in KLF6 +/- and wild type KLF6 mice. Inactivation of the KLF6 tumor suppressor is common in HCC due to hepatitis C virus (HCV), consistent with its anti-proliferative activity in HCC-derived cell lines and in hepatocytes of transgenic mice. We have evaluated the impact of KLF6 depletion on human HCC and experimental hepatocarcinogenesis. In patients with surgically resected HCC, those with significantly reduced tumor expression of KLF6 had a significantly decreased survival. We modeled this event in KLF6 +/- mice, which displayed significantly more tumorigenicity than KLF6 +/+ animals in response to the hepatic carcinogen DEN, associated with recapitulation of gene signatures in both surrounding tissue and tumors that are associated with aggressive human HCCs. In DNA microarrays, mdm2 mRNA expression was increased in tumors from KLF6 +/- compared to KLF6 +/+ mice, which was validated by realtime qPCR and Western blot in both human HCC and DEN-induced murine tumors. Moreover, chromosomal immunoprecipitation and co-transfection assays established the P2 intronic promoter of mdm2 as a bona fide transcriptional target repressed by KLF6. Whereas KLF6 over-expression in HCC cell lines led to reduced MDM2 levels and increased p53 protein and transcriptional activity, reduction in KLF6 by siRNA led to increased MDM2 and reduced p53. Our findings indicate that KLF6 deficiency contributes significantly to the carcinogenic milieu in human and murine HCC, and uncover a novel tumor suppressor activity of KLF6 in HCC, by linking its transcriptional repression of MDM2 to stabilization of p53. Keywords: Liver, Hepatocellular carcinoma, Expression array, Exon array, Affymetrix KLF6 +/- mice were previously generated by homologous recombination in which exon 2 was targeted using an 11-kb targeting construct, and replaced with neomycin/lacZ cassette. After selection with neomycin, the ES clones were injected into C57BL/6 mouse blastocysts and implanted into pseudo pregnant females; two lines of KLF6 +/- mice were generated from the resulting chimeric animals (Blood 107;1357, Oncogene 26;4428). Whereas KLF6 -/- mice are embryonic lethal, KLF6 +/- animals had no demonstrable abnormalities in the absence of any stressor. Male KLF6 +/- mice were bred with wild type C57BL/6 to generate mixed litters of KLF6 +/- and KLF6 +/+ animals. Progeny were genotyped using PCR-amplified tail DNA, using primers as previously described (Oncogene 26;4428). Amplified fragments were separated on a 2.5% agarose gel, revealing bands of ~200 bp (wild type KLF6) and ~100 bp (Neo), as expected. At 2 weeks of age, KLF6 +/+ and KLF6 +/- mice were injected intraperitoneally with either a single dose of diethyl nitrosamine (DEN), 5 µg/g body weight in 100 µl of saline, or vehicle alone. Vehicle and DEN-treated mice were maintained on standard chow, and then sacrificed 3, 6 or 9 months later. At the time of sacrifice the animals were weighed, and blood and liver samples were harvested for analysis and tumor quantification.

Project description:Gene-expression profiles of rat hepatocellular carcinoma induced by diethylnitrosamine (DEN) and the effect of erlotinib Hepatocellular carcinoma (HCC) is the sixth most common solid tumor worldwide and the third leading cause of cancer-related death. Given the lack of successful treatment options, chemoprevention in high-risk patients has been proposed as an alternative strategy. Mounting evidence supports a role for epidermal growth factor (EGF) during chronic liver disease and hepatocellular transformation. We address the hypothesis that blocking the EGF-EGF receptor (EGFR) pathway may be an effective strategy for inhibiting fibrogenesis and hepatocarcinogenesis. A rat model of diethylnitrosamine (DEN)-induced cirrhosis was used to examine the effects of erlotinib on underlying chronic liver disease and HCC formation. The DEN-induced rat model closely resembles disease progression in humans both pathologically and molecularly. Erlotinib significantly prevented the development of HCC tumor nodules in a dose-dependent fashion. Further, erlotinib inhibited the activation of hepatic stellate cells and prevented fibrogenesis. Erlotinib also reduced hepatotoxicity and improved liver function. Finally, a gene expression signature predictive of poor survival in human cirrhosis patients was reversed in response to erlotinib. Our data demonstrate for the first time that EGFR inhibition prevents liver fibrogenesis. Further, our results suggest that erlotinib is a potentially effective HCC chemoprevention strategy through inhibition of cirrhosis progression which can be monitored at the molecular level. Animals received humane care according to the criteria outlined in the M-bM-^@M-^\Guide for the Care and Use of Laboratory AnimalsM-bM-^@M-^] of the National Academy of Sciences. All animals were maintained in accordance with the institutional guidelines of the Massachusetts General Hospital Subcommittee on Research Animal Care. Male Wistar rats received weekly IP injections of diethylnitrosamine (DEN) at 50 mg/kg, 100mg/kg, or vehicle control (PBS) for 18 weeks. A subset of rats received either daily (5X a week) IP injections of 2 mg/kg erlotinib or vehicle control during weeks 13 - 18. In a separate study, the erlotinib dose was lowered to 0.5 mg/kg. The vehicle groups from the two studies were not significantly different so they were combined together for analysis. Rats were weighed at the end of each week. Animals were sacrificed at 9, 13 and 19 weeks after a one-week washout period to eliminate acute effects of DEN. At the time of sacrifice, the non-tumor liver tissues were collected in RNase-free tubes and snap-frozen in liquid nitrogen. Frozen tissues were stored at -80M-BM-0C until RNA extraction.

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Gene expression data from DEN-induced hepatocellular carcinoma mice

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