Project description:We found that concomitant deletion of Trp53 and overexpression of c-MET (c-MET/sgp53) in the mouse liver led to HCC formation in vivo. Subsequently, a stably passaged cell line derived from a c-MET/sgp53 HCC were generated. We then performed gene expression profiling analysis using data obtained from RNA-seq of the c-MET/sgp53 HCC cell line. Wild-type FVB/N mouse liver were used as control.
Project description:SUMMARY: Basal breast cancer has been associated with mutations in a number of specific tumor suppressor genes, however, the mechanism by which these tumors express a basal lineage remains unknown. Notch signaling suppresses mammary stem cell (MaSC) self-renewal, while promoting luminal cell fate specification. Here we show that Lfng, a sugar transferase that facilitates Notch activation, suppresses mammary stem/bipotent progenitor cell proliferation. Targeted deletion of Lfng in mammary epithelium induces basal tumors with reduced expression of Notch targets, amplification of the Met/Caveolin gene locus, and elevated Met and Igf-1R signaling. Human basal breast cancer, a disease associated with elevated MET receptor signaling and Caveolin protein, express low levels of LFNG. Thus, reduced LFNG expression cooperates with a Met/ Caveolin amplicon to promote basal breast disease. SIGNIFICANCE: Anti-Notch therapy is currently being tested for efficacy against basal-like breast cancer in humans. Here we report that LFNG, which controls Notch receptor activation, is consistently expressed at a low level in basal tumors and that deletion of this gene in the mouse mammary gland reduces Notch signaling, increases proliferation and induces basal mammary tumors in cooperation with amplification of the Met/Caveolin gene locus. These mutations interact to promote basal gene expression by decreasing Notch pathway activation, as well as to enhance Met and Igf-1R signaling. These pathways can be targeted at multiple levels in humans harboring basal breast cancer with amplification of MET and CAV1/2 32 array samples
Project description:SUMMARY: Basal breast cancer has been associated with mutations in a number of specific tumor suppressor genes, however, the mechanism by which these tumors express a basal lineage remains unknown. Notch signaling suppresses mammary stem cell (MaSC) self-renewal, while promoting luminal cell fate specification. Here we show that Lfng, a sugar transferase that facilitates Notch activation, suppresses mammary stem/bipotent progenitor cell proliferation. Targeted deletion of Lfng in mammary epithelium induces basal tumors with reduced expression of Notch targets, amplification of the Met/Caveolin gene locus, and elevated Met and Igf-1R signaling. Human basal breast cancer, a disease associated with elevated MET receptor signaling and Caveolin protein, express low levels of LFNG. Thus, reduced LFNG expression cooperates with a Met/ Caveolin amplicon to promote basal breast disease. SIGNIFICANCE: Anti-Notch therapy is currently being tested for efficacy against basal-like breast cancer in humans. Here we report that LFNG, which controls Notch receptor activation, is consistently expressed at a low level in basal tumors and that deletion of this gene in the mouse mammary gland reduces Notch signaling, increases proliferation and induces basal mammary tumors in cooperation with amplification of the Met/Caveolin gene locus. These mutations interact to promote basal gene expression by decreasing Notch pathway activation, as well as to enhance Met and Igf-1R signaling. These pathways can be targeted at multiple levels in humans harboring basal breast cancer with amplification of MET and CAV1/2
Project description:HGF has been reported to have both positive and negative effects on carcinogenesis. Here we show that the loss of c-Met signaling in hepatocytes enhanced rather than suppressed the early stages of chemical hepatocarcinogenesis. c-Met conditional knockout mice (c-metfl/fl, AlbCre+/-; MetLivKO) treated with N-nitrosodiethylamine (DEN) developed significantly more and bigger tumors and with a shorter latency as compared with control (wt/wt, AlbCre+/-; Cre-Ctrl) mice. Accelerated tumor development was associated with increased rate of cell proliferation and prolonged activation of epidermal growth factor receptor (EGFR) signaling. MetLivKO livers treated with DEN also displayed elevated lipid peroxidation, decreased ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG), and upregulation of superoxide dismutase 1 (Sod1) and heat shock protein 70 (Hsp70), all consistent with increased oxidative stress. Likewise, gene expression profiling performed at 3 and 5 months after DEN treatment revealed upregulation of genes associated with cell proliferation and stress responses in c-Met mutant livers. The negative effects of c-Met-deficiency were reversed by chronic oral administration of anti-oxidant N-acetylcysteine (NAC). NAC blocked the EGFR activation and reduced the DEN-initiated hepatocarcinogenesis to the levels of Cre-Ctrl mice. These results argue that intact HGF/c-Met signaling is essential for maintaining normal redox homeostasis in the liver and has tumor suppressor effect(s) during the early stages of DEN-induced hepatocarcinogenesis. Keywords: compound treatment design
Project description:HGF has been reported to have both positive and negative effects on carcinogenesis. Here we show that the loss of c-Met signaling in hepatocytes enhanced rather than suppressed the early stages of chemical hepatocarcinogenesis. c-Met conditional knockout mice (c-metfl/fl, AlbCre+/-; MetLivKO) treated with N-nitrosodiethylamine (DEN) developed significantly more and bigger tumors and with a shorter latency as compared with control (wt/wt, AlbCre+/-; Cre-Ctrl) mice. Accelerated tumor development was associated with increased rate of cell proliferation and prolonged activation of epidermal growth factor receptor (EGFR) signaling. MetLivKO livers treated with DEN also displayed elevated lipid peroxidation, decreased ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG), and upregulation of superoxide dismutase 1 (Sod1) and heat shock protein 70 (Hsp70), all consistent with increased oxidative stress. Likewise, gene expression profiling performed at 3 and 5 months after DEN treatment revealed upregulation of genes associated with cell proliferation and stress responses in c-Met mutant livers. The negative effects of c-Met-deficiency were reversed by chronic oral administration of anti-oxidant N-acetylcysteine (NAC). NAC blocked the EGFR activation and reduced the DEN-initiated hepatocarcinogenesis to the levels of Cre-Ctrl mice. These results argue that intact HGF/c-Met signaling is essential for maintaining normal redox homeostasis in the liver and has tumor suppressor effect(s) during the early stages of DEN-induced hepatocarcinogenesis. Keywords: compound treatment design To address a role for c-Met in liver carcinogenesis, we employed a hepatocyte specific c-Met conditional knockout mouse model generated in our laboratory. Mice received a single intraperitoneal injection of 10 µg/g body weight of N-nitrosodiethylamine (DEN) (Sigma-Aldrich, Inc., St. Louis, MO, USA) at 14 days of age. Livers were examined at 3 and 5 months after DEN injection. Expression profiling was conducted on five animals from each genotype per time point. Total RNA pooled from five wild-type B6/129 strain mouse livers was used as universal hybridization reference. All experiments were performed in duplicates following a dye-swapping design. Arrays were scanned with a GenePix 4000A scanner (Axon Instruments Ltd., Burlingame, CA) in a way to achieve optimal signal intensity at both channels with less than 1% saturated spots. After excluding the invalid features, all arrays were normalized to the 50th percentile of the median signal intensity using the mAdb data analysis suite (http://nciarray.nci.nih.gov/). Unsupervised cluster analysis was performed with the Cluster and TreeView programs (http://rana.lbl.gov/EisenSoftware.htm). The BRB ArrayTools V3.3.0 software package (Biometric Research Branch, National Cancer Institute; http://linus.nci.nih.gov/BRB-ArrayTools.html) was used for the supervised comparison. Differentially expressed genes were selected using a univariate 2-sample t-test (P<0.001) with a random variance model (15). Functional classification of the significant genes was based on the Gene Ontology (GO) annotations (www.geneontology.org).
Project description:Mammary specific deletion of Lfng induces basal-like and claudin-low tumors with accumulation of Notch intracellular domain fragments, increased expression of proliferation-associated Notch targets, amplification of the Met/Caveolin locus, and elevated Met and Igf-1R signaling.
Project description:Mammary specific deletion of Lfng induces basal-like and claudin-low tumors with accumulation of Notch intracellular domain fragments, increased expression of proliferation-associated Notch targets, amplification of the Met/Caveolin locus, and elevated Met and Igf-1R signaling. Tumor DNAs from Lfngflox/flox; MMTV-Cre conditional mutant mice are being compared to control DNAs from the same animals in order to identify common alterations associated with tumor progression