Project description:In many mouse models of skin cancer, only a few tumors typically form although many cells competent for tumorigenesis receive the same oncogenic mutations. These observations suggest a selection process for defining tumor initiating cells. Here we use quantitative mRNA- and miR-Seq to determine the impact of HRasG12V on the transcriptome of keratinocytes. We discover that microRNA-203 is downregulated by HRasG12V. Using a knockout mouse model, we demonstrate that loss of microRNA-203 promotes selection and expansion of tumor-initiating cells. Conversely, restoration of microRNA-203 with an inducible model potently inhibits proliferation of these cells. We comprehensively identify microRNA-203 targets required for HRas-initiated tumorigenesis. These targets include important effectors of the Ras pathway and essential genes required for cell division. Together, this study establishes a role for the loss of microRNA-203 in promoting selection and expansion of HRas mutated cells and identifies a mechanism through which microRNA-203 antagonizes HRas-mediated tumorigenesis. Identifying mRNA and microRNA networks regulated by oncogenic HRasG12V in primary keratinocytes through the use of 3Seq and small-RNA-Sequencing. Additionally we utilize ribosome-profiling, 3Seq, Microarray and Ago2-HITS-CLIP approaches to identify novel miR-203 target genes.
Project description:In many mouse models of skin cancer, only a few tumors typically form although many cells competent for tumorigenesis receive the same oncogenic mutations. These observations suggest a selection process for defining tumor initiating cells. Here we use quantitative mRNA- and miR-Seq to determine the impact of HRasG12V on the transcriptome of keratinocytes. We discover that microRNA-203 is downregulated by HRasG12V. Using a knockout mouse model, we demonstrate that loss of microRNA-203 promotes selection and expansion of tumor-initiating cells. Conversely, restoration of microRNA-203 with an inducible model potently inhibits proliferation of these cells. We comprehensively identify microRNA-203 targets required for HRas-initiated tumorigenesis. These targets include important effectors of the Ras pathway and essential genes required for cell division. Together, this study establishes a role for the loss of microRNA-203 in promoting selection and expansion of HRas mutated cells and identifies a mechanism through which microRNA-203 antagonizes HRas-mediated tumorigenesis. Identifying mRNA and microRNA networks regulated by oncogenic HRasG12V in primary keratinocytes through the use of 3Seq and small-RNA-Sequencing. Additionally we utilize ribosome-profiling, 3Seq, Microarray and Ago2-HITS-CLIP approaches to identify novel miR-203 target genes.
Project description:In many mouse models of skin cancer, only a few tumors typically form although many cells competent for tumorigenesis receive the same oncogenic mutations. These observations suggest a selection process for defining tumor initiating cells. Here we use quantitative mRNA- and miR-Seq to determine the impact of HRasG12V on the transcriptome of keratinocytes. We discover that microRNA-203 is downregulated by HRasG12V. Using a knockout mouse model, we demonstrate that loss of microRNA-203 promotes selection and expansion of tumor-initiating cells. Conversely, restoration of microRNA-203 with an inducible model potently inhibits proliferation of these cells. We comprehensively identify microRNA-203 targets required for HRas-initiated tumorigenesis. These targets include important effectors of the Ras pathway and essential genes required for cell division. Together, this study establishes a role for the loss of microRNA-203 in promoting selection and expansion of HRas mutated cells and identifies a mechanism through which microRNA-203 antagonizes HRas-mediated tumorigenesis.
Project description:In many mouse models of skin cancer, only a few tumors typically form although many cells competent for tumorigenesis receive the same oncogenic mutations. These observations suggest a selection process for defining tumor initiating cells. Here we use quantitative mRNA- and miR-Seq to determine the impact of HRasG12V on the transcriptome of keratinocytes. We discover that microRNA-203 is downregulated by HRasG12V. Using a knockout mouse model, we demonstrate that loss of microRNA-203 promotes selection and expansion of tumor-initiating cells. Conversely, restoration of microRNA-203 with an inducible model potently inhibits proliferation of these cells. We comprehensively identify microRNA-203 targets required for HRas-initiated tumorigenesis. These targets include important effectors of the Ras pathway and essential genes required for cell division. Together, this study establishes a role for the loss of microRNA-203 in promoting selection and expansion of HRas mutated cells and identifies a mechanism through which microRNA-203 antagonizes HRas-mediated tumorigenesis.
Project description:Silencing of gene expression by methylation of CpG islands in regulatory elements is frequently observed in cancer. However, an influence of the most common oncogenic signalling pathways onto DNA methylation has not yet been investigated thoroughly. To address this issue, we identified genes suppressed in HRAS-transformed rat fibroblasts but up-regulated after treatment with the demethylating agent 5-Aza-CdR and with the MEK1,2 inhibitor U0126. Analysis of gene expression by microarray and Northern blot analysis revealed the MEK/ERK target genes clusterin, Mmp2, Ppicap, syndecan 4, Timp2, Thbs1 to be repressed in the HRAS-transformed FE-8 cells in a MEK/ERK- and in a methylation-dependent manner. Hypermethylation of putative regulatory elements in HRAS-transformed cells as compared to immortalized fibroblasts was detected within a CpG island 14.5 kb upstream of clusterin, within the clusterin promoter and within a CpG island of the Mmp2 promoter by bisulphite sequencing. Furthermore, hypermethylation of the clusterin promoter was observed ten days after induction of HRAS in immortalized rat fibroblasts and a clear correlation between reduced clusterin expression and hypermethlyation could also be observed in distinct rat tissues. These results suggest that silencing of individual genes by DNA methylation is controlled by oncogenic signalling pathways, yet the mechanisms responsible for initial target gene suppression are variable. Experiment Overall Design: Gene expression was analyzed in immortal (208F) and HRAS oncogene-transformed (FE8) rat fibroblasts after demethylation by 5-aza-2'-deoxycytidine. Genes potentially methylated in RAS-transformed cells were identified by bisulphite sequencing
Project description:Silencing of gene expression by methylation of CpG islands in regulatory elements is frequently observed in cancer. However, an influence of the most common oncogenic signalling pathways onto DNA methylation has not yet been investigated thoroughly. To address this issue, we identified genes suppressed in HRAS-transformed rat fibroblasts but up-regulated after treatment with the demethylating agent 5-Aza-CdR and with the MEK1,2 inhibitor U0126. Analysis of gene expression by microarray and Northern blot analysis revealed the MEK/ERK target genes clusterin, Mmp2, Ppicap, syndecan 4, Timp2, Thbs1 to be repressed in the HRAS-transformed FE-8 cells in a MEK/ERK- and in a methylation-dependent manner. Hypermethylation of putative regulatory elements in HRAS-transformed cells as compared to immortalized fibroblasts was detected within a CpG island 14.5 kb upstream of clusterin, within the clusterin promoter and within a CpG island of the Mmp2 promoter by bisulphite sequencing. Furthermore, hypermethylation of the clusterin promoter was observed ten days after induction of HRAS in immortalized rat fibroblasts and a clear correlation between reduced clusterin expression and hypermethlyation could also be observed in distinct rat tissues. These results suggest that silencing of individual genes by DNA methylation is controlled by oncogenic signalling pathways, yet the mechanisms responsible for initial target gene suppression are variable. Keywords: expression analysis
Project description:Oncogenic activating mutations in Ras genes are among the most common drivers of human disease. Treating mouse skin with the chemical carcinogen DMBA induces a characteristic mutation in Hras at codon 61. To understand how skin responds to a constitutive lack of Hras, we generated a cohort of Hras knockout mice.
Project description:Oncogenic activating mutations in Ras genes are among the most common drivers of human disease. Treating mouse skin with the chemical carcinogen DMBA induces a characteristic mutation in Hras at codon 61. To understand how skin responds to a constitutive lack of Hras, we generated a cohort of Hras knockout mice. A backcross was generated using male Mus spretus and female FVB/N Hras-/- mice; female F1 hybrids were mated with male FVB/N Hras -/- or Hras -/+ mice to generate a backcross population. This series contains mice that were Hras -/-. Mice were aged to 8 weeks and a tail skin sample was snap frozen.