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 transformation of individual cell fates by developmental signaling cascades and transcription factors triggers diverse cancer types. Chordoma is a rare, aggressive tumor arising from transformed notochord remnants. Various potentially oncogenic factors have been found deregulated in chordoma and its metastases, yet clear causation remains uncertain. In particular, expression of the notochord-controlling transcription factor Brachyury is hypothesized as key molecular driver in chordoma formation, yet an in vivo model to causally test its oncogenic potential in the notochord is missing. Here, we apply a zebrafish model of chordoma onset to identify the notochord-transforming potential of tumor-implicated candidate genes in vivo. We find that overexpression of human and zebrafish Brachyury, including a version with augmented transcriptional activity, is insufficient to initiate notochord hyperplasia in vivo. In contrast, the repeatedly chordoma-implicated receptor tyrosine kinase (RTK) genes EGFR and KDR/VEGFR2 are sufficient to transform developmental notochord cells, akin to direct activation of Ras. Analysis of transcriptome and sub-cellular organization from transformed notochords suggests that aberrant activation of RTK/Ras signaling attenuates processes required for the differentiation of notochord cells. Taken together, our results provide first in vivo indication for a lack of tumor-initiating potential of Brachyury expression in the notochord, and suggest activated RTK signaling as potent hyperplasia-initiating event in chordoma.
Project description:Arsenic trioxide (ATO) and all-trans retinoic acid (ATRA) combination safely cures fatal acute promyelocytic leukemia, but the mechanisms underlying their action and synergy remain elusive. ATRA inhibits APL, breast and liver cancers by targeting isomerase Pin1, a master regulator of oncogenic signaling. Here we show that ATO targets Pin1 and cooperates with ATRA to exert potent anticancer activity. ATO inhibits and degrades Pin1, and suppresses its oncogenic function by noncovalent binding to Pin1’s active site. ATRA increases cellular ATO uptake through upregulating aquaporin-9. ATO and ATRA, at clinically safe doses, cooperatively ablate Pin1 to block numerous cancer-driving pathways and inhibit the growth of triple-negative breast cancer cells and tumor-initiating cells in cell and animal models including patient-derived orthotopic xenografts, similar to Pin1 CRISPR knockout, which is substantiated by comprehensive protein and microRNA analyses. Thus, synergistic Pin1 inhibition by ATO and ATRA offers an attractive approach to combating breast and other cancers.