Project description:Malignant melanoma is characterized by frequent metastasis, however specific changes that regulate this process have not been clearly delineated. Although it is well known that Wnt signaling is frequently dysregulated in melanoma, the functional implications of this observation are unclear. By modulating beta-catenin levels in a mouse model of melanoma that is based on melanocyte-specific Pten loss and BrafV600E mutation, we demonstrate that beta-catenin is a central mediator of melanoma metastasis to lymph node and lung. In addition to altering metastasis, beta-catenin levels control tumor differentiation and regulate both MAPK/Erk and PI3K/Akt signaling. Highly metastatic tumors with beta-catenin stabilization are very similar to a subset of human melanomas; together these findings establish Wnt signaling as a metastasis regulator in melanoma. MoGene-1_0-st-v1: Four samples total. Two biological replicates of uncultured Pten/Braf murine melanomas and two biological replicates of uncultured Pten/Braf/Bcat-STA murine melanomas. MoEx-1_0-st-v1: Two samples total. Dissociated tumor and FACS-enriched Pten/Braf and Pten/Braf/Bcat-STA murine melanoma.
Project description:Malignant melanoma is characterized by frequent metastasis, however specific changes that regulate this process have not been clearly delineated. Although it is well known that Wnt signaling is frequently dysregulated in melanoma, the functional implications of this observation are unclear. By modulating beta-catenin levels in a mouse model of melanoma that is based on melanocyte-specific Pten loss and BrafV600E mutation, we demonstrate that beta-catenin is a central mediator of melanoma metastasis to lymph node and lung. In addition to altering metastasis, beta-catenin levels control tumor differentiation and regulate both MAPK/Erk and PI3K/Akt signaling. Highly metastatic tumors with beta-catenin stabilization are very similar to a subset of human melanomas; together these findings establish Wnt signaling as a metastasis regulator in melanoma.
Project description:Approximately 50% of melanomas harbor an activating BRAFV600E mutation. Standard of care involves a combination of inhibitors targeting mutant BRAF and MEK1/2, the substrate for BRAF in the MAPK pathway. PTEN loss of function mutations occur in 40% of BRAFV600E melanomas, resulting in increased PI3K/AKT activity that enhances resistance to BRAF/MEK combination inhibitor therapy. To compare the response of PTEN null to PTEN wild type cells in an isogenic background, CRISPR was used to knock out PTEN in the A375 melanoma cell line that harbors a BRAFV600E mutation. RNA sequencing and functional kinome analysis revealed the loss of PTEN led to an induction of FOXD3 and an increase in expression of the FOXD3 target gene, ERBB3/HER3. Inhibition of BRAFand MEK1/2 in PTEN null, BRAFV600E cells dramatically induced expression of ERBB3/HER3 relative to wild type cells. A synergy screen of epigenetic modifiers and kinase inhibitors in combination with inhibitors for mutant BRAF/MEK1/2 identified the pan ERBB/HER inhibitor, neratinib, as reversing the resistance observed in PTEN null, BRAFV600E cells. The findings indicate PTEN null BRAFV600E melanoma becomes dependent on ERBB/HER signaling when treated with clinically approved BRAF and MEK inhibitors. Future studies are warranted to test neratinib reversal of resistance in patient melanomas expressing ERBB3/HER3 in combination with its dimerization partner ERBB2/HER2.
Project description:Approximately 50% of melanomas harbor an activating BRAFV600E mutation. Standard of care involves a combination of inhibitors targeting mutant BRAF and MEK1/2, the substrate for BRAF in the MAPK pathway. PTEN loss of function mutations occur in 40% of BRAFV600E melanomas, resulting in increased PI3K/AKT activity that enhances resistance to BRAF/MEK combination inhibitor therapy. To compare the response of PTEN null to PTEN wild type cells in an isogenic background, CRISPR was used to knock out PTEN in the A375 melanoma cell line that harbors a BRAFV600E mutation. Kinome profiling was performed using the parental line and two PTEN KO clones (5 and 11), treated with DMSO, or treated with 100nM dabrafenib and 10nM trametinib for 1 day or for 7 days. PTEN KO cells showed dramatically increased binding of HER3 and AKT3 compared to wild type. The activation of the SOX10-FOXD3-HER3-AKT axis in PTEN KO cells could be targeted with the ERBB/HER inhibitor neratinib.
Project description:To investigate the mechanism underlying the effect of Brn2-loss we extracted mRNA from Braf-Pten-Brn2-wt, Braf-Pten-Brn2-het, and Braf-Pten-Brn2-hom mouse melanomas and performed microarray-based transcriptome analysis.
Project description:To investigate the mechanism underlying the effect of Brn2-loss we extracted mRNA from Braf-Pten-Brn2-wt, Braf-Pten-Brn2-het, and Braf-Pten-Brn2-hom mouse melanomas and performed microarray-based transcriptome analysis.
Project description:Only a subset of melanoma patients has evidence for spontaneous T cell infiltration into tumor sites, previously associated with clinical responses. However, the molecular mechanisms explaining absence of a T cell response are not yet defined. Analyses of human melanoma metastases have revealed that T cell signature low tumors show alterations in the Wnt/b-catenin signaling pathway. We utilized an inducible mouse model driven by inducible BrafV600E and PTEN-deletion, with or without active b-catenin (CAT-STA) to test if tumor intrinsic active b-catenin can block anti-tumor immunity. While Braf/PTEN melanomas showed presence of a T cell infiltrate, T cells were nearly completely eliminated in tumors expressing active b-catenin. Adoptive transfer experiments revealed defective T cell priming when tumors expressed active b-catenin. Analysis of the antigen-presenting cell compartment revealed a selective decrease in the CD103+ DC subset within the tumor microenvironment, which could be associated with b-catenin depended inhibition of expression of the chemokine CCL4 within tumor cells. Here we used 3 mice of each genotype BrafV600E/PTEN-/- and BrafV600E/PTEN-/-/Cat-STA and compared their gene-expression profiles. we used 3 mice of each genotype BrafV600E/PTEN-/- and BrafV600E/PTEN-/-/Cat-STA and compared their gene-expression profiles.
Project description:β-catenin signaling can be both a physiological and an oncogenic pathway in the liver. It controls compartmentalized gene expression, allowing the liver to ensure its essential metabolic function. It is activated by mutations in 20 to 40% of hepatocellular carcinomas with specific metabolic features. We decipher the molecular determinants of β-catenin-dependent zonal transcription using mice with β-catenin-activated or -inactivated hepatocytes, characterizing in vivo their chromatin occupancy by Tcf4 and β-catenin, their transcriptome and their metabolome. We find that Tcf4 DNA-bindings depend on β-catenin. Tcf4/β-catenin binds Wnt-responsive elements preferentially around β-catenin-induced genes. In contrast, genes repressed by β-catenin bind Tcf4 on Hnf4-responsive elements. β-catenin, Tcf4 and Hnf4α interact, dictating β-catenin transcription which is antagonistic to that elicited by Hnf4α. Finally, we find the drug/bile metabolism pathway to be the one most heavily targeted by β-catenin, partly through xenobiotic nuclear receptors. We conclude that β-catenin patterns the zonal liver together with Tcf4, Hnf4α and xenobiotic nuclear receptors. This network represses lipid metabolism, and exacerbates glutamine, drug and bile metabolism, mirroring hepatocellular carcinomas with β-catenin mutational activation. In vivo liver samples in 4 conditions: Betacat activated (WCE, Tcf4 chipseq, Betacat chipseq, mRNAseq with 2 replicates), Betacat null (WCE, Tcf4 chipseq, mRNAseq with 2 replicates), Betacat control (mRNAseq with 2 replicates), Wild type (mRNAseq with 2 replicates)
Project description:β-catenin signaling can be both a physiological and an oncogenic pathway in the liver. It controls compartmentalized gene expression, allowing the liver to ensure its essential metabolic function. It is activated by mutations in 20 to 40% of hepatocellular carcinomas with specific metabolic features. We decipher the molecular determinants of β-catenin-dependent zonal transcription using mice with β-catenin-activated or -inactivated hepatocytes, characterizing in vivo their chromatin occupancy by Tcf4 and β-catenin, their transcriptome and their metabolome. We find that Tcf4 DNA-bindings depend on β-catenin. Tcf4/β-catenin binds Wnt-responsive elements preferentially around β-catenin-induced genes. In contrast, genes repressed by β-catenin bind Tcf4 on Hnf4-responsive elements. β-catenin, Tcf4 and Hnf4α interact, dictating β-catenin transcription which is antagonistic to that elicited by Hnf4α. Finally, we find the drug/bile metabolism pathway to be the one most heavily targeted by β-catenin, partly through xenobiotic nuclear receptors. We conclude that β-catenin patterns the zonal liver together with Tcf4, Hnf4α and xenobiotic nuclear receptors. This network represses lipid metabolism, and exacerbates glutamine, drug and bile metabolism, mirroring hepatocellular carcinomas with β-catenin mutational activation.