MITF Expression Predicts Therapeutic Vulnerability to p300 Inhibition in Human Melanoma
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ABSTRACT:
PROVIDER: PRJNA528651 | ENA |
REPOSITORIES: ENA
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Project description:Histone modifications, largely regulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs) have been recognized as major regulatory mechanisms governing human diseases including cancer. Despite significant effort and recent advances, the mechanism by which the p300 transcriptional coactivator mediates tumorigenesis remains unclear. Here, we use a genetic and chemical approach to identify the Microphthalmia-associated transcription factor (MITF) as a critical downstream target of p300 driving human melanoma growth. We find that direct transcriptional control of MITF by p300-dependent histone acetylation within proximal gene regulatory regions is coupled to cellular proliferation, suggesting a significant growth regulatory axis. Further analysis revealed Forkhead Box M1 (FOXM1) as a key effector of the p300-MITF axis driving cell growth, which is selectively activated in human melanomas. Targeted chemical inhibition of p300 histone acetyltransferase activity using a potent and selective catalytic p300/CBP inhibitor confirmed the critical role of the p300-MITF-FOXM1 axis in melanoma and demonstrated significant growth inhibitory effects in melanoma cells expressing high levels of MITF. These data support p300 as a promising novel epigenetic therapeutic target in human melanoma.
2020-03-22 | GSE128737 | GEO
Project description:Histone modifications, largely regulated by histone acetyltransferases (HAT) and histone deacetylases, have been recognized as major regulatory mechanisms governing human diseases, including cancer. Despite significant effort and recent advances, the mechanism by which the HAT and transcriptional coactivator p300 mediates tumorigenesis remains unclear. Here, we use a genetic and chemical approach to identify the microphthalmia-associated transcription factor (MITF) as a critical downstream target of p300 driving human melanoma growth. Direct transcriptional control of MITF by p300-dependent histone acetylation within proximal gene regulatory regions was coupled to cellular proliferation, suggesting a significant growth regulatory axis. Further analysis revealed forkhead box M1 (FOXM1) as a key effector of the p300-MITF axis driving cell growth that is selectively activated in human melanomas. Targeted chemical inhibition of p300 acetyltransferase activity using a potent and selective catalytic p300/CBP inhibitor demonstrated significant growth inhibitory effects in melanoma cells expressing high levels of MITF. Collectively, these data confirm the critical role of the p300-MITF-FOXM1 axis in melanoma and support p300 as a promising novel epigenetic therapeutic target in human melanoma. SIGNIFICANCE: These results show that MITF is a major downstream target of p300 in human melanoma whose expression is predictive of melanoma response to small-molecule inhibition of p300 HAT activity.
| S-EPMC6522293 | biostudies-literature
Project description:Increased MITF expression contributes to melanoma progression and resistance to BRAF pathway inhibition. We show that, unexpectedly, lack of MITF is associated with more severe resistance to a range of inhibitors. Indeed, the presence of endogenous MITF was essential for robust drug responses. Both in primary and acquired resistance, MITF levels inversely correlated with expression of several activated receptor tyrosine kinases, most commonly AXL. The MITF-low/AXL-high/drug resistance phenotype was seen in roughly half of BRAF mutant and the majority of NRAS mutant melanoma cell lines. The dichotomous behavior of MITF in drug response was corroborated in vemurafenib-resistant biopsies, including MITF high and low clones in a relapsed patient. Drug cocktails containing AXL inhibitor enhanced melanoma cell elimination by BRAF or ERK inhibition. Our results demonstrate that a low MITF/AXL ratio predicts early resistance to multiple targeted drugs, and warrant clinical validation of AXL inhibitors to combat resistance of BRAF and NRAS mutant MITF-low melanomas. Experssion analysis by RNAseq of 14 melanoma cell lines.
2014-09-19 | E-GEOD-61544 | biostudies-arrayexpress
Project description:Increased MITF expression contributes to melanoma progression and resistance to BRAF pathway inhibition. We show that, unexpectedly, lack of MITF is associated with more severe resistance to a range of inhibitors. Indeed, the presence of endogenous MITF was essential for robust drug responses. Both in primary and acquired resistance, MITF levels inversely correlated with expression of several activated receptor tyrosine kinases, most commonly AXL. The MITF-low/AXL-high/drug resistance phenotype was seen in roughly half of BRAF mutant and the majority of NRAS mutant melanoma cell lines. The dichotomous behavior of MITF in drug response was corroborated in vemurafenib-resistant biopsies, including MITF high and low clones in a relapsed patient. Drug cocktails containing AXL inhibitor enhanced melanoma cell elimination by BRAF or ERK inhibition. Our results demonstrate that a low MITF/AXL ratio predicts early resistance to multiple targeted drugs, and warrant clinical validation of AXL inhibitors to combat resistance of BRAF and NRAS mutant MITF-low melanomas.
2014-09-19 | GSE61544 | GEO
Project description:Cutaneous melanoma (CM) and uveal melanoma (UM) both originate from the melanocytic lineage but are primarily driven by distinct oncogenic drivers, BRAF/NRAS or GNAQ/GNA11 respectively. The melanocytic master transcriptional regulator, MITF, is essential for both CM development and maintenance, but its role in UM is largely unexplored. Here, we use zebrafish models to dissect the key UM oncogenic signaling events, and establish the role of MITF in UM tumors. Remarkably, mitfa deficiency was profoundly UM promoting, dramatically accelerating the onset and progression of tumors induced by Tg(mitfa:GNAQQ209L);tp53M214K/M214K. To further explore the role of MITF in GNAQ-driven tumorigenesis, we performed phospho-proteomics and total proteomics on 5 zebrafish GNAQ Tg(mitfa:GNAQQ209L);tp53M214K/M214K tumors and 5 zebrafish GNAQ Tg(mitfa:GNAQQ209L);tp53M214K/M214K;mitfa-/- tumors.
2023-03-11 | PXD030527 | Pride
Project description:We identified a novel germline mutation of the microphthalmia-associated transcription factor (MITF - E318K). This mutation was found to be present in numerous melanoma families, as well as the general population, where its association with melanoma has a significant effect. We determined the effect of the E318K mutation on global MITF target gene transcription. We developed a tetracycline-inducible system for expression of wild type MITF or the E318K variant in melanoma cell lines with constitutively low or undetectable levels of endogenous MITF (HT144 and C32). We examined whole-genome expression profiles in these cells following induction of either wild-type or E318K MITF for 48 hours. Analysis suggests that the MITF E318K mutant exhibits differential transcriptional activity against some, though not all, target genes. Expression profiling by array
2011-12-01 | E-GEOD-31269 | biostudies-arrayexpress
Project description:To assess the effects of permanent loss of MITF in melanoma cells, we used the clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 technique to generate MITF knockout (KO) cell lines in the human hypo-tetraploid SkMel28 melanoma cell line (containing four copies of MITF). We targeted exon 6 (containing the DNA binding domain) of MITF the resulting isogenic cell line is hereafter referred to as ΔMITF-X6. We also performed siRNA mediated transient knock down of MITF along with control siCTRL in 501Mel cells. Furthermore, we used a stable doxycycline inducible over-expression cell line containing FLAG tagged MITF and a control cells with empty vector FLAG in A375P. From our RNA-sequencing studies we found that MITF plays a critical role as a repressor of extracellular matrix gene expression and is actively involved in shaping the microenvironment of melanoma cells in a cell-autonomous manner.
2020-12-22 | GSE163646 | GEO
Project description:Chromatin features are widely used for genome-scale mapping of enhancers. However, discriminating active enhancers from other cis-regulatory elements, predicting enhancer strength, and identifying their target genes remains challenging. Here we establish histone H2B N-terminus multisite lysine acetylation (H2BNTac) as a genuine signature of active enhancers. H2BNTac prominently marks candidate active enhancers and a subset of promoters and discriminates them from ubiquitously active promoters. Two mechanisms afford the distinct H2BNTac specificity. (1) Unlike H3K27ac, H2BNTac is specifically catalyzed by CBP/p300. (2) H2A-H2B, but not H3-H4, are rapidly exchanged through transcription-induced nucleosome remodeling. H2BNTac-positive candidate enhancers show a high validation rate in orthogonal enhancer activity assays, and a vast majority of endogenously active enhancers are marked by H2BNTac and H3K27ac. Notably, H2BNTac intensity predicts enhancer strength and outperforms the current state-of-the-art models in predicting CBP/p300 target genes. These findings have broad implications for generating fine-grained enhancer maps and modeling CBP/p300-dependent gene regulation.
2023-02-23 | GSE186349 | GEO
Project description:The transcription factors PAX3 and MITF are required for the development of the neural crest and melanocyte lineage, and both proteins play important roles in melanoma cell growth and survival. PAX3 transcriptionally activates MITF expression during neural crest development, but the relationship between these transcription factors during melanocyte development and in melanoma cells is currently poorly understood. This study aimed to further our understanding of the interaction between transcriptional networks controlled by PAX3 and MITF by assessing the effect of siRNA-mediated knockdown of PAX3 and MITF in metastatic melanoma cell lines. The goals of this study were to determine (i) if PAX3 is required for maintaining expression of MITF in melanoma and melanocyte cell lines; (ii) whether PAX3 and MITF independently, or redundantly, influence growth and survival in melanoma cell lines; and (iii) to investigate the respective roles of PAX3 and MITF expression in melanoma cell differentiation. Microarrays were used to measure global changes in transcript expression in response to siRNA-mediated knockdown of PAX3 or MITF compared to non-targeting controls in two metastatic melanoma cells lines. RNA was isolated from two different metastatic melanoma cell lines 30 hours after one of four different treaments: (i) transfection with siRNA targeting PAX3; or (ii) transfection with siRNA targeting MITF; or (iii) or transfection with siRNA targeting luciferase (non-targeting negative control); or (iv) treatment with media only (control). Therefore, eight samples were used for gene expression profiling by using GeneChip arrays, with one replicate per cell line per treatment.
2010-01-01 | E-GEOD-16249 | biostudies-arrayexpress
Project description:The ability of cancer cells to switch phenotype in response to a dynamic intra-tumor microenvironment is a major barrier to effective therapy. In melanoma, down-regulation of the lineage addiction oncogene MITF (Microphthalmia-associated transcription factor) is a hallmark of the proliferative-to-invasive phenotype switch. Yet how MITF promotes proliferation and suppresses invasion is poorly understood. Here we show that expression of the key lipogenic enzyme stearoyl-CoA desaturase (SCD) is activated by MITF, but suppressed by the stress-responsive transcription factor ATF4. SCD expression is required for MITF-positive melanoma cell proliferation,. By contrast, MITF-low cells express reduced levels of SCD and are insensitive to its inhibition, indicating that cell phenotype dictates response to drugs targeting lipid metabolism. Since SCD suppresses inflammatory signalling and ATF4 expression, the results identify a positive feedback-loop that can maintain an invasive phenotype, uncover a key role for MITF and ATF4 in metabolic reprograming, and reveal fatty acid composition as a driver of melanoma phenotype-switching.
2019-11-19 | PXD010254 | Pride