ABCB5 is activated by MITF and b-catenin and is associated with melanoma differentiation
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ABSTRACT:
PROVIDER: PRJNA563692 | ENA |
REPOSITORIES: ENA
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Project description:Defining markers of different phenotypic states in melanoma is important for understanding disease progression, determining the response to therapy, and defining the molecular mechanisms underpinning phenotype-switching driven by the changing intratumor microenvironment. The ABCB5 transporter is implicated in drug-resistance and has been identified as a marker of melanoma-initiating cells. Indeed, ongoing studies are using ABCB5 to define stem cell populations. However, we show here that the ABCB5 is a direct target for the Microphthalmia-associated transcription factor MITF and its expression can be induced by b-catenin, a key activator and co-factor for MITF. Consequently, ABCB5 mRNA expression is primarily associated with melanoma cells exhibiting differentiation markers. The results suggest first that ABCB5 is unlikely to represent a marker of dedifferentiated melanoma stem cells, and second that ABCB5 may contribute to the non-genetic drug-resistance associated with highly differentiated melanoma cells. To reconcile the apparently conflicting observations in the field we propose a model in which ABCB5 may mark a slow-cycling differentiated population of melanoma cells.
2019-10-16 | GSE136803 | GEO
Project description:Functional analysis of ABCB5 in A375 and G3361 melanoma cells, by comparing stably-transfected controls to ABCB5-shRNA-targeted cells. 12 samples total. Replicates n=3 for the following 4 groups: A375 pSUPER-retro-puro-Vector vs. A375 pSUPER-retro-puro-ABCB5-KD; G3361 pSUPER-retro-puro-shCNTRL vs. G3361 pSUPER-retro-puro-ABCB5-KD.
2014-06-17 | E-GEOD-38290 | biostudies-arrayexpress
Project description:Functional analysis of ABCB5 in A375 and G3361 melanoma cells, by comparing stably-transfected controls to ABCB5-shRNA-targeted cells.
2014-06-17 | GSE38290 | GEO
Project description:Canonical Wnt signaling plays an important role in development and disease, regulating transcription of target genes and stabilizing many proteins phosphorylated by Glycogen Synthase Kinase 3 (GSK3). We observed that the MiT family of transcription factors, which includes the melanoma oncogene MITF and the lysosomal master regulator TFEB, had the highest phylogenetic conservation of three consecutive putative GSK3 phosphorylation sites in animal proteomes. This prompted us to examine the relationship between MITF, endolysosomal biogenesis and Wnt signaling. Here we report that MITF expression levels correlated with the expression of a large subset of lysosomal genes in melanoma cell lines. MITF expression in the Tetracycline-inducible C32 melanoma model caused a marked increase in vesicular structures, and increased expression of late endosomal proteins such as Rab7, LAMP1, and CD63. These late endosomes were not functional lysosomes as they were less active in proteolysis, yet were able to concentrate Axin1, phospho-LRP6, phospho-β-Catenin, and GSK3 in the presence of Wnt ligands. This relocalization significantly enhanced Wnt signaling by increasing the number of multivesicular bodies (MVBs) into which the Wnt signalosome/destruction complex becomes localized upon Wnt signaling. We also show that the MITF protein was stabilized by Wnt signaling, through the novel C-terminal GSK3 phosphorylations identified here. MITF stabilization caused an increase in MVB biosynthesis, which in turn increased Wnt signaling, generating a positive feed-back loop that may function during the proliferative stages of melanoma. The results underscore the importance of misregulated endolysosomal biogenesis in Wnt signaling and cancer. Expression of selected Lysosomal genes and CLEAR element plus MITF were compared in 51 melanoma cell lines to a mixed reference pool containing equal amounts of 47 melanoma cell lines.
2014-12-24 | E-GEOD-64497 | 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. Experssion analysis by RNAseq of 14 melanoma cell lines.
2014-09-19 | E-GEOD-61544 | 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
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: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 most critical stage in initiation of melanoma metastasis is the radial to vertical growth transition, yet the triggers of this transition remain elusive. We introduce a novel perspective, suggesting that the microenvironment drives melanoma metastasis independently of mutation acquisition. Here we examined the changes in microenvironment that occur during melanoma radial growth. We show that direct contact of melanoma cells with the remote epidermal layer triggers vertical invasion via Notch signaling activation, the latter serving to inhibit MITF function. Briefly, within the native Notch ligand-free microenvironment, MITF, the melanocyte lineage master regulator, binds and represses miR-222/221 promoter in an RBPJK-dependent manner. However, when radial growth brings melanoma cells into contact with distal differentiated keratinocytes that express Notch ligands, the activated Notch intracellular domain impairs MITF binding to miR-222/221 promoter. This de-repression of miR-222/221 expression triggers initiation of invasion. Our findings may direct novel prevention opportunities via targeting specific microenvironment. Two replicates of Notch-activated cells that were seeded on Delta-like-1 (DLL1) (2 ng/µl ) coated plates were compared to two replicates of cells without Notch activation. The goal of this experiment is to evaluate the changes of miRs expression in melanoma cells upon Notch signaling activation.
2015-07-30 | E-GEOD-69403 | biostudies-arrayexpress