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Project description:Despite the improvement of therapeutic options for melanoma, patients with advanced metastatic disease are still in high need of durable and tolerated treatments. Analysis of clinical data from patients receiving targeted and/or immunotherapy, along with genetic and functional studies in preclinical melanoma models, show that lineage addiction to MITF is retained throughout disease progression, thus providing the rationale to pursue therapeutic inhibition of MITF. However, direct targeting of MITF or other basic helix-loop-helix leucine zipper (bHLH-LZ) transcription factors is unprecedented. Here, we report on the fragment-based discovery of high-affinity ligands for MITF. Fragment screening by NMR led to the discovery of weak binders to the kink pocket of MITF, which were optimized to sub-micromolar affinity by structure-based design enabled by crystallography and biophysics. Furthermore, NMR experiments and molecular dynamics simulations revealed a dynamic conformational exchange of the two helices in the asymmetric homodimer, which is perturbed by ligand binding. This work advances our knowledge on direct targeting of bHLH-LZ domains and sets the basis to further explore pharmacological inhibition of MITF.
2025-11-26 | GSE283855 | GEO
Project description:Despite the improvement of therapeutic options for melanoma, patients with advanced metastatic disease are still in high need of durable and tolerated treatments. Analysis of clinical data from patients receiving targeted and/or immunotherapy, along with genetic and functional studies in preclinical melanoma models, show that lineage addiction to MITF is retained throughout disease progression, thus providing the rationale to pursue therapeutic inhibition of MITF. However, direct targeting of MITF or other basic helix-loop-helix leucine zipper (bHLH-LZ) transcription factors is unprecedented. Here, we report on the fragment-based discovery of high-affinity ligands for MITF. Fragment screening by NMR led to the discovery of weak binders to the kink pocket of MITF, which were optimized to sub-micromolar affinity by structure-based design enabled by crystallography and biophysics. Furthermore, NMR experiments and molecular dynamics simulations revealed a dynamic conformational exchange of the two helices in the asymmetric homodimer, which is perturbed by ligand binding. This work advances our knowledge on direct targeting of bHLH-LZ domains and sets the basis to further explore pharmacological inhibition of MITF.
2025-11-26 | GSE283856 | GEO
Project description:Direct Targeting of the Oncogene Microphthalmia-Associated Transcription Factor (MITF) by Fragment-Based Discovery
| PRJNA1195915 | ENA
Project description:Direct Targeting of the Oncogene Microphthalmia-Associated Transcription Factor (MITF) by Fragment-Based Discovery [RNA-seq]
| PRJNA1195918 | ENA
Project description:Direct Targeting of the Oncogene Microphthalmia-Associated Transcription Factor (MITF) by Fragment-Based Discovery [Cut & Tag]
| PRJNA1195919 | ENA
Project description:Microphthalmia-associated transcription factor (MITF) is a key transcription factor in melanoma development and progression. MITF amplification and downregulation have been observed in a significant proportion of melanoma patients and correlate with clinical outcomes. Here, we have investigated the effect of MITF on melanoma chemokine expression and immune cell attraction. In B16F10 melanoma cells, MITF knockdown reduced expression of CXCL10, with concomitantly decreased attraction of immune cells and accelerated tumor outgrowth. Conversely, overexpression of MITF in YUMM1.1 melanoma cells also led to an increased immune cell attraction in vitro. Subcutaneous YUMM1.1 melanomas overexpressing MITF however showed a reduced immune infiltration of lymphocytes and an increased tumor growth. In human melanoma cell lines, silencing of MITF enhanced chemokine production and immune cell attraction, while overexpression of MITF led to lower immune cell attraction. In summary, our results show that MITF regulates chemokine expression in murine and in human melanoma cells, and affects in vivo immune cell attraction and tumor growth. These results reveal a functional relationship between MITF and immune cell infiltration, which may be exploited for cancer therapy.
| S-EPMC6290759 | biostudies-literature
Project description:Melanoma, a melanocyte-origin neoplasm, is a highly metastatic and treatment-resistance cancer. While it is well established that notch signaling activation promotes melanoma progression, little is known about the reciprocal interactions between Notch signaling and melanoma-specific pathways. Here we reveal a negative regulatory loop between Notch signaling and microphthalmia-associated transcription factor (MITF), the central regulator of melanoma progression and the driver of melanoma plasticity. We further demonstrate that Notch signaling activation, in addition to the known competition-based repression mechanism of MITF transcriptional activity, inhibits the transcription of MITF, leading to a decrease in MITF expression. We also found that MITF binds to the promoter of the gene encoding the master regulator of Notch signaling, recombination signal binding protein J kappa (RBPJK), leading to its upregulation. Our findings suggest that, once activated, Notch signaling represses MITF signaling to maintain the melanoma invasiveness and metastatic phenotype.
| S-EPMC6387231 | biostudies-literature
Project description:The history of the discovery of the microphthalmia locus and its gene, now called Mitf, is a testament to the triumph of serendipity. Although the first microphthalmia mutation was discovered among the descendants of a mouse that was irradiated for the purpose of mutagenesis, the mutation most likely was not radiation induced but occurred spontaneously in one of the parents of a later breeding. Although Mitf might eventually have been identified by other molecular genetic techniques, it was first cloned from a chance transgene insertion at the microphthalmia locus. And although Mitf was found to encode a member of a well-known transcription factor family, its analysis might still be in its infancy had Mitf not turned out to be of crucial importance for the physiology and pathology of many distinct organs, including eye, ear, immune system, bone, and skin, and in particular for melanoma. In fact, near seven decades of Mitf research have led to many insights about development, function, degeneration, and malignancies of a number of specific cell types, and it is hoped that these insights will one day lead to therapies benefitting those afflicted with diseases originating in these cell types.
| S-EPMC2964399 | biostudies-literature
Project description:ObjectivesTo characterize the clinical presentation, genomic alterations, pathologic phenotype and clinical management of microphthalmia-associated transcription factor (MITF) familial renal cell carcinoma (RCC), caused by a member of the TFE3, TFEB, and MITF family of transcription factor genes.MethodsThe clinical presentation, family history, tumor histopathology, and surgical management were evaluated and reported herein. DNA sequencing was performed on blood DNA, tumor DNA and DNA extracted from adjacent normal kidney tissue. Copy number and gene expression analyses on tumor and normal tissues were performed by Real-Time Polymerase chain reaction. TCGA gene expression data were used for comparative analysis. Protein expression and subcellular localization were evaluated by immunohistochemistry.ResultsGermline genomic analysis identified the MITF p.E318K variant in a patient with bilateral, multifocal type 1 papillary RCC and a family history of RCC. All tumors displayed the MITF variant and were characterized by amplification of chromosomes 7 and 17, hallmarks of type 1 papillary RCC. We demonstrated that MITF p.E318K variant results in altered transcriptional activity and that downstream targets of MiT family members, such as GPNMB, are dysregulated in the tumors.ConclusionAssociation of the pathogenic MITF variant with bilateral and multifocal type 1 papillary RCC in this family supports its role as a risk allele for the development of RCC and emphasizes the importance of screening for MITF variants irrelevant of the RCC histologic subtype. This study identifies potential biomarkers for the disease, such as GPNMB expression, that may facilitate the development of targeted therapies for patients affected with MITF-associated RCC.
| S-EPMC8728951 | biostudies-literature
Project description:Mutations in the microphthalmia-associated transcription factor (Mitf) gene can cause retinal pigment epithelium (RPE) and retinal dysfunction and degeneration. We examined retinal and RPE structure and function in 3 month old mice homo- or heterozygous or compound heterozygous for different Mitf mutations (Mitfmi-vga9/+, Mitfmi-enu22(398)/Mitfmi-enu22(398), MitfMi-Wh/+ and MitfMi-Wh/Mitfmi) which all have normal eye size with apparently normal eye pigmentation. Here we show that their vision and retinal structures are differentially affected. Hypopigmentation was evident in all the mutants while bright-field fundus images showed yellow spots with non-pigmented areas in the Mitfmi-vga9/+ mice. MitfMi-Wh/+ and MitfMi-Wh/Mitfmi mice showed large non-pigmented areas. Fluorescent angiography (FA) of all mutants except Mitfmi-vga9/+ mice showed hyperfluorescent areas, whereas FA from both Mitf-Mi-Wh/+ and MitfMi-Wh/Mitfmi mice showed reduced capillary network as well as hyperfluorescent areas. Electroretinogram (ERG) recordings show that MitfMi-Wh/+ and MitfMi-Wh/Mitfmi mice are severely impaired functionally whereas the scotopic and photopic ERG responses of Mitfmi-vga9/+ and Mitfmi-enu22(398)/Mitfmi-enu22(398) mice were not significantly different from wild type mice. Histological sections demonstrated that the outer retinal layers were absent from the MitfMi-Wh/+ and MitfMi-Wh/Mitfmi blind mutants. Our results show that Mitf mutations affect eye function, even in the heterozygous condition and that the alleles studied can be arranged in an allelic series in this respect.
| S-EPMC6817937 | biostudies-literature