Fyrirlesari: Remina Dilixiati, doktorsnemi á rannsóknastofu Eiríks Steingrímssonar, Sturlugötu 8
Titill: Role of MITF in melanoma phenotype switching
Útdráttur: Microphthalmia-associated transcription factor (MITF) acts as a master regulator of melanocyte development and differentiation, and is known as a melanoma oncogene. A rheostat model has been described for MITF activity, where high levels of MITF favor proliferation and differentiation and low levels of MITF promote a stem cell-like phenotype. According to this model, MITF forms the basis of cellular heterogeneity in melanoma. The scope of this study was to further characterize the role of MITF in melanoma phenotype switching. To this end, we used MITF CRISPR knock out cell lines (SKMEL28) to compare cellular morphology and behavior to MITF wild type cells. Results from BrdU and MTT assay showed that MITF CRISPR knock out cell lines have a reduced proliferation rate compared to the parental line. Flow cytometry analysis revealed that MITF null cells are increased in size and appear more granular. The migration and invasion ability of MITF null cells was found to be significantly reduced as validated by transwell migration and invasion assays. By performing RNA sequencing, we found that differentially expressed genes overlap extensively with the gene signatures of MITFhigh and MITFlow melanoma tumors reported in the Cancer Genome Atlas. GO term analysis showed that differentially expressed genes were associated with extracellular matrix, cell adhesion and pigmentation. Taken together, our results indicate that MITF null cells are less migratory and proliferative due to a downregulation of proliferation-associated genes and overexpression of stem cell marker genes. Currently, we are testing the metastatic potential of these cell lines in vivo, and we are looking for specific gene sets responsible for the observed phenotype.