Modulation of the transcriptional response to TNF-alpha in the human melanoma cell line MZ7 by MITF
ABSTRACT: We analyzed the transcriptional response of the human melanoma cell line MZ7 to TNF-alpha (24 hours) in a dose-dependent manner (TNF-alpha 10U/ml, 100U/ml, 1000U/ml) either transfected with control siRNA (siNT = non-targeting siRNA) or transfected with siRNAs (pool of 4 active and independent siRNAs) against the melanocytic transcription factor and lineage oncogene MITF. (Microphthalmia-associated transcription factor). The experiment was performed as biological duplicate. As MITF is critical for melanoma cell state control, we aimed to explore how MITF expression intersects with inflammation-induced plasticity pathways in melanoma. Total RNA was obtained from siRNA/TNF-treated MZ7 melanoma cell lines at various conditions and global gene expression profiling was done using the Illumina Human HT12 v4 platform.
Project description:Ma-Mel-15 human melanoma cell cultures were transiently transfected (RNAiMax, Lipofectamin) with control siRNA, siRNA against MITF (pool of 4 siRNAs), siRNA against c-JUN (pool of 4 siRNAs) or combinations of siMITF and siJUN. Cells were then either treated with TNF-alpha (1000U/ml) for 24 hours or left untreated. The experiment was performed as biological duplicates. We aimed to determine how c-JUN cooperates with acute MITF-loss in human melanoma cells to increase inflammatory responsiveness and cell plasticity. Total RNA was obtained from siRNA/TNF-treated Ma-Mel-15 melanoma cell lines and global gene expression profiling was done using the Illumina Human HT12 v4 platform.
Project description:We analyzed the transcriptional response of the human melanoma cell line Ma-Mel-15 either transfected with control siRNA (siNT = non-targeting siRNA) or transfected with siRNAs (pool of 4 active and independent siRNAs) directed against the melanocytic transcription factor and lineage oncogene MITF (Microphthalmia-associated transcription factor). The experiment was performed as biological duplicates and RNA was isolated 48 hours after siRNA transfection. We aimed to determine novel markers and pathways of melanoma cell plasticity. Total RNA was obtained from siRNA-treated Ma-Mel-15 melanoma cell lines and global gene expression profiling was done using the Illumina Human HT12 v4 platform.
Project description:It is unclear whether siRNA-based agents can be a safe and effective therapy for diseases. In this study, we demonstrate that microphthalmia-associated transcription factor-siRNA (MITF-siR)-silenced MITF gene expression effectively induced a significant reduction in tyrosinase (TYR), tyrosinase-related protein 1, and melanocortin 1 receptor (MC1R) levels. The siRNAs caused obvious inhibition of melanin synthesis and melanoma cell apoptosis. Using a novel type of transdermal peptide, we developed the formulation of an MITF-siR cream. Results demonstrated that hyperpigmented facial lesions of siRNA-treated subjects were significantly lighter after 12 weeks of therapy than before treatment (P < 0.001); overall improvement was first noted after 4 weeks of siRNA treatment. At the end of treatment, clinical and colorimetric evaluations demonstrated a 90.4% lightening of the siRNA-treated lesions toward normal skin color. The relative melanin contents in the lesions and adjacent normal skin were decreased by 26% and 7.4%, respectively, after treatment with the MITF-siR formulation. Topical application of siRNA formulation significantly lightens brown facial hypermelanosis and lightens normal skin in Asian individuals. This treatment represents a safe and effective therapy for melasma, suggesting that siRNA-based agents could be developed for treating other diseases such as melanoma.
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.
Project description:A panel of 17 human melanoma cell lines with known BRAF and NRAS mutation status was stimulated with TNF-alpha for 72 hours. The goal of the study was to correlate the transcriptional response in BRAF versus NRAS mutated melanoma cell lines. Total RNA was obtained from a panel of 17 human melanoma cell lines treated for 72 hours with TNF-alpha or left untreated. Gene expression profiling was done using the Illumina Human HT12 v4 platform.
Project description:BACKGROUND:We recently reported that the progestagen-associated endometrial protein (PAEP) gene is overexpressed and promotes tumor proliferation and metastasis in human melanoma. METHODS:To identify the molecules that regulate its expression and oncogenic properties, we analyzed the gene microarray profiling of melanoma samples of serial clinical stage. RESULTS:We found that the expression profile of the PAEP gene parallels that of microphthalmia-associated transcription factor (MITF, r ?=? 0.86), a master regulator of melanocyte development and melanoma progression. This parallelism was further confirmed with semiquantitative reverse transcriptase polymerase chain reaction analysis of melanoma-derived daughter cells. Transfection of melanoma cells with MITF small interfering RNA (siRNA) specifically diminishes PAEP gene expression, whereas PAEP siRNA transfection has no effect on MITF. Furthermore, knockdown of either the MITF or PAEP gene reveals a significant inhibition of tumor cell migration. CONCLUSIONS:Our data indicate that PAEP expression is regulated in part by MITF and may thus play a role in MITF-mediated cell migration in human melanoma.
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.
Project description:CITED1 is a non-DNA binding transcriptional co-regulator whose expression can distinguish the 'proliferative' from 'invasive' signature in the phenotype-switching model of melanoma. We have found that, in addition to other 'proliferative' signature genes, CITED1 expression is repressed by TGF? while the 'invasive' signature genes are upregulated. In agreement, CITED1 positively correlates with MITF expression and can discriminate the MITF-high/pigmentation tumour molecular subtype in a large cohort (120) of melanoma cell lines. Interestingly, CITED1 overexpression significantly suppressed MITF promoter activation, mRNA and protein expression levels while MITF was transiently upregulated following siRNA mediated CITED1 silencing. Conversely, MITF siRNA silencing resulted in CITED1 downregulation indicating a reciprocal relationship. Whole genome expression analysis identified a phenotype shift induced by CITED1 silencing and driven mainly by expression of MITF and a cohort of MITF target genes that were significantly altered. Concomitantly, we found changes in the cell-cycle profile that manifest as transient G1 accumulation, increased expression of CDKN1A and a reduction in cell viability. Additionally, we could predict survival outcome by classifying primary melanoma tumours using our in vitro derived 'CITED1-silenced' gene expression signature. We hypothesize that CITED1 acts a regulator of MITF, functioning to maintain MITF levels in a range compatible with tumourigenesis.
Project description:Investigation of expression differences between skin and melanomas from a transgenic BRAFV600E zebrafish model of melanoma The embryos described in this study are further analyzed in a manuscript submitted for publication by White, et al. A 15 chip study using RNA extracted from either WT zebrafish skin, mitf-BRAFV600E;p53-/- skin or mitf-BRAFV600E;p53-/- melanoma
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.