Project description:Primary and metastatic human melanoma cells were transfected with control siRNA or siSTAT3 to silence its expression. The global gene expression was evaluated after 48 h and related to gene levels in cells transfected with siRNA control.
Project description:The phenomenon that metastatic lesion developed on injured sites has long been recognized in a number of cancers, such as melanoma. The factors associated with wound healing that attract circulating tumor cells have remained unknown, however. A patient with acral lentiginous melanoma presented with a metastatic lesion that appeared 1 month after trauma. To explore the molecular mechanism underlying the promotion of wound metastasis in melanoma, we performed microarray analysis of the metastatic lesions (n = 2) and the primary lesions (n = 3) of the patient. Using Human Genome U133 Plus 2.0 array, we compared global gene expression profiles of tissues derived from the patient’s primary (n = 3) and wound metastatic (n = 2) lesions to search for particular biological functions in genes of which expression intensities were increased in the wound metastasic lesions of melanoma.
Project description:The phenomenon that metastatic lesion developed on injured sites has long been recognized in a number of cancers, such as melanoma. The factors associated with wound healing that attract circulating tumor cells have remained unknown, however. A patient with acral lentiginous melanoma presented with a metastatic lesion that appeared 1 month after trauma. To explore the molecular mechanism underlying the promotion of wound metastasis in melanoma, we performed microarray analysis of the metastatic lesions (n = 2) and the primary lesions (n = 3) of the patient.
Project description:We sought to identify genes and gene signatures which correlate with progression by sampling human melanomas from nevi, primary, and metastatic tumors. The large number of samples also permits analysis within groups. Human melanoma samples were isolated from historical frozen patient specimens. RNA was extracted and run on the human Affymetrix U133A microarray chip.
Project description:Human melanomas frequently harbor amplifications of EZH2. However, the oncogenic contribution of this methyltransferase to melanoma formation has remained elusive. Taking advantage of murine melanoma models, we now show that EZH2 drives tumorigenesis from benign BrafV600E or NrasQ61K-expressing melanocytes. EZH2 oncogenicity results from silencing of genes relevant for the integrity of the primary cilium, a signaling organelle projecting from the surface of vertebrate cells. Consequently, gain of EZH2 function promotes loss of primary cilia in benign melanocytic lesions. In contrast, blockade of EZH2 activity evokes ciliogenesis and cilia-dependent growth inhibition in malignant melanoma. Finally, we demonstrate that loss of cilia enhances pro-tumorigenic WNT/β-catenin signaling and is itself sufficient to drive metastatic melanoma in benign cells. Thus, primary cilia deconstruction is a key process in EZH2-driven melanomagenesis.
Project description:Metastatic melanoma is hallmarked by its ability to switch oncogenic MITF expression. Here we tested the impact of STAT3 on melanoma onset and progression in association with MITF expression levels. We established a mouse melanoma model for deleting Stat3 specifically in melanocytes with specific expression of human hyperactive NRASQ61K in an Ink4a deficient background. Mice with tissue specific Stat3 deletion showed an early onset of disease, but displayed significantly diminished lung metastasis. Whole genome expression profiling also revealed a reduced invasion phenotype, which was functionally confirmed in 3D melanoma model systems. Notably, loss or knockdown of STAT3 in mouse or human cells resulted in up-regulation of MITF and induction of cell proliferation. Mechanistically we show that STAT3 induced CEBPa/b expression was sufficient to suppress MITF transcription. Epigenetic analysis by ATAC-seq confirmed that STAT3 enabled CEBPa/b binding to the MITF enhancer region thereby silencing it. We conclude that STAT3 is a metastasis driver able to antagonize the MITF oncogene via direct induction of CEBP family member transcription facilitating RAS-RAF-driven melanoma metastasis.