title: Beta-catenin-induced melanoma growth requires the downstream target Microphthalmia-associated transcription factor.
abstract: The transcription factor Microphthalmia-associated transcription factor (MITF) is a lineage-determination factor, which modulates melanocyte differentiation and pigmentation. MITF was recently shown to reside downstream of the canonical Wnt pathway during melanocyte differentiation from pluripotent neural crest cells in zebrafish as well as in mammalian melanocyte lineage cells. Although expression of many melanocytic/pigmentation markers is lost in human melanoma, MITF expression remains intact, even in unpigmented tumors, suggesting a role for MITF beyond its role in differentiation. A significant fraction of primary human melanomas exhibit deregulation (via aberrant nuclear accumulation) of beta-catenin, leading us to examine its role in melanoma growth and survival. Here, we show that beta-catenin is a potent mediator of growth for melanoma cells in a manner dependent on its downstream target MITF. Moreover, suppression of melanoma clonogenic growth by disruption of beta-catenin-T-cell transcription factor/LEF is rescued by constitutive MITF. This rescue occurs largely through a prosurvival mechanism. Thus, beta-catenin regulation of MITF expression represents a tissue-restricted pathway that significantly influences the growth and survival behavior of this notoriously treatment-resistant neoplasm.
authors.affiliation: Department of Pediatric Oncology, Dana-Farber Cancer Institute, Dana 630, 44 Binney Street, Boston, MA 02115, USA.
authors.forename: Hans R
authors.initials: HR
authors.lastname: Widlund
authors.forename: Martin A
authors.initials: MA
authors.lastname: Horstmann
authors.forename: E Roydon
authors.initials: ER
authors.lastname: Price
authors.forename: Junqing
authors.initials: J
authors.lastname: Cui
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Lessnick
authors.forename: Min
authors.initials: M
authors.lastname: Wu
authors.forename: Xi
authors.initials: X
authors.lastname: He
authors.forename: David E
authors.initials: DE
authors.lastname: Fisher
mesh_terms: D000818:Animals; D017209:Apoptosis; D002455:Cell Division; D002460:Cell Line; D003598:Cytoskeletal Proteins / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015972:Gene Expression Regulation, Neoplastic; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D051821:Lymphoid Enhancer-Binding Factor 1; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008546:Melanoma, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D051379:Mice; D051739:Microphthalmia-Associated Transcription Factor; D011401:Promoter Regions, Genetic; D015534:Trans-Activators / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism / Q000502:physiology*; D015533:Transcriptional Activation; D014162:Transfection; D014407:Tumor Cells, Cultured; D051176:beta Catenin
chemical_list: C495270:CTNNB1 protein, human; C495267:CTNNB1 protein, mouse; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; D051821:Lymphoid Enhancer-Binding Factor 1; C497234:MITF protein, human; D051739:Microphthalmia-Associated Transcription Factor; C497235:Mitf protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D051176:beta Catenin; D049452:Green Fluorescent Proteins