RESUMO
Uveal melanoma (UM) is characterized by mutually exclusive activating mutations in GNAQ, GNA11, CYSLTR2, and PLCB4, four genes in a linear pathway to activation of PLCß in almost all tumors and loss of BAP1 in the aggressive subset. We generated mice with melanocyte-specific expression of GNA11Q209L with and without homozygous Bap1 loss. The GNA11Q209L mice recapitulated human Gq-associated melanomas, and they developed pigmented neoplastic lesions from melanocytes of the skin and non-cutaneous organs, including the eye and leptomeninges, as well as at atypical sites, including the lymph nodes and lungs. The addition of Bap1 loss increased tumor proliferation and cutaneous melanoma size. Integrative transcriptome analysis of human and murine melanomas identified RasGRP3 to be specifically expressed in GNAQ/GNA11-driven melanomas. In human UM cell lines and murine models, RasGRP3 is specifically required for GNAQ/GNA11-driven Ras activation and tumorigenesis. This implicates RasGRP3 as a critical node and a potential target in UM.
Assuntos
Subunidades alfa de Proteínas de Ligação ao GTP/metabolismo , Melanócitos/metabolismo , Melanoma/metabolismo , Melanoma/patologia , Transdução de Sinais , Neoplasias Uveais/metabolismo , Neoplasias Uveais/patologia , Fatores ras de Troca de Nucleotídeo Guanina/metabolismo , Animais , Linhagem Celular Tumoral , Linhagem da Célula/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Neoplasias do Sistema Nervoso Central/patologia , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Melanócitos/efeitos dos fármacos , Melanócitos/patologia , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Invasividade Neoplásica , Inibidores de Proteínas Quinases/farmacologia , Transdução de Sinais/efeitos dos fármacos , Neoplasias Cutâneas/patologia , Proteínas Supressoras de Tumor/metabolismo , Ubiquitina Tiolesterase/metabolismoRESUMO
Fusion between TMPRSS2 and ERG, placing ERG under the control of the TMPRSS2 promoter, is the most frequent genetic alteration in prostate cancer, present in 40-50% of cases. The fusion event is an early, if not initiating, event in prostate cancer, implicating the TMPRSS2-positive prostate epithelial cell as the cancer cell of origin in fusion-positive prostate cancer. To introduce genetic alterations into Tmprss2-positive cells in mice in a temporal-specific manner, we generated a Tmprss2-CreERT2 knock-in mouse. We found robust tamoxifen-dependent Cre activation in the prostate luminal cells but not basal epithelial cells, as well as epithelial cells of the bladder and gastrointestinal (GI) tract. The knock-in allele on the Tmprss2 locus does not noticeably impact prostate, bladder, or gastrointestinal function. Deletion of Pten in Tmprss2-positive cells of adult mice generated neoplasia only in the prostate, while deletion of Apc in these cells generated neoplasia only in the GI tract. These results suggest that this new Tmprss2-CreERT2 mouse model will be a useful resource for genetic studies on prostate and colon.
Assuntos
Neoplasias do Colo/genética , Neoplasias da Próstata/genética , Serina Endopeptidases/genética , Animais , Fusão Gênica Artificial/métodos , Modelos Animais de Doenças , Feminino , Técnicas de Introdução de Genes , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Regiões Promotoras Genéticas , Tamoxifeno/farmacologiaRESUMO
Uveal melanomas are molecularly distinct from cutaneous melanomas and lack mutations in BRAF, NRAS, KIT, and NF1. Instead, they are characterized by activating mutations in GNAQ and GNA11, two highly homologous α subunits of Gαq/11 heterotrimeric G proteins, and in PLCB4 (phospholipase C ß4), the downstream effector of Gαq signaling. We analyzed genomics data from 136 uveal melanoma samples and found a recurrent mutation in CYSLTR2 (cysteinyl leukotriene receptor 2) encoding a p.Leu129Gln substitution in 4 of 9 samples that lacked mutations in GNAQ, GNA11, and PLCB4 but in 0 of 127 samples that harbored mutations in these genes. The Leu129Gln CysLT2R mutant protein constitutively activates endogenous Gαq and is unresponsive to stimulation by leukotriene. Expression of Leu129Gln CysLT2R in melanocytes enforces expression of a melanocyte-lineage signature, drives phorbol ester-independent growth in vitro, and promotes tumorigenesis in vivo. Our findings implicate CYSLTR2 as a uveal melanoma oncogene and highlight the critical role of Gαq signaling in uveal melanoma pathogenesis.