RESUMO
Tyrosine phosphorylation is important in signaling pathways underlying tumorigenesis. We performed a mutational analysis of the protein tyrosine kinase (PTK) gene family in cutaneous metastatic melanoma. We identified 30 somatic mutations affecting the kinase domains of 19 PTKs and subsequently evaluated the entire coding regions of the genes encoding these 19 PTKs for somatic mutations in 79 melanoma samples. We found ERBB4 mutations in 19% of individuals with melanoma and found mutations in two other kinases (FLT1 and PTK2B) in 10% of individuals with melanomas. We examined seven missense mutations in the most commonly altered PTK gene, ERBB4, and found that they resulted in increased kinase activity and transformation ability. Melanoma cells expressing mutant ERBB4 had reduced cell growth after shRNA-mediated knockdown of ERBB4 or treatment with the ERBB inhibitor lapatinib. These studies could lead to personalized therapeutics specifically targeting the kinases that are mutationally altered in individual melanomas.
Assuntos
Receptores ErbB/genética , Melanoma/genética , Mutação , Proteínas Tirosina Quinases/análise , Proteínas Tirosina Quinases/genética , Neoplasias Cutâneas/genética , Animais , Antineoplásicos/farmacologia , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Transformação Celular Neoplásica/genética , Humanos , Lapatinib , Melanoma/enzimologia , Melanoma/patologia , Camundongos , Quinazolinas/farmacologia , Interferência de RNA , Receptor ErbB-4 , Neoplasias Cutâneas/enzimologia , Neoplasias Cutâneas/patologiaRESUMO
Microphthalmia-associated transcription factor (MITF) is involved in melanocyte cell development, pigmentation and neoplasia. To determine whether MITF is somatically mutated in melanoma, we compared the sequence of MITF from primary and metastatic lesions to patient-matched normal DNA. In the 50 metastatic melanoma tumor lines analysed, we discovered four samples that had genomic amplifications of MITF and four that had MITF mutations in the regions encoding the transactivation, DNA binding or basic, helix-loop-helix domains. Sequence analysis for SOX10, a transcription factor, which both acts upstream of MITF and synergizes with MITF, identified an additional three samples with frameshift or nonsense mutations. Microphthalmia-associated transcription factor and SOX10 were found to be mutated in a mutually exclusive fashion, possibly suggesting disruption in a common genetic pathway. Taken together we found that over 20% of the metastatic melanoma cases had alterations in the MITF pathway. We show that the MITF pathway is also altered in primary melanomas: 2/26 demonstrated mutations in MITF and 6/55 demonstrated mutations in SOX10. Our findings suggest that altered MITF function during melanomagenesis can be achieved by MITF amplification, MITF single base substitutions or by mutation of its regulator SOX10.
Assuntos
Melanoma/metabolismo , Fator de Transcrição Associado à Microftalmia/fisiologia , Mutação , Neoplasias Cutâneas/metabolismo , Linhagem Celular Tumoral , Códon sem Sentido , Mutação da Fase de Leitura , Genes ras/fisiologia , Humanos , Melanoma/genética , Melanoma/patologia , Fator de Transcrição Associado à Microftalmia/genética , Metástase Neoplásica , Proteínas Proto-Oncogênicas B-raf/metabolismo , Fatores de Transcrição SOXE/genética , Fatores de Transcrição SOXE/fisiologia , Neoplasias Cutâneas/genética , Neoplasias Cutâneas/patologiaRESUMO
A mutational analysis of the matrix metalloproteinase (MMP) gene family in human melanoma identified somatic mutations in 23% of melanomas. Five mutations in one of the most commonly mutated genes, MMP8, reduced MMP enzyme activity. Expression of wild-type but not mutant MMP8 in human melanoma cells inhibited growth on soft agar in vitro and tumor formation in vivo, suggesting that wild-type MMP-8 has the ability to inhibit melanoma progression.