title: A two-hit model for development of multiple endocrine neoplasia type 2B by RET mutations.
abstract: Multiple endocrine neoplasia (MEN) type 2B mutations have been reported at methionine 918 or alanine 883 in the tyrosine kinase domain of the RET proto-oncogene. Recently, a new combination of two germline missense mutations at valine 804 and tyrosine 806 was identified in a patient with MEN 2B-like clinical phenotypes including medullary thyroid carcinoma, mucosal neuroma, and marfanoid habitus. In this case, valine 804 and tyrosine 806 were replaced with methionine and cysteine, respectively. In the present study, biological activities of RET with these new mutations were compared with those with known MEN 2A or MEN 2B mutations. The transforming activity of RET with the V804M/Y806C mutation was about 8- to 13-fold higher than that of RET with a single V804M or Y806C mutation. Like RET with the M918T or A883F MEN 2B mutation, the transforming activity of RET with the V804M/Y806C mutation was not affected by substitution of phenylalanine for tyrosine 905 that abolished the activity of RET with the MEN 2A mutation. On the other hand, substitution of phenylalanine for tyrosines 864 and 952 drastically diminished the activity of RET with the V804M/Y806C, M918T or A883F mutation, suggesting that these three mutant proteins have similar biological properties.
authors.affiliation: Department of Pathology, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Iwashita
authors.forename: H
authors.initials: H
authors.lastname: Murakami
authors.forename: K
authors.initials: K
authors.lastname: Kurokawa
authors.forename: K
authors.initials: K
authors.lastname: Kawai
authors.forename: A
authors.initials: A
authors.lastname: Miyauchi
authors.forename: H
authors.initials: H
authors.lastname: Futami
authors.forename: S
authors.initials: S
authors.lastname: Qiao
authors.forename: M
authors.initials: M
authors.lastname: Ichihara
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
mesh_terms: D016475:3T3 Cells; D000328:Adult; D019943:Amino Acid Substitution; D000818:Animals; D029721:Drosophila Proteins; D005260:Female; D018095:Germ-Line Mutation; D006801:Humans; D008297:Male; D051379:Mice; D008957:Models, Genetic; D018814:Multiple Endocrine Neoplasia Type 2b / Q000235:genetics* / Q000378:metabolism; D020125:Mutation, Missense; D010375:Pedigree; D017434:Protein Structure, Tertiary; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics*; D051096:Proto-Oncogene Proteins c-ret; D011519:Proto-Oncogenes; D020794:Receptor Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics*; D014170:Transformation, Genetic; D014443:Tyrosine / Q000235:genetics
chemical_list: D029721:Drosophila Proteins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D014443:Tyrosine; D051096:Proto-Oncogene Proteins c-ret; D020794:Receptor Protein-Tyrosine Kinases; C416649:Ret protein, Drosophila; C494999:Ret protein, mouse