title: Genomic structure and loss of heterozygosity of EPHB2 in colorectal cancer.
abstract: EphB2, a member of the Eph receptor protein-tyrosine kinase family, is overexpressed in several human gastrointestinal tumors. Furthermore, the EphB2 gene is localized at 1p35-p36.1, a frequently deleted region in colon and other cancers. So, despite its overexpression in some kind of tumors, we decided to study the possibility of involvement in the EphB2 gene (EPHB2) mutation in colon cancers, because some of the well known tumor suppressor genes (e.g. p53) is overexpressed (really accumulated) in tumors. Fifty colon tumor samples of matched with their respective normal tissues, were studied for mutation of the EPHB2. Analysis of the genomic structure of EphB2 and survey of all 16 exons revealed an infrequent polymorphism (intron 2) and mutation (intron 8). Another polymorphism in exon 6, localized at nucleotide 1359 (A-->G) was found to be rather frequent in Japanese and Chinese subjects, but very rare in Caucasians. Taking advantage of this polymorphism within EPHB2, we surveyed the loss of heterozygosity (LOH) status of this gene in Japanese colorectal tumors. Among the 50 samples analyzed, 24 were informative, and LOH was found in five of the15 (33.3%) informative rectal cancer cases. Mutation analysis covering all 16 exons in the remaining allele did not reveal any mutations. Thus, EPHB2 is not a classical tumor suppressor gene.
authors.affiliation: First Department of Pathology, Hamamatsu University School of Medicine, 3600 Handa-cho, Hamamatsu, 431-3192, Japan.
authors.forename: S M
authors.initials: SM
authors.lastname: Oba
authors.forename: Y J
authors.initials: YJ
authors.lastname: Wang
authors.forename: J P
authors.initials: JP
authors.lastname: Song
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Li
authors.forename: K
authors.initials: K
authors.lastname: Kobayashi
authors.forename: S
authors.initials: S
authors.lastname: Tsugane
authors.forename: G S
authors.initials: GS
authors.lastname: Hamada
authors.forename: M
authors.initials: M
authors.lastname: Tanaka
authors.forename: H
authors.initials: H
authors.lastname: Sugimura
mesh_terms: D000368:Aged; D000483:Alleles; D001315:Australia; D002681:China; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1; D003110:Colonic Neoplasms / Q000235:genetics; D015179:Colorectal Neoplasms / Q000235:genetics*; D004252:DNA Mutational Analysis; D005091:Exons; D005260:Female; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D007438:Introns; D007564:Japan; D019656:Loss of Heterozygosity; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009154:Mutation; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics*; D036183:Receptor, EphB2; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012737:Sex Factors; D013557:Switzerland; D019680:Trinucleotide Repeat Expansion
chemical_list: D020794:Receptor Protein-Tyrosine Kinases; D036183:Receptor, EphB2