Analysis of specific gene mutations in the transforming growth factor-beta signal transduction pathway in human ovarian cancer.
Several proteins, including transforming growth factor beta (TGF-beta) receptor type I (RI), TGF-beta receptor type II (RII), Smad2, Smad3, and Smad4/DPC4, have been identified in the transduction pathway of the tumor suppressor TGF-beta. Mutations in TGF-beta RI, TGF-beta RII, Smad2, and Smad4/DPC4 genes are associated with several human cancers. The present study examines these gene mutations in 32 human ovarian cancers and 14 patient-matched normal tissues. For the first time, mutations in the Smad2 and Smad4 genes were analyzed in relation to human ovarian cancer. Gene mutations of TGF-beta RI, TGF-beta RII, Smad2, and Smad4 were analyzed using specific primers by PCR-single-strand conformational polymorphism (SSCP), and the results revealed a frameshift mutation at codons 276-277 (CTCTGG-->CTGCGTGG) in exon 5 of TGF-beta RI in 10 of 32 tumor samples (31.3%). This mutation was associated with reduced or absent expression of TGF-beta RI protein and p53 protein in tumor tissues. We detected SSCP variants of TGF-beta RII in exon 2 in 20 of 32 tumors. Sequence analysis of these variants revealed an A to G transition at the seventh band of intron 2. In this A to G polymorphism in intron 2, 12 samples (37.5%) had A/A alleles, 12 (37.5%) had A/G alleles, and 8 (25%) had G/G alleles. We detected Smad2 SSCP variants in exon 4 in 12 of 32 tumors (37.5%). Sequence analysis revealed a 2-bp deletion in the polypyrimidine tract of intron 3, which is located at position -39 to -56 in the splice acceptor site of the intron 3-exon 4 junction. No SSCP variants were detected in the Smad4 gene. These findings suggest that mutations in the TGF-beta RI and in its signal transduction pathway are likely responsible for human ovarian carcinogenesis.
Wang
D
D
Department of Obstetrics and Gynecology, Gunma University School of Medicine, Japan.
Kanuma
T
T
Mizunuma
H
H
Takama
F
F
Ibuki
Y
Y
Wake
N
N
Mogi
A
A
Shitara
Y
Y
Takenoshita
S
S
D030201:Activin Receptors, Type I; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D016368:Frameshift Mutation / Q000235:genetics*; D006801:Humans; D019656:Loss of Heterozygosity / Q000235:genetics*; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics* / Q000502:physiology; D051899:Smad2 Protein; D051901:Smad4 Protein; D015534:Trans-Activators / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000502:physiology
D004268:DNA-Binding Proteins; D018125:Receptors, Transforming Growth Factor beta; C497782:SMAD2 protein, human; C497796:SMAD4 protein, human; D051899:Smad2 Protein; D051901:Smad4 Protein; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II