title: High frequency of p53 mutations in human oral epithelial dysplasia and primary squamous cell carcinoma detected by yeast functional assay.
abstract: To determine the timing and actual incidence of p53 mutations in oral epithelial lesions, we examined 33 primary squamous cell carcinomas (SCCs), 14 dysplasias and six hyperplasias from Japanese patients by a combination of yeast functional assay and DNA sequencing. The assay detects mutations of p53 mRNA between codons 67 and 347 on the basis of the DNA-binding activity of the protein. Twenty-six SCCs (79%) and five dysplasias (36%) were positive for p53 mutation, while all six hyperplasias were negative for the mutation. Human papillomavirus type 16 E6 mRNA was detected in one of seven p53 mutation-negative SCCs by reverse transcription polymerase chain reaction (RT-PCR). We further examined p53 mutations in 17 Sri Lankan oral SCCs using the yeast functional assay and the single-strand conformation polymorphism analysis of PCR-amplified DNA fragments (PCR-SSCP) of exon 5-8. The mutations were confirmed by DNA sequencing and the detection sensitivity was compared between the two methods. Six samples (35%) were positive for p53 mutation in PCR-SSCP analysis, while nine samples (53%) were positive in yeast functional assay. This suggests that the incidence of p53 mutations has been considerably underestimated in the conventional SSCP analysis. The present data indicate that p53 mutations are extremely frequent in oral cancers in the Japanese, and suggest that the timing and significance of p53 mutation in oral tumor progression vary in different ethnic populations and areas.
authors.affiliation: Division of Cell Biology, Cancer Institute, Hokkaido University School of Medicine, Sapporo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kashiwazaki
authors.forename: H
authors.initials: H
authors.lastname: Tonoki
authors.forename: M
authors.initials: M
authors.lastname: Tada
authors.forename: I
authors.initials: I
authors.lastname: Chiba
authors.forename: M
authors.initials: M
authors.lastname: Shindoh
authors.forename: Y
authors.initials: Y
authors.lastname: Totsuka
authors.forename: R
authors.initials: R
authors.lastname: Iggo
authors.forename: T
authors.initials: T
authors.lastname: Moriuchi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D004279:DNA, Viral / Q000032:analysis; D004848:Epithelium / Q000473:pathology; D005260:Female; D005821:Genetic Techniques; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000235:genetics*; D009154:Mutation; D009856:Oncogene Proteins, Viral / Q000235:genetics; D027383:Papillomaviridae / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D018807:Polymorphism, Single-Stranded Conformational; D011230:Precancerous Conditions; D012097:Repressor Proteins; D012680:Sensitivity and Specificity; D013188:Sri Lanka; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*; D015003:Yeasts / Q000235:genetics
chemical_list: D004279:DNA, Viral; C068651:E6 protein, Human papillomavirus type 16; D009856:Oncogene Proteins, Viral; D012097:Repressor Proteins; D016159:Tumor Suppressor Protein p53