title: Abnormalities of tumor suppressor genes P16 and P15 in primary maxillofacial squamous cell carcinomas.
abstract: As members of the same gene family, tumor suppressor genes P16/CDKN2/INK4A and P15/INK4B have a high degree of structural and functional homology with both P16 and P15 proteins involved directly in the regulation of cell cycles. However, the status of P16 and P15 genes in primary maxillofacial squamous cell carcinomas (MSCC) has not been reported. Studies on abnormalities of these genes including homozygous deletion, methylation of the 5'CpG islands, and mutations were carried out in 65 primary MSCC with polymerase chain reaction (PCR), methylation-specific PCR (MSP), PCR-SSCP (single-strand conformation polymorphism), and DNA sequencing techniques. Of the 65 tumors, 22 (34%) were methylated; 7 (11%) displayed point mutations. The total frequency of alteration of the P16 gene was 43% (28/65). The methylation rate of P15 was 12% (8/65). No homozygous deletion was found in either the P16 gene or P15 gene. In all MSCC samples, almost half (49%) harbored an alteration of the P16 or P15 gene. The P16 gene was altered more frequently than P15, and therefore is inactivated by methylation or mutation in a significant proportion of MSCC. The P15 gene appeared to play a lesser role in tumorigenesis of these tumors.
authors.affiliation: Department of Medical Genetics, First Affiliated Hospital, West China University of Medical Sciences, People's Republic of China.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.forename: S
authors.initials: S
authors.lastname: Zhang
authors.forename: B
authors.initials: B
authors.lastname: Fu
authors.forename: C
authors.initials: C
authors.lastname: Xiao
mesh_terms: D000328:Adult; D000368:Aged; D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D018797:Cell Cycle Proteins; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D004247:DNA; D019175:DNA Methylation; D005260:Female; D017353:Gene Deletion; D006258:Head and Neck Neoplasms / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D014157:Transcription Factors / Q000235:genetics*; D025521:Tumor Suppressor Proteins
chemical_list: C493966:CDKN2B protein, human; D018797:Cell Cycle Proteins; D050762:Cyclin-Dependent Kinase Inhibitor p15; D019941:Cyclin-Dependent Kinase Inhibitor p16; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D004247:DNA