title: The p16INK4alpha/p19ARF gene mutations are infrequent and are mutually exclusive to p53 mutations in Indian oral squamous cell carcinomas.
abstract: Eighty-seven untreated primary oral squamous cell carcinomas (SCCs) associated with betel quid and tobacco chewing from Indian patients were analysed for the presence of mutations in the commonly shared exon 2 of p16INK4alpha/p19ARF genes. Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and sequencing analysis were used to detect mutations. SSCP analysis indicated that only 9% (8/87) of the tumours had mutation in p16INK4alpha/p19ARF genes. Seventy-two tumours studied here were previously analysed for p53 mutations and 21% (15/72) of them were found to have mutations in p53 gene. Only one tumour was found to have mutation at both p53 and p16INK4alpha/p19ARF genes. Thus, the mutation rates observed were 21% for p53, 9% for p16INK4alpha/p19ARF, and 1% for both. Sequencing analysis revealed two types of mutations; i) G to C (GCAG to CCAG) transversion type mutation at intron 1-exon 2 splice junction and ii) another C to T transition type mutation resulting in CGA to TGA changing arginine to a termination codon at p16INK4alpha gene codon 80 and the same mutation will alter codon 94 of p19ARF gene from CCG to CTG (proline to leucine). These results suggest that p16INK4alpha/p19ARF mutations are less frequent than p53 mutations in Indian oral SCCs. The p53 and p16INK4alpha/p19ARF mutational events are independent and are mutually exclusive suggesting that mutational inactivation of either p53 or p16INK4alpha/p19ARF may alleviate the need for the inactivation of the other gene.
authors.affiliation: Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: K
authors.initials: K
authors.lastname: Kannan
authors.forename: A K
authors.initials: AK
authors.lastname: Munirajan
authors.forename: J
authors.initials: J
authors.lastname: Krishnamurthy
authors.forename: V
authors.initials: V
authors.lastname: Bhuvarahamurthy
authors.forename: B K
authors.initials: BK
authors.lastname: Mohanprasad
authors.forename: K H
authors.initials: KH
authors.lastname: Panishankar
authors.forename: N
authors.initials: N
authors.lastname: Tsuchida
authors.forename: G
authors.initials: G
authors.lastname: Shanmugam
mesh_terms: D000293:Adolescent; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D005260:Female; D019942:Genes, p16; D016158:Genes, p53; D006801:Humans; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000235:genetics*; D009154:Mutation; D011506:Proteins / Q000235:genetics*; D025803:Tumor Suppressor Protein p14ARF
chemical_list: D011506:Proteins; D025803:Tumor Suppressor Protein p14ARF