title: Low incidence of p53 mutations in betel quid and tobacco chewing-associated oral squamous carcinoma from India.
abstract: Mutations of the p53 tumor suppressor gene have been found to be the single most frequent event in human cancers. In India and other southeast Asian countries tobacco chewing with betel quid was attributed to be the major factor in oral carcinogenesis. We have analyzed 72 untreated primary oral squamous cell carcinomas (SCCs) for mutations in the tumor suppressor gene p53 exons 4-9 by PCR-SSCP and DNA sequencing. Sequencing analysis revealed 16 missense mutations, one silent mutation in codon 307 and four A to G substitution polymorphism in codon 213. The incidence of p53 mutation was 21% (15 of 72) excluding the polymorphism and the silent mutation. Eight mutations were clustered in codons 266-282 of exon 8. Of the total mutation events 37.5% were G to A transitions and 31.3% were G to T transversions. These results indicate the possible involvement of tobacco derived nitrosamines and their adducts in the genesis of oral cancer among Indians.
authors.affiliation: Cancer Biology Division, School of Biological Sciences, Madurai Kamaraj University, Madurai 625 021, India.
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: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001114:Areca / Q000009:adverse effects*; D001483:Base Sequence; D002294:Carcinoma, Squamous Cell / Q000737:chemistry / Q000453:epidemiology / Q000235:genetics*; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D005260:Female; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000139:chemically induced / Q000453:epidemiology / Q000235:genetics*; D009154:Mutation; D010946:Plants, Medicinal; D010947:Plants, Toxic; D018807:Polymorphism, Single-Stranded Conformational; D014030:Tobacco, Smokeless / Q000009:adverse effects*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
chemical_list: D004273:DNA, Neoplasm; D016159:Tumor Suppressor Protein p53