Determination of p53 genotypes in oral cancer patients from India

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Abstract
The p53 tumour suppressor gene is inactivated in various types of human cancers, and has been implicated as an early event in several cancers. A p53 Pro/Arg polymorphism at exon 4 codon 72, has been suggested to be involved in susceptibility to cancers as well. Hence, in the current study, we investigated p53 exon 4 codon 72 polymorphism using Proline or Arginine specific primers from the peripheral blood cells (PBC) representing constitutional DNA from 72 oral cancer patients. PBC from 153 normal healthy individuals were used to determine the frequency of the p53 genotypes, Pro/Pro, Arg/Arg and Pro/Arg, in the Indian population. The frequency of distribution of genotypes in the normal healthy individuals was, Pro/Pro - 0.20 (31/153), Arg/Arg -- 0.14 (22/153) and Pro/Arg -- 0.65 (100/153); and in the oral cancer patients was, Pro/Pro -- 0.19 (14/72), Arg/Arg -- 0.08 (6/72) and Pro/Arg -- 0.72 (52/72). Thus, we observed an equidistribution of the genotypes in normal control and oral cancer patients (chi(2)= 1.77, df = 2, 0.3 <P< 0.5). Further, DNA from corresponding tumours from the 72 oral cancer patients were examined for loss of heterozygosity in the p53 gene. Allelic loss was observed in 8 of 52 (15%) heterozygous informative oral cancer patients. Our data indicates an equidistribution of the genotypes and absence of over-representation of either Pro/Pro or Arg/Arg genotypes in the oral cancer patients as compared to the normal healthy controls. Hence, association of the p53 genotypes with susceptibility to oral cancer, was not observed.