Comprehensive Mutation Analysis of PIK3CA, p14ARF, p16INK4a and p21^Waf1/Cip1Genes is Suggestive of a Non- Neoplastic Nature of Phenytoin Induced Gingival Overgrowth

Abstract

Background: Dilantin sodium (phenytoin) is an antiepileptic drug, which is routinely used to control generalized tonic clonic seizure and partial seizure episodes. A few case reports of oral squamous cell carcinomas arising from regions of phenytoin induced gingival overgrowth (GO), and overexpression of mitogenic factors and p53 have presented this condition as a pathology with potential to transform into malignancy. We recently investigated the genetic status of p53 and H-ras, which are known to be frequently mutated in Indian oral carcinomas in GO tissues and found them to only contain wild type sequences, which suggested a non-neoplastic nature of phenytoin induced GO. However, besides p53 and H-ras, other oncogenes and tumor suppressors such as PIK3CA, p14ARF, p16INK4a and p21 Waf1/Cip1 , are frequently altered in oral squamous cell carcinoma, and hence are required to be analyzed in phenytoin induced GO tissues to be affirmative of its non-neoplastic nature. Methods: 100ng of chromosomal DNA isolated from twenty gingival overgrowth tissues were amplified with primers for exons 9 and 20 of PIK3CA, exons 1α, 1β and 2 of p16INK4a and p14ARF, and exon 2 of p21 Waf1/Cip1 , in independent reactions. PCR amplicons were subsequently gel purified and eluted products were sequenced. Results: Sequencing analysis of the twenty samples of phenytoin induced gingival growth showed no mutations in the analyzed exons of PIK3CA, p14ARF, p16INK4a and p21 Waf1/Cip1 . Conclusion: The present data indicate that the mutational alterations of genes, PIK3CA, p14ARF, p16INK4a and p21 Waf1/Cip1 that are frequently mutated in oral squamous cell carcinomas are rare in phenytoin induced gingival growth. Thus the findings provide further evidence that phenytoin induced gingival overgrowth as a non-neoplastic lesion, which may be considered as clinically significant given the fact that the epileptic patients are routinely administered with phenytoin for the rest of their lives to control seizure episodes. Keywords:Cancer from gingival overgrowth -phenytoin induced gingival carcinoma -drug induced gingival carcinoma RESEARCH ARTICLEComprehensive Mutation Analysis of PIK3CA, p14ARF, p16INK4a and p21 Waf1/Cip1

Absence of the frequently reported PIK3CA,CASP8, and NOTCH1 mutations in South Indian oral cancers

“…The PIK3CA hotspot mutations H1047R and E545K were frequently described in many human cancers including brain, breast, colorectal, gastric, lung, ovarian, and oral cancer (Samuels et al , ; Murugan et al , ). Although the PIK3CA mutation has been analyzed in South Indian patients, it was only on phenytoin‐induced gingival overgrowth, but not in oral cancer samples, and this study found no mutation in the analyzed samples (Swamikannu et al , ). We did not find any PIK3CA gene (exons 9 and 20) hotspot mutations in the South Indian oral cancer although the frequency of the PIK3CA has been shown to be ~10% of OSCC in Asian and Caucasian population (Kozaki et al , ; Qiu et al , ; Murugan et al , ).…”