Comprehensive Mutation Analysis of PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1 Genes is Suggestive of a Non-Neoplastic Nature of Phenytoin Induced Gingival Overgrowth

Background: Dilantin sodium (phenytoin) is an antiepileptic drug, which is routinely used to controlgeneralized tonic clonic seizure and partial seizure episodes. A few case reports of oral squamous cell carcinomasarising from regions of phenytoin induced gingival overgrowth (GO), and overexpression of mitogenic factorsand p53 have presented this condition as a pathology with potential to transform into malignancy. We recentlyinvestigated the genetic status of p53 and H-ras, which are known to be frequently mutated in Indian oralcarcinomas in GO tissues and found them to only contain wild type sequences, which suggested a non-neoplasticnature of phenytoin induced GO. However, besides p53 and H-ras, other oncogenes and tumor suppressors suchas PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1, are frequently altered in oral squamous cell carcinoma, andhence 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 withprimers for exons 9 and 20 of PIK3CA, exons 1α, 1β and 2 of p16INK4a and p14ARF, and exon 2 of p21Waf1/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 mutationsin the analyzed exons of PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1.
Conclusion: The present data indicate thatthe mutational alterations of genes, PIK3CA, p14ARF, p16INK4a and p21Waf1/Cip1 that are frequently mutated inoral squamous cell carcinomas are rare in phenytoin induced gingival growth. Thus the findings provide furtherevidence that phenytoin induced gingival overgrowth as a non-neoplastic lesion, which may be considered asclinically significant given the fact that the epileptic patients are routinely administered with phenytoin for therest of their lives to control seizure episodes.