Genetic alterations of the PIK3CA oncogene in human oral squamous cell carcinoma in an Indian population

Objective. The phosphatidylinositol 3-kinase (PIK3) genes, which code for heterodimeric lipid kinases, consist of a catalytic subunit, p110a (PIK3CA), which regulates cell proliferation, apoptosis, and metastasis. Recently, a high frequency of somatic mutations was observed in the PIK3CA gene in various cancer types, including oral squamous cell carcinoma (OSCC). This study aimed to determine the frequency of oncogenic hotspot mutations in exons 9 and 20 of the PIK3CA gene and its correlation with the clinical characteristics of OSCC patients in an Indian population. Study Design. We analyzed exons 9 and 20 of the PIK3CA gene using polymerase chain reaction (PCR) and direct genomic sequencing of 50 OSCC primary tumors. Results. We observed two hotspot oncogenic mutations (E542 K, E545 K) in exon 9 and two synonymous mutations (A994 A, T1025 T) in exon 20. Moreover, we identified two single nucleotide polymorphisms (SNPs), rs114587137 (C>T) and rs17849071 (T>G), in intron 9 of the PIK3CA gene. Both oncogenic hotspot mutations were reported primarily in patients with advanced-stage cancer of the buccal mucosa. Conclusions. We have observed a 4% oncogenic mutation frequency of the PIK3CA gene, which plays a minor role in the development of OSCC in an Indian population.