Mutational analysis of PTEN/PIK3CA/AKT pathway in oral squamous cell carcinoma

The phosphoinositide 3-kinase (PI3K)/v-akt murine thymoma (AKT) viral oncogene pathway is involved in regulating the signaling of multiple biological processes such as apoptosis, metabolism, cell proliferation, and cell growth. Mutations in the genes associated with the PI3K/AKT pathway including PI3K, AKT, RAS and PTEN, are infrequently found within head and neck squamous cell carcinoma and more specifically are rarely reported in oral squamous cell carcinoma (OSCC) cases. We aimed to investigate the frequency of mutations in AKT1, PTEN, PIK3CA, and RAS (K-RAS, N-RAS, H-RAS) genes in 37 cases of oral squamous cell carcinoma (OSCC). Mutational analysis of PTEN, RAS, PIK3CA and AKT genes was performed using chip-based matrix-assisted laser desorption time-of-flight (MALDI-TOF) mass spectrometry and by direct sequencing. The only gene mutated in our series was the PIK3CA. Missense mutations of the PIK3CA gene were found in 4 of our cases (10.8%); no correlation has been found with oral location, stage and survival. The absence of mutations in AKT1, PTEN, and RAS genes in the present study is in accordance with previous studies confirming that these genes are rarely mutated in OSCC. Our data confirm that PIK3CA is important to OSCC tumorigenesis and can contribute to oncogene activation of the PIK3CA/AKT pathway in OSCC. The knowledge of the PIK3CA's involvement in OSCC is important because a specific kinase inhibitor could be considered as a future therapeutic option for OSCC patients with PIK3CA mutations.