Genetic deregulation of the PIK3CA oncogene in oral cancer

• PIK3CA gene encodes the catalytic subunit of phosphatidylinositol 3-kinase (PI3K).
• Genetic deregulation of PIK3CA and genes of PI3K/Akt signaling accounts for 31% and 74%, respectively in oral cancer.
• The PIK3CA mutations are oncogenic and the deregulated PIK3CA constitutively activates PI3K/Akt signaling pathway.
• Inhibiting PI3K pathway effectors, such as Akt and/or mTOR pave the way for molecular targeted therapeutic strategies.
• Targeting genetically altered PIK3CA may be an alternative strategy for improving prognosis and therapeutic outcomes.

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway is one of the most commonly deregulated pathways in human cancers. PI3K comprises a catalytic (p110α) and regulatory subunit (p85), and p110α is encoded by the PIK3CA gene. Here, we summarize the known genetic alterations, including amplifications and mutations, of the PIK3CA oncogene in oral cancer. We discuss in detail PIK3CA mutations and their mutual exclusivity with pathway genes in addition to the incidence of PIK3CA mutations in relation to ethnicity. We describe the constitutive activation of PI3K signaling, oncogenicity, and the genetic deregulation of the PIK3CA gene and its association with oral cancer disease stage. We emphasize the importance of therapeutically targeting the genetically deregulated PIK3CA oncogene and its signaling. We also discuss the implications of targeting Akt and/or mTOR, which are the downstream effectors of PI3K that may possibly pave the way for molecular therapeutic targets for PIK3CA-driven oral carcinogenesis. Furthermore, this critical review provides a complete picture of the PIK3CA oncogene and its deregulation in oral cancer, which may facilitate early diagnosis and improve prognosis through personalized molecular targeted therapy in oral cancer.