PIK3CA

The PIK3CA gene provides instructions for making the p110 alpha (p110α) protein, which is one piece (subunit) of an enzyme called phosphatidylinositol 3-kinase (PI3K). The p110α protein is called the catalytic subunit because it performs the action of PI3K, while the other subunit (produced by a different gene) regulates the enzyme‘s activity.

The class IA PI3K p110α is mutated in many cancers. Many of these mutations cause the kinase to be more active. It is the single most mutated kinase in glioblastoma, the most malignant primary brain tumor.[22] The PtdIns(3,4,5)P3 phosphatase PTEN that antagonises PI3K signaling is absent from many tumours. In addition, the epidermal growth factor receptor EGFR that functions upstream of PI3K is mutationally activated or overexpressed in cancer.[22][23] Hence, PI3K activity contributes significantly to cellular transformation and the development of cancer.