PIK3CA
Phosphatidylinositol 3-kinase catalytic subunit
PIK3CA (phosphatidylinositol 3-kinase catalytic subunit) is an oncogene that encodes one piece (a subunit) of an enzyme called phosphatidylinositol 3-kinase (PI3-Kinase).1 PIK3CA plays a role in the control of cell growth, cell survival, and cell migration. Mutations in the PIK3CA gene can lead to uncontrolled cell growth and contribute to the proliferation and progression of cancer.2
The PI3-Kinase pathway is one of many signaling pathways that are important for cell growth, transformation, adhesion, apoptosis, survival and invasion.3 PI3-Kinases are heterodimeric lipid kinases composed of catalytic and adaptor/regulatory subunits encoded by separate genes and alternative splicing. In the case of oncogenes, including PIK3CA, genetic changes such as a mutation can result in a cellular state whereby the PIK3CA gene product is constantly activated. Ultimately, this contributes toward uncontrolled cellular growth and other features that are the hallmarks of cancer.1
Gene amplifications, deletions and more recently, somatic missense mutations in the PIK3CA gene have been reported in many human cancer types including cancers of the colon, breast, brain, liver, stomach and lung. These somatic missense mutations were proposed to increase the kinase activity of PIK3CA contributing to cellular transformation.3
PIK3CA mutations are found in 20% to 25% of colon cancers and 10% of rectal cancers. In addition to colorectal cancer, PIK3CA oncogene mutations are involved in several human cancers including breast cancer, ovarian cancer, and non-small cell lung cancer (NSCLC).2
