APC gene

The APC gene (Adenomatous Polyposis Coli) is a tumor suppressor gene that plays a critical role in the regulation of cell growth and division. It is located on the long arm of chromosome 5 (5q22.2) and is known for its involvement in the Wnt signaling pathway. Mutations in the APC gene are associated with several types of cancer, most notably colorectal cancer.

Function

The APC gene encodes a protein that is involved in the regulation of cell adhesion and the maintenance of the cytoskeleton. It is a key component of the Wnt signaling pathway, where it helps regulate the levels of beta-catenin in the cell. In the absence of Wnt signals, the APC protein forms a complex with other proteins, such as axin and glycogen synthase kinase 3 beta (GSK-3β), to promote the degradation of beta-catenin. This prevents beta-catenin from entering the nucleus and activating transcription of target genes that promote cell proliferation.

Clinical significance

Mutations in the APC gene are most commonly associated with familial adenomatous polyposis (FAP), an inherited condition characterized by the development of hundreds to thousands of polyps in the colon and rectum. These polyps have a high risk of becoming malignant, leading to colorectal cancer if not managed appropriately.

In addition to FAP, somatic mutations in the APC gene are frequently observed in sporadic cases of colorectal cancer. These mutations often result in a truncated APC protein that is unable to regulate beta-catenin levels, leading to uncontrolled cell growth and tumor development.

Research and therapeutic implications

Understanding the role of the APC gene in cancer has significant implications for the development of targeted therapies. Researchers are investigating ways to restore the function of the APC protein or to inhibit the downstream effects of its loss, such as the accumulation of beta-catenin.

Also see

• Wnt signaling pathway
• Beta-catenin
• Familial adenomatous polyposis
• Colorectal cancer
• Tumor suppressor gene