Catenine

The degradation of the freely available portion of catenins in the cytosol is regulated by secreted glycoproteins of the Wnt family (Wingless-Integrated, named after the relationship to the wg = wingless gene of Drosophila).

Free beta-catenin is the most important effector of the Wnt signaling pathway. Nuclear beta-catenin is considered to be a major oncoprotein because it acts as a transcription activator of oncogenes such as c-jun, c-myc and cyclin D1.

The triggering of tumors is postulated by mutations in components of the Wnt/beta-catenin signaling pathway, which leads to increased cell division and prolonged survival of affected cells. At the centre of this signalling cascade is a multiprotein complex that controls the amount, function and activity of the beta-catenin signalling molecule in response to activating or inhibiting signals. Increased beta-catenin concentrations have been detected in numerous tumors (including colon cancer, malignant melanoma, ovarian cancer, prostate cancer, medulloblastoma).

In malignant melanoma this mutation seems to play a rather minor role (Held L et al. 2011).

1. Held L et al (2011) Oncogenics of melanoma: Basis for molecular diagnostics and therapy. J Dtsch Dermatol Ges 9: 510-517
2. Nelson WJ, Nusse R (2004) Convergence of Wnt, beta-catenin, and cadherin pathways. Science 303: 1483-1487
3. Oloumi A, McPhee T, Dedhar S (2004) Regulation of E-cadherin expression and beta-catenin/Tcf transcriptional activity by the integrin-linked kinase. Biochim Biophys Acta 1691: 1-15
4. Widelitz RB (2004) Regulating the regulators: routing the Wnt-beta-catenin--Lef signals. J Invest Dermatol 123: VIII-X