The versatility of cytokeratins as tumor markers

Cytokeratins are particularly versatile tools in tumor biology both experim entally and clinically. Previously regarded as a rigid intracellular skelet on, the cytokeratins are now known to provide a more dynamic structural int egrity within epithelial cells. This more flexible nature of cytokeratin fu nction occurs through rapid shifts in assemly/disassembly states, geared by phosphorylations/dephosphorylations in the 'head' and 'tail' regions of th e monomeric filaments. When released from proliferating or dying tumor cell s, they provide a useful marker for epithelial malignancies, as evidenced b y the number of available immunochemical assays for cytokeratins. Another s ignificant area of interest that highlights their utility is the deposition of cytokeratins in the necrotic areas of tumors, providing an effective ta rget for radioimmunotherapy and radioimmunolocalization. Moreover, the appe arence of cytokeratin neodeterminants seems to be a very early event during apoptosis. Indeed, the involvement of specific cytokeratin degradation pat tern's resulting from the activity of caspases during apoptosis highlights yet another developing field of research devoted to these highly pleomorphi c and complex structures. Copyright (C) 2000 S. Karger AG, Basel.