BIOCHEMICAL PATHWAYS REGULATING THE RESPONSIVENESS OF CELLS TO HORMONES

The main factors responsible for changes in the responsiveness of cell s to steroid hormones observed in the course of neoplasia and ageing h ave been analyzed. The decreased responsiveness is frequently reversib le and appears to be unrelated to disturbances of the receptor apparat us. The concept of multifunctional regulation of cell responsiveness t o steroid hormones is advanced. Regulation is thought to involve two l evels: receptor-mediated (signal transduction) and receptor-independen t (changes in the activity of intracellular enzyme systems controlled by the hormones). The role of microenvironment in the development of t arget cell responses to steroid hormones is also discussed.