MDR gene acts by -
Ans. is 'c' i.e., Causes efflux of drug Multi drug resistance o Resistance develops to a variety of anticancer drugs. o It is associated with increased expression of a normal gene MDR1 gene. o MDR I gene encodes for P-glycoprotein Pcgp). P glycoprotein is a protective mechanism possessed by normal cells. o Pgp is an ATP dependent membrane efflux pump. o Its function is to expel a variety offoreign molecules including antitumour drugs from the cell. o Long lived cells such as the haemopoietic stem cells, Cells on excretory surfaces such as biliary hepatocytes, proximal renal tubules and intestinal cells and the cells of the blood-brain barrier, all have high expression of Pgp. o The MDR phenomenon illustrates how tumour cells adapt and enhance normal cell mechanism to deal with the effects of chemotherapy and how repeated cycles of chemotherapy select out a population of cells which have developed adaptive survival mechanism e.g. in myeloma where MDR proteins are rare at diagnosis but common at progression.
Block drug activation
Block intracellular DNA synthesis
Causes efflux of drug
DNA repair inhibition