LUNG RESISTANCE PROTEIN (LRP) EXPRESSION IN HUMAN NORMAL-TISSUES IN COMPARISON WITH THAT OF MDR1 AND MRP

MDR1 (P-glycoprotein), multidrug resistance-associated protein (MRP) a nd lung resistance protein (LRP) are associated with multidrug resista nce in various cancer cells. It is known that P-glycoprotein and MRP a re also expressed in several normal tissues, However, the exact locati on of LRP in normal tissues is still unclear. In order to obtain more insight into the physiological role of LRP, its expression in human no rmal tissues was examined by an immunohistochemical technique, using o ne monoclonal antibody, LRP-56. Reverse transcriptase-polymerase chain reaction (RT-PCR) was also utilized for several cell lines and fresh- frozen tissues. P-glycoprotein was found to be expressed in the kidney , adrenal, brain vessels, muscle, lung, pancreas, liver, intestine, pl acenta and testis. MRP was expressed in the kidney, adrenal, lung, pan creas, muscle, intestine, thyroid and prostate, and its distribution m ostly overlapped with that of P-glycoprotein. Interestingly, MRP was n ot expressed in the liver. LRP at 110 kDa was expressed in the kidney, adrenal, heart, lung, muscle, thyroid, prostate, bone marrow and test is. These findings suggest that LRP as well as P-glycoprotein and MRP plays distinct roles in the physiology of various organs. (C) 1997 Els evier Science Ireland Ltd.