Structure and Function of the Human Breast Cancer Resistance Protein (BCRP/ABCG2)

Zhanglin      Ni; Zsolt      Bikadi; Mark      F. Rosenberg; Qingcheng      Mao

doi:10.2174/138920010792927325

Abstract

The human breast cancer resistance protein (BCRP/ABCG2) is the second member of the G subfamily of the large ATPbinding cassette (ABC) transporter superfamily. BCRP was initially discovered in multidrug resistant breast cancer cell lines where it confers resistance to chemotherapeutic agents such as mitoxantrone, topotecan and methotrexate by extruding these compounds out of the cell. BCRP is capable of transporting non-chemotherapy drugs and xenobiotiocs as well, including nitrofurantoin, prazosin, glyburide, and 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine. BCRP is frequently detected at high levels in stem cells, likely providing xenobiotic protection. BCRP is also highly expressed in normal human tissues including the small intestine, liver, brain endothelium, and placenta. Therefore, BCRP has been increasingly recognized for its important role in the absorption, elimination, and tissue distribution of drugs and xenobiotics. At present, little is known about the transport mechanism of BCRP, particularly how it recognizes and transports a large number of structurally and chemically unrelated drugs and xenobiotics. Here, we review current knowledge of structure and function of this medically important ABC efflux drug transporter.

Keywords: Breast cancer resistance protein, BCRP, ATP-binding cassette transporter, ABCG2, multidrug resistance, drug disposition, homology model, mutation analysis, BCRP/ABCG2, mitoxantrone-resistant human cancer cell lines, MXR, human placenta, ABCP, nucleotide binding domains, membrane spanning domains, MSDs, affinity constants, SAR, QSAR, flavonoids, tamoxifen analogues, cyclindependent kinase inhibitors, tariquidar analogues, FTC analogues, 2D-QSAR, CoMFA, CoMSIA, 3D-QSAR, MIFs, HEK cells, Pichia pastoris, Lactococcus lactis, fluorescence resonance energy transfer v, MODELLER