title: Hedgehog pathway inhibitor HhAntag691 is a potent inhibitor of ABCG2/BCRP and ABCB1/Pgp.
abstract: HhAntag691 (GDC-0449), a low-molecular weight inhibitor of the tumor-promoting hedgehog (Hh) signaling pathway, has been used to treat medulloblastoma in animal models and has recently entered clinical trials for a variety of solid tumors. Here, we show that HhAntag691 inhibits multiple ATP-binding cassette (ABC) transporters. ATP-binding cassette transporters are within a family of membrane proteins, the overexpression of which is associated with multidrug resistance, a major impediment to successful cancer treatment. HhAntag691 is a potent inhibitor of two ABC transporters, ABCG2/BCRP and ABCB1/Pgp, and is a mild inhibitor of ABCC1/MRP1. In ABCG2-overexpressing HEK293 cells, HhAntag691 increased retention of the fluorescent ABCG2 substrate BODIPY-prazosin and resensitized these cells to mitoxantrone, an antineoplastic ABCG2 substrate. In Madin-Darby canine kidney II cells engineered to overexpress Pgp or MRP1, HhAntag691 increased the retention of calcein-AM and resensitized them to colchicine. HhAntag691 also resensitized human non-small cell lung carcinoma cells NCI-H460/par and NCI-H460/MX20, which overexpress ABCG2 in response to mitoxantrone, to mitoxantrone, and to topotecan or SN-38. The IC(50) values of HhAntag691 for inhibition of ABCG2 and Pgp were approximately 1.4 and approximately 3.0 microM, respectively. Because ABC transporters are highly expressed at the blood-brain barrier and on many tumor cells, they contribute significantly to treatment failure of many types of cancer, particularly of those within the neuraxis. In addition to its effect on Hh signaling, the ability of HhAntag691 and related compounds to inhibit two key ABC transporters could contribute to their effectiveness in treating malignancies.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, MD 21231, USA.
authors.forename: Yimao
authors.initials: Y
authors.lastname: Zhang
authors.forename: John
authors.initials: J
authors.lastname: Laterra
authors.forename: Martin G
authors.initials: MG
authors.lastname: Pomper
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000037:antagonists & inhibitors*; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors*; D000813:Anilides; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001562:Benzimidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000473:pathology; D002478:Cells, Cultured; D003078:Colchicine / Q000008:administration & dosage; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004353:Drug Evaluation, Preclinical; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D053823:Hedgehog Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000473:pathology; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000037:antagonists & inhibitors; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors*; D011725:Pyridines; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000813:Anilides; D000970:Antineoplastic Agents; D001562:Benzimidazoles; D003078:Colchicine; D053823:Hedgehog Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D011725:Pyridines; C513055:ABCB1 protein, human; C116614:ABCG2 protein, human; C538724:HhAntag691; C421109:multidrug resistance-associated protein 1