title: The major facilitative folate transporters solute carrier 19A1 and solute carrier 46A1: biology and role in antifolate chemotherapy of cancer.
abstract: This review summarizes the biology of the major facilitative membrane transporters, the reduced folate carrier (RFC) (Solute Carrier 19A1) and the proton-coupled folate transporter (PCFT) (Solute Carrier 46A1). Folates are essential vitamins, and folate deficiency contributes to a variety of health disorders. RFC is ubiquitously expressed and is the major folate transporter in mammalian cells and tissues. PCFT mediates the intestinal absorption of dietary folates and appears to be important for transport of folates into the central nervous system. Clinically relevant antifolates for cancer, such as methotrexate and pralatrexate, are transported by RFC, and loss of RFC transport is an important mechanism of methotrexate resistance in cancer cell lines and in patients. PCFT is expressed in human tumors, and is active at pH conditions associated with the tumor microenvironment. Pemetrexed is an excellent substrate for both RFC and PCFT. Novel tumor-targeted antifolates related to pemetrexed with selective membrane transport by PCFT over RFC are being developed. In recent years, there have been major advances in understanding the structural and functional properties and the regulation of RFC and PCFT. The molecular bases for methotrexate resistance associated with loss of RFC transport and for hereditary folate malabsorption, attributable to mutant PCFT, were determined. Future studies should continue to translate molecular insights from basic studies of RFC and PCFT biology into new therapeutic strategies for cancer and other diseases.
authors.affiliation: Department of Oncology (L.H.M., M.R.W., Z.H.) and Department of Pharmacology (L.H.M.), Wayne State University School of Medicine, Detroit, Michigan; and Molecular Therapeutics Program, Barbara Ann Karmanos Cancer Institute, Detroit, Michigan (L.H.M., Z.H.).
authors.forename: Larry H
authors.initials: LH
authors.lastname: Matherly
authors.forename: Mike R
authors.initials: MR
authors.lastname: Wilson
authors.forename: Zhanjun
authors.initials: Z
authors.lastname: Hou
mesh_terms: D000630:Aminopterin / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000627:therapeutic use; D000818:Animals; D019008:Drug Resistance, Neoplasm; D005492:Folic Acid / Q000378:metabolism*; D005493:Folic Acid Antagonists / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D006801:Humans; D008727:Methotrexate / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use; D009369:Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D058979:Proton-Coupled Folate Transporter / Q000235:genetics / Q000378:metabolism*; D058978:Reduced Folate Carrier Protein / Q000235:genetics / Q000378:metabolism*
chemical_list: C418863:10-propargyl-10-deazaaminopterin; D005493:Folic Acid Antagonists; D058979:Proton-Coupled Folate Transporter; D058978:Reduced Folate Carrier Protein; C548699:SLC19A1 protein, human; D005492:Folic Acid; D000630:Aminopterin; D008727:Methotrexate