title: Therapeutic targeting malignant mesothelioma with a novel 6-substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolate via its selective uptake by the proton-coupled folate transporter.
abstract: OBJECTIVE
  We examined whether the novel 6-substituted pyrrolo[2,3-d]pyrimidine thienoyl antifolate, compound 2, might be an effective treatment for malignant pleural mesothelioma (MPM), reflecting its selective membrane transport by the proton-coupled folate transport (PCFT) over the reduced folate carrier (RFC).
  
  
  METHODS
  HeLa sublines expressing exclusively PCFT (R1-11-PCFT4) or RFC (R1-11-RFC6) and H2452 MPM cells were assayed for transport with [(3)H]compound 2. [(3)H]Polyglutamate metabolites of compound 2 were measured in R1-11-PCFT4 and H2452 cells. In vitro cell proliferation assays and colony formation assays were performed. Inhibition of glycinamide ribonucleotide formyltransferase (GARFTase) was assayed by nucleoside protection assays and in situ GARFTase assays with [(14)C]glycine. In vivo efficacy was established with early- and advanced-stage H2452 xenografts in severe-combined immunodeficient (SCID) mice administered intravenous compound 2.
  
  
  RESULTS
  [(3)H]Compound 2 was selectively transported by PCFT and was metabolized to polyglutamates. Compound 2 selectively inhibited proliferation of R1-11-PCFT4 cells over R1-11-RFC6 cells. H2452 human MPM cells were sensitive to the antiproliferative effects of compound 2. By colony-forming assays with H2452 cells, compound 2 was cytotoxic. Compound 2 inhibited GARFTase in de novo purine biosynthesis. In vivo efficacy was confirmed toward early- and advanced-stage H2452 xenografts in SCID mice administered compound 2.
  
  
  CONCLUSIONS
  Our results demonstrate potent antitumor efficacy of compound 2 toward H2452 MPM cells in vitro and in vivo, reflecting its efficient membrane transport by PCFT, synthesis of polyglutamates, and inhibition of GARFTase. Selectivity for non-RFC cellular uptake processes by tumor-targeted antifolates such as compound 2 presents an exciting new opportunity for treating solid tumors.
authors: Department of Oncology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors: Christina
authors: C
authors: Cherian
authors: Sita
authors: S
authors: Kugel Desmoulin
authors: Lei
authors: L
authors: Wang
authors: Lisa
authors: L
authors: Polin
authors: Kathryn
authors: K
authors: White
authors: Juiwanna
authors: J
authors: Kushner
authors: Mark
authors: M
authors: Stout
authors: Zhanjun
authors: Z
authors: Hou
authors: Aleem
authors: A
authors: Gangjee
authors: Larry H
authors: LH
authors: Matherly
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D005493:Folic Acid Antagonists / Q000493:pharmacokinetics / Q000494:pharmacology / Q000627:therapeutic use*; D006367:HeLa Cells; D006801:Humans; D008654:Mesothelioma / Q000188:drug therapy*; D051379:Mice; D016513:Mice, SCID; D051026:Phosphoribosylglycinamide Formyltransferase / Q000037:antagonists & inhibitors; D011099:Polyglutamic Acid / Q000378:metabolism; D058979:Proton-Coupled Folate Transporter / Q000502:physiology*; D011743:Pyrimidines / Q000493:pharmacokinetics / Q000627:therapeutic use*; D011758:Pyrroles / Q000493:pharmacokinetics / Q000627:therapeutic use*; D023041:Xenograft Model Antitumor Assays
chemical_list: D005493:Folic Acid Antagonists; D058979:Proton-Coupled Folate Transporter; D011743:Pyrimidines; D011758:Pyrroles; D011099:Polyglutamic Acid; D051026:Phosphoribosylglycinamide Formyltransferase