title: Impact of cellular folate status and epidermal growth factor receptor expression on BCRP/ABCG2-mediated resistance to gefitinib and erlotinib.
abstract: The effect of folate status on breast cancer resistance protein (BCRP)-mediated drug resistance to epidermal growth factor receptor (EGFR)-targeted drugs, such as gefitinib and erlotinib, was investigated in two human colon cancer cell lines, WiDr and Caco-2, of which the latter displayed greater sensitivity to these drugs due to high EGFR expression. Caco-2 LF/LV cells, growing under low-folate (LF) conditions, showed increased BCRP protein expression compared with the high-folate (HF) counterpart, which was associated with 1.8-fold resistance to gefitinib. Of note, the BCRP-specific inhibitor Ko143 completely reverted this phenotype. WiDr LF cells also showed slightly increased BCRP expression compared with the HF cells, but no differences in gefitinib sensitivity were observed. Both Caco-2 LF/LV and WiDr LF cells showed 2.4- and 2.3-fold resistance to erlotinib, respectively, compared with their HF counterparts, which mechanistically seemed BCRP unrelated, as Ko143 had no effect on erlotinib activity. In conclusion, our data suggest that in EGFR-expressing Caco-2 cells, BCRP is one of the determinants of gefitinib resistance but not of erlotinib resistance. Beyond this, folate depletion can provoke an additional decrease in gefitinib and erlotinib activity by mechanisms dependent or independent of BCRP modulation.
authors.affiliation: Department of Biochemistry (U38-FCT), Faculty of Medicine, University of Porto, Porto, Portugal. lemosc@gmail.com
authors.forename: C
authors.initials: C
authors.lastname: Lemos
authors.forename: I
authors.initials: I
authors.lastname: Kathmann
authors.forename: E
authors.initials: E
authors.lastname: Giovannetti
authors.forename: C
authors.initials: C
authors.lastname: Calhau
authors.forename: G
authors.initials: G
authors.lastname: Jansen
authors.forename: G J
authors.initials: GJ
authors.lastname: Peters
mesh_terms: D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm; D066246:ErbB Receptors / Q000032:analysis* / Q000037:antagonists & inhibitors*; D000069347:Erlotinib Hydrochloride; D005492:Folic Acid / Q000502:physiology*; D000077156:Gefitinib; D005838:Genotype; D006801:Humans; D009363:Neoplasm Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology*
chemical_list: C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D009363:Neoplasm Proteins; D011799:Quinazolines; D005492:Folic Acid; D000069347:Erlotinib Hydrochloride; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt; D000077156:Gefitinib