title: PCFT/SLC46A1 promoter methylation and restoration of gene expression in human leukemia cells.
abstract: The proton-coupled folate transporter (PCFT/SLC46A1) displays optimal and prominent folate and antifolate transport activity at acidic pH in human carcinoma cells but poor activity in leukemia cells. Consistently herein, human leukemia cell lines expressed poor PCFT transcript levels, whereas various carcinoma cell lines showed substantial PCFT gene expression. We identified a CpG island with high density at nucleotides -200 through +100 and explored its role in PCFT promoter silencing. Leukemia cells with barely detectable PCFT transcripts consistently harbored 85-100% methylation of this CpG island, whereas no methylation was found in carcinoma cells. Treatment with 5-Aza-2'-deoxycytidine which induced demethylation but not with the histone deacetylase inhibitor trichostatin A, restored 50-fold PCFT expression only in leukemia cells. These findings constitute the first demonstration of the dominant epigenetic silencing of the PCFT gene in leukemia cells. The potential translational implications of the restoration of PCFT expression in chemotherapy of leukemia are discussed.
authors.affiliation: The Fred Wyszkowski Cancer Research Laboratory, Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: Nitzan
authors.initials: N
authors.lastname: Gonen
authors.forename: Eran E
authors.initials: EE
authors.lastname: Bram
authors.forename: Yehuda G
authors.initials: YG
authors.lastname: Assaraf
mesh_terms: D001374:Azacitidine / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D018899:CpG Islands; D019175:DNA Methylation / Q000187:drug effects; D000077209:Decitabine; D015870:Gene Expression; D015973:Gene Expression Regulation, Leukemic; D020868:Gene Silencing; D006801:Humans; D007938:Leukemia / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000235:genetics*; D011401:Promoter Regions, Genetic; D058979:Proton-Coupled Folate Transporter
chemical_list: D026901:Membrane Transport Proteins; D058979:Proton-Coupled Folate Transporter; C505058:SLC46A1 protein, human; D000077209:Decitabine; D001374:Azacitidine