title: Effects of folylpolyglutamate synthase modulation on global and gene-specific DNA methylation and gene expression in human colon and breast cancer cells.
abstract: Folylpolyglutamate synthase (FPGS) plays a critical role in intracellular folate homeostasis. FPGS-induced polyglutamylated folates are better substrates for several enzymes involved in the generation of S-adenosylmethionine, the primary methyl group donor, and hence FPGS modulation may affect DNA methylation. DNA methylation is an important epigenetic determinant in gene expression and aberrant DNA methylation is mechanistically linked cancer development. We investigated whether FPGS modulation would affect global and gene-specific promoter DNA methylation with consequent functional effects on gene expression profiles in HCT116 colon and MDA-MB-435 breast cancer cells. Although FPGS modulation altered global DNA methylation and DNA methyltransferases (DNMT) activity, the effects of FPGS modulation on global DNA methylation and DNMT activity could not be solely explained by intracellular folate concentrations and content of long-chain folylpolyglutamates, and it may be cell-specific. FPGS modulation influenced differential gene expression and promoter cytosine-guanine dinucleotide sequences (CpG) DNA methylation involved in cellular development, cell cycle, cell death and molecular transport. Some of the altered gene expression was associated with promoter CpG DNA methylation changes. In both the FPGS-overexpressed HCT116 and MDA-MB-435 cell lines, we identified several differentially expressed genes involved in folate biosynthesis and one-carbon metabolism, which might in part have contributed to the observed increased efficacy of 5-fluorouracil in response to FPGS overexpression. Our data suggest that FPGS modulation affects global and promoter CpG DNA methylation and expression of several genes involved in important biological pathways. The potential role of FPGS modulation in DNA methylation and its associated downstream functional effects warrants further studies.
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada M5S 1A8; Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, Canada M5B 1T8. Electronic address: sungeun.kim@alum.utoronto.ca.
authors.forename: Sung-Eun
authors.initials: SE
authors.lastname: Kim
authors.affiliation: Center for Epigenetics, Van Andel Research Institute, Grand Rapids, MI 49503-2518, USA.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Hinoue
authors.affiliation: Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, Canada M5B 1T8.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, Canada M5B 1T8; Department of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8.
authors.forename: Kyoung-Jin
authors.initials: KJ
authors.lastname: Sohn
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada M5S 1A8.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Cho
authors.affiliation: USC Epigenome Center, University of Southern California, Los Angeles, CA 90089-9601, USA; Department of Biochemistry and Molecular Biology, University of Southern California, Los Angeles, CA 90089-9601, USA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Weisenberger
authors.affiliation: Center for Epigenetics, Van Andel Research Institute, Grand Rapids, MI 49503-2518, USA.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Laird
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada M5S 1A8; Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, Canada M5B 1T8; Department of Medicine, University of Toronto, Toronto, ON, Canada M5S 1A8; Division of Gastroenterology, St. Michael's Hospital, Toronto, ON, Canada M5B 1W8.
authors.forename: Young-In
authors.initials: YI
authors.lastname: Kim
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000201:enzymology / Q000235:genetics* / Q000473:pathology; D019175:DNA Methylation / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D010453:Peptide Synthases / Q000378:metabolism*
chemical_list: D010453:Peptide Synthases; C023103:folylpolyglutamate synthetase
keywords: Breast cancer; Colon cancer; DNA methylation; Folate; Folylpolyglutamate synthase (FPGS); Gene expression