title: Increased expression of T-fimbrin gene after DNA damage in CHO cells and inactivation of T-fimbrin by CpG methylation in human colorectal cancer cells.
abstract: When DNA damage is induced by unprogrammed extrinsic events, activating-cell-cycle checkpoints delay cell-cycle progression in the G1 or G2 phases and allow repair of a damaged template. In this study, we evaluated changes in gene expression upon radiation-induced G2 cell-cycle arrest using Chinese hamster ovary (CHO) cells. T-fimbrin, an actin-binding protein, was overexpressed in CHO cells in which G2 arrest had been induced by X-radiation. Northern blot analysis revealed that T-fimbrin gene expression was induced not only by X-radiation but also by a topoisomerase II inhibitor, etoposide. Transfection of CHO cells with a vector encoding T-fimbrin antisense RNA demonstrated that reduced T-fimbrin expression induced alterations in cell-cycle control; radiation-induced G2 arrest was short and decreased in cells transfected with antisense T-fimbrin. Additionally, T-fimbrin gene expression was suppressed in a human colorectal cancer cell line, SW948, because of promoter-specific DNA methylation. These results suggest that downregulation of T-fimbrin may be involved in cancer development through G2/M cell-cycle control in mammalian cells.
authors.affiliation: First Department of Internal Medicine, Sapporo Medical University School of Medicine, S-1, W-6, Chuo-ku, Sapporo, 060-8543, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Sasaki
authors.forename: Fumio
authors.initials: F
authors.lastname: Itoh
authors.forename: Toshihisa
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Takefumi
authors.initials: T
authors.lastname: Kikuchi
authors.forename: Hiromu
authors.initials: H
authors.lastname: Suzuki
authors.forename: Minoru
authors.initials: M
authors.lastname: Toyota
authors.forename: Kohzoh
authors.initials: K
authors.lastname: Imai
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D016466:CHO Cells / Q000378:metabolism; D002453:Cell Cycle / Q000528:radiation effects*; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000378:metabolism; D018899:CpG Islands / Q000235:genetics*; D006224:Cricetinae; D004249:DNA Damage; D019175:DNA Methylation; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000235:genetics; D016195:G2 Phase / Q000528:radiation effects; D015870:Gene Expression; D020869:Gene Expression Profiling / Q000379:methods; D008562:Membrane Glycoproteins / Q000235:genetics*; D008840:Microfilament Proteins; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D012333:RNA, Messenger; C026742:plastin