title: Expression of O(6)-methylguanine-DNA methyltransferase causes lomustine resistance in canine lymphoma cells.
abstract: The DNA repair protein O (6)-methylguanine-DNA methyltransferase (MGMT) causes resistance to nitrosoureas in various human cancers. In this study, we analyzed the correlation between canine lymphomas and MGMT in vitro. Two of five canine lymphoma cell lines required higher concentrations of lomustine to inhibit cell growth by 50%, but their sensitivity to the drug increased when they were cultured with an MGMT inhibitor. Fluorometric oligonucleotide assay and real-time polymerase chain reaction of these cell lines revealed MGMT activity and high MGMT mRNA expression, respectively. We analyzed the methylation status of the CpG islands of the canine MGMT gene by the bisulfite-sequencing method. Unlike human cells, the canine lymphoma cell lines did not show significant correlation between methylation status and MGMT suppression levels. Our results suggest that in canine lymphoma MGMT activity may influence sensitivity to nitrosoureas; thus, inhibition of MGMT activity would benefit nitrosourea-resistant patients. Additional studies are necessary to elucidate the mechanism of regulation of MGMT expression.
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kambayashi
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Kouji
authors.initials: K
authors.lastname: Minami
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Yuka
authors.initials: Y
authors.lastname: Ogawa
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Takehiro
authors.initials: T
authors.lastname: Hamaji
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Chung Chew
authors.initials: CC
authors.lastname: Hwang
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Masaya
authors.initials: M
authors.lastname: Igase
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Hiroko
authors.initials: H
authors.lastname: Hiraoka
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Takako Shimokawa
authors.initials: TS
authors.lastname: Miyama
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Noguchi
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Kenji
authors.initials: K
authors.lastname: Baba
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Takuya
authors.initials: T
authors.lastname: Mizuno
authors.affiliation: Laboratory of Veterinary Internal Medicine, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Hwang, Noguchi, Baba, Mizuno, Okuda); Laboratory of Veterinary Internal Medicine, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Kambayashi, Minami, Ogawa, Hamaji, Hiraoka, Shimokawa Miyama, Baba, Okuda); Laboratory of Molecular Diagnostics and Therapeutics, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Hwang, Igase, Noguchi, Mizuno); Biomedical Science Center for Translational Research, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan (Mizuno, Okuda).
authors.forename: Masaru
authors.initials: M
authors.lastname: Okuda
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D018899:CpG Islands; D015254:DNA Modification Methylases / Q000235:genetics / Q000378:metabolism*; D004283:Dog Diseases / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D004285:Dogs; D019008:Drug Resistance, Neoplasm / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D015972:Gene Expression Regulation, Neoplastic / Q000502:physiology*; D008130:Lomustine / Q000494:pharmacology; D008223:Lymphoma / Q000201:enzymology / Q000235:genetics / Q000378:metabolism / Q000662:veterinary*
chemical_list: D000970:Antineoplastic Agents; D008130:Lomustine; D015254:DNA Modification Methylases