title: Acquisition of chemoresistance to gemcitabine is induced by a loss-of-function missense mutation of DCK.
abstract: The anti-tumor activity of gemcitabine (GEM) has been clinically proven in several solid tumors, including pancreatic cancer, biliary tract cancer, urinary bladder cancer, and non-small cell lung cancer. However, problems remain with issues such as acquisition of chemoresistance against GEM. GEM is activated after phosphorylation by deoxycytidine kinase (DCK) inside of the cell; thus, DCK inactivation is one of the important mechanisms for acquisition of GEM resistance. We previously investigated the DCK gene in multiple GEM resistant cancer cell lines and identified frequent inactivating mutations. In this study, we identified two crucial genetic alteration in DCK. (1) A total deletion of DCK in RTGBC1-TKB, an acquired GEM resistant cell line derived from a gall bladder cancer cell line TGBC1-TKB. (2) An E197K missense alteration of DCK in MKN28, a gastric cancer cell line; its acquired GEM resistant cancer cell line, RMKN28, showed a loss of the normal E197 allele. We introduced either normal DCK or altered DCK_E197K into RMKN28 and proved that only the introduction of normal DCK restored GEM sensitivity. Furthermore, we analyzed 104 healthy volunteers and found that none of them carried the same base substitution observed in MKN28. These results strongly suggest that (1) the E197K alteration in DCK causes inactivation of DCK, and that (2) loss of the normal E197 allele is the crucial mechanism in acquisition of GEM resistance in RMKN28.
authors.affiliation: Department of Molecular Pathology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Nakano
authors.affiliation: Department of Molecular Pathology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Saiki
authors.affiliation: Department of Molecular Pathology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Chiharu
authors.initials: C
authors.lastname: Kudo
authors.affiliation: Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan.
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Hirayama
authors.affiliation: Department of Molecular Pathology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Mizuguchi
authors.affiliation: Department of Molecular Pathology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Fujiwara
authors.affiliation: Institute for Advanced Biosciences, Keio University, Tsuruoka, Yamagata, Japan.
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Soga
authors.affiliation: Department of Molecular Pathology, Tohoku University School of Medicine, Sendai, Japan; Department of Digestive Tract Surgery and Transplantation Surgery, Tokyo Medical University Hachioji Medical Center, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Sunamura
authors.affiliation: Department of Molecular Pathology, Tohoku University School of Medicine, Sendai, Japan; Division of Cardiovascular Surgery, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Nobutoshi
authors.initials: N
authors.lastname: Matsumura
authors.affiliation: Department of Surgery, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Fuyuhiko
authors.initials: F
authors.lastname: Motoi
authors.affiliation: Department of Surgery, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Michiaki
authors.initials: M
authors.lastname: Unno
authors.affiliation: Department of Molecular Pathology, Tohoku University School of Medicine, Sendai, Japan. Electronic address: horii@med.tohoku.ac.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Horii
mesh_terms: D019943:Amino Acid Substitution; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology; D001483:Base Sequence; D045744:Cell Line, Tumor; D004249:DNA Damage; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000235:genetics; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D003842:Deoxycytidine Kinase / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005091:Exons; D005706:Gallbladder Neoplasms / Q000188:drug therapy / Q000201:enzymology / Q000235:genetics; D017353:Gene Deletion; D006801:Humans; D020125:Mutation, Missense; D000093542:Gemcitabine
chemical_list: D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D003841:Deoxycytidine; D003842:Deoxycytidine Kinase; D000093542:Gemcitabine
keywords: Chemoresistance; Deoxycytidine kinase; Gemcitabine; MKN28; TGBC1-TKB