title: The modulation of radiation-induced cell death by genistein in K562 cells: activation of thymidine kinase 1.
abstract: Ionizing radiation is one of the most effective tools in cancer therapy. In a previous study, we reported that protein tyrosine kinase (PTK) inhibitors modulate the radiation responses in the human chronic myelogenous leukemia (CML) cell line K562. The receptor tyrosine kinase inhibitor, genistein, delayed radiation-induced cell death, while non-recepter tyrosine kinase inhibitor, herbimycin A (HMA) enhances radiation-induced apoptosis. In this study, we focused on the modulation of radiation-induced cell death by genistein and performed PCR-select suppression subtractive hybridization (SSH) to understand its molecular mechanism. We identified human thymidine kinase 1 (TK1), which is cell cycle regulatory gene and confirmed expression of TK1 mRNA by Northern blot analysis. Expression of TK1 mRNA and TK1 enzymatic activity were parallel in their increase and decrease. TK1 is involved in G1-S phase transition of cell cycle progression. In cell cycle analysis, we showed that radiation induced G2 arrest in K562 cells but it was not able to sustain. However, the addition of genistein to irradiated cells sustained a prolonged G2 arrest up to 120 h. In addition, the expression of cell cycle-related proteins, cyclin A and cyclin B1, provided the evidences of G1/S progression and G2-arrest, and their relationship with TK1 in cells treated with radiation and genistein. These results suggest that the activation of TK1 may be critical to modulate the radiation-induced cell death and cell cycle progression in irradiated K562 cells.
authors.affiliation: Research Supporting Center for Medical Science (BK21 program), Dong-A University College of Medicine, Busan, Korea.
authors.forename: Min Ho
authors.initials: MH
authors.lastname: Jeong
authors.forename: Young Hee
authors.initials: YH
authors.lastname: Jin
authors.forename: Eun Young
authors.initials: EY
authors.lastname: Kang
authors.forename: Wol Soon
authors.initials: WS
authors.lastname: Jo
authors.forename: Hwan Tae
authors.initials: HT
authors.lastname: Park
authors.forename: Jae Dong
authors.initials: JD
authors.lastname: Lee
authors.forename: Yeo Jin
authors.initials: YJ
authors.lastname: Yoo
authors.forename: Soo Jin
authors.initials: SJ
authors.lastname: Jeong
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D019925:Cyclin A / Q000378:metabolism; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D004789:Enzyme Activation; D016193:G1 Phase / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D016195:G2 Phase / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D018816:Genes, cdc / Q000187:drug effects / Q000502:physiology*; D019833:Genistein / Q000494:pharmacology*; D006801:Humans; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000201:enzymology* / Q000235:genetics / Q000532:radiotherapy; D009693:Nucleic Acid Hybridization / Q000379:methods; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D016196:S Phase / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D013937:Thymidine Kinase / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; C534699:CCNB1 protein, human; D019925:Cyclin A; D019926:Cyclin B; D056744:Cyclin B1; D012333:RNA, Messenger; D019833:Genistein; D013937:Thymidine Kinase; C092717:thymidine kinase 1