title: Clock and ATF4 transcription system regulates drug resistance in human cancer cell lines.
abstract: The mechanisms underlying cellular drug resistance have been extensively studied, but little is known about its regulation. We have previously reported that activating transcription factor 4 (ATF4) is upregulated in cisplatin-resistant cells and plays a role in cisplatin resistance. Here, we find out a novel relationship between the circadian transcription factor Clock and drug resistance. Clock drives the periodical expression of many genes that regulate hormone release, cell division, sleep-awake cycle and tumor growth. We demonstrate that ATF4 is a direct target of Clock, and that Clock is overexpressed in cisplatin-resistant cells. Furthermore, Clock expression significantly correlates with cisplatin sensitivity, and that the downregulation of either Clock or ATF4 confers sensitivity of A549 cells to cisplatin and etoposide. Notably, ATF4-overexpressing cells show multidrug resistance and marked elevation of intracellular glutathione. The microarray study reveals that genes for glutathione metabolism are generally downregulated by the knockdown of ATF4 expression. These results suggest that the Clock and ATF4 transcription system might play an important role in multidrug resistance through glutathione-dependent redox system, and also indicate that physiological potentials of Clock-controlled redox system might be important to better understand the oxidative stress-associated disorders including cancer and systemic chronotherapy.
authors.affiliation: Department of Molecular Biology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Fukuoka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Igarashi
authors.forename: H
authors.initials: H
authors.lastname: Izumi
authors.forename: T
authors.initials: T
authors.lastname: Uchiumi
authors.forename: K
authors.initials: K
authors.lastname: Nishio
authors.forename: T
authors.initials: T
authors.lastname: Arao
authors.forename: M
authors.initials: M
authors.lastname: Tanabe
authors.forename: H
authors.initials: H
authors.lastname: Uramoto
authors.forename: K
authors.initials: K
authors.lastname: Sugio
authors.forename: K
authors.initials: K
authors.lastname: Yasumoto
authors.forename: Y
authors.initials: Y
authors.lastname: Sasaguri
authors.forename: K Y
authors.initials: KY
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Otsuji
authors.forename: K
authors.initials: K
authors.lastname: Kohno
mesh_terms: D051701:Activating Transcription Factor 4 / Q000235:genetics* / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology; D015152:Blotting, Northern; D015153:Blotting, Western; D056926:CLOCK Proteins; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D047369:Chromatin Immunoprecipitation; D002945:Cisplatin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005047:Etoposide / Q000494:pharmacology; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D010084:Oxidation-Reduction; D034622:RNA Interference; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C497109:ATF4 protein, human; D000970:Antineoplastic Agents; D015534:Trans-Activators; D051701:Activating Transcription Factor 4; D005047:Etoposide; D056926:CLOCK Proteins; C538943:CLOCK protein, human; D005978:Glutathione; D002945:Cisplatin