Sensitization of human cancer cells to gemcitabine by the Chk1 inhibitor MK-8776: cell cycle perturbation and impact of administration schedule in vitro and in vivo

Autor: Ruth Thompson, Alan Eastman, Injae Chung, Huagang Hou, Nadeem Khan, Ryan Montano
Rok vydání: 2013
Předmět:
Cancer Research
Pharmacology
Deoxycytidine
Mice
chemistry.chemical_compound
0302 clinical medicine
Antineoplastic Combined Chemotherapy Protocols
Sensitization
0303 health sciences
MK-8776
Drug combinations
Drug Synergism
CHK1 Inhibitor MK-8776
Tumor Burden
3. Good health
medicine.anatomical_structure
Oncology
030220 oncology & carcinogenesis
S Phase Cell Cycle Checkpoints
Cell cycle perturbation
Stem cell
Research Article
medicine.drug
Pancreas cancer xenografts
Chk1
Mice
Nude
Analogs & derivatives
Drug Administration Schedule
03 medical and health sciences
In vivo
Cell Line
Tumor
Genetics
medicine
Animals
Humans
Homologous recombination
030304 developmental biology
business.industry
Recombinational DNA Repair
Xenograft Model Antitumor Assays
Gemcitabine
Pancreatic Neoplasms
Pyrimidines
chemistry
Drug Resistance
Neoplasm
Cytarabine
Pyrazoles
business
DNA Damage
Zdroj: BMC Cancer
ISSN: 1471-2407
DOI: 10.1186/1471-2407-13-604
Popis: Background Chk1 inhibitors have emerged as promising anticancer therapeutic agents particularly when combined with antimetabolites such as gemcitabine, cytarabine or hydroxyurea. Here, we address the importance of appropriate drug scheduling when gemcitabine is combined with the Chk1 inhibitor MK-8776, and the mechanisms involved in the schedule dependence. Methods Growth inhibition induced by gemcitabine plus MK-8776 was assessed across multiple cancer cell lines. Experiments used clinically relevant “bolus” administration of both drugs rather than continuous drug exposures. We assessed the effect of different treatment schedules on cell cycle perturbation and tumor cell growth in vitro and in xenograft tumor models. Results MK-8776 induced an average 7-fold sensitization to gemcitabine in 16 cancer cell lines. The time of MK-8776 administration significantly affected the response of tumor cells to gemcitabine. Although gemcitabine induced rapid cell cycle arrest, the stalled replication forks were not initially dependent on Chk1 for stability. By 18 h, RAD51 was loaded onto DNA indicative of homologous recombination. Inhibition of Chk1 at 18 h rapidly dissociated RAD51 leading to the collapse of replication forks and cell death. Addition of MK-8776 from 18–24 h after a 6-h incubation with gemcitabine induced much greater sensitization than if the two drugs were incubated concurrently for 6 h. The ability of this short incubation with MK-8776 to sensitize cells is critical because of the short half-life of MK-8776 in patients’ plasma. Cell cycle perturbation was also assessed in human pancreas tumor xenografts in mice. There was a dramatic accumulation of cells in S/G2 phase 18 h after gemcitabine administration, but cells had started to recover by 42 h. Administration of MK-8776 18 h after gemcitabine caused significantly delayed tumor growth compared to either drug alone, or when the two drugs were administered with only a 30 min interval. Conclusions There are two reasons why delayed addition of MK-8776 enhances sensitivity to gemcitabine: first, there is an increased number of cells arrested in S phase; and second, the arrested cells have adequate time to initiate recombination and thereby become Chk1 dependent. These results have important implications for the design of clinical trials using this drug combination.
Databáze: OpenAIRE
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