title: Probabilistic modeling of DNA mismatch repair effects on cell cycle dynamics and iododeoxyuridine-DNA incorporation.
abstract: Previous studies in our laboratory have described increased and preferential radiosensitization of mismatch repair-deficient (MMR(-)) HCT116 colon cancer cells with 5-iododeoxyuridine (IUdR). Indeed, our studies showed that MMR is involved in the repair (removal) of IUdR-DNA, principally the G:IU mispair. Consequently, we have shown that MMR(-) cells incorporate 25% to 42% more IUdR than MMR(+) cells, and that IUdR and ionizing radiation (IR) interact to produce up to 3-fold greater cytotoxicity in MMR(-) cells. The present study uses the integration of probabilistic mathematical models and experimental data on MMR(-) versus MMR(+) cells to describe the effects of IUdR incorporation upon the cell cycle for the purpose of increasing IUdR-mediated radiosensitivity in MMR(-) cells. Two computational models have been developed. The first is a stochastic model of the progression of cell cycle states, which is applied to experimental data for two synchronized isogenic MMR(+) and MMR(-) colon cancer cell lines treated with and without IUdR. The second model defines the relation between the percentage of cells in the different cell cycle states and the corresponding IUdR-DNA incorporation at a particular time point. These models can be combined to predict IUdR-DNA incorporation at any time in the cell cycle. These mathematical models will be modified and used to maximize therapeutic gain in MMR(-) tumors versus MMR(+) normal tissues by predicting the optimal dose of IUdR and optimal timing for IR treatment to increase the synergistic action using xenograft models and, later, in clinical trials.
authors.affiliation: Department of Electrical Engineering and Computer Science, Case Western Reserve University, and University Hospitals Case Medical Center, Cleveland, Ohio 44106-6068, USA.
authors.forename: Evren
authors.initials: E
authors.lastname: Gurkan
authors.forename: Jane E
authors.initials: JE
authors.lastname: Schupp
authors.forename: Mohammad A
authors.initials: MA
authors.lastname: Aziz
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Kinsella
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Loparo
mesh_terms: D002453:Cell Cycle; D045744:Cell Line, Tumor; D004247:DNA / Q000737:chemistry*; D053843:DNA Mismatch Repair; D006801:Humans; D007065:Idoxuridine / Q000737:chemistry*; D007700:Kinetics; D008957:Models, Genetic; D015233:Models, Statistical; D008962:Models, Theoretical; D009368:Neoplasm Transplantation; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D011336:Probability; D011839:Radiation, Ionizing
chemical_list: D019384:Nucleic Acid Synthesis Inhibitors; D004247:DNA; D007065:Idoxuridine