Thymineless Death by the Fluoropyrimidine Polymer F10 Involves Replication Fork Collapse and Is Enhanced by Chk1 Inhibition

• DOI: 10.1016/j.neo.2018.10.006
• Publication Date: 2018-11-12T05:26:26Z
• Authors: Chinnadurai Mani; Sachin Pai; Cinta Maria Papke; Komaraiah Palle; William H. Gmeiner
• Keywords: CHEK1; Comet Assay

We are developing the fluoropyrimidine polymer F10 to overcome limitations of 5-fluorouracil (5-FU) that result from inefficient metabolism 5-fluoro-2'-deoxyuridine-5'-mono- and tri-phosphate, deoxyribonucleotide metabolites responsible for 5-FU's anticancer activity. is much more cytotoxic than 5-FU colorectal cancer (CRC) cells; however, mechanism enhanced cytotoxicity remains incompletely characterized. Using DNA fiber analysis, we establish decreases replication fork velocity causes collapse, while 1000-fold excess required achieve similar endpoints. Treatment HCT-116 cells with results in Chk1 phosphorylation activation intra-S-phase checkpoint. Combining pharmacological inhibition either PF-477736 or prexasertib CRC damage relative single-agent treatment as assessed by γH2AX intensity COMET assay. co-treatment also inhibited upregulation Rad51 levels response F10, resulting reduced homologous repair. siRNA knockdown increased F10-induced sensitized F10. However, did not inhibit indicating scaffolding activity imparts repair distinct enzymatic Our indicate part through subsequent collapse. ~1000-fold potent at inducing replication-mediated which correlates overall potency 5-FU. efficacy can be Chk1.