title: Effect of ON 01910.Na, an anticancer mitotic inhibitor, on cell-cycle progression correlates with RanGAP1 hyperphosphorylation.
abstract: The benzyl styryl sulfone, ON 01910.Na, is a novel anticancer agent that inhibits mitotic progression and induces apoptosis in most cancer cell lines. We examined the effect of ON 01910.Na on DNA damage-signaling molecules upstream of Cdc25C (Chk1, Chk2, and H2AX), as well as on Ran GTPase-activating protein 1 conjugated to small ubiquitin-related modifier 1 (RanGAP1·SUMO1), a mitosis coordinator. Prostate cancer, lymphoma, and leukemic cells were incubated with the drug for 4, 16, or 24 hours. Cell lysates were resolved on SDS-PAGE and analyzed by Western blot. Camptothecin and doxorubicin treatment caused activation/phosphorylation of DNA damage-responsive molecules by 4 hours, whereas ON 01910.Na did not do so. ON 01910.Na caused hyperphosphorylation of RanGAP1·SUMO1 within 4 hours that was sustained for more than 24 hours. Mild phosphorylation of Chk2 was observed only after 24-hour exposure, indicating that DNA damage response was not an initial effect of ON 01910.Na. MOLT-3 cells, synchronized by double-thymidine block, when released into a medium containing ON 01910.Na, accumulated mitotic cell number with a peak from 10 to 14 hours and remained near plateau for 20 hours, which corresponded with the time of RanGAP phosphorylation. ON 01910.Na had minimal effects on tubulin polymerization. These findings imply that ON 01910.Na neither induces DNA damage directly nor acts as a tubulin toxin. Its biological activity appears to rely on prolonged phosphorylation/hyperphosphorylation of RanGAP1·SUMO1. M-phase arrest and the consequent induction of apoptosis that follows could possibly be attributed to it. ON 01910.Na may act as an inhibitor of a RanGAP1·SUMO1 phosphatase or a stimulant of a new kinase. RanGAP1·SUMO1 appears to be a new target pathway for cancer chemotherapy.
authors.affiliation: Division of Hematology and Medical Oncology, The Samuel Bronfman Department of Medicine and Tisch Cancer Institute, Mount Sinai School of Medicine, New York, New York, USA.
authors.forename: Irina A
authors.initials: IA
authors.lastname: Oussenko
authors.forename: James F
authors.initials: JF
authors.lastname: Holland
authors.forename: E Premkumar
authors.initials: EP
authors.lastname: Reddy
authors.forename: Takao
authors.initials: T
authors.lastname: Ohnuma
mesh_terms: D002166:Camptothecin / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D004249:DNA Damage; D004317:Doxorubicin / Q000494:pharmacology; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006801:Humans; D008938:Mitosis / Q000187:drug effects; D010766:Phosphorylation; D058105:Polymerization; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D025842:SUMO-1 Protein / Q000378:metabolism; D015398:Signal Transduction; D013450:Sulfones / Q000494:pharmacology*; D014404:Tubulin / Q000378:metabolism
chemical_list: D020690:GTPase-Activating Proteins; C092317:RANGAP1 protein, human; D025842:SUMO-1 Protein; C495501:SUMO1 protein, human; D013450:Sulfones; D014404:Tubulin; C507134:ON 01910; D004317:Doxorubicin; D005998:Glycine; D002166:Camptothecin