title: 5-Flurouracil disrupts nuclear export and nuclear pore permeability in a calcium dependent manner.
abstract: Regulation of nuclear transport is an essential component of apoptosis. As chemotherapy induced cell death progresses, nuclear transport and the nuclear pore complex (NPC) are slowly disrupted and dismantled. 5-Fluorouracil (5-FU) and the camptothecin derivatives irinotecan and topotecan, are linked to altered nuclear transport of specific proteins; however, their general effects on the NPC and transport during apoptosis have not been characterized. We demonstrate that 5-FU, but not topotecan, increases NPC permeability, and disrupts Ran-mediated nuclear transport before the disruption of the NPC. This increased permeability is dependent on increased cellular calcium, as the Ca2+chelator BAPTA-AM, abolishes the effect. Furthermore, increased calcium alone was sufficient to disrupt the Ran gradient. Combination treatments of 5-FU with topotecan or irinotecan, similarly disrupted nuclear transport before disassembly of the NPC. In both single and combination treatments nuclear transport was disrupted before caspase 9 activation, indicating that 5-FU induces an early caspase-independent increase in NPC permeability and alteration of nuclear transport. Because Crm1-mediated nuclear export of tumor suppressors is linked to drug resistance we also examined the effect of 5-FU on the nuclear export of a specific target, topoisomerase. 5-FU treatment led to accumulation of topoisomerase in the nucleus and recovered the loss nuclear topoisomerase induced by irinotecan or topotecan, a known cause of drug resistance. Furthermore, 5-FU retains its ability to cause nuclear accumulation of p53 in the presence of irinotecan or topotecan. Our results reveal a new mechanism of action for these therapeutics during apoptosis, opening the door to other potential combination chemotherapies that employ 5-FU as a calcium mediated inhibitor of Crm1-induced nuclear export of tumor suppressors.
authors.affiliation: Department of Biology Hoyt Science Center 222, Westminster College, 319 S Market Street, New Wilmington, PA, 16172, USA.|Dana-Farber Cancer Institute, 450 Brookline Ave, Boston, MA, 02215, USA.
authors.forename: Kelly J
authors.initials: KJ
authors.lastname: Higby
authors.affiliation: Department of Biology Hoyt Science Center 222, Westminster College, 319 S Market Street, New Wilmington, PA, 16172, USA.|Ohio Valley Hospital, 25 Heckel Road, Pittsburgh, PA, 15136, USA.
authors.forename: Melissa M
authors.initials: MM
authors.lastname: Bischak
authors.affiliation: Department of Biology Hoyt Science Center 222, Westminster College, 319 S Market Street, New Wilmington, PA, 16172, USA.|Cook MyoSite Inc., 105 Delta Drive, Pittsburgh, PA, 15238, USA.
authors.forename: Christina A
authors.initials: CA
authors.lastname: Campbell
authors.affiliation: Department of Biology Hoyt Science Center 222, Westminster College, 319 S Market Street, New Wilmington, PA, 16172, USA.|Department of Cancer Biology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA.
authors.forename: Rebecca G
authors.initials: RG
authors.lastname: Anderson
authors.affiliation: Department of Biology Hoyt Science Center 222, Westminster College, 319 S Market Street, New Wilmington, PA, 16172, USA.|MCBG Program, Drexel University College of Medicine, Philadelphia, PA, 19102, USA.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Broskin
authors.affiliation: Department of Biology Hoyt Science Center 222, Westminster College, 319 S Market Street, New Wilmington, PA, 16172, USA.|Division of Biological Sciences, University of Montana, Missoula, MT, 59812-4824, USA.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Foltz
authors.affiliation: Department of Biology Hoyt Science Center 222, Westminster College, 319 S Market Street, New Wilmington, PA, 16172, USA.
authors.forename: Jarrett A
authors.initials: JA
authors.lastname: Koper
authors.affiliation: Department of Biology Hoyt Science Center 222, Westminster College, 319 S Market Street, New Wilmington, PA, 16172, USA.
authors.forename: Audrey C
authors.initials: AC
authors.lastname: Nickle
authors.affiliation: Department of Biology Hoyt Science Center 222, Westminster College, 319 S Market Street, New Wilmington, PA, 16172, USA. resendkk@westminster.edu.
authors.forename: Karen K
authors.initials: KK
authors.lastname: Resendes
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000502:physiology*; D002166:Camptothecin / Q000031:analogs & derivatives / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D004347:Drug Interactions; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005472:Fluorouracil / Q000494:pharmacology*; D006367:HeLa Cells; D006801:Humans; D000077146:Irinotecan; D009363:Neoplasm Proteins / Q000502:physiology; D022022:Nuclear Pore / Q000187:drug effects*; D010539:Permeability; D019772:Topotecan / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000502:physiology
chemical_list: D000964:Antimetabolites, Antineoplastic; D009363:Neoplasm Proteins; C120587:RAN protein, human; D016159:Tumor Suppressor Protein p53; C070379:1,2-bis(2-aminophenoxy)ethane N,N,N',N'-tetraacetic acid acetoxymethyl ester; D004533:Egtazic Acid; D000077146:Irinotecan; D019772:Topotecan; D020169:Caspases; D020931:ran GTP-Binding Protein; D004264:DNA Topoisomerases, Type I; C528909:TOP1 protein, human; D002118:Calcium; D005472:Fluorouracil; D002166:Camptothecin
keywords: 5-Flurouracil; Calcium; Nuclear transport; Ran; Topoisomerase