RT Journal Article
SR Electronic
T1 Spermine Deficiency Resulting from Targeted Disruption of the Spermine Synthase Gene in Embryonic Stem Cells Leads to Enhanced Sensitivity to Antiproliferative Drugs
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 231
OP 238
DO 10.1124/mol.59.2.231
VO 59
IS 2
A1 Veli-Pekka Korhonen
A1 Kirsi Niiranen
A1 Maria Halmekytö
A1 Marko Pietilä
A1 Paula Diegelman
A1 Jyrki J. Parkkinen
A1 Terho Eloranta
A1 Carl W. Porter
A1 Leena Alhonen
A1 Juhani Jänne
YR 2001
UL http://molpharm.aspetjournals.org/content/59/2/231.abstract
AB Polyamines are known to be essential for normal cell growth and differentiation. However, despite numerous studies, specific cellular functions of polyamines in general and individual polyamines in particular have remained only tentative, because of a lack of appropriate cell lines in which genes of polyamine-synthesizing enzymes have been disrupted by gene targeting. With the use of homologous recombination technique, we disrupted the gene encoding spermine synthase in mouse embryonic stem cells. The spermine synthase gene is located on X chromosome in mouse and, because the cells used in this study were of XY karyotype, a single targeting event was sufficient to result in null genotype. The targeted cells did not have any measurable spermine synthase activity and were totally devoid of the polyamine spermine. Spermine deficiency led to a substantial increase in spermidine content, but the total polyamine content was nearly unchanged. Despite the lack of spermine, these cells displayed a growth rate that was nearly similar to that of the parental cells and showed no overt morphological changes. However, the spermine-deficient cells were significantly more sensitive to the growth inhibition exerted by 2-difluoromethylornithine, an inhibitor of ornithine decarboxylase. Similarly, methylglyoxal bis(guanylhydrazone), an inhibitor ofS-adenosylmethionine decarboxylase, and diethylnorspermine, a polyamine analog, although exerting cytostatic growth inhibition on wild-type cells, were clearly cytotoxic to the spermine-deficient cells. The spermine-deficient cells were also much more sensitive to etoposide-induced DNA damage than their wild-type counterparts.