title: Potent modulation of intestinal tumorigenesis in Apcmin/+ mice by the polyamine catabolic enzyme spermidine/spermine N1-acetyltransferase.
abstract: Intracellular polyamine pools are homeostatically maintained by processes involving biosynthesis, catabolism, and transport. Although most polyamine-based anticancer strategies target biosynthesis, we recently showed that activation of polyamine catabolism at the level of spermidine/spermine N(1)-acetyltransferase-1 (SSAT) suppresses tumor outgrowth in a mouse prostate cancer model. Herein, we examined the effects of differential SSAT expression on intestinal tumorigenesis in the Apc(Min/+) (MIN) mouse. When MIN mice were crossed with SSAT-overproducing transgenic mice, they developed 3- and 6-fold more adenomas in the small intestine and colon, respectively, than normal MIN mice. Despite accumulation of the SSAT product, N(1)-acetylspermidine, spermidine and spermine pools were only slightly decreased due to a huge compensatory increase in polyamine biosynthetic enzyme activities that gave rise to enhanced metabolic flux. When MIN mice were crossed with SSAT knock-out mice, they developed 75% fewer adenomas in the small intestine, suggesting that under basal conditions, SSAT contributes significantly to the MIN phenotype. Despite the loss in catabolic capability, tumor spermidine and spermine pools failed to increase significantly due to a compensatory decrease in biosynthetic enzyme activity giving rise to a reduced metabolic flux. Loss of heterozygosity at the Apc locus was observed in tumors from both SSAT-transgenic and -deficient MIN mice, indicating that loss of heterozygosity remained the predominant oncogenic mechanism. Based on these data, we propose a model in which SSAT expression alters flux through the polyamine pathway giving rise to metabolic events that promote tumorigenesis. The finding that deletion of SSAT reduces tumorigenesis suggests that small-molecule inhibition of the enzyme may represent a nontoxic prevention and/or treatment strategy for gastrointestinal cancers.
authors.affiliation: Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, USA.
authors.forename: Jody M
authors.initials: JM
authors.lastname: Tucker
authors.forename: John T
authors.initials: JT
authors.lastname: Murphy
authors.forename: Nicholas
authors.initials: N
authors.lastname: Kisiel
authors.forename: Paula
authors.initials: P
authors.lastname: Diegelman
authors.forename: Karen W
authors.initials: KW
authors.lastname: Barbour
authors.forename: Celestia
authors.initials: C
authors.lastname: Davis
authors.forename: Moussumi
authors.initials: M
authors.lastname: Medda
authors.forename: Leena
authors.initials: L
authors.lastname: Alhonen
authors.forename: Juhani
authors.initials: J
authors.lastname: Jänne
authors.forename: Debora L
authors.initials: DL
authors.lastname: Kramer
authors.forename: Carl W
authors.initials: CW
authors.lastname: Porter
authors.forename: Franklin G
authors.initials: FG
authors.lastname: Berger
mesh_terms: D000123:Acetyltransferases / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000818:Animals; D015317:Biogenic Polyamines / Q000096:biosynthesis / Q000378:metabolism*; D005260:Female; D017491:Genes, APC; D007414:Intestinal Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D019656:Loss of Heterozygosity; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D000099228:Diamine N-Acetyltransferase
chemical_list: D000123:Acetyltransferases; D015317:Biogenic Polyamines; D000099228:Diamine N-Acetyltransferase