title: Combination of 5-fluorouracil and N1,N11-diethylnorspermine markedly activates spermidine/spermine N1-acetyltransferase expression, depletes polyamines, and synergistically induces apoptosis in colon carcinoma cells.
abstract: The thymidylate synthase inhibitor 5-fluorouracil (5-FU) is used widely for chemotherapy of colorectal carcinoma. Recent studies showed that 5-FU affects polyamine metabolism in colon carcinoma cells. We therefore examined whether combinations of 5-FU with drugs that specifically target polyamine metabolism, i.e. N1,N11-diethylnorspermine (DENSPM) or alpha-difluoromethylornithine (DFMO), have synergistic effects in killing HCT116 colon carcinoma cells with wild-type or absent p53. Our results showed that simultaneous 5-FU and DENSPM, a spermine analogue, synergistically increased transcript levels of the polyamine catabolism enzyme spermidine/spermine N1-acetyltransferase, depleted spermine and spermidine, increased acetylated spermidine, and produced synergistic tumor cell apoptosis in both p53 wild-type and p53-null variants. By contrast, simultaneous combination of 5-FU with DFMO, an inhibitor of the polyamine biosynthetic enzyme ornithine decarboxylase, depleted putrescine but did not produce synergistic cell killing. Some pre-treatment and post-treatment regimens of DENSPM and DFMO were antagonistic to 5-FU depending on cellular p53 status. Protein and transcriptome expression analysis showed that combined 5-FU and DENSPM treatment activated caspase 9, but not caspase 3, and significantly suppressed NADH dehydrogenases and cytochrome c oxidases, consistent with the observed increase in hydrogen peroxide, loss of mitochondrial membrane potential, and release of cytochrome c. Our findings demonstrate the importance of the polyamine pathway in 5-FU effects and suggest that the combination of 5-FU with DENSPM has potential for development as therapy for colorectal carcinoma.
authors.affiliation: Department of Pathology, Division of Pathology and Laboratory Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Woonyoung
authors.initials: W
authors.lastname: Choi
authors.forename: Eugene W
authors.initials: EW
authors.lastname: Gerner
authors.forename: Latha
authors.initials: L
authors.lastname: Ramdas
authors.forename: Jheri
authors.initials: J
authors.lastname: Dupart
authors.forename: Jennifer
authors.initials: J
authors.lastname: Carew
authors.forename: Lynsey
authors.initials: L
authors.lastname: Proctor
authors.forename: Peng
authors.initials: P
authors.lastname: Huang
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Stanley R
authors.initials: SR
authors.lastname: Hamilton
mesh_terms: D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D004357:Drug Synergism; D005472:Fluorouracil / Q000494:pharmacology*; D017353:Gene Deletion; D045325:HCT116 Cells; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism*; D013096:Spermine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D014158:Transcription, Genetic / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000235:genetics; D000099228:Diamine N-Acetyltransferase
chemical_list: D000123:Acetyltransferases; D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D000975:Antioxidants; D053453:Caspase 9; D020169:Caspases; D045304:Cytochromes c; D005472:Fluorouracil; D006861:Hydrogen Peroxide; D011073:Polyamines; D013096:Spermine; D016159:Tumor Suppressor Protein p53; D000099228:Diamine N-Acetyltransferase; C059685:N(1),N(11)-diethylnorspermine; C506433:CASP9 protein, human