Detoxification of the polyamine analogue N1-ethyl-N11-[(cycloheptyl)methy]-4,8-diazaundecane (CHENSpm) by polyamine oxidase.
OBJECTIVE
Analogues of the naturally occurring polyamines, alkylated on both terminal amines, are being developed as anticancer drugs. Because bisalkylated derivatives of putrescine (1,4-diaminobutane) are potent inhibitors of the flavin adenine dinucleotide-dependent polyamine oxidase (PAO), we asked whether PAO could detoxify synthetic bisalkylated polyamines with chain lengths longer than putrescine.


METHODS
We investigated the effects of one polyamine analogue in Chinese hamster ovary (CHO) and HCT116 human colon tumor-derived cells, which express dramatically different levels of PAO activity, and in these same cells treated with an inhibitor of PAO.


RESULTS
Concentrations of N1-ethyl-N11-[(cycloheptyl)methyl]-4,8-diazaundecane (CHENSpm), ranging from 0.3 to 10 microM, caused growth arrest and reduced cell survival in HCT116 cells but not in CHO cells. This cell line-specific difference in CHENSpm toxicity was not attributable to differences in analogue uptake, because intracellular levels of the drug were similar in CHO and HCT116 cells treated with equivalent concentrations of CHENSpm in the presence of MDL 72,527, a specific inhibitor of PAO. The PAO inhibitor, in combination with CHENSpm, caused a significant increase in intracellular CHENSpm levels and increased growth inhibition and cell damage in CHO cells but not in HCT116 cells. CHO cells, but not HCT116 cells, produced two primary amine-containing metabolites from CHENSpm that were suppressed by MDL 72,527.


CONCLUSIONS
These data demonstrate that CHENSpm is detoxified in PAO-expressing CHO cells, but not in PAO-deficient HCT116 cells, by a mechanism yielding products containing free primary amine groups and implicate PAO as the detoxification enzyme. Because other studies suggest that PAO may be self-regulated in some tumors, differential expression of PAO may be the basis for selective toxicity of CHENSpm and other N-substituted polyamine analogues in certain cancers.
Lawson
Kathryn R
KR
Department of Radiation Oncology and Biochemistry, The University of Arizona, Arizona Cancer Center, Tucson 85724, USA.
Marek
Sarah
S
Linehan
Jennifer A
JA
Woster
Patrick M
PM
Casero
Robert A
RA
Payne
Claire M
CM
Gerner
Eugene W
EW
D000818:Animals; D016466:CHO Cells; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008854:Microscopy, Electron; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000378:metabolism*; D011073:Polyamines / Q000378:metabolism* / Q000494:pharmacology; D011700:Putrescine / Q000031:analogs & derivatives* / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D000097667:Polyamine Oxidase
D000587:Oxidoreductases Acting on CH-NH Group Donors; D011073:Polyamines; D011700:Putrescine; D000097667:Polyamine Oxidase; C118771:N(1)-ethyl-N-(11)-((cycloheptyl)methyl)-4,8-diazaundecane; C044445:MDL 72527