Polyamines are small polycationic alkylamines involved in many fundamental cellular processes, including proliferation, nucleic acid synthesis, apoptosis, and protection from oxidative damage. It has been proposed that in addition to these functions, elevated levels of polyamines promote longevity in various biological systems, including yeast, drosophila, and murine models. A series of in vitro mechanistic studies by multiple investigators has led to the conclusion that addition of exogenous spermidine promotes longevity through autophagy induction; however, these experiments were confounded by the use of mammalian cell culture systems supplemented with fetal bovine serum (FBS). Using cell viability assays, LC3B immunoblots, and live-cell fluorescence microscopy, we report here that in the presence of ruminant serum, exogenously added polyamines are quickly oxidized by the copper-containing bovine serum amine oxidase (BSAO). This polyamine oxidation resulted in the production of harmful byproducts including hydrogen peroxide, ammonia, and reactive aldehydes. Our data demonstrate that it is critically important to prevent confounding BSAO-induced cytotoxicity in mechanistic studies of the roles of polyamines in autophagy.
Keywords: amine oxidase; autophagy; beta-oxidation; bovine serum amine oxidase; cytotoxicity; hydrogen peroxide; oxidative stress; polyamine; spermidine; spermine.
Published under license by The American Society for Biochemistry and Molecular Biology, Inc.
Nanoparticle strategies for cancer therapeutics: Nucleic acids, polyamines, bovine serum amine oxidase and iron oxide nanoparticles (Review).Int J Oncol. 2015 Jan;46(1):5-16. doi: 10.3892/ijo.2014.2706. Epub 2014 Oct 14. Int J Oncol. 2015. PMID: 25333509 Review.
Induction of phase 2 enzymes by serum oxidized polyamines through activation of Nrf2: effect of the polyamine metabolite acrolein.Biochem Biophys Res Commun. 2003 Jun 6;305(3):662-70. doi: 10.1016/s0006-291x(03)00834-9. Biochem Biophys Res Commun. 2003. PMID: 12763045
Aldehyde dehydrogenase and cytotoxicity of purified bovine serum amine oxidase and spermine in Chinese hamster ovary cells.Biochem Cell Biol. 1994 Jan-Feb;72(1-2):36-42. doi: 10.1139/o94-006. Biochem Cell Biol. 1994. PMID: 8068243
Potential anticancer application of polyamine oxidation products formed by amine oxidase: a new therapeutic approach.Amino Acids. 2010 Feb;38(2):353-68. doi: 10.1007/s00726-009-0431-8. Epub 2009 Dec 10. Amino Acids. 2010. PMID: 20012114 Review.
Heat enhancement of cytotoxicity induced by oxidation products of spermine in Chinese hamster ovary cells.Biochem Pharmacol. 1994 Sep 15;48(6):1181-6. doi: 10.1016/0006-2952(94)90155-4. Biochem Pharmacol. 1994. PMID: 7945412