There is an increasing recognition of the role that cancer cell derived exosomes play in intercellular signaling upon fusion or uptake with a target cell, including immune system evasion, tumor growth and metastasis. To date, however, although exosomal membrane and cargo lipids are expected to play a pivotal role in exosome biogenesis and secretion, as well as in fusion or uptake and target cell functional response, the detailed characterization of cancer cell derived exosome lipids across a range of different cancers has not yet been broadly explored. Here, a simple and straightforward lipidome analysis strategy consisting of optimized sample extraction and novel sample derivatization techniques, coupled with high-resolution ‘shotgun’ mass spectrometry and ‘targeted’ tandem mass spectrometry methods, is demonstrated for the rapid identification of >520 individual lipids in 36 lipid classes and sub classes from exosomes secreted by the colorectal cancer cell line, LIM1215. Relative quantification and comparison of exosome versus cellular lipid profiles reveals significant enrichment of certain lipid classes, as well as substantial lipid subclass remodeling and changes in abundance of individual lipids, including sphingolipids, sterol lipids, glycerolipids and glycerophospholipids, and particularly plasmalogen- and alkyl ether-containing glycerophospholipids. This analysis strategy therefore provides a platform for comprehensive lipidome profiling across a wide range of cancer cell or tissue derived exosomes, that will facilitate subsequent functional studies aimed at elucidating the role of specific cellular or exosome lipids in the onset and progression of colorectal cancer, or to identify specific lipid(s) that could serve as effective diagnostic or prognostic disease biomarkers.

The direct-acting mutagen 4-nitro-o-phenylenediamine (NOP) was activated in vitro by pea or tobacco S-9 into a more potent mutagen in Salmonella typhimurium strain TA98. NOP mutagenicity was not altered by Aroclor 1254-induced rat liver S-9. The plant S-9 activation of NOP was heat-sensitive but was not NADPH-dependent, did not involve superoxide radicals, and was not inhibited by CO. A direct relationship between plant peroxidase and NOP activation was established. Several purified peroxidases including horseradish peroxidase, chloroperoxidase, and lactoperoxidase also activated NOP. The perodoxidative process was not H2O2-dependent but was partially inhibited by a peroxidase inhibitor.

Townsend, S.E., and S.N. Sehgal: Mutagenicity evaluation of tetrahydro-amino acridine by the Salmonella/microsome mutagenicity Ames test. Drug Dev. Res. 14:91-94, 1988.1,2,3,4-tetrahydr0-5-amino acridine (THA), a cholinesterase inhibitor currently under investigation for use in the treatment of senile dementia, exhibited mutagenic activity with and without metabolic microsomal S-9 activation against tester strain TA97a in the Salmonella fyphimurium incorporation assay. The mutagenic response was concentration-dependent within the dose range of 500 to 2,500 Fg/plate.

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