N-Glycolylneuraminic acid (Neu5Gc) is a sialic acid that is found in non-human primate tissues.1,2 It is not endogenously produced in humans due to a mutation in the gene that encodes CMP-Neu5Ac hydroxylase, the enzyme that hydrolyzes N-acetylneuraminic acid to form Neu5Gc, but accumulates in human cells after exogenous ingestion from dietary sources such as red meat and dairy products. Neu5Gc accumulates in human tumors, including retinoblastomas, melanomas, colon carcinomas, and breast cancer, and Neu5Gc uptake is enhanced under hypoxic conditions.2
1.Nguyen, D.H., Tangvoranuntakul, P., and Varki, A.Effects of natural human antibodies against a nonhuman sialic acid that metabolically incorporates into activated and malignant immune cellsJ. Immunol.175(1)228-236(2005) 2.Hedlund, M., Padler-Karavani, V., Varki, N.M., et al.Evidence for a human-specific mechanism for diet and antibody-mediated inflammation in carcinoma progressionProc. Natl. Acad. Sci. USA105(48)18936-18941(2008)