From T-antigen to plasmalogen-derived aldehydes: The identification of a marker of colorectal cancer in human rectal mucous

Abstract

Recently, a simple noninvasive screening test for colorectal cancer was proposed, based on a hypothesis involving galactose-containing carbohydrate moieties such as the Thomsen–Friedenreich antigen. According to the hypothesis, such carbohydrate moieties, present in the human rectal mucous of patients with colorectal cancer, can be specifically oxidized with galactose oxidase to form substances that, upon reaction with Schiff reagent, yield purple (magenta) coloured compounds. While evaluating this proposed test, we discovered that the colour formation is not due to the proposed reaction between oxidized galactose moieties present in rectal mucous and Schiff reagent. We found instead that the mucous from colorectal cancer patients contains compounds that form purple (magenta) adducts with the Schiff reagent directly, i.e., they do not require oxidation by galactose oxidase. We have identified these compounds as long-chain aliphatic aldehydes, mainly palmitic aldehyde C15H31CH=O and stearic aldehyde C17H35CH=O. We have further found that the aldehydes originate from plasmalogens present in the phospholipid fraction of the mucous obtained from colorectal cancer patients. The aldehydes, present in plasmalogens as enol ethers, are released by the acidity of the Schiff reagent and in turn react with the Schiff reagent to form the coloured adducts. Correct identification of these markers could lead to the development of a more accurate colorectal cancer screening tool and to a deeper understanding of colorectal carcinogenesis.Key words: T-antigen, plasmalogen-derived aldehydes, colorectal cancer marker.

Thomsen-Friedenreich and Tn Antigens in Nipple Fluid: Carbohydrate Biomarkers for Breast Cancer Detection

“…The immunoassays were done on the samples using monoclonal antibodies to expressly capture the TF and Tn antigens in NAF. Antigen capture, in contrast to less specific chemical methods for mucin NAF analysis (13,14), allowed for the detection of TF and Tn. The monoclonal antibodies (anti-TF A78-G/A7, NeoMarkers, Freemont, CA; anti-Tn V 1053, Biomeda, Foster City, CA) were applied to Nunc-immunomaxi 96-well plates (Nunc A/S, Roskilde, Denmark) for 4 hours at 37jC.…”