Determination of Aldehyde Dehydrogenase (ALDH) Isozymes in Human Cancer Samples - Comparison of Kinetic and Immunochemical Assays

Quentin Hayes

A fluorimetric assay of aldehyde dehydrogenase isozymes, based on naphthaldehyde oxidation, is compared with Western Blotting analysis on several clinical samples obtained from surgery. The comparison reveals qualitatively good correlation of ALDH1A1 isozyme detection with two methods and somewhat worse on ALDH3A1 assay It has been confirmed that two cytosolic ALDH isozymes, ALDH1A1 and ALDH3A1 (formerly known as ALDH-1 and ALDH-3) are those primarily responsible for drug inactivation. The activity levels of the foregoing isozymes also reveal some predictive potential for cancer metastasis level. Evaluation of ALDH activity levels in clinical material by traditional spectrophotometric approach, i.e., using either acetaldehyde or propionic aldehyde as a substrate, and measuring NADH production rate, is not isozyme-specific and usually requires prior separation of the enzymes from the clinical sample.