Class 3 Aldehyde Dehydrogenase

Abstract

Mammalian Class 3 aldehyde dehydrogenase includes both constitutively-expressed and xenobiotic-inducible forms encoded by at least 2 separate genes (Lindahl, 1992; Petersen and Lindahl, 1997). The rat microsomal form of Class 3 ALDH, encoded by the ALDH4 gene, is constitutively expressed. Depending on the tissue, the product of the rat ALDH3 gene is either constitutively expressed or inducible. In liver, no constitutive expression of ALDH3 is detectable (Lindahl, 1992). However, following exposure to either polycyclic aromatic hydrocarbons such as 3-methylcholanthrene (3-MC) or dioxins such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), increases in both hepatic ALDH3 transcript and Class 3 ALDH enzyme activity occur (Lindahl, 1992). Constitutive expression of ALDH3 occurs in a variety of normal tissues, including the urinary bladder, lung, stomach and particularly the cornea of the eye (Lindahl, 1992). Class 3 ALDH activity is also elevated in both chemically-induced and spontaneous neoplasms from a variety of tissues, such as liver, colon, breast and leukemias as well as a number of tumor-derived cell lines (Lindahl, 1992).