Dihydrodiol Dehydrogenase

DDH is a member of aldo-keto reductase superfamily1,2, which catalyzes reduction of aldehyde or ketone to a corresponding alcohol by using NADH or NADPH as a cofactor. In liver, the enzyme is abundantly located in the cytoplasm as a monomeric 34-36 kDa protein3,4. Interestingly, by differential display Shen et al.5 has shown that overexpression of DDH could be identified in ethacrynic acid-induced drug-resistant human colon cancer cells. Detection of DDH overexpression in drug-resistant human stomach cancer cells, which were selected by the gradual adaptation to daunorubicin, further suggested that DDH might be associated with the drug-resistance in cancer cells6.In a recent study, DDH expression was further shown to have prognostic significance in patients with NSCLC. By using an immunohistochemical method to determine DDH expression in surgical specimens, DDH expression was identified in patients with leukemia, lung cancer, esophageal cancer, transitional cancer and breast cancer. Furthermore, overexpression of DDH was confirmed by immunoblotting and in situ hybridization. Correlation between clinicopathological parameters and DDH expression as well as the prognostic significance of DDH expression in patients with advanced cancer was indicated.