Downexpression of aldehyde dehydrogenase 1 in murine lung tumors

We analyzed the expression of the cytosolic aldehyde dehydrogenase 1 (Aldh1) gene in mouse lung tumors by northern blotting and immunocytochemical analysis. Aldh1 was abundantly expressed in normal lung tissue, with a predominant cellular localization on bronchiolar cells. However, expression of Aldh1 was strongly reduced (more than tenfold) in lung tumors. As aldehyde dehydrogenases metabolize some antitumor alkylating drugs to inactive compounds, the low expression of Aldh1 in lung tumors may account for the drug sensitivity of these tumors to chemotherapeutic agents.