Materials and methods

NAD, aprotinin, leupeptin, and disulfiram were purchased from the Sigma Chemical Co.(St. Louis. MO). 4-(Diethylamino) benzaldehyde(DEAB), 4-(dimethylamino) benzaldehvde(DMAB). 4-(diethvlaminolbenzoic acid (DEABA), 4-(diethylamino) salicylaldehyde(DEAS), and N, N-diethylaniline (DEA) were obtained from the Aldrich Chemical Co.(Milwaukee, WI), and propionaldehyde and benzaldehyde were from the Kodak Chemical Co.(Rochester, NY). 4-Bis (2chloroethyl) aminobenzaldehyde (BAM) was synthesized as previously described [181.

Female BD2Fl mice, weighing 20-25 g, were used for ip passage of L1210/CPA cells. Ascites tumor cells (5 x lOscells/mouse) were collected on day 8 post-injection and cooled in phosphate-buffered saline (PBS) at 4”. Cells were washed three times in cold PBS and resuspended in freeze/thaw buffer (0.1 M sodium phosphate, pH 7.4, 1 mM EDTA, 5 mM 2-mercaotoethanol. 200 units/ml aorotinin, and 5d pg/ml leupep&) with 260 PI/~ x lo7 &Is. The cells were subjected to three cycles of freezing/thawing in a solid CO,/methanol bath and centrifuged for 10 min at 5008 g. The lipid layer was discarded, and the supernatant fraction was removed and centrifuged for 45 min at 48,008 g. The supernatant fraction was collected (urotein concentration approximately 10 mg/ml) and uyed for ALDH assays. The WEHI-cell line. a mouse mvelomonocytic leukemia line (gift from James Ihle, Frederick Cancer Research Center, Frederick, MD) was grown in RPM1 1640 medium containing 10% fetal bovine serum, 100 units/ml penicillin, and 100 pg/ml streptomycin. The 1ClC7 cell line, a mouse hepatoma line (gift of Mary DeLong, Department of Pharmacology, Johns Hopkins School of Medicine, Baltimore, MD), was maintained in