N-Acetyltransferase activities were determined in tumor (12 malignant and 6
benign) and control (non-cancerous) breast tissues from 18 female patients
. The activities of matched 12 malignant tumor and control tissue cytosols
showed 6 rapid, 4 intermediate and 2 slow acetylators based on p-aminobenzo
ic acid (NAT1) and sulfamethazine (NAT2) as substrates, Compared to the act
ivities of slow acetylators, the rapid acetylators exhibited mean apparent
V-max values about 5- and 50-fold greater for p-aminobenzoic acid and sulfa
methazine, respectively. No correlation was observed between the blood and
breast tissue N-acetyltransferase (NAT1 and NAT2) activities. When the mean
apparent N-acetyltransferase activities of the malignant and benign breast
tumor tissues were compared, the results showed an increased activity for
both p-aminobenzoic acid (PABA) and sulfamethazine (SMZ) acetylation in the
malignant tissues compared to benign ones, and also control tissues showed
lower activities compared to tumor tissues. Moreover, the mean NAT2 activi
ty was about 2-fold greater in the malignant tissues when compared to NAT1
activity.