Arylamine N-acetyltransferase 1 knockout in immortalized human bronchial cells results in a reduction of cellular growth

Arylamine N-acetyltransferase 1 (NAT1) is a xenobiotic metabolizing enzyme. NAT1 has recently been proposed to have a non-canonical role in cancer cells, where NAT1 knockout (KO) results in reduced cell growth, cancer properties, and altered mitochondria metabolism. The non-canonical role of NAT1 in human lung cells remains unknown. This study aimed to understand if the loss of NAT1 in human bronchial cells, both epithelial (BEP2D) and fibroblast (WTHBF-6), impacted cell growth. We constructed cell lines stably expressing Cas9 and then inserted two different guide RNA (gRNA) sequences for NAT1 into BEP2D cells and WTHBF-6 cells. We expanded colonies of both cell lines for each gRNA and confirmed the loss of NAT1 by measuring the N-acetylation of a NAT1 selective substrate (p-aminobenzoic acid). We measured cell growth via growth curves and colony formation. We also screened the karyotype of each clone to determine if NAT1 had an impact on genomic stability. We found a reduction in the growth of NAT1 KO cells compared to parental cells. Interestingly, there was no change in colony number for NAT1 KO cells, but there was a reduction in the colony cell density (qualitatively observed) for these cells. NAT1 knockout did not induce genomic instability. These data provide further evidence suggesting that NAT1 has a non-canonical role outside of substrate acetylation, and results indicate that NAT1 KO reduces cell growth of non-tumorigenic human lung cells.