The Role of Arylamine N‐acetyltransferase 1 in Breast Cancer Progression

Abstract

Breast cancer is a leading cause of cancer death among women in the United States. Arylamine N‐acetyltransferase 1 (NAT1) has been linked to breast cancer because of its role in the metabolic activation and detoxification of carcinogens. However, recent studies suggest it may play an important role in cancer biology. Higher NAT1 expression is associated with more aggressive cancers and poorer prognosis. Increased NAT1 levels in primary tumors are significantly associated with increased metastasis to the bone. We have observed NAT1 inhibition decreased proliferation and invasiveness of MDA‐MB‐231 breast cancer cells. To delineate the mechanisms by which NAT1 inhibition decreases cell invasion and proliferation, MDA‐MB‐231 and MCF‐7 breast cancer cell lines were treated with siRNA targeting NAT1, or a non‐targeting siRNA. Cells were collected at 24, 48, 72 and 96 hours after treatment. In vitro assays using a NAT1‐specific substrate, para‐aminobenzoic acid (PABA) were conducted to measure NAT1 activity by HPLC. NAT1 mRNA was measured using qRT‐PCR. Optimal knockdown of NAT1 occurred at 96 and 72 hours in MCF‐7 and MDA‐MB‐231 cells, with 65% (p < 0.005) of NAT1 activity remaining after treatment in both cell lines. NAT1 mRNA decreased 60% (p < 0.0001) and 34% (p < 0.001) in MCF‐7 and MDA‐MB‐231 cells, respectively. These samples will undergo whole genome analysis using a GeneArray to identify potential gene expression signatures which may be altered as a result of NAT1 inhibition. [Partially supported by NIEHS T32‐ESO11564]