The Drug Salicylamide Is an Antagonist of the Aryl Hydrocarbon Receptor That Inhibits Signal Transduction Induced by 2,3,7,8-Tetrachlorodibenzo-P-Dioxin
[CANCER RESEARCH 64, 429–434, January 1, 2004] The Drug Salicylamide Is an Antagonist of the Aryl Hydrocarbon Receptor That Inhibits Signal Transduction Induced by 2,3,7,8-Tetrachlorodibenzo-p-dioxin Christopher J. MacDonald, Henry P. Ciolino, and Grace Chao Yeh Cellular Defense and Carcinogenesis Section, Basic Research Laboratory, Center for Cancer Research, National Cancer Institute-Frederick, NIH, Frederick, Maryland ABSTRACT (a)pyrene, and heterocyclic amines such as 2-amino-1-methyl-6- phenylimidazo[4,5-b]pyridine. These classes of xenobiotics are all 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a widespread environ- suspected human carcinogens. For example, TCDD, a widespread mental contaminant, that has been linked with a variety of deleterious environmental contaminant generated by a variety of industrial pro- effects on human health, including increased cancer rates and reproduc- tive anomalies. The detrimental effects of TCDD are mediated via the aryl cesses, has been linked to an increase in many types of human hydrocarbon receptor (AhR), a transcription factor that regulates the cancers, including hepatocellular cancer (3, 4). In animal models, expression of the carcinogen-activating enzymes cytochromes P-450 TCDD has been shown to cause acute toxicity (5), increased oxidative (CYP) 1A1, 1A2, and 1B1. In the present study, we examined the ability stress (6), impaired ovulation (7), and immunotoxicity (8). These of synthetic derivatives of salicylic acid to affect TCDD-stimulated AhR- effects in animal models are believed to closely reflect the deleterious mediated signal transduction in human hepatoma HepG2 cells. Salicyl- effects of TCDD in humans (9). TCDD has the highest affinity for the amide (SAL), an analgesic drug, caused a potent and long-lasting inhibi- AhR of any known compound, and is considered the prototypical AhR tion of TCDD-induced CYP enzyme activity.
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