title: Tolfenamic acid suppresses cytochrome P450 2E1 expression in mouse liver.
abstract: Non-steroidal anti-inflammatory drugs (NSAIDs) play a significant role in the chemoprevention of cancer. We recently showed the chemopreventive response of a NSAID, 2-[(3-chloro-2-methylphenyl)amino]benzoic acid) known as tolfenamic acid (TA) in N-nitrosomethylbenzylamine (NMBA)-induced esophageal tumors in rats. Pre-clinical studies showed that TA inhibits Specificity protein (Sp) transcription factors and acts as an anti-cancer agent in several cancer models; however the pertinent mechanisms associated with its chemopreventive response in esophageal cancer are not known. Since the bioactivation of carcinogens through cytochrome P450 (CYP) is critical for the induction of cancer, we have studied the effect of TA on critical CYP isozymes in mouse liver samples. Athymic nude mice were treated with vehicle (corn oil) or TA (50 mg kg(-1), 3 times per week) for 4 weeks. Protein extracts (whole cell lysates and microsomal fractions) were prepared from liver tissue and the expression of various CYP isozymes was determined by Western blot analysis. Rat (Sprague-Dawley) livers were harvested and primary hepatocyte cultures were treated with vehicle (DMSO) or TA (50 μM) and cell viability was assessed at 2 and 5 days post-treatment. TA caused remarkable decrease in the expression of CYP2E1 in both liver lysates and sub-cellular fraction, while its response on other tested isozymes was marginal. TA did not affect the body weight of animals (mice) and viability of rat hepatocytes. These results demonstrate that TA modulates the expression of CYP2E1 which is associated with the bioactivation of carcinogens without causing apparent toxicity. These data suggest that TA-induced inhibition of CYP2E1 attenuates the bioactivation of carcinogens potentially leading to the chemoprevention of NMBA-induced esophageal tumorigenesis in rats.
authors: Cancer Research Institute, MD Anderson Cancer Center Orlando, 6900 Lake Nona Blvd, Orlando, FL 32827, USA.
authors: Mohammed I
authors: MI
authors: Shukoor
authors: Samata
authors: S
authors: Tiwari
authors: Umesh T
authors: UT
authors: Sankpal
authors: Pius
authors: P
authors: Maliakal
authors: Sarah F
authors: SF
authors: Connelly
authors: Shaila
authors: S
authors: Siddiqi
authors: Shadab A
authors: SA
authors: Siddiqi
authors: Riyaz
authors: R
authors: Basha
mesh_terms: D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects; D019392:Cytochrome P-450 CYP2E1 / Q000096:biosynthesis*; D065691:Cytochrome P-450 CYP2E1 Inhibitors; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008099:Liver / Q000187:drug effects* / Q000201:enzymology*; D008297:Male; D051379:Mice; D008819:Mice, Nude; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D017207:Rats, Sprague-Dawley; D062367:ortho-Aminobenzoates / Q000494:pharmacology*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D065691:Cytochrome P-450 CYP2E1 Inhibitors; D062367:ortho-Aminobenzoates; C009500:tolfenamic acid; D019392:Cytochrome P-450 CYP2E1