Brueggemeier Robert W, Díaz-Cruz Edgar S, Li Pui-Kai, Sugimoto Yasuro, Lin Young C, Shapiro Charles L
College of Pharmacy, The Ohio State University, 500 W. 12th Avenue, Columbus, OH 43210, USA.
J Steroid Biochem Mol Biol. 2005 May;95(1-5):129-36. doi: 10.1016/j.jsbmb.2005.04.013.
Aromatase expression and enzyme activity in breast cancer patients is greater in or near the tumor tissue compared with the normal breast tissue. Regulation of aromatase expression in human tissues is quite complex, involving alternative promoter sites that provide tissue-specific control. Previous studies in our laboratories suggested a strong association between aromatase (CYP19) gene expression and the expression of cyclooxygenase (COX) genes. Our hypothesis is that higher levels of COX expression result in higher levels of prostaglandin E2 (PGE2), which in turn increases CYP19 expression through increases in intracellular cyclic AMP levels. This biochemical mechanism may explain the beneficial effects of non-steroidal anti-inflammatory drugs (NSAIDs) on reducing the risks of breast cancer. The effects of NSAIDs (ibuprofen, piroxicam, and indomethacin), a COX-1 selective inhibitor (SC-560), and COX-2 selective inhibitors (celecoxib, niflumic acid, nimesulide, NS-398, and SC-58125) on aromatase activity and CYP19 expression were investigated in breast cancer cell culture systems. Dose-dependent decreases in aromatase activity were observed following treatment with an NSAID or COX inhibitor, with the most effective agents being COX selective inhibitors. Real time PCR analysis of aromatase gene expression showed a significant decrease in mRNA levels in treated cells when compared to vehicle control. These results suggest that the effect of COX inhibitors on aromatase occurs at the transcriptional level. To further probe these interactions, short interfering RNAs (siRNA) were designed against either human CYP19 mRNA or human COX-2 mRNA. Treatment of breast cancer cells with aromatase siRNAs suppressed CYP19 mRNA and aromatase enzyme activity. Finally, treatment with COX-2 siRNAs downregulated the expression of COX-2 mRNA; furthermore, the siCOX-2-mediated suppression of COX-2 also resulted in suppression of aromatase mRNA. In summary, pharmacological regulation of aromatase and cyclooxygenases can act locally in an autocrine fashion to decrease the biosynthesis of estrogen and may provide additional therapy options for patients with hormone-dependent breast cancer.
与正常乳腺组织相比，乳腺癌患者肿瘤组织内或其附近的芳香化酶表达及酶活性更高。人体组织中芳香化酶表达的调控相当复杂，涉及能提供组织特异性控制的可变启动子位点。我们实验室之前的研究表明，芳香化酶（CYP19）基因表达与环氧化酶（COX）基因表达之间存在密切关联。我们的假设是，较高水平的COX表达会导致较高水平的前列腺素E2（PGE2），而PGE2又会通过提高细胞内环磷酸腺苷水平来增加CYP19表达。这种生化机制或许可以解释非甾体抗炎药（NSAIDs）在降低乳腺癌风险方面的有益作用。在乳腺癌细胞培养系统中研究了NSAIDs（布洛芬、吡罗昔康和吲哚美辛）、一种COX-1选择性抑制剂（SC-560）以及COX-2选择性抑制剂（塞来昔布、尼氟酸、尼美舒利、NS-398和SC-58125）对芳香化酶活性和CYP19表达的影响。用NSAID或COX抑制剂处理后，观察到芳香化酶活性呈剂量依赖性降低，其中最有效的药物是COX选择性抑制剂。与溶剂对照相比，芳香化酶基因表达的实时PCR分析显示，处理后的细胞中mRNA水平显著降低。这些结果表明，COX抑制剂对芳香化酶的作用发生在转录水平。为了进一步探究这些相互作用，设计了针对人CYP19 mRNA或人COX-2 mRNA的小干扰RNA（siRNA）。用芳香化酶siRNA处理乳腺癌细胞可抑制CYP19 mRNA和芳香化酶活性。最后，用COX-2 siRNA处理下调了COX-2 mRNA的表达；此外，siCOX-2介导的COX-2抑制也导致了芳香化酶mRNA的抑制。总之，芳香化酶和环氧化酶的药理调控可以以自分泌方式在局部发挥作用，减少雌激素的生物合成，并且可能为激素依赖性乳腺癌患者提供更多治疗选择。
