Synthesis and reactivity of a potential carcinogenic metabolite of tamoxifen: 3,4-dihydroxytamoxifen-o-quinone.
Synthesis and reactivity of a potential carcinogenic metabolite of tamoxifen: 3,4-dihydroxytamoxifen-o-quinone.
复制标题
DOI：
10.1021/tx990145n
复制
发表时间：
2000
影响因子：
4.1
通讯作者：
Fagen Zhang;Peter W. Fan;Xuemei Liu;Lixin Shen;R. Breemen;Judy L. Bolton
中科院分区：
文献类型：
--
作者：
Fagen Zhang;Peter W. Fan;Xuemei Liu;Lixin Shen;R. Breemen;Judy L. Bolton
尽管他莫昔芬被批准用于治疗激素依赖型乳腺癌以及预防高危女性的乳腺癌，但在动物模型中的几项研究表明，他莫昔芬是致癌的，在人类中，他莫昔芬与子宫内膜癌的风险增加有关。他莫昔芬致癌的一个潜在机制可能涉及他莫昔芬代谢成3，4-二羟基他莫昔芬，然后氧化成一种高活性的邻苯二酚，它可能在体内烷化和/或氧化细胞大分子。在本研究中，我们合成了3，4-二羟基三苯氧胺，用化学法和酶法制备了邻苯二酚，并研究了邻苯二酚与谷胱甘肽和脱氧核苷的反应活性。采用简明的合成路线(四步法)合成了3，4-二羟基三苯氧胺的E(反式)和Z(顺式)异构体。该方法基于关键4-(2-chloroethoxy)-3，4-methylenedioxybenzophenone与苯丙酮之间的McMurry反应，然后用bCL(3)选择性地去除(E，Z)-1-[4-[2-(N，N-二甲氨基)乙氧基]苯基]-1-(3，4-亚甲二氧基苯基)-2-苯基-1-丁烯的亚甲二氧基环。3，4-二羟基三苯氧胺被活化的氧化银或酪氨酸酶氧化生成E和Z异构体的混合物。所得邻苯二酚在生理条件下的半衰期约为80分钟。邻苯二酚与GSH反应生成两个双GSH结合物和三个单GSH结合物。3，4-二羟基三苯氧胺与GSH在微粒体P450存在的情况下孵育得到相同的GSH结合物，在与人乳腺癌细胞(MCF-7)的孵育中也能检测到这种结合物。3，4-二羟基三苯氧胺邻苯二酚与脱氧核苷反应，只生成胸苷和脱氧鸟苷加合物，未检测到脱氧腺苷和脱氧胞苷加合物。对人乳腺癌细胞株的初步研究表明，3，4-二羟基他莫昔芬在雌激素受体阴性(ER-)细胞系(MDA-MB-231)中的细胞毒性与4-羟基他莫昔芬和他莫昔芬相似；而在ER(+)细胞系(MCF-7)中，邻苯二酚代谢产物的毒性约为其他两种化合物的一半。最后，在微粒和GSH的存在下，4-羟基三苯氧胺生成了本期前一篇论文中报道的主要是喹啉甲基GSH结合物[Fan，P.W.，et al.(2000)Chem.Toxicol资源。13，XX-XX]。然而，在酪氨酸酶和GSH的存在下，4-羟基他莫昔芬主要转化为邻苯二酚GSH结合物。这些结果表明，他莫昔芬的邻苯二酚代谢产物可能通过形成3，4-二羟基三苯氧胺邻苯二酚而在体内引起细胞毒性。
Although tamoxifen is approved for the treatment of hormone-dependent breast cancer as well as for the prevention of breast cancer in high-risk women, several studies in animal models have shown that tamoxifen is heptocarcinogenic, and in humans, tamoxifen has been associated with an increased risk of endometrial cancer. One potential mechanism of tamoxifen carcinogenesis could involve metabolism of tamoxifen to 3,4-dihydroxytamoxifen followed by oxidation to a highly reactive o-quinone which has the potential to alkylate and/or oxidize cellular macromolecules in vivo. In the study presented here, we synthesized the 3,4-dihydroxytamoxifen, prepared its o-quinone chemically and enzymatically, and studied the reactivity of the o-quinone with GSH and deoxynucleosides. The E (trans) and Z (cis) isomers of 3,4-dihydroxytamoxifen were synthesized using a concise synthetic pathway (four steps). This approach is based on the McMurry reaction between the key 4-(2-chloroethoxy)-3,4-methylenedioxybenzophenone and propiophenone, followed by selective removal of the methylenedioxy ring of (E, Z)-1-[4-[2-(N,N-dimethylamino)ethoxy]phenyl]-1-(3, 4-methylenedioxyphenyl)-2-phenyl-1-butene with BCl(3). Oxidation of 3,4-dihydroxytamoxifen by activated silver oxide or tyrosinase gave 3,4-dihydroxytamoxifen-o-quinone as a mixture of E and Z isomers. The resulting o-quinone has a half-life of approximately 80 min under physiological conditions. Reaction of the o-quinone with GSH gave two di-GSH conjugates and three mono GSH conjugates. Incubation of 3,4-dihydroxytamoxifen with GSH in the presence of microsomal P450 gave the same GSH conjugates which were also detected in incubations with human breast cancer cells (MCF-7). Reaction of 3, 4-dihydroxytamoxifen-o-quinone with deoxynucleosides gave only thymidine and deoxyguanosine adducts; neither deoxyadenosine nor deoxycytosine adducts were detected. Preliminary studies conducted with human breast cancer cell lines showed that 3, 4-dihydroxytamoxifen exhibited cytotoxic potency similar to that of 4-hydroxytamoxifen and tamoxifen in an estrogen receptor negative (ER(-)) cell line (MDA-MB-231); however, in the ER(+) cell line (MCF-7), the catechol metabolite was about half as toxic as the other two compounds. Finally, in the presence of microsomes and GSH, 4-hydroxytamoxifen gave predominantly quinone methide GSH conjugates as reported in the previous paper in this issue [Fan, P. W., et al. (2000) Chem. Res. Toxicol. 13, XX-XX]. However, in the presence of tyrosinase and GSH, 4-hydroxytamoxifen was primarily converted to o-quinone GSH conjugates. These results suggest that the catechol metabolite of tamoxifen has the potential to cause cytotoxicity in vivo through formation of 3,4-dihydroxytamoxifen-o-quinone.