Yamazaki Y, Ogawa Y, Afify A S, Kageyama Y, Okada T, Okuno H, Yoshii Y, Nose T
National Institute of Bioscience and Human Technology, Agency of Industrial Science and Technology, Ibaraki, Japan.
Biochim Biophys Acta. 1995 Apr 13;1243(3):300-8. doi: 10.1016/0304-4165(94)00153-o.
This study has aimed at taking information necessary for design of anticancer prodrugs modified with chiral acyl group, especially about the effect of chirality of the acyl group on its enzymic removal in specific cells. Thus, 13 species of chiral esters were synthesized and stereoselectivity in their enzymic hydrolysis was investigated with six cancer cell lines, solid tumors, and the corresponding normal tissues. Cultured cancer cells from rat liver, pancreas, and muscle hydrolyzed the R enantiomer of (+/-)-ethyl 2-methoxy-2-phenylacetate (3c) more preferentially than its antipode, whereas this stereoselectivity was reversed in the reaction by homogenate of the corresponding normal tissue of rat. The difference in stereoselectivity between cancer cells and normal tissue was also found in the hydrolysis of other esters including those of actual anticancer agents, p-hydroxyaniline mustard and 5-fluorouridine. The investigation was expanded to real tumor to show that the degree of stereoselectivity or the hydrolytic activity was significantly different between a human brain tumor and its surrounding normal tissue for such substrates as (+/-)-ethyl 2-phenoxypropanoate and N-trifluoroacetylphenylalaninate. The esterases of rat liver cancer cells (Anr4) and normal rat liver gave different band patterns in active staining after gel electrophoresis. The enzymes were fractionated by ion exchange column chromatography and then tested on their stereoselectivity against (+/-)-3c. Comparison of the results and electrophoretograms of the fractions suggests that esterases with different stereoselectivity are expressed in different ways by normal and cancer cells. These results show that stereoselectivity in enzymic hydrolysis of some synthetic chiral esters is different between cancer and normal cells, leading to the possibility that specific activation of ester-type anticancer prodrugs in cancer cells would be controlled by the chiral structure of the acyl group.
本研究旨在获取设计手性酰基修饰的抗癌前药所需的信息，尤其是关于酰基手性对其在特定细胞中酶促去除的影响。因此，合成了13种手性酯，并利用6种癌细胞系、实体瘤及相应的正常组织研究了它们酶促水解的立体选择性。大鼠肝脏、胰腺和肌肉的培养癌细胞对(±)-2-甲氧基-2-苯基乙酸乙酯（3c）的R对映体的水解优先于其对映体，而在大鼠相应正常组织匀浆的反应中，这种立体选择性则相反。在包括实际抗癌剂对羟基苯胺氮芥和5-氟尿苷的酯在内的其他酯的水解中，也发现了癌细胞和正常组织之间立体选择性的差异。研究扩展到实际肿瘤，结果表明，对于(±)-2-苯氧基丙酸乙酯和N-三氟乙酰苯丙氨酸酯等底物，人脑肿瘤与其周围正常组织之间的立体选择性程度或水解活性存在显著差异。大鼠肝癌细胞（Anr4）和正常大鼠肝脏的酯酶在凝胶电泳后的活性染色中呈现不同的条带模式。通过离子交换柱色谱对酶进行分离，然后测试它们对(±)-3c的立体选择性。各馏分的结果和电泳图谱比较表明，正常细胞和癌细胞以不同方式表达具有不同立体选择性的酯酶。这些结果表明，某些合成手性酯的酶促水解中的立体选择性在癌细胞和正常细胞之间存在差异，这导致酯型抗癌前药在癌细胞中的特异性活化可能受酰基手性结构控制的可能性。
