利用化学交换饱和转移磁共振检测前药激活酶羧肽酶G2的活性。
Detection of the prodrug-activating enzyme carboxypeptidase G2 activity with chemical exchange saturation transfer magnetic resonance.
作者信息
Jamin Yann, Eykyn Thomas R, Poon Evon, Springer Caroline J, Robinson Simon P
机构信息
Cancer Research UK and EPRSC Cancer Imaging Centre, Division of Radiotherapy and Imaging, The Institute of Cancer Research and Royal Marsden NHS Foundation Trust, 15 Cotswold Road, Sutton, Surrey, SM2 5NG, UK,
出版信息
Mol Imaging Biol. 2014 Apr;16(2):152-7. doi: 10.1007/s11307-013-0680-5.
PURPOSE
The purpose of this study is to evaluate if the differential exchange rates with bulk water between amine and amide protons can be exploited using chemical exchange saturation transfer magnetic resonance (CEST-MR) to monitor the release of glutamate induced by carboxypeptidase G2 (CPG2), an enzyme utilized in cancer gene therapy.
PROCEDURES
Z spectra of solutions of the CPG2 substrate, 3,5-difluorobenzoyl-L-glutamate (amide), and glutamate (amine) were acquired at 11.7 T, 37 °C, across different pH (5-8). The ability of CEST-MR to monitor CPG2-mediated release of glutamate was assessed in extracts of CPG2-expressing cancer cells and purified solution of CPG2.
RESULTS
The addition of CPG2 to a solution containing 3,5-difluorobenzoyl-L-glutamate led to a marked and progressively increasing CEST effect (+3 ppm), concomitant with the time-dependent release of glutamate induced by CPG2.
CONCLUSION
CEST-MR allows the detection of CPG2 activity in vitro and supports the translation of CEST-MRI to assess CPG2-based gene therapy in vivo.
目的
本研究的目的是评估是否可以利用化学交换饱和转移磁共振（CEST-MR）技术，通过检测胺质子和酰胺质子与大量水分子之间的差异交换率，来监测羧肽酶G2（CPG2，一种用于癌症基因治疗的酶）诱导的谷氨酸释放。
程序
在11.7 T、37°C条件下，于不同pH值（5 - 8）下采集CPG2底物3,5 - 二氟苯甲酰 - L - 谷氨酸（酰胺）和谷氨酸（胺）溶液的Z谱。在表达CPG2的癌细胞提取物和纯化的CPG2溶液中评估CEST-MR监测CPG2介导的谷氨酸释放的能力。
结果
向含有3,5 - 二氟苯甲酰 - L - 谷氨酸的溶液中添加CPG2会导致显著且逐渐增加的CEST效应（+3 ppm），同时伴随着CPG2诱导的谷氨酸随时间的释放。
结论
CEST-MR能够在体外检测CPG2活性，并支持将CEST-MRI转化用于评估体内基于CPG2的基因治疗。
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