Development of a Gd(III)-Based Receptor-Induced Magnetization Enhancement (RIME) Contrast Agent for β-Glucuronidase Activity Profiling
Development of a Gd(III)-Based Receptor-Induced Magnetization Enhancement (RIME) Contrast Agent for β-Glucuronidase Activity Profiling
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DOI：
10.1021/ic301827p
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发表时间：
2012-11-19
影响因子：
4.6
通讯作者：
Wang, Yun-Ming
中科院分区：
文献类型：
--
作者：
Chen, Shih-Hsien;Kuo, Yu-Ting;Wang, Yun-Ming
β-葡萄糖醛酸酶是一种关键的溶酶体酶，通常在坏死的肿瘤块中过度表达。我们在此报告了前受体诱导磁化增强（pro RIME）磁共振成像（MRI）造影剂（[Gd（DOTA-FP beta Gu）]）的合成，用于肿瘤组织中β-葡萄糖醛酸酶活性的分子成像。造影剂由两部分组成，钆复合物和β-葡萄糖醛酸酶底物（β-D-吡喃葡萄糖醛酸）。 [Gd(DOTA-FP beta Gu)]的结合缔合常数（K-A）为7.42 X 10(2)，显着低于市售MS-325（K-A = 3.0 x 10(4)）RIME造影剂。 [Gd(DOTA-FP beta Gu)] 的低 K-A 值是由于侧链 β-D-吡喃葡萄糖醛酸部分所致。因此，[Gd(DOTA-FP beta Gu)]可以通过RIME调制用于检测β-葡萄糖醛酸酶。通过LC-MS阐明了[Gd(DOTA-FP beta Gu)]酶促激活的详细机制。 pH 7.4 时，β-葡萄糖醛酸酶催化水解 [Eu(DOTA-FP beta Gu)] 的动力学最符合 Miechalis-Menten 动力学模式，其中 K-m = 1.38 mM、K-cat = 3.76 x 10(3) 和 k(cat)/K-m = 2.72 x 10(3) M-1 s(-1)。低 K-m 值表明 β-葡萄糖醛酸酶在生理 pH 下对 [Gd(DOTA-FP beta Gu)] FP beta Gu) 具有高亲和力。弛豫研究表明，[Gd(DOTA-FP beta Gu)] 的 T-1 弛豫率随 β-葡萄糖醛酸酶浓度的变化而变化。与弛豫研究一致，[Gd(DOTA-FP beta Gu)] 在存在 β-葡萄糖醛酸酶和 HSA 的情况下显示 MR 图像信号的显着变化。体外和体内 MR 图像显示，细胞系和肿瘤异种移植物中的信号增强存在明显差异，具体取决于其 β-葡萄糖醛酸酶的表达水平。[图表]。
beta-Glucuronidase is a key lysosomal enzyme and is often overexpressed in necrotic tumor masses. We report here the synthesis of a pro receptor induced magnetization enhancement (pro RIME) magnetic resonance imaging (MRI) contrast agent ([Gd(DOTA-FP beta Gu)]) for molecular imaging of beta-glucuronidase activity in tumor tissues. The contrast agent consists of two parts, a gadolinium complex and a beta-glucuronidase substrate (beta-D-glucopyranuronic acid). The binding association constant (K-A) of [Gd(DOTA-FP beta Gu)] is 7.42 X 10(2), which is significantly lower than that of a commercially available MS-325 (K-A = 3.0 x 10(4)) RIME contrast agent. The low K-A value of [Gd(DOTA-FP beta Gu)] is due to the pendant beta-D-glucopyranuronic acid moiety. Therefore, [Gd(DOTA-FP beta Gu)] can be used for detection of beta-glucuronidase through RIME modulation. The detail mechanism of enzymatic activation of [Gd(DOTA-FP beta Gu)] was elucidated by LC-MS. The kinetics of beta-glucuronidase catalyzed hydrolysis of [Eu(DOTA-FP beta Gu)] at pH 7.4 best fit the Miechalis-Menten kinetic mode with K-m = 1.38 mM, K-cat = 3.76 x 10(3), and k(cat)/K-m = 2.72 x 10(3) M-1 s(-1). The low K-m value indicates high affinity of beta-glucuronidase for [Gd(DOTA-FP beta Gu)] FP beta Gu) at physiological pH. Relaxometric studies revealed that T-1 relaxivity of [Gd(DOTA-FP beta Gu)] changes in response to the concentration of beta-glucuronidase. Consistent with the relaxometric studies, [Gd(DOTA-FP beta Gu)] showed significant change in MR image signal in the presence of beta-glucuronidase and HSA. In vitro and in vivo MR images demonstrated appreciable differences in signal enhancement in the cell lines and tumor xenografts in accordance to their expression levels of beta-glucuronidase.[GRAPHICS].