Induction of β-Glucuronidase Release by Cytostatic Agents in Small Tumors
Induction of β-Glucuronidase Release by Cytostatic Agents in Small Tumors
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DOI：
10.1021/mp300327w
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发表时间：
2012-11-01
影响因子：
4.9
通讯作者：
de Vries，Erik F. J.
中科院分区：
文献类型：
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作者：
Antunes，Ines F.;Haisma，Hidde J.;de Vries，Erik F. J.
肿瘤细胞外β-葡萄糖醛酸酶（β-GUS）是前药治疗的靶酶。然而，尽管令人鼓舞的临床前结果，动物研究也表明，前药治疗的成功可能会受到前药转化酶活性不足的限制，特别是在小肿瘤中。我们假设单剂量的细胞抑制药物可能诱导小肿瘤中β-GUS的释放，导致细胞外β-GUS水平增加，从而提高前药治疗的功效。在此，我们使用正电子发射断层扫描（PET）和示踪剂1-O-（4-（2-氟乙基-氨甲酰氧基甲基）-2-硝基苯基）-O-β-d-葡萄糖吡喃糖醛酸盐[18 F]FEAnGA（已被证明对细胞外β-GUS具有选择性）检测了多柔比星（DOX）、卡莫司汀（BCNU）和肿瘤坏死因子α（TNF-α）单次治疗后小C6胶质瘤中β-GUS释放的程度。首先在培养的C6胶质瘤细胞中研究了β-GUS释放的诱导。此外，在用不同细胞抑制剂单次处理后48小时，在C6荷瘤大鼠中进行[18 F]FEAnGA PET研究，以评价β-葡萄糖醛酸苷酶释放的程度。在肿瘤匀浆中分析β-GUS对[18F]FEAnGA的切割。组织化学分析和流式细胞术证实了肿瘤坏死和白细胞浸润的诱导。体外研究表明，所有处理均导致活细胞数下降，胞外β-GUS活性升高。PET研究证实，β-GUS在体内释放，PET示踪剂[18 F]FEAnGA在C6胶质瘤中的分布体积显著增加15- 70%，这取决于治疗。肿瘤的组织化学分析表明，卡莫司汀和TNF-α治疗引起更大的坏死区域，缺乏浸润的免疫细胞，而阿霉素诱导白细胞浸润增加。这些结果得到了流式细胞术的证实。总之，本研究表明，单剂量的细胞生长抑制剂能够增加β-GUS的释放。β-GUS中的释放可以通过[18F]FEAnGA PET以非侵入性方式监测。这项研究可能开辟了两步化疗-前药方法的道路，其中在前药治疗之前用单剂量的细胞抑制药物治疗肿瘤。
Extracellular β-glucuronidase (β-GUS) in tumors has been investigated as a target enzyme for prodrug therapy. However, despite encouraging preclinical results, animal studies also indicate that the success of prodrug therapy might be limited by the insufficient prodrug-converting enzyme activity, especially in small tumors. We hypothesized that a single dose of a cytostatic drug might induce the release of β-GUS in small tumors, resulting in increased levels of extracellular β-GUS and consequently a higher efficacy of the prodrug treatment. Here we examine the extent of β-GUS release in small C6 glioma tumors after a single treatment of doxorubicin (DOX), carmustine (BCNU) and tumor necrosis factor α (TNF-α) with positron emission tomography (PET) and the tracer 1-O-(4-(2-fluoroethyl-carbamoyloxymethyl)-2-nitrophenyl)-O-β-d-glucopyronuronate, [18F]FEAnGA, which has been proven to be selective for extracellular β-GUS. Induction of β-GUS release was first investigated in cultured C6 glioma cells. In addition, a [18F]FEAnGA PET study was performed in C6 tumor-bearing rats 48 h after a single treatment with different cytostatics to evaluate the extent of β-glucuronidase release. The cleavage of [18F]FEAnGA by β-GUS was analyzed in tumor homogenates. The induction of tumor necrosis and leukocyte infiltration was confirmed by histochemical analysis and flow cytometry. Thein vitrostudies indicated that all treatments resulted in a decline of viable cells and an increase of extracellular β-GUS activity. PET studies confirmed that β-GUS was releasedin vivoand the distribution volume of the PET tracer [18F]FEAnGA in C6 gliomas was increased significantly by 15–70%, depending on the treatment. Histochemical analysis of the tumors indicated that carmustine and TNF-α treatment caused a larger necrotic area with the absence of infiltrating immune cells, whereas doxorubicin induced an increase in leukocyte infiltration. These results were confirmed by flow cytometry. In conclusion, the present study demonstrates that a single dose of a cytostatic agent is able to increase the release of β-GUS. The release in β-GUS can be monitored by [18F]FEAnGA PET in a noninvasive manner. This study may open the way to a two-step chemotherapy–prodrug approach, in which tumors are treated with a single dose of a cytostatic drug prior to prodrug treatment.