Yu Zhiqiang, Paul Rakesh, Bhattacharya Chandrabali, Bozeman Trevor C, Rishel Michael J, Hecht Sidney M
†Center for Bioenergetics, Biodesign Institute, and Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287, United States.
‡GE Global Research, 1 Research Circle, Niskayuna, New York 12309, United States.
Biochemistry. 2015 May 19;54(19):3100-9. doi: 10.1021/acs.biochem.5b00277. Epub 2015 May 6.
We have shown previously that the bleomycin (BLM) carbohydrate moiety can recapitulate the tumor cell targeting effects of the entire BLM molecule, that BLM itself is modular in nature consisting of a DNA-cleaving aglycone which is delivered selectively to the interior of tumor cells by its carbohydrate moiety, and that there are disaccharides structurally related to the BLM disaccharide which are more efficient than the natural disaccharide at tumor cell targeting/uptake. Because BLM sugars can deliver molecular cargoes selectively to tumor cells, and thus potentially form the basis for a novel antitumor strategy, it seemed important to consider additional structural features capable of affecting the efficiency of tumor cell recognition and delivery. These included the effects of sugar polyvalency and net charge (at physiological pH) on tumor cell recognition, internalization, and trafficking. Since these parameters have been shown to affect cell surface recognition, internalization, and distribution in other contexts, this study has sought to define the effects of these structural features on tumor cell recognition by bleomycin and its disaccharide. We demonstrate that both can have a significant effect on tumor cell binding/internalization, and present data which suggests that the metal ions normally bound by bleomycin following clinical administration may significantly contribute to the efficiency of tumor cell uptake, in addition to their characterized function in DNA cleavage. A BLM disaccharide-Cy5** conjugate incorporating the positively charged dipeptide d-Lys-d-Lys was found to associate with both the mitochondria and the nuclear envelope of DU145 cells, suggesting possible cellular targets for BLM disaccharide-cytotoxin conjugates.
我们之前已经表明，博来霉素（BLM）的碳水化合物部分能够重现整个BLM分子的肿瘤细胞靶向作用，BLM本身本质上是模块化的，由一个DNA切割苷元组成，该苷元通过其碳水化合物部分选择性地递送至肿瘤细胞内部，并且存在与BLM二糖结构相关的二糖，它们在肿瘤细胞靶向/摄取方面比天然二糖更有效。由于BLM糖类可以将分子货物选择性地递送至肿瘤细胞，从而有可能构成一种新型抗肿瘤策略的基础，因此考虑能够影响肿瘤细胞识别和递送效率的其他结构特征似乎很重要。这些特征包括糖多价性和净电荷（在生理pH下）对肿瘤细胞识别、内化和运输的影响。由于这些参数已被证明在其他情况下会影响细胞表面识别、内化和分布，本研究旨在确定这些结构特征对博来霉素及其二糖的肿瘤细胞识别的影响。我们证明两者都可能对肿瘤细胞结合/内化产生显著影响，并提供数据表明临床给药后博来霉素通常结合的金属离子除了在DNA切割中具有已确定的功能外，可能对肿瘤细胞摄取效率有显著贡献。发现一种结合带正电荷二肽d-Lys-d-Lys的BLM二糖-Cy⁵⁺共轭物与DU145细胞的线粒体和核膜都有关联，这表明BLM二糖-细胞毒素共轭物可能存在细胞靶点。
