Kramer Lovro, Renko Miha, Završnik Janja, Turk Dušan, Seeger Markus A, Vasiljeva Olga, Grütter Markus G, Turk Vito, Turk Boris
Jozef Stefan Institute, Department of Biochemistry and Molecular and Structural Biology, Ljubljana, Slovenia.
International Postgraduate School Jozef Stefan, Ljubljana, Slovenia.
Theranostics. 2017 Jul 8;7(11):2806-2821. doi: 10.7150/thno.19081. eCollection 2017.
Cysteine cathepsins often contribute to cancer progression due to their overexpression in the tumour microenvironment and therefore present attractive targets for non-invasive diagnostic imaging. However, the development of highly selective and versatile small molecule probes for cathepsins has been challenging. Here, we targeted tumour-associated cathepsin B using designed ankyrin repeat proteins (DARPins). The selective DARPin inhibited cathepsin B with picomolar affinity (K = 35 pM) by binding to a site with low structural conservation in cathepsins, as revealed by the X-ray structure of the complex. DARPin blocked cathepsin B activity in tumours and was successfully applied in optical imaging in two mouse breast cancer models, in which cathepsin B was bound to the cell membrane or secreted to the extracellular milieu by tumour and stromal cells. Our approach validates cathepsin B as a promising diagnostic and theranostic target in cancer and other inflammation-associated diseases.
半胱氨酸组织蛋白酶常常因其在肿瘤微环境中的过表达而促进癌症进展，因此成为非侵入性诊断成像颇具吸引力的靶点。然而，开发用于组织蛋白酶的高选择性和多功能小分子探针颇具挑战性。在此，我们使用设计锚蛋白重复序列蛋白（DARPins）靶向肿瘤相关组织蛋白酶B。如复合物的X射线结构所示，选择性DARPin通过与组织蛋白酶中结构保守性低的位点结合，以皮摩尔亲和力（K = 35 pM）抑制组织蛋白酶B。DARPin阻断肿瘤中的组织蛋白酶B活性，并成功应用于两种小鼠乳腺癌模型的光学成像，其中组织蛋白酶B由肿瘤细胞和基质细胞结合至细胞膜或分泌到细胞外环境中。我们的方法验证了组织蛋白酶B作为癌症及其他炎症相关疾病中一个有前景的诊断和治疗靶点。
