Esposito Carla L, Van Roosbroeck Katrien, Santamaria Gianluca, Rotoli Deborah, Sandomenico Annamaria, Wierda William G, Ferrajoli Alessandra, Ruvo Menotti, Calin George A, de Franciscis Vittorio, Catuogno Silvia
IEOS-Istituto per l'endocrinologia e l'oncologia "Gaetano Salvatore", CNR, 80131 Naples, Italy.
Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Cancers (Basel). 2021 Oct 18;13(20):5220. doi: 10.3390/cancers13205220.
The transmembrane glycoprotein cluster of differentiation 19 (CD19) is a B cell-specific surface marker, expressed on the majority of neoplastic B cells, and has recently emerged as a very attractive biomarker and therapeutic target for B-cell malignancies. The development of safe and effective ligands for CD19 has become an important need for the development of targeted conventional and immunotherapies. In this regard, aptamers represent a very interesting class of molecules. Additionally referred to as 'chemical antibodies', they show many advantages as therapeutics, including low toxicity and immunogenicity. Here, we isolated a nuclease-resistant RNA aptamer binding to the human CD19 glycoprotein. In order to develop an aptamer also useful as a carrier for secondary reagents, we adopted a cell-based SELEX (Systematic Evolution of Ligands by EXponential Enrichment) protocol adapted to isolate aptamers able to internalise upon binding to their cell surface target. We describe a 2'-fluoro pyrimidine modified aptamer, named B85.T2, which specifically binds to CD19 and shows an exquisite stability in human serum. The aptamer showed an estimated dissociation constant (K) of 49.9 ± 13 nM on purified human recombinant CD19 (rhCD19) glycoprotein, a good binding activity on human B-cell chronic lymphocytic leukaemia cells expressing CD19, and also an effective and rapid cell internalisation, thus representing a promising molecule for CD19 targeting, as well as for the development of new B-cell malignancy-targeted therapies.
跨膜糖蛋白分化簇19（CD19）是一种B细胞特异性表面标志物，在大多数肿瘤性B细胞上表达，最近已成为B细胞恶性肿瘤非常有吸引力的生物标志物和治疗靶点。开发安全有效的CD19配体已成为开发靶向传统疗法和免疫疗法的重要需求。在这方面，适配体代表了一类非常有趣的分子。它们也被称为“化学抗体”，作为治疗剂具有许多优点，包括低毒性和低免疫原性。在这里，我们分离出一种与人类CD19糖蛋白结合的耐核酸酶RNA适配体。为了开发一种也可用作二级试剂载体的适配体，我们采用了一种基于细胞的SELEX（指数富集配体系统进化）方案，以分离能够在与其细胞表面靶点结合后内化的适配体。我们描述了一种2'-氟嘧啶修饰的适配体，命名为B85.T2，它特异性结合CD19，并在人血清中表现出出色的稳定性。该适配体在纯化的人重组CD19（rhCD19）糖蛋白上的估计解离常数（K）为49.9±13 nM，对表达CD19的人B细胞慢性淋巴细胞白血病细胞具有良好的结合活性，并且还具有有效且快速的细胞内化能力，因此代表了一种有前途的CD19靶向分子，以及用于开发新的B细胞恶性肿瘤靶向疗法。
