Herrmann Andreas, Priceman Saul J, Swiderski Piotr, Kujawski Maciej, Xin Hong, Cherryholmes Gregory A, Zhang Wang, Zhang Chunyan, Lahtz Christoph, Kowolik Claudia, Forman Steve J, Kortylewski Marcin, Yu Hua
J Clin Invest. 2014 Jul;124(7):2977-87. doi: 10.1172/JCI73174. Epub 2014 Jun 2.
Intracellular therapeutic targets that define tumor immunosuppression in both tumor cells and T cells remain intractable. Here, we have shown that administration of a covalently linked siRNA to an aptamer (apt) that selectively binds cytotoxic T lymphocyte-associated antigen 4 (CTLA4(apt)) allows gene silencing in exhausted CD8⁺ T cells and Tregs in tumors as well as CTLA4-expressing malignant T cells. CTLA4 expression was upregulated in CD8⁺ T cells in the tumor milieu; therefore, CTLA4(apt) fused to a STAT3-targeting siRNA (CTLA4(apt)-STAT3 siRNA) resulted in internalization into tumor-associated CD8⁺ T cells and silencing of STAT3, which activated tumor antigen-specific T cells in murine models. Both local and systemic administration of CTLA4(apt)-STAT3 siRNA dramatically reduced tumor-associated Tregs. Furthermore, CTLA4(apt)-STAT3 siRNA potently inhibited tumor growth and metastasis in various mouse tumor models. Importantly, CTLA4 expression is observed in T cells of patients with blood malignancies, and CTLA4(apt)-STAT3 siRNA treatment of immunodeficient mice bearing human T cell lymphomas promoted tumor cell apoptosis and tumor growth inhibition. These data demonstrate that a CTLA4(apt)-based siRNA delivery strategy allows gene silencing in both tumor-associated T cells and tumor cells and inhibits tumor growth and metastasis.
在肿瘤细胞和T细胞中定义肿瘤免疫抑制的细胞内治疗靶点仍然难以解决。在这里，我们已经表明，将共价连接的siRNA与一种适配体（apt）结合，该适配体选择性结合细胞毒性T淋巴细胞相关抗原4（CTLA4(apt)），可使肿瘤中耗竭的CD8⁺T细胞和调节性T细胞（Tregs）以及表达CTLA4的恶性T细胞中的基因沉默。肿瘤微环境中CD8⁺T细胞的CTLA4表达上调；因此，与靶向信号转导和转录激活因子3（STAT3）的siRNA融合的CTLA4(apt)（CTLA4(apt)-STAT3 siRNA）导致内化到肿瘤相关的CD8⁺T细胞中，并使STAT3沉默，从而在小鼠模型中激活肿瘤抗原特异性T细胞。局部和全身给予CTLA4(apt)-STAT3 siRNA均可显著减少肿瘤相关的Tregs。此外，CTLA4(apt)-STAT3 siRNA在各种小鼠肿瘤模型中均能有效抑制肿瘤生长和转移。重要的是，在血液恶性肿瘤患者的T细胞中观察到CTLA4表达，用CTLA4(apt)-STAT3 siRNA治疗携带人T细胞淋巴瘤的免疫缺陷小鼠可促进肿瘤细胞凋亡并抑制肿瘤生长。这些数据表明，基于CTLA4(apt)的siRNA递送策略可使肿瘤相关T细胞和肿瘤细胞中的基因沉默，并抑制肿瘤生长和转移。
