Novel therapeutic strategies in gliomas, based on the inhibition of the oncogenic signal transduction pathways Pim-1 / STAT3 through RNA interference and miRNA replacement

恶性胶质瘤的特点是对常规治疗有很强的抵抗力，导致预后极差。因此，对相关信号转导途径的详细分析是未来靶向和个性化治疗方法不可或缺的基础。在我们之前的研究中，我们能够深入了解丝氨酸/苏氨酸激酶Pim-1在其他实体肿瘤（结肠癌）中的功能相关性，并阐明致癌转录因子STAT3和STAT3靶基因Mcl-1在介导胶质瘤化疗耐药中的关键作用。此外，我们的研究表明，Pim-1在胶质瘤中过表达，表明miRNAs miR-33a和miR-15b对Pim-1表达具有调节作用，并强烈提示Pim-1与STAT3之间存在广泛的细胞串音。然而，在胶质瘤中，这既没有被研究，也没有在治疗上被探索。本项目利用不同的体外细胞模型、体内同种胶质瘤模型、小鼠异种移植模型和胶质瘤患者原发肿瘤材料，重点研究皮姆-1/STAT3/Mcl-1信号转导轴在胶质瘤中的肿瘤学相关性。除了功能分析之外，还将探讨该信号轴作为治疗干预目标的治疗意义。为此，rnai介导的基因敲低、药物抑制、miRNA替代和递送sirna /miRNA的纳米颗粒系统将被采用，也将与现有的化疗相结合，旨在开发新的治疗策略。更具体地说，本项目将分析Pim-1抑制对胶质瘤细胞信号转导的分子效应，以及下游效应物STAT3和Mcl-1，并将它们与细胞增殖、-迁移、-侵袭和细胞凋亡抵抗的改变联系起来。此外，我们将确定与Pim-1相关的miRNA miR-33a和miR-15b在胶质瘤中的功能作用，并分析miRNA替代阻断Pim-1/STAT3/Mcl-1轴的效果，并与其他Pim-1抑制策略进行比较。信号轴的抑制也将通过对常规化疗的增敏来研究协同效应。在治疗方面，将在临床前小鼠模型中探索Pim-1/STAT3/Mcl-1轴，通过使用纳米颗粒系统在体内递送sirna /miRNAs，单独或与替莫唑胺联合，旨在建立新的基于纳米载体的恶性胶质瘤治疗策略。

Malignant gliomas are characterized by their strong resistance towards conventional therapies, resulting in an extremely poor prognosis. Thus, the detailed analysis of relevant signal transduction pathways is an indispensable basis for future targeted and personalized therapeutic approaches. In our previous studies, we were able to gain substantial insight into the functional relevance of the serine/threonine kinase Pim-1 in other solid tumors (colon carcinoma), and to elucidate the pivotal role of the oncogenic transcription factor STAT3 and the STAT3 target gene Mcl-1 in mediating resistance of gliomas towards chemotherapy. Furthermore, our studies indicate that Pim-1 is overexpressed in gliomas, demonstrate regulatory functions of the miRNAs miR-33a and miR-15b on the Pim-1 expression and strongly suggest an extensive cellular crosstalk between Pim-1 and STAT3. In gliomas, however, this has neither been investigated nor explored therapeutically. This project focuses on the oncological relevance of the Pim-1/STAT3/Mcl-1 signal transduction axis in gliomas, using different in vitro cell models, syngenic in vivo glioma models, mouse xenograft models and primary tumor material derived from glioma patients. Beyond functional analyses, the therapeutic implications of this signal axis as a target for therapeutic intervention will be explored. To this end, RNAi-mediated gene knockdown, pharmacological inhibition, miRNA replacement and nanoparticulate systems for the delivery of siRNAs/miRNAs will be employed, also in combination with established chemotherapy and aiming at the development of novel therapeutic strategies. More specifically, this project will analyse the molecular effects of a Pim-1 inhibition on the cellular signal transduction of glioma cells with regard to the downstream effectors STAT3 and Mcl-1, and correlate them with alterations in cell proliferation, -migration, -invasion and resistance towards apoptosis. Furthermore, the functional role of the Pim-1-relevant miRNAs miR-33a and miR-15b will be determined in gliomas, and the efficacy of the blockage of the Pim-1/STAT3/Mcl-1 axis by miRNA replacement will be analysed and compared with the other strategies of Pim-1 inhibition. The inhibition of the signal axis will also be studied with regard to synergistic effects through sensitization towards conventional chemotherapy. Therapeutically, the Pim-1/STAT3/Mcl-1 axis will be explored in preclinical mouse models by employing nanoparticulate systems for the delivery of siRNAs/miRNAs in vivo, alone or in combination with temozolomid, aiming at the establishment of novel, nanocarrier-based strategies for the therapy of malignant gliomas.