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

恶性神经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，对相关信号转导通路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。在我们以前的研究中，我们能够获得大量的丝氨酸/苏氨酸激酶Pim-1在其他实体瘤（结肠癌）中的功能相关性，并阐明致癌转录因子STAT 3和STAT 3靶基因Mcl-1在介导胶质瘤对化疗的耐药性中的关键作用。此外，我们的研究表明Pim-1在胶质瘤中过表达，证明了miRNAs miR-33 a和miR-15 b对Pim-1表达的调节功能，并强烈表明Pim-1和STAT 3之间存在广泛的细胞串扰。然而，在神经胶质瘤中，这既没有被研究也没有被探索治疗。该项目的重点是Pim-1/STAT 3/Mcl-1信号转导轴在胶质瘤中的肿瘤学相关性，使用不同的体外细胞模型，同基因体内胶质瘤模型，小鼠异种移植模型和来自胶质瘤患者的原发性肿瘤材料。除了功能分析，将探讨该信号轴作为治疗干预靶点的治疗意义。为此，将采用RNAi介导的基因敲除、药理学抑制、miRNA替代和用于递送siRNA/miRNA的纳米颗粒系统，还与已建立的化疗组合，并旨在开发新的治疗策略。更具体地说，该项目将分析Pim-1抑制对神经胶质瘤细胞下游效应物STAT 3和Mcl-1的细胞信号转导的分子效应，并将其与细胞增殖、迁移、侵袭和抗凋亡的改变相关联。此外，将确定Pim-1相关miRNA miR-33 a和miR-15 b在神经胶质瘤中的功能作用，并分析通过miRNA替代阻断Pim-1/STAT 3/Mcl-1轴的功效，并与Pim-1抑制的其他策略进行比较。还将通过对常规化疗的敏化研究信号轴的抑制的协同效应。在治疗上，Pim-1/STAT 3/Mcl-1轴将在临床前小鼠模型中通过采用纳米颗粒系统在体内单独或与替莫唑胺组合递送siRNA/miRNA来探索，旨在建立用于治疗恶性胶质瘤的新型基于纳米载体的策略。

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.