胰腺神经内分泌肿瘤（PNETs）是一种明显高血管化的肿瘤实体，通常在转移阶段被诊断出。抗血管生成多激酶抑制剂的治疗效果常受原发性或获得性耐药的限制。本研究旨在表征体外和体内抗血管生成多酪氨酸激酶（TKI）抑制剂Regorafenib的分子作用模式以及耐药机制。体外方面，相比于PNETs中临床使用的其他TKIs，我们对人类和小鼠胰腺神经内分泌细胞系进行了Regorafenib和其他TKIs的比较治疗。分析了对细胞存活率和增殖的影响。在体内方面，我们对转基因RIP1Tag2小鼠在癌变过程中的两个不同时间点进行了Regorafenib的治疗，并评估了其对血管生成和肿瘤进展的影响。与Sunitinib和Everolimus等已建立的TKI治疗方案相比，Regorafenib在体外对细胞存活率和增殖的影响最强，但无法诱导细胞凋亡。与体外结果相反，我们在RIP1Tag2小鼠的早期肿瘤发展阶段发现Regorafenib反而增强了细胞增殖，并在晚期肿瘤进展阶段没有显著影响。此外，侵袭性在两个时间点均有增加。在机制上，我们发现抗Regorafenib治疗后，可能存在了促生存蛋白Bcl-2的上调、COX2-PGE2通路的诱导以及CSF1R阳性免疫细胞的肿瘤浸润作为潜在的耐药机制。我们的数据揭示了抗血管生成疗法耐药的重要的肿瘤细胞自主和基质依赖机制。© 2023. 作者。

Pancreatic neuroendocrine tumors (PNETs) represent a distinct hypervascularized tumor entity, often diagnosed at metastatic stage. Therapeutic efficacy of anti-angiogenic multi-kinase inhibitors is frequently limited by primary or acquired resistance in vivo. This study aimed to characterize the molecular mode of action as well as resistance mechanisms to the anti-angiogenic multi-tyrosine kinase inhibitor (TKI) Regorafenib in vitro and in vivo.In vitro, human and murine pancreatic neuroendocrine cell lines were comparatively treated with Regorafenib and other TKIs clinically used in PNETs. Effects on cell viability and proliferation were analyzed. In vivo, transgenic RIP1Tag2 mice were treated with Regorafenib at two different time periods during carcinogenesis and its impact on angiogenesis and tumor progression was evaluated.Compared to the established TKI therapies with Sunitinib and Everolimus, Regorafenib showed the strongest effects on cell viability and proliferation in vitro, but was unable to induce apoptosis. Unexpectedly and in contrast to these in vitro findings, Regorafenib enhanced proliferation during early tumor development in RIP1Tag2 mice and had no significant effect in late tumor progression. In addition, invasiveness was increased at both time points. Mechanistically, we could identify an upregulation of the pro-survival protein Bcl-2, the induction of the COX2-PGE2-pathway as well as the infiltration of CSF1R positive immune cells into the tumors as potential resistance mechanisms following Regorafenib treatment.Our data identify important tumor cell-autonomous and stroma-dependent mechanisms of resistance to antiangiogenic therapies.© 2023. The Author(s).