School of Pharmacy and Pharmacology, College of Health and Medicine, University of Tasmania, Hobart, Tasmania, 7001, Australia.
Central Science Laboratory, University of Tasmania, Hobart, Tasmania, 7001, Australia.
Mol Neurobiol. 2022 May;59(5):2932-2945. doi: 10.1007/s12035-022-02771-0. Epub 2022 Mar 4.
Medulloblastoma (MB) is the most common malignant paediatric brain tumour. In our previous studies, we developed a novel 3D assay for MB cells that was used to screen a panel of plasma membrane calcium channel modulators for their effect on the 3D growth of D341 MB cells. These studies identified T-type (CaV3) channel inhibitors, mibefradil and NNC-55-0396 (NNC) as selective inhibitors of MB cell growth. Mibefradil was originally approved for the treatment of hypertension and angina pectoris, and recently successfully completed a phase I trial for recurrent high-grade glioma. NNC is an analogue of mibefradil with multiple advantages compared to mibefradil that makes it attractive for potential future clinical trials. T-type channels have a unique low voltage-dependent activation/inactivation, and many studies suggest that they have a direct regulatory role in controlling Ca signalling in non-excitable tissues, including cancers. In our previous study, we also identified overexpression of CaV3.2 gene in MB tissues compared to normal brain tissues. In this study, we aimed to characterise the effect of mibefradil and NNC on MB cells and elucidate their mechanism of action. This study demonstrates that the induction of toxicity in MB cells is selective to T-type but not to L-type Ca channel inhibitors. Addition of CaV3 inhibitors to vincristine sensitised MB cells to this MB chemotherapeutic agent, suggesting an additive effect. Furthermore, CaV3 inhibitors induced cell death in MB cells via apoptosis. Supported by proteomics data and cellular assays, apoptotic cell death was associated with reduced mitochondrial membrane potential and reduced ATP levels, which suggests that both compounds alter the metabolism of MB cells. This study offers new insights into the action of mibefradil and NNC and will pave the way to test these molecules or their analogues in pre-clinical MB models alone and in combination with vincristine to assess their suitability as a potential MB therapy.
髓母细胞瘤（MB）是最常见的儿童脑恶性肿瘤。在我们之前的研究中，我们开发了一种用于 MB 细胞的新型 3D 测定法，用于筛选一组质膜钙通道调节剂对 D341 MB 细胞 3D 生长的影响。这些研究确定 T 型（CaV3）通道抑制剂米贝地尔和 NNC-55-0396（NNC）为 MB 细胞生长的选择性抑制剂。米贝地尔最初被批准用于治疗高血压和心绞痛，最近成功完成了复发性高级别神经胶质瘤的 I 期试验。NNC 是米贝地尔的类似物，与米贝地尔相比具有多种优势，使其成为未来临床试验的潜在选择。T 型通道具有独特的低电压依赖性激活/失活，许多研究表明它们在控制非兴奋性组织（包括癌症）中的 Ca 信号方面具有直接的调节作用。在我们之前的研究中，我们还发现与正常脑组织相比，MB 组织中 CaV3.2 基因表达过度。在这项研究中，我们旨在研究米贝地尔和 NNC 对 MB 细胞的影响，并阐明其作用机制。本研究表明，MB 细胞的毒性诱导对 T 型而非 L 型钙通道抑制剂具有选择性。向长春新碱中添加 CaV3 抑制剂可使 MB 细胞对这种 MB 化疗药物敏感，表明存在相加作用。此外，CaV3 抑制剂通过细胞凋亡诱导 MB 细胞死亡。蛋白质组学数据和细胞测定支持，细胞凋亡与线粒体膜电位降低和 ATP 水平降低有关，这表明这两种化合物改变了 MB 细胞的代谢。这项研究为米贝地尔和 NNC 的作用提供了新的见解，并将为在单独和与长春新碱联合的 MB 模型中测试这些分子或其类似物以评估其作为潜在 MB 治疗方法的适用性铺平道路。
