Jiménez-Madrona Enrique, Morado-Díaz Camilo J, Talaverón Rocío, Tabernero Arantxa, Pastor Angel M, Sáez Juan C, Matarredona Esperanza R
Departamento de Fisiología, Facultad de Biología, Universidad de Sevilla, Seville, Spain.
Instituto de Neurociencias de Castilla y León (INCYL), Universidad de Salamanca, Salamanca, Spain.
Front Neurosci. 2023 Aug 16;17:1211467. doi: 10.3389/fnins.2023.1211467. eCollection 2023.
The subventricular zone (SVZ) is a brain region that contains neural stem cells and progenitor cells (NSCs/NPCs) from which new neurons and glial cells are formed during adulthood in mammals. Recent data indicate that SVZ NSCs are the cell type that acquires the initial tumorigenic mutation in glioblastoma (GBM), the most aggressive form of malignant glioma. NSCs/NPCs of the SVZ present hemichannel activity whose function has not yet been fully elucidated. In this work, we aimed to analyze whether hemichannel-mediated communication affects proliferation of SVZ NPCs and GBM cells.
For that purpose, we used boldine, an alkaloid derived from the boldo tree (), that inhibits connexin and pannexin hemichannels, but without affecting gap junctional communication. Boldine treatment (50 μM) of rat SVZ NPCs grown as neurospheres effectively inhibited dye uptake through hemichannels and induced a significant reduction in neurosphere diameter and in bromodeoxyuridine (BrdU) incorporation. However, the differentiation pattern was not modified by the treatment. Experiments with specific blockers for hemichannels formed by connexin subunits (D4) or pannexin 1 (probenecid) revealed that probenecid, but not D4, produced a decrease in BrdU incorporation similar to that obtained with boldine. These results suggest that inhibition of pannexin 1 hemichannels could be partially responsible for the antiproliferative effect of boldine on SVZ NPCs. Analysis of the effect of boldine (25-600 μM) on different types of primary human GBM cells (GBM59, GBM96, and U87-MG) showed a concentration-dependent decrease in GBM cell growth. Boldine treatment also induced a significant inhibition of hemichannel activity in GBM cells.
Altogether, we provide evidence of an antimitotic action of boldine in SVZ NPCs and in GBM cells which may be due, at least in part, to its hemichannel blocking function. These results could be of relevance for future possible strategies in GBM aimed to suppress the proliferation of mutated NSCs or glioma stem cells that might remain in the brain after tumor resection.
脑室下区（SVZ）是哺乳动物成年期产生新神经元和神经胶质细胞的脑区，其中含有神经干细胞和祖细胞（NSCs/NPCs）。近期数据表明，SVZ神经干细胞是胶质母细胞瘤（GBM）中获得初始致瘤性突变的细胞类型，GBM是恶性胶质瘤中最具侵袭性的形式。SVZ的NSCs/NPCs具有半通道活性，但其功能尚未完全阐明。在本研究中，我们旨在分析半通道介导的通讯是否影响SVZ神经祖细胞和GBM细胞的增殖。
为此，我们使用了从波尔多树叶中提取的生物碱波尔定碱，它能抑制连接蛋白和泛连接蛋白半通道，但不影响缝隙连接通讯。用50μM的波尔定碱处理培养成神经球的大鼠SVZ神经祖细胞，能有效抑制通过半通道的染料摄取，并使神经球直径和溴脱氧尿苷（BrdU）掺入量显著降低。然而，处理并未改变分化模式。用连接蛋白亚基形成的半通道特异性阻滞剂（D4）或泛连接蛋白1阻滞剂（丙磺舒）进行的实验表明，丙磺舒而非D4能使BrdU掺入量降低，其效果与波尔定碱相似。这些结果表明，抑制泛连接蛋白1半通道可能部分介导了波尔定碱对SVZ神经祖细胞的抗增殖作用。分析25 - 600μM波尔定碱对不同类型原代人GBM细胞（GBM59、GBM96和U87 - MG）的影响，结果显示GBM细胞生长呈浓度依赖性下降。波尔定碱处理还显著抑制了GBM细胞的半通道活性。
总之，我们提供了证据表明波尔定碱对SVZ神经祖细胞和GBM细胞具有抗有丝分裂作用，这可能至少部分归因于其半通道阻断功能。这些结果可能与未来GBM的潜在治疗策略相关，旨在抑制肿瘤切除后可能残留在脑内的突变神经干细胞或胶质瘤干细胞的增殖。
