Department of Medical-Surgical Sciences and Biotechnologies, University of Rome "Sapienza", Polo Pontino, Latina, Italy.
Department of Chemistry, Biology and Biotechnology, University of Perugia, Perugia, Italy.
J Cell Physiol. 2018 Sep;233(9):6866-6877. doi: 10.1002/jcp.26448. Epub 2018 Mar 25.
Glioblastoma (GBM) cells express large-conductance, calcium-activated potassium (BK) channels, whose activity is important for several critical aspects of the tumor, such as migration/invasion and cell death. GBMs are also characterized by a heavy hypoxic microenvironment that exacerbates tumor aggressiveness. Since hypoxia modulates the activity of BK channels in many tissues, we hypothesized that a hypoxia-induced modulation of these channels may contribute to the hypoxia-induced GBM aggressiveness. In U87-MG cells, hypoxia induced a functional upregulation of BK channel activity, without interfering with their plasma membrane expression. Wound healing and transwell migration assays showed that hypoxia increased the migratory ability of U87-MG cells, an effect that could be prevented by BK channel inhibition. Toxicological experiments showed that hypoxia was able to induce chemoresistance to cisplatin in U87-MG cells and that the inhibition of BK channels prevented the hypoxia-induced chemoresistance. Clonogenic assays showed that BK channels are also used to increase the clonogenic ability of U87-MG GBM cells in presence, but not in absence, of cisplatin. BK channels were also found to be essential for the hypoxia-induced de-differentiation of GBM cells. Finally, using immunohistochemical analysis, we highlighted the presence of BK channels in hypoxic areas of human GBM tissues, suggesting that our findings may have physiopathological relevance in vivo. In conclusion, our data show that BK channels promote several aspects of the aggressive potential of GBM cells induced by hypoxia, such as migration and chemoresistance to cisplatin, suggesting it as a potential therapeutic target in the treatment of GBM.
胶质母细胞瘤（GBM）细胞表达大电导、钙激活钾（BK）通道，其活性对于肿瘤的几个关键方面很重要，如迁移/侵袭和细胞死亡。GBM 还具有严重的缺氧微环境，这加剧了肿瘤的侵袭性。由于缺氧可调节许多组织中的 BK 通道活性，我们假设这些通道的缺氧诱导调节可能有助于缺氧诱导的 GBM 侵袭性。在 U87-MG 细胞中，缺氧诱导 BK 通道活性的功能性上调，而不干扰其质膜表达。划痕愈合和 Transwell 迁移实验表明，缺氧增加了 U87-MG 细胞的迁移能力，BK 通道抑制可阻止这种作用。毒理学实验表明，缺氧能够诱导 U87-MG 细胞对顺铂的耐药性，而 BK 通道抑制可防止缺氧诱导的耐药性。集落形成实验表明，BK 通道也用于增加 U87-MG GBM 细胞在存在顺铂时的集落形成能力，但在不存在顺铂时则不能。还发现 BK 通道对于 GBM 细胞的缺氧诱导去分化是必需的。最后，通过免疫组织化学分析，我们强调了 BK 通道在人 GBM 组织缺氧区域的存在，表明我们的发现可能在体内具有生理病理学相关性。总之，我们的数据表明，BK 通道促进了缺氧诱导的 GBM 细胞侵袭性的几个方面，如迁移和对顺铂的耐药性，这表明它可能是治疗 GBM 的潜在治疗靶点。
