Souza Bomfim Guilherme H, Mitaishvili Erna, Aguiar Talita Ferreira, Lacruz Rodrigo S
Department of Molecular Pathobiology, New York University College of Dentistry, New York, NY, 10010, USA.
Department of Urology, New York University School of Medicine, New York, NY, 10010, USA.
Mol Biomed. 2021 Apr 30;2(1):12. doi: 10.1186/s43556-021-00037-0.
Mibefradil is a tetralol derivative originally developed as an antagonist of T-type voltage-gated calcium (Ca) channels to treat hypertension when used at nanomolar dosage. More recently, its therapeutic application in hypertension has declined and has been instead repurposed as a treatment of cancer cell proliferation and solid tumor growth. Beyond its function as a Ca blocker, the micromolar concentration of mibefradil can stimulate a rise in [Ca] although the mechanism is poorly known. The chanzyme TRPM7 (transient receptor potential melastanin 7), the release of intracellular Ca pools, and Ca influx by ORAI channels have been associated with the increase in [Ca] triggered by mibefradil. This study aims to investigate the cellular targets and pathways associated with mibefradil's effect on [Ca]. To address these questions, we monitored changes in [Ca] in the specialized mouse epithelial cells (LS8 and ALC) and the widely used HEK-293 cells by stimulating these cells with mibefradil (0.1 μM to 100 μM). We show that mibefradil elicits an increase in [Ca] at concentrations above 10 μM (IC around 50 μM) and a fast Ca increase capacity at 100 μM. We found that inhibiting IP receptors, depleting the ER-Ca stores, or blocking phospholipase C (PLC), significantly decreased the capacity of mibefradil to elevate [Ca] Moreover, the transient application of 100 μM mibefradil triggered Ca influx by store-operated Ca entry (SOCE) mediated by the ORAI channels. Our findings reveal that IPR and PLC are potential new targets of mibefradil offering novel insights into the effects of this drug.
米贝地尔是一种四氢萘酚衍生物，最初开发用作T型电压门控钙（Ca）通道拮抗剂，在纳摩尔剂量下用于治疗高血压。最近，其在高血压治疗中的应用有所减少，转而被重新用于治疗癌细胞增殖和实体瘤生长。除了作为钙阻滞剂的功能外，微摩尔浓度的米贝地尔可刺激[Ca]升高，尽管其机制尚不清楚。通道酶TRPM7（瞬时受体电位黑素瘤7）、细胞内钙库的释放以及由ORAI通道介导的钙内流与米贝地尔触发的[Ca]升高有关。本研究旨在探讨与米贝地尔对[Ca]作用相关的细胞靶点和途径。为了解决这些问题，我们通过用米贝地尔（0.1μM至100μM）刺激这些细胞，监测了特殊的小鼠上皮细胞（LS8和ALC）以及广泛使用的HEK-293细胞中[Ca]的变化。我们发现，米贝地尔在浓度高于10μM（IC约为50μM）时会引起[Ca]升高，在100μM时具有快速升高钙的能力。我们发现，抑制IP受体、耗尽内质网钙库或阻断磷脂酶C（PLC），会显著降低米贝地尔升高[Ca]的能力。此外，短暂应用100μM米贝地尔会触发由ORAI通道介导的钙库操纵性钙内流（SOCE）引起的钙内流。我们的研究结果表明，IPR和PLC是米贝地尔的潜在新靶点，为该药物的作用提供了新的见解。
