Gasparre Giuseppe, Abate Carmen, Carlucci Roberto, Berardi Francesco, Cassano Giuseppe
Department of Biosciences, Biotechnologies and Biopharmaceutics, Università di Bari, Bari, Italy.
Dipartimento di Farmacia-Scienze del Farmaco, Università di Bari, Bari, Italy.
Pharmacol Rep. 2017 Jun;69(3):542-545. doi: 10.1016/j.pharep.2017.01.022. Epub 2017 Jan 28.
The intracellular [Ca] is modulated by σ receptors. An important component of the cellular machinery governing the intracellular [Ca] is Store-Operated Calcium Entry (SOCE). Here we want to investigate whether ligands of σ receptors affect SOCE.
The intracellular [Ca] was monitored, with the fluorescent Ca-sensitive probe Fura-2, in four cell lines with a different expression of σ receptors, namely MCF7 (expressing σ receptors with a low density and overexpressing σ receptors), MCF7σ (overexpressing σ receptors), SK-N-SH, and HT-29.
When thapsigargin was used to deplete intracellular Ca stores, in a Ca-free incubation medium, the Ca influx (following Ca re-addition) was significantly increased by 1μM (+)-pentazocine (σ receptor agonist) in MCF7σ (by 22.5%) and SK-N-SH (by 45.6%), but not in HT-29 and MCF7 cells. We have used, as a second approach, the "Mn quenching" protocol. In MCF7σ cells, after thapsigargin treatment, the fluorescence quenching induced by Mn influx (evidence of Ca influx) was significantly increased (by 25.8%) by 1μM (+)-pentazocine, significantly decreased (by 18.0%) by BD1063 (σ receptor antagonist), and not affected by the presence of both ligands. These effects were not observed in MCF7 cells. Finally, in MCF7 cells, 1μM PB28 (σ receptor agonist), did not affect both the Ca response after Ca re-addition and the fluorescence quenching induced by Mn influx.
We propose that the σ receptor agonist (+)-pentazocine increases SOCE in MCF7σ and SK-N-SH cell lines. The σ receptor agonist PB28 does not affect SOCE in MCF7 cells.
细胞内钙离子浓度（[Ca]）受σ受体调节。细胞内[Ca]调控机制的一个重要组成部分是储存-操作性钙内流（SOCE）。在此，我们想要研究σ受体配体是否会影响SOCE。
使用荧光钙敏探针Fura-2监测四种σ受体表达不同的细胞系中的细胞内[Ca]，这四种细胞系分别为MCF7（低密度表达σ受体且过表达σ受体）、MCF7σ（过表达σ受体）、SK-N-SH和HT-29。
当使用毒胡萝卜素耗尽细胞内钙储存后，在无钙孵育培养基中，1μM（+）-喷他佐辛（σ受体激动剂）可使MCF7σ细胞（增加22.5%）和SK-N-SH细胞（增加45.6%）中钙内流（重新添加钙后）显著增加，但在HT-29和MCF7细胞中无此现象。作为第二种方法，我们采用了“锰淬灭”方案。在MCF7σ细胞中，毒胡萝卜素处理后，1μM（+）-喷他佐辛可使锰内流诱导的荧光淬灭（钙内流的证据）显著增加（25.8%），BD1063（σ受体拮抗剂）使其显著降低（18.0%），两种配体同时存在时则无影响。在MCF7细胞中未观察到这些效应。最后，在MCF7细胞中，1μM PB28（σ受体激动剂）对重新添加钙后的钙反应以及锰内流诱导的荧光淬灭均无影响。
我们提出σ受体激动剂（+）-喷他佐辛可增加MCF7σ和SK-N-SH细胞系中的SOCE。σ受体激动剂PB28对MCF7细胞中的SOCE无影响。
