Zeng Chenbo, Rothfuss Justin M, Zhang Jun, Vangveravong Suwanna, Chu Wenhua, Li Shihong, Tu Zhude, Xu Jinbin, Mach Robert H
Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA.
Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA.
Anal Biochem. 2014 Mar 1;448:68-74. doi: 10.1016/j.ab.2013.12.008. Epub 2013 Dec 12.
The sigma-2 receptor has been identified as a biomarker in proliferating tumors. To date there is no well-established functional assay for defining sigma-2 agonists and antagonists. Many sigma-2 ligands with diverse structures have been shown to induce cell death in a variety of cancer cells by triggering caspase-dependent and independent apoptosis. Therefore, in the current study, we used the cell viability assay and the caspase-3 activity assay to determine sigma-2 agonists and antagonists. Three classes of sigma-2 ligands developed in our laboratory were evaluated for their potency to induce cell death in two tumor cell lines, mouse breast cancer cell line EMT-6 and human melanoma cell line MDA-MB-435. The data showed that the EC50 values of the sigma-2 ligands using the cell viability assay ranged from 11.4μM to >200μM, which were comparable with the EC50 values obtained using the caspase-3 assay. Based on the cytotoxicity of a sigma-2 ligand relative to that of siramesine, a commonly accepted sigma-2 agonist, we have categorized our sigma-2 ligands into agonists, partial agonists, and antagonists. The establishment of functional assays for defining sigma-2 agonists and antagonists will facilitate functional characterization of sigma-2 receptor ligands and sigma-2 receptors.
σ-2受体已被确定为增殖性肿瘤中的一种生物标志物。迄今为止，尚无用于定义σ-2激动剂和拮抗剂的成熟功能测定方法。许多具有不同结构的σ-2配体已被证明可通过触发半胱天冬酶依赖性和非依赖性凋亡，在多种癌细胞中诱导细胞死亡。因此，在本研究中，我们使用细胞活力测定法和半胱天冬酶-3活性测定法来确定σ-2激动剂和拮抗剂。对我们实验室开发的三类σ-2配体在两种肿瘤细胞系（小鼠乳腺癌细胞系EMT-6和人黑色素瘤细胞系MDA-MB-435）中诱导细胞死亡的效力进行了评估。数据显示，使用细胞活力测定法时，σ-2配体的EC50值范围为11.4μM至>200μM，这与使用半胱天冬酶-3测定法获得的EC50值相当。基于一种σ-2配体相对于公认的σ-2激动剂西拉美新的细胞毒性，我们将我们的σ-2配体分为激动剂、部分激动剂和拮抗剂。用于定义σ-2激动剂和拮抗剂的功能测定方法的建立将有助于对σ-2受体配体和σ-2受体进行功能表征。
