title: Functional assays to define agonists and antagonists of the sigma-2 receptor.
abstract: 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.
authors: Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA. Electronic address: zengc@mail.med.upenn.edu.
authors: Chenbo
authors: C
authors: Zeng
authors: Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA.
authors: Justin M
authors: JM
authors: Rothfuss
authors: Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA.
authors: Jun
authors: J
authors: Zhang
authors: Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA.
authors: Suwanna
authors: S
authors: Vangveravong
authors: Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA.
authors: Wenhua
authors: W
authors: Chu
authors: Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA.
authors: Shihong
authors: S
authors: Li
authors: Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA.
authors: Zhude
authors: Z
authors: Tu
authors: Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA.
authors: Jinbin
authors: J
authors: Xu
authors: Department of Radiology, Division of Radiological Sciences, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA; Department of Cell Biology and Physiology, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA.
authors: Robert H
authors: RH
authors: Mach
mesh_terms: D000818:Animals; D053961:Azabicyclo Compounds / Q000737:chemistry / Q000494:pharmacology; D001549:Benzamides / Q000737:chemistry / Q000494:pharmacology; D001681:Biological Assay; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D007211:Indoles / Q000737:chemistry / Q000494:pharmacology; D008024:Ligands; D051379:Mice; D011485:Protein Binding / Q000187:drug effects; D017480:Receptors, sigma / Q000819:agonists* / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013141:Spiro Compounds / Q000737:chemistry / Q000494:pharmacology; D014326:Tropanes / Q000737:chemistry / Q000494:pharmacology
chemical_list: D053961:Azabicyclo Compounds; D001549:Benzamides; D007211:Indoles; D008024:Ligands; C109644:Lu 28-179; D017480:Receptors, sigma; D013141:Spiro Compounds; D014326:Tropanes; C106107:sigma-2 receptor; C037689:benzamide; D053148:Caspase 3
keywords: Agonist; Antagonist; Caspase-3; Cell viability; Functional assay; Sigma-2 receptor