title: Sigma-2 receptor as potential indicator of stem cell differentiation.
abstract: OBJECTIVE
  The sigma-2 (σ(2)) receptor is a potential biomarker of proliferative status of solid tumors. Specific synthetic probes using N-substituted-9-azabicyclo [3.3.1]nonan-3α-yl carbamate analogs have been designed and implemented for experimental cancer diagnosis and therapy.
  
  
  METHODS
  We employed the fluorescently labeled σ(2) receptor probe, SW120, to evaluate σ(2) receptor expression in human stem cells (SC), including: bone marrow stromal, neural progenitor, amniotic fluid, hematopoetic, and embryonic stem cells. We concurrently evaluated the intensity of SW120 and 5-ethynyl-2'-deoxyuridine (EdU) relative to passage number and multi-potency.
  
  
  RESULTS
  We substantiated significantly higher σ(2) receptor density among proliferating SC relative to lineage-restricted cell types. Additionally, cellular internalization of the σ(2) receptor in SC was consistent with receptor-mediated endocytosis and confocal microscopy indicated SW120 specific co-localization with a fluorescent marker of lysosomes in all SC imaged.
  
  
  CONCLUSIONS
  These results suggest that σ(2) receptors may serve to monitor stem cell differentiation in future experimental studies.
authors: Frank Laboratory, Department of Radiology and Imaging Sciences, Clinical Center, National Institutes of Health, Clinical Center, Bethesda, MD 20892, USA. hallerjod@cc.nih.gov
authors: Jodi L
authors: JL
authors: Haller
authors: Irina
authors: I
authors: Panyutin
authors: Aneeka
authors: A
authors: Chaudhry
authors: Chenbo
authors: C
authors: Zeng
authors: Robert H
authors: RH
authors: Mach
authors: Joseph A
authors: JA
authors: Frank
references: Cancer Res. 2002 Jan 1;62(1):313-22
references: 11782394
references: Stem Cells Dev. 2011 Jan;20(1):53-66
references: 20528146
references: Cancer Res. 1997 Jan 1;57(1):156-61
references: 8988058
references: Blood. 2000 May 15;95(10):3106-12
references: 10807776
references: Br J Cancer. 2000 Mar;82(6):1223-32
references: 10735510
references: Nat Biotechnol. 2007 Jan;25(1):100-6
references: 17206138
references: Gene Ther. 2008 Feb;15(3):161-70
references: 18033312
references: Cell Transplant. 2008;17(8):911-22
references: 19069634
references: Nat Med. 2007 May;13(5):642-8
references: 17417652
references: FEBS Lett. 2010 Sep 10;584(17):3826-30
references: 20674573
references: Cancer Res. 2009 Apr 1;69(7):2709-13
references: 19318556
references: Tissue Eng Part C Methods. 2008 Mar;14(1):15-23
references: 18454642
references: PLoS One. 2010 Jul 07;5(7):e11462
references: 20628641
references: Brain Res. 2010 Mar 10;1319:21-32
references: 20064490
references: J Clin Invest. 2001 Jun;107(11):1395-402
references: 11390421
references: Circulation. 2002 Jan 1;105(1):93-8
references: 11772882
references: Stem Cells. 2009 May;27(5):1077-87
references: 19415778
references: PET Clin. 2009 Jan 1;4(1):1-15
references: 20046891
references: J Pharmacol Exp Ther. 1976 Jun;197(3):517-32
references: 945347
references: Cancer Res. 2007 Jul 15;67(14):6708-16
references: 17638881
references: J Transl Med. 2009 Mar 26;7:24
references: 19323815
references: Hum Gene Ther. 2010 Nov;21(11):1506-12
references: 20649487
references: Stem Cells. 2009 Aug;27(8):1921-31
references: 19544438
references: Inflammation. 2012 Feb;35(1):167-75
references: 21336677
references: J Immunol. 1984 Oct;133(4):1710-5
references: 6206131
references: Stem Cells Dev. 2010 Jan;19(1):47-52
references: 19473101
references: Nat Rev Genet. 2008 Feb;9(2):115-28
references: 18202695
references: Bioorg Med Chem. 2006 Oct 15;14(20):6988-97
references: 16837201
references: Cancer Res. 2007 Mar 1;67(5):2217-25
references: 17332352
references: Cytotherapy. 2009;11(7):864-73
references: 19903099
references: Autophagy. 2008 May;4(4):487-99
references: 18305408
references: Mayo Clin Proc. 1984 Feb;59(2):107-17
references: 6366382
references: Int J Artif Organs. 2008 Mar;31(3):252-7
references: 18373319
references: Cent Nerv Syst Agents Med Chem. 2009 Sep;9(3):230-45
references: 20021357
references: Future Oncol. 2008 Oct;4(5):623-8
references: 18922119
references: Biochem Cell Biol. 1988 Jun;66(6):478-89
references: 3048326
references: J Cell Physiol. 2000 Mar;182(3):311-22
references: 10653597
references: Pharmacol Ther. 2009 Nov;124(2):195-206
references: 19619582
references: Stem Cells Dev. 2008 Dec;17(6):1023-9
references: 18491958
references: Cell Res. 2009 Mar;19(3):370-9
references: 19114988