title: The σ1receptor agonist (+)-pentazocine increases store-operated Ca2+entry in MCF7σ1and SK-N-SH cell lines.
abstract: BACKGROUND
  The intracellular [Ca2+] is modulated by σ receptors. An important component of the cellular machinery governing the intracellular [Ca2+] is Store-Operated Calcium Entry (SOCE). Here we want to investigate whether ligands of σ receptors affect SOCE.
  
  
  METHODS
  The intracellular [Ca2+] was monitored, with the fluorescent Ca2+-sensitive probe Fura-2, in four cell lines with a different expression of σ receptors, namely MCF7 (expressing σ1receptors with a low density and overexpressing σ2receptors), MCF7σ1(overexpressing σ1receptors), SK-N-SH, and HT-29.
  
  
  RESULTS
  When thapsigargin was used to deplete intracellular Ca2+stores, in a Ca2+-free incubation medium, the Ca2+influx (following Ca2+re-addition) was significantly increased by 1μM (+)-pentazocine (σ1receptor agonist) in MCF7σ1(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 "Mn2+quenching" protocol. In MCF7σ1cells, after thapsigargin treatment, the fluorescence quenching induced by Mn2+influx (evidence of Ca2+influx) was significantly increased (by 25.8%) by 1μM (+)-pentazocine, significantly decreased (by 18.0%) by BD1063 (σ1receptor antagonist), and not affected by the presence of both ligands. These effects were not observed in MCF7 cells. Finally, in MCF7 cells, 1μM PB28 (σ2receptor agonist), did not affect both the Ca2+response after Ca2+re-addition and the fluorescence quenching induced by Mn2+influx.
  
  
  CONCLUSIONS
  We propose that the σ1receptor agonist (+)-pentazocine increases SOCE in MCF7σ1and SK-N-SH cell lines. The σ2receptor agonist PB28 does not affect SOCE in MCF7 cells.
authors.affiliation: Department of Biosciences, Biotechnologies and Biopharmaceutics, Università di Bari, Bari, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Gasparre
authors.affiliation: Dipartimento di Farmacia-Scienze del Farmaco, Università di Bari, Bari, Italy.
authors.forename: Carmen
authors.initials: C
authors.lastname: Abate
authors.affiliation: Department of Biology, Università di Bari, Bari, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Carlucci
authors.affiliation: Dipartimento di Farmacia-Scienze del Farmaco, Università di Bari, Bari, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Berardi
authors.affiliation: Department of Biosciences, Biotechnologies and Biopharmaceutics, Università di Bari, Bari, Italy. Electronic address: giuseppe.cassano@uniba.it.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Cassano
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D005453:Fluorescence; D019073:HT29 Cells; D006801:Humans; D008024:Ligands; D061986:MCF-7 Cells; D009447:Neuroblastoma / Q000378:metabolism; D010423:Pentazocine / Q000494:pharmacology*; D017480:Receptors, sigma / Q000819:agonists* / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology
chemical_list: D000701:Analgesics, Opioid; D008024:Ligands; D017480:Receptors, sigma; D019284:Thapsigargin; D010423:Pentazocine; D002118:Calcium
keywords: (+)-Pentazocine; Cell imaging; Endoplasmic reticulum; Neuromodulation; Sigma receptor