title: Transient receptor potential vanilloid 1 expression and functionality in mcf-7 cells: a preliminary investigation.
abstract: OBJECTIVE
  Transient receptor potential vanilloid 1 (TRPV1) is a nonselective cation channel belonging to the transient receptor potential family, and it is expressed in different neoplastic tissues. Its activation is associated with regulation of cancer growth and progression. The aim of this research was to study the expression and pharmacological characteristics of TRPV1 in cells derived from human breast cancer MCF-7 cells.
  
  
  METHODS
  TRPV1 presence was assessed by binding studies and Western blotting. Receptor binding characteristics were evaluated through competition assays, while 3-(4,5-dimethylthiazol-2-yl)-2,5,-dipheyltetrazolium bromide reduction assays were performed to confirm an early hypothesis regarding the modulation of cancer cell proliferation. The functionality of TRPV1 was evaluated by measuring Ca(2+) uptake in the presence of increasing concentrations of TRPV1 agonists and antagonists.
  
  
  RESULTS
  Binding studies identified a single class of TRPV1 (Bmax 1,492±192 fmol/mg protein), and Western blot showed a signal at 100 kDa corresponding to the molecular weight of human TRPV1. Among the different tested agonists and antagonists, anandamide (Ki: 2.8×10(-11) M) and 5-iodoresiniferatoxin (5-I-RTX) (Ki: 5.6×10(-11) M) showed the highest degrees of affinity for TRPV1, respectively. All tested TRPV1 agonists and antagonists caused a significant (p<0.05) decrease in cell growth rate in MCF-7 cells. For agonists and antagonists, the efficacy of tested compounds displayed the following rank order: resiniferatoxin>anandamide>capsaicin and 5-I-RTX=capsazepine, respectively.
  
  
  CONCLUSIONS
  These data indicate that both TRPV1 agonists and antagonists induce significant inhibition of MCF-7 cell growth. Even though the mechanisms involved in the antiproliferative effects of TRPV1 agonists and antagonists should be further investigated, it has been suggested that agonists cause desensitization of the receptor, leading to alteration in Ca(2+)-influx regulation. By contrast, antagonists cause a functional block of the receptor with consequent fatal dysregulation of cell homeostasis.
authors.affiliation: Department of Veterinary Sciences, Section of Pharmacology and Toxicology, University of Turin, Grugliasco, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Vercelli
authors.affiliation: Department of Veterinary Sciences, Section of Pharmacology and Toxicology, University of Turin, Grugliasco, Italy.
authors.forename: Raffaella
authors.initials: R
authors.lastname: Barbero
authors.affiliation: Department of Veterinary Sciences, Section of Pharmacology and Toxicology, University of Turin, Grugliasco, Italy.
authors.forename: Barbara
authors.initials: B
authors.lastname: Cuniberti
authors.affiliation: Department of Clinical and Biological Sciences, Azienda Ospedaliero-Universitaria San Luigi Gonzaga, Orbassano, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Racca
authors.affiliation: Department of Clinical and Biological Sciences, Azienda Ospedaliero-Universitaria San Luigi Gonzaga, Orbassano, Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Abbadessa
authors.affiliation: Department of Clinical and Biological Sciences, Azienda Ospedaliero-Universitaria San Luigi Gonzaga, Orbassano, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Piccione
authors.affiliation: Department of Veterinary Sciences, Section of Pharmacology and Toxicology, University of Turin, Grugliasco, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Re
keywords: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide; Competition assays; Functionality assays; MCF-7 cells; TRPV1 receptor