title: Estrogen regulation of TRPM8 expression in breast cancer cells.
abstract: BACKGROUND
  The calcium-permeable cation channel TRPM8 (melastatin-related transient receptor potential member 8) is over-expressed in several cancers. The present study aimed at investigating the expression, function and potential regulation of TRPM8 channels by ER alpha (estrogen receptor alpha) in breast cancer.
  
  
  METHODS
  RT-PCR, Western blot, immuno-histochemical, and siRNA techniques were used to investigate TRPM8 expression, its regulation by estrogen receptors, and its expression in breast tissue. To investigate the channel activity in MCF-7 cells, we used the whole cell patch clamp and the calcium imaging techniques.
  
  
  RESULTS
  TRPM8 channels are expressed at both mRNA and protein levels in the breast cancer cell line MCF-7. Bath application of the potent TRPM8 agonist Icilin (20 microM) induced a strong outwardly rectifying current at depolarizing potentials, which is associated with an elevation of cytosolic calcium concentration, consistent with established TRPM8 channel properties. RT-PCR experiments revealed a decrease in TRPM8 mRNA expression following steroid deprivation for 48 and 72 hours. In steroid deprived medium, addition of 17-beta-estradiol (E2, 10 nM) increased both TRPM8 mRNA expression and the number of cells which respond to Icilin, but failed to affect the Ca2+ entry amplitude. Moreover, silencing ERalpha mRNA expression with small interfering RNA reduced the expression of TRPM8. Immuno-histochemical examination of the expression of TRPM8 channels in human breast tissues revealed an over-expression of TRPM8 in breast adenocarcinomas, which is correlated with estrogen receptor positive (ER+) status of the tumours.
  
  
  CONCLUSIONS
  Taken together, these results show that TRPM8 channels are expressed and functional in breast cancer and that their expression is regulated by ER alpha.
authors.affiliation: Laboratoire de Physiologie Cellulaire et Moléculaire, JE 2530: Canaux ioniques dans cancer du sein, Faculté des Sciences, Université Picardie Jules Vernes, 33 rue Saint Leu, 80000, Amiens, France.
authors.forename: Dechen
authors.initials: D
authors.lastname: Chodon
authors.forename: Arnaud
authors.initials: A
authors.lastname: Guilbert
authors.forename: Isabelle
authors.initials: I
authors.lastname: Dhennin-Duthille
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gautier
authors.forename: Marie-Sophie
authors.initials: MS
authors.lastname: Telliez
authors.forename: Henri
authors.initials: H
authors.lastname: Sevestre
authors.forename: Halima
authors.initials: H
authors.lastname: Ouadid-Ahidouch
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D004958:Estradiol / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D011744:Pyrimidinones / Q000494:pharmacology; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050053:TRPM Cation Channels / Q000819:agonists / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors
chemical_list: D047628:Estrogen Receptor alpha; D011744:Pyrimidinones; D012333:RNA, Messenger; D050053:TRPM Cation Channels; C425966:TRPM8 protein, human; D004958:Estradiol; C490483:icilin; D002118:Calcium