title: Orai1/CRACM1 overexpression suppresses cell proliferation via attenuation of the store-operated calcium influx-mediated signalling pathway in A549 lung cancer cells.
abstract: BACKGROUND
  Orai1/CRACM1 is a principal component of the store-operated calcium channels. Store-operated calcium influx is highly correlated with inflammatory reactions, immunological regulation, and cell proliferation. Epidermal growth factor (EGF), which plays an important role in the regulation of cell proliferation, can activate store-operated calcium channels. However, the consequences of Orai1/CRACM1 overexpression in EGF-mediated lung cancer cells growth are not known.
  
  
  METHODS
  To investigate the role of Orai1/CRACM1 in EGF-mediated lung cancer cell proliferation, Orai1/CRACM1 plasmids were transfected into cells by lipofection. A cell proliferation assay, immunofluorescence staining, flow cytometry, and real-time polymerase chain reaction were employed to monitor cell proliferation. The calcium influx signals were investigated using a fluorescent-based calcium assay.
  
  
  RESULTS
  Transfection of Orai1/CRACM1 plasmids resulted in the inhibition of EGF-mediated cell proliferation. ERK1/2 and Akt phosphorylation were inhibited by Orai1/CRACM1 overexpression. Expression of the cell cycle modulator p21 was induced in the Orai1/CRACM1-overexpressing cells, whereas the expression of cyclin D3 was reduced. Flow cytometry revealed that overexpression of Orai1/CRACM1 resulted in G0/G1 cell cycle arrest. Importantly, Orai1/CRACM1 overexpression significantly attenuated EGF-mediated store-operated calcium influx. In addition, application of 2-APB, a store-operated calcium channel inhibitor, resulted in the inhibition of EGF-mediated cancer cell proliferation.
  
  
  CONCLUSIONS
  We conclude that Orai1/CRACM1 overexpression attenuates store-operated Ca(2+) influx that in turn blocks EGF-mediated proliferative signaling and drives cell cycle arrest.
authors.affiliation: Cancer Center, Kaohsiung Medical University Hospital, Taiwan.
authors.forename: Ming-Feng
authors.initials: MF
authors.lastname: Hou
authors.forename: Ho-Chang
authors.initials: HC
authors.lastname: Kuo
authors.forename: Jih-Heng
authors.initials: JH
authors.lastname: Li
authors.forename: Yu-Shiuan
authors.initials: YS
authors.lastname: Wang
authors.forename: Chen-Chia
authors.initials: CC
authors.lastname: Chang
authors.forename: Ku-Chung
authors.initials: KC
authors.lastname: Chen
authors.forename: Wei-Chiao
authors.initials: WC
authors.lastname: Chen
authors.forename: Chien-Chih
authors.initials: CC
authors.lastname: Chiu
authors.forename: Shengyu
authors.initials: S
authors.lastname: Yang
authors.forename: Wei-Chiao
authors.initials: WC
authors.lastname: Chang
mesh_terms: D001483:Base Sequence; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D017931:DNA Primers; D006801:Humans; D017136:Ion Transport; D008175:Lung Neoplasms / Q000378:metabolism* / Q000473:pathology; D000071740:ORAI1 Protein; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
chemical_list: D015220:Calcium Channels; D017931:DNA Primers; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; D002118:Calcium