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  • Title: Calcium-dependent c-myc proto-oncogene expression and proliferation of Caco-2 cells: a role for a luminal extracellular calcium-sensing receptor.
    Author: Kállay E, Kifor O, Chattopadhyay N, Brown EM, Bischof MG, Peterlik M, Cross HS.
    Journal: Biochem Biophys Res Commun; 1997 Mar 06; 232(1):80-3. PubMed ID: 9125156.
    Abstract:
    The human colonic cell line Caco-2 responds to a reduction of ambient [Ca++]o to levels at and below 0.25 mM by a twofold increase in [3H]thymidine labelling of their DNA. [Ca++]o signals sensed preferentially across the luminal aspect of Caco-2 cells, are rapidly (4 h) transduced via PKC activation into up to sixfold increases in c-myc expression. This suggests the presence of a [Ca++]o-sensing membrane receptor (CaR) similar to that described by Brown et al. (1) in parathyroid and kidney cells. By RT-PCR we were able to amplify a 426 bp fragment from Caco-2 mRNA with 98% nucleotide identity to a part of the coding region for the extracellular domain of the parathyroid CaR. Immunohistochemical staining with a monoclonal antiparathyroid CaR antibody demonstrates CaR protein at the plasma membrane of confluent Caco-2 cells. Our results imply that the intestinal CaR is a potential mediator for the transduction of low luminal [Ca++]o into tumor promoting signals in human colonocytes.
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