Characterization of the vitamin D receptor from the Caco-2 human colon carcinoma cell line: effect of cellular differentiation

Arch Biochem Biophys. 1991 Mar;285(2):261-9. doi: 10.1016/0003-9861(91)90358-p.


The human colon carcinoma cell line, Caco-2, is the only intestinal cell line to spontaneously differentiate in culture to a population exhibiting structural and biochemical characteristics of mature enterocytes. We conducted studies to establish the presence of the vitamin D receptor (VDR), determine changes in VDR concentration and affinity with differentiation and determine whether 1 alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3) mediates a functional response in this cell line. We found that Caco-2 cells possess a specific 1,25(OH)2D3 binding protein similar to the mammalian VDR. It has an equilibrium dissociation constant (Kd) of 0.72 nM, binds vitamin D analogues in order of their biological activities in vivo (1,25(OH)2D3 greater than 25(OH)D3 greater than 24,25(OH)2D3), sediments as a single peak on sucrose density gradients at 3.7 S, and is eluted from a DNA-cellulose column by 0.16 M KCl. The maximum number of binding sites was 2.6-fold greater in the differentiated cell (Day 15) compared to the preconfluent, undifferentiated (Day 4) cell (23 fmol/mg protein vs 56 fmol/mg protein). Cell growth was reduced 59% when exposed to 10(-7) M 1,25(OH)2D3 for 8 days. Alkaline phosphatase activity significantly increased in cultures incubated with 10(-8) M 1,25(OH)2D3 for up to 4 days when treatment was started in both undifferentiated cells (Day 5) and differentiated cells (Day 11). These findings suggest that the VDR present in undifferentiated and differentiated Caco-2 cells is functional. Caco-2 cells provide a unique in vitro model to study vitamin D-regulated functions in differentiated mammalian enterocytes.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alkaline Phosphatase / metabolism
  • Binding, Competitive
  • Calcitriol / metabolism
  • Calcitriol / pharmacology
  • Cell Differentiation
  • Cell Division / drug effects
  • Centrifugation, Density Gradient
  • Colonic Neoplasms / metabolism*
  • Colonic Neoplasms / pathology
  • DNA / metabolism
  • Humans
  • Microvilli / enzymology
  • Receptors, Calcitriol
  • Receptors, Steroid / physiology*
  • Sucrase / metabolism
  • Tumor Cells, Cultured


  • Receptors, Calcitriol
  • Receptors, Steroid
  • DNA
  • Alkaline Phosphatase
  • Sucrase
  • Calcitriol