TY - JOUR
T1 - Synthetic low-calcaemic vitamin D3 analogues inhibit secretion of insulin-like growth factor II and stimulate production of insulin-like growth factor-binding protein-6 in conjunction with growth suppression of HT-29 colon cancer cells
AU - Oh, Yoon S.
AU - Kim, Eun J.
AU - Schaffer, Beverly S.
AU - Kang, Young H.
AU - Binderup, Lise
AU - MacDonald, Richard G.
AU - Park, Jung H.Y.
N1 - Funding Information:
The authors wish to acknowledge the financial supports of the Korea Research Foundation made in the programme year of 1998 (No. 1998-001-D00969) and the Hallym Academy of Sciences, Hallym University, Korea, 2001. The authors are grateful to Mrs M.H. Niedenthal for the provision of recombinant human IGF-II and Dr S. Shimasaki for IGFBP-6 cDNA.
PY - 2001/10/25
Y1 - 2001/10/25
N2 - The aims of the present study were to compare the ability of various synthetic analogues of 1α,25-dihydroxyvitamin D3 [1α,25-(OH)2D3] to inhibit proliferation of HT-29 cells, a human colon adenocarcinoma cell line. HT-29 cells were incubated for 144 h with various concentrations (0-100 nM) of 1α,25-(OH)2D3, or the analogues EB1089, CB1093 or 1β,25-(OH)2D3. All these analogues except 1β,25-(OH)2D3 inhibited cell proliferation, but relative potencies and efficacies of EB1089 and CB1093 were much greater than that of the native vitamin. Cells grew in serum-free medium, reaching a plateau density at day 10 of culture, and addition of 10 nM 1α,25-(OH)2D3 or 1β,25-(OH)2D3 did not alter the long-term growth characteristics of HT-29 cells. However, cells treated with 10 nM EB1089 or CB1093 grew at a rate slower than control and reached final densities that were 53±1 and 36±2% lower than control, respectively. Immunoblot analysis of serum-free conditioned medium using a monoclonal anti-insulin-like growth factor-(IGF)-II antibody showed that both 10 nM EB1089 and CB1093 markedly inhibited secretion of both mature 7500 Mr and higher Mr forms of IGF-II. Ligand blot and immunoblot analyses of conditioned media revealed the presence of IGFBPs of Mr 24,000 (IGFBP-4), 30,000 (glycosylated IGFBP-4), 35,000 (IGFBP-2) and 32,000-34,000 (IGFBP-6). The level of IGFBP-2 was decreased by 42±8 and 49±7% by 10 nM EB 1089 and CB1093, respectively, compared to controls. IGFBP-6 was increased approximately twofold by EB1089 and CB1093, and exogenously added IGFBP-6 inhibited HT-29 cell proliferation. These results suggest that inhibition of HT-29 cell proliferation by EB1089 and CB1093 may be attributed, at least in part, to the decreased secretion of IGF-II. The increase in IGFBP-6 concentration coupled with its high affinity for IGF-II may also contribute to decreased cellular proliferation by an indirect mechanism involving sequestration of endogenously produced IGF-II.
AB - The aims of the present study were to compare the ability of various synthetic analogues of 1α,25-dihydroxyvitamin D3 [1α,25-(OH)2D3] to inhibit proliferation of HT-29 cells, a human colon adenocarcinoma cell line. HT-29 cells were incubated for 144 h with various concentrations (0-100 nM) of 1α,25-(OH)2D3, or the analogues EB1089, CB1093 or 1β,25-(OH)2D3. All these analogues except 1β,25-(OH)2D3 inhibited cell proliferation, but relative potencies and efficacies of EB1089 and CB1093 were much greater than that of the native vitamin. Cells grew in serum-free medium, reaching a plateau density at day 10 of culture, and addition of 10 nM 1α,25-(OH)2D3 or 1β,25-(OH)2D3 did not alter the long-term growth characteristics of HT-29 cells. However, cells treated with 10 nM EB1089 or CB1093 grew at a rate slower than control and reached final densities that were 53±1 and 36±2% lower than control, respectively. Immunoblot analysis of serum-free conditioned medium using a monoclonal anti-insulin-like growth factor-(IGF)-II antibody showed that both 10 nM EB1089 and CB1093 markedly inhibited secretion of both mature 7500 Mr and higher Mr forms of IGF-II. Ligand blot and immunoblot analyses of conditioned media revealed the presence of IGFBPs of Mr 24,000 (IGFBP-4), 30,000 (glycosylated IGFBP-4), 35,000 (IGFBP-2) and 32,000-34,000 (IGFBP-6). The level of IGFBP-2 was decreased by 42±8 and 49±7% by 10 nM EB 1089 and CB1093, respectively, compared to controls. IGFBP-6 was increased approximately twofold by EB1089 and CB1093, and exogenously added IGFBP-6 inhibited HT-29 cell proliferation. These results suggest that inhibition of HT-29 cell proliferation by EB1089 and CB1093 may be attributed, at least in part, to the decreased secretion of IGF-II. The increase in IGFBP-6 concentration coupled with its high affinity for IGF-II may also contribute to decreased cellular proliferation by an indirect mechanism involving sequestration of endogenously produced IGF-II.
KW - 1α,25-Dihydroxyvitamin D3
KW - CB1093
KW - Colon cancer cells
KW - EB1089
KW - Insulin-like growth factor
KW - Insulin-like growth factor binding proteins
KW - Vitamin D
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UR - http://www.scopus.com/inward/citedby.url?scp=0035950393&partnerID=8YFLogxK
U2 - 10.1016/S0303-7207(01)00598-6
DO - 10.1016/S0303-7207(01)00598-6
M3 - Article
C2 - 11604234
AN - SCOPUS:0035950393
SN - 0303-7207
VL - 183
SP - 141
EP - 149
JO - Molecular and Cellular Endocrinology
JF - Molecular and Cellular Endocrinology
IS - 1-2
ER -