TY - JOUR
T1 - Vitamin D receptor content and transcriptional activity do not fully predict antiproliferative effects of vitamin D in human prostate cancer cell lines
AU - Zhuang, S. H.
AU - Schwartz, G. G.
AU - Cameron, D.
AU - Burnstein, K. L.
N1 - Funding Information:
We thank Dr Leonard Freedman (Memorial Sloan-Kettering Cancer Center) for the VDR expression vector and Dr Paul Braunschweiger (University of Miami) for the many insightful comments on the manuscript. This work was supported by a Developmental Grant from the Sylvester Comprehensive Cancer Center and NIH DK45478 (to K.L.B.).
PY - 1997/1/3
Y1 - 1997/1/3
N2 - Prostate cancer cell lines exhibit variable growth suppression by the hormonal form of vitamin D3, 1,25-Dihydroxyvitamin D3 [1,25 (OH)2D] (1,25 D3). To understand the molecular basis for this differential sensitivity to 1,25 D3, we compared growth response to 1,25 D3, vitamin D receptor (VDR) content and VDR transcriptional activity in four well-characterized human prostate cancer cell lines: LNCaP, DU145, PC-3 and ALVA-31. In PC-3 and DU145 cells, relative lack of growth inhibition by 1,25 D3 (< 10% inhibition) correlates with very low levels of VDR (9-15 fmol/mg protein) compared to classical vitamin D3 target tissues (~ 75-200 fmol/mg protein). Transfection of DU145 and PC-3 cells with a VDR cDNA expression vector is sufficient to establish growth sensitivity to 1,25 D3, suggesting that low VDR levels are responsible for the failure of these cell lines to respond to 1,25 D3. LNCaP cells are highly sensitive to growth inhibition by 1,25 D3 (~ 55% inhibition) and contain ~ 2-3-fold more VDR (25 fmol/mg) than the relatively 1,25 D3-insensitive PC-3 and DU145 cell lines. However, ALVA-31 cells display less than 20% growth inhibition to 1,25 D3 although they contain the highest levels of VDR (45 fmol/mg) of the four cell lines. Thus, sensitivity to growth inhibition by 1,25 D3 does not correlate with VDR content in ALVA-31 and LNCaP cells. This lack of correlation between VDR density and growth responses to 1,25 D3 led us to investigate VDR-mediated gene transcription in these cell lines. We employed two different naturally-occurring vitamin D response elements (VDREs) linked to a reporter gene. Reporter gene activation by 1,25 D3 correlated well with VDR content in all four cell lines. Therefore, compared to LNCaP cells, decreased sensitivity of ALVA-31 to growth inhibition by 1,25 D3 is not due to a decrease in the general transcriptional activity of VDR. We conclude that growth inhibition by 1,25 D3 in prostate cancer cells requires VDR but that this response is modulated by non-receptor factors that are cell line-specific.
AB - Prostate cancer cell lines exhibit variable growth suppression by the hormonal form of vitamin D3, 1,25-Dihydroxyvitamin D3 [1,25 (OH)2D] (1,25 D3). To understand the molecular basis for this differential sensitivity to 1,25 D3, we compared growth response to 1,25 D3, vitamin D receptor (VDR) content and VDR transcriptional activity in four well-characterized human prostate cancer cell lines: LNCaP, DU145, PC-3 and ALVA-31. In PC-3 and DU145 cells, relative lack of growth inhibition by 1,25 D3 (< 10% inhibition) correlates with very low levels of VDR (9-15 fmol/mg protein) compared to classical vitamin D3 target tissues (~ 75-200 fmol/mg protein). Transfection of DU145 and PC-3 cells with a VDR cDNA expression vector is sufficient to establish growth sensitivity to 1,25 D3, suggesting that low VDR levels are responsible for the failure of these cell lines to respond to 1,25 D3. LNCaP cells are highly sensitive to growth inhibition by 1,25 D3 (~ 55% inhibition) and contain ~ 2-3-fold more VDR (25 fmol/mg) than the relatively 1,25 D3-insensitive PC-3 and DU145 cell lines. However, ALVA-31 cells display less than 20% growth inhibition to 1,25 D3 although they contain the highest levels of VDR (45 fmol/mg) of the four cell lines. Thus, sensitivity to growth inhibition by 1,25 D3 does not correlate with VDR content in ALVA-31 and LNCaP cells. This lack of correlation between VDR density and growth responses to 1,25 D3 led us to investigate VDR-mediated gene transcription in these cell lines. We employed two different naturally-occurring vitamin D response elements (VDREs) linked to a reporter gene. Reporter gene activation by 1,25 D3 correlated well with VDR content in all four cell lines. Therefore, compared to LNCaP cells, decreased sensitivity of ALVA-31 to growth inhibition by 1,25 D3 is not due to a decrease in the general transcriptional activity of VDR. We conclude that growth inhibition by 1,25 D3 in prostate cancer cells requires VDR but that this response is modulated by non-receptor factors that are cell line-specific.
KW - Calcitriol
KW - Cellular proliferation
KW - Prostate cancer cell lines
KW - Reporter gene assay
KW - Vitamin D
KW - Vitamin D receptors
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U2 - 10.1016/S0303-7207(96)03974-3
DO - 10.1016/S0303-7207(96)03974-3
M3 - Article
C2 - 9027366
AN - SCOPUS:0031023616
SN - 0303-7207
VL - 126
SP - 83
EP - 90
JO - Molecular and Cellular Endocrinology
JF - Molecular and Cellular Endocrinology
IS - 1
ER -