Inhibition of proliferation and induction of apoptosis by 25-hydroxyvitamin D3-3beta-(2)-Bromoacetate, a nontoxic and vitamin D receptor-alkylating analog of 25-hydroxyvitamin D3 in prostate cancer cells.
The 25-hydroxyvitamin D(3) (25-OH-D(3)) is a nontoxic and low-affinity vitamin D receptor (VDR)-binding metabolic precursor of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)]. We hypothesized that covalent attachment of a 25-OH-D(3) analog to the hormone-binding pocket of VDR might convert the latter into transcriptionally active holo-form, making 25-OH-D(3) biologically active. Furthermore, it might be possible to translate the nontoxic nature of 25-OH-D(3) into its analog. We showed earlier that 25-hydroxyvitamin D(3)-3-bromoacetate (25-OH-D(3)-3-BE) alkylated the hormone-binding pocket of VDR. In this communication we describe that 10(-6) mol/L of 25-OH-D(3)-3-BE inhibited the growth of keratinocytes, LNCaP, and LAPC-4 androgen-sensitive and PC-3 and DU145 androgen-refractory prostate cancer cells, and PZ-HPV-7 immortalized normal prostate cells with similar or stronger efficacy as 1,25(OH)(2)D(3). But its effect was strongest in LNCaP, PC-3, LAPC-4, and DU145 cells. Furthermore, 25-OH-D(3)-3-BE was toxic to these prostate cancer cells and caused these cells to undergo apoptosis as shown by DNA-fragmentation and caspase-activation assays. In a reporter assay with COS-7 cells, transfected with a 1alpha,25-dihydroxyvitamin D(3)-24-hydroxylase (24-OHase)-construct and VDR-expression vector, 25-OH-D(3)-3-BE induced 24-OHase promoter activity. In a "pull down assay" with PC-3 cells, 25-OH-D(3)-3-BE induced strong interaction between VDR and general transcription factors, retinoid X receptor, and GRIP-1. Collectively, these results strongly suggested that the cellular effects of 25-OH-D(3)-3-BE were manifested via 1,25(OH)(2)D(3)/VDR signaling pathway. A toxicity study in CD-1 mice showed that 166 microg/kg of 25-OH-D(3)-3-BE did not raise serum-calcium beyond vehicle control. Collectively, these results strongly suggested that 25-OH-D(3)-3-BE has a strong potential as a therapeutic agent for androgen-sensitive and androgen-refractory prostate cancer.
Swamy
Narasimha
N
Endocrinology, Diabetes and Nutrition, Department of Medicine, Boston University School of Medicine, 85 East Newton Street, Boston, MA 02118, USA. bapi@bu.edu
Chen
Tai C
TC
Peleg
Sara
S
Dhawan
Puneet
P
Christakos
Sylvia
S
Stewart
Lamonica V
LV
Weigel
Nancy L
NL
Mehta
Rajendra G
RG
Holick
Michael F
MF
Ray
Rahul
R
D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D019556:COS Cells; D002117:Calcitriol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002352:Carrier Proteins / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D015500:Chloramphenicol O-Acetyltransferase; D002522:Chlorocebus aethiops; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects; D008297:Male; D051379:Mice; D009376:Neoplasms, Hormone-Dependent / Q000188:drug therapy* / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011467:Prostate / Q000166:cytology / Q000187:drug effects; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000473:pathology; D018167:Receptors, Calcitriol / Q000378:metabolism; D047488:Retinoid X Receptors / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
C104313:1,25-dihydroxyvitamin D3-3-bromoacetate; D002352:Carrier Proteins; C491310:GRIP1 protein, human; D009419:Nerve Tissue Proteins; D018167:Receptors, Calcitriol; D047488:Retinoid X Receptors; D015090:25-Hydroxyvitamin D3 1-alpha-Hydroxylase; D015500:Chloramphenicol O-Acetyltransferase; D020169:Caspases; D002117:Calcitriol; D013936:Thymidine