title: Induction of differentiation by 1alpha-hydroxyvitamin D(5) in T47D human breast cancer cells and its interaction with vitamin D receptors.
abstract: The role of the active metabolite of vitamin D, 1,25 dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), in cell differentiation is well established. However, its use as a differentiating agent in a clinical setting is precluded due to its hypercalcaemic activity. Recently, we synthesised a relatively non-calcaemic analogue of vitamin D(5), 1alpha-hydroxyvitamin D(5) (1alpha(OH)D(5)), which inhibited the development of carcinogen-induced mammary lesions in culture and suppressed the incidence of chemically induced mammary carcinogmas in rats. In the present study, we determined the differentiating effects of 1alpha-(OH)D(5) in T47D human breast cancer cells and compared its effects with 1,25(OH)(2)D(3). Cells incubated with either 10 or 100 nM of the analogues inhibited cell proliferation in a dose-dependent manner, as measured by the dimethylthiazolyl-2,5-diphenyltetrazolium bromide (MTT) assay. Similar growth-inhibitory effects were also observed for MCF10(neo) cells. Both vitamin D analogues induced cell differentiation, as determined by induction of casein expression and lipid production. However, MCF10(neo) cells failed to respond to either vitamin D analogue and did not undergo cell differentiation. Since the cell differentiating effect of vitamin D is considered to be mediated via the vitamin D receptor (VDR), we examined the induction of VDR using reverse transcriptase-polymerase chain reaction (RT-PCR) in both cells. The results showed that, in T47D cells, both 1,25(OH)(2)D(3) and 1alpha(OH)D(5) induced VDR in a dose-dependent manner. Moreover, both analogues of vitamin D upregulated the expression of vitamin D response element-chloramphenicol acetyl transferase (VDRE-CAT). These results collectively indicate that 1alpha-(OH)D(5) may mediate its cell-differentiating action via VDR in a manner similar to that of 1,25(OH)(2)D(3).
authors.affiliation: Department of Surgical Oncology, University of Illinois College of Medicine, 840 S. Wood St (M/C 820), Chicago 60612, USA.
authors.forename: G
authors.initials: G
authors.lastname: Lazzaro
authors.forename: A
authors.initials: A
authors.lastname: Agadir
authors.forename: W
authors.initials: W
authors.lastname: Qing
authors.forename: M
authors.initials: M
authors.lastname: Poria
authors.forename: R R
authors.initials: RR
authors.lastname: Mehta
authors.forename: R M
authors.initials: RM
authors.lastname: Moriarty
authors.forename: T K
authors.initials: TK
authors.lastname: Das Gupta
authors.forename: X K
authors.initials: XK
authors.lastname: Zhang
authors.forename: R G
authors.initials: RG
authors.lastname: Mehta
mesh_terms: D001943:Breast Neoplasms / Q000473:pathology*; D002117:Calcitriol / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D005260:Female; D015870:Gene Expression; D006801:Humans; D006887:Hydroxycholecalciferols / Q000378:metabolism / Q000494:pharmacology*; D012333:RNA, Messenger / Q000235:genetics; D018167:Receptors, Calcitriol / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation / Q000187:drug effects; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: C103958:1-hydroxyvitamin D5; D006887:Hydroxycholecalciferols; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D002117:Calcitriol