MCF‐7/VD^R: A new vitamin D resistant cell line

Abstract

Several in vitro and in vivo experiments have demonstrated potent cell regulatory effects of vitamin D compounds in cancer cells. Moreover, a promising phase I study with the vitamin D analogue Seocalcitol (EB 1089) in patients with advanced breast and colon cancer has already been carried out and more clinical trials evaluating the clinical effectiveness of EB 1089 in other cancer types are in progress (Mørk Hansen et al. [2000a]). However, only little is known about the mechanisms underlying the actions of vitamin D or about the possible development of drug resistance in the patients. Therefore, in an attempt to gain more insight into these aspects, we have developed the MCF-7/VD(R) cell line, a stable subclone of the human MCF-7 breast cancer cell line, which is resistant to the growth inhibitory and apoptosis inducing effects of 1alpha,25(OH)(2)D(3). Despite this characteristic, receptor studies on the VDR have clearly demonstrated that the MCF-7/VD(R) cells contain fully functional VDRs, although in a lower number than seen with the parental MCF-7 cells. The regulation of the 24-hydroxylase enzyme appeared to be intact in the MCF-7/VD(R) cells and no differences with regard to growth rate and morphological appearance between the MCF-7/VD(R) cells and the parental MCF-7 cells were observed. Interestingly, however, the sensitivity of the MCF-7/VD(R) cells to the pure anti-estrogen ICI 182,780 was found to be increased. The MCF-7/VD(R) cell line shows characteristics different from those of previously described vitamin D resistant breast cancer cell lines but also some similarities. Together such vitamin D resistant cell lines therefore serve as a useful tool for studying the exact mechanism of action of vitamin D and the development of vitamin D resistance.

The immunomodulatory drug lenalidomide restores a vitamin D sensitive phenotype to the vitamin D resistant breast cancer cell line MDA-MB-231 through inhibition of BCL-2: potential for breast cancer therapeutics

“…The supplementary figure C shows a representative blot from the three experiments. No effects on the expression of these proteins are seen in any of the treatments.Effects of lenalidomide/1,25-D3 treatment on MCF-7/ VD R and HBL-100 viability In order to validate the previous results obtained in MDA-MB-231 cells, two other vitamin D resistant cell lines, MCF-7/VD R[23] and HBL-100 cells, were investigated. First the effect of lenalidomide on these cell lines was investigated.…”

Identification of VDR-Responsive Gene Signatures in Breast Cancer Cells

“…3 H-thymidine incorporation was measured after 72 h to confirm the differential effects of 1α,25(OH) 2 D 3 on the proliferation of parental MCF-7 and 1α,25(OH) 2 D 3 -resistant variant MCF-7 Res cells, which have been established previously [20]. MCF-7 cells had an ED 50 (dose required to inhibit cell proliferation by 50%) of approximately 1 n M and the ED 75 (dose required to inhibit cell proliferation by 75%) was approximately 100 n M .…”

“…MCF-7 Res is a variant of MCF-7 cells, generously supplied by Dr. Christina Mork Hansen (University of Kuopio, Kuopio, Finland), which were generated by long-term culture in the presence of 1α,25(OH) 2 D 3 , resulting in the isolation of a clone that was resistant to the anti-proliferative action of 1α,25(OH) 2 D 3 [20]. All cell lines were supplemented with 100 U/ml penicillin, 100 ag/ml streptomycin and 10% fetal bovine serum (Life Technologies, Paisley, UK) in RPMI.…”

Autocrine Metabolism of Vitamin D in Normal and Malignant Breast Tissue

“…For each assay, [ 3 H]25OHD 3 (10 nmol/L; specific activity, 152 Ci/mmol, Amersham, London, United Kingdom) was added to tissue homogenates prepared in PBS from snap-frozen tumor biopsies (n = 6) or nonneoplastic tissue (n = 6). Aliquots of homogenate used in the assays contained 0.4 mg protein, 0.2 mol/L cofactor (NADPH), and 0.5 mmol/L protease inhibitor (phenylmethylsulfonyl fluoride (32). All cell lines were supplemented with 100 units/mL penicillin, 100 Ag/mL streptomycin, and 10% fetal bovine serum (Life Technologies, Paisley, United Kingdom) in RPMI.…”