Biomedical subjects

L Binderup

Publications and source records attributed to L Binderup.

At least 37 records · Page 2Linked to original sources

PubMed2000

Seocalcitol (EB 1089): a vitamin D analogue of anti-cancer potential. Background, design, synthesis, pre-clinical and clinical evaluation.

It is well established that the metabolically active form of vitamin D, 1alpha,25-dihydroxyvitamin D3 (1alpha,25(OH)2D3) plays a key role in the establishment and maintenance of the calcium metabolism in the body. In addition to this classic effect of 1alpha,25(OH)2D3, substantial evidence has emerged demonstrating that 1alpha,25(OH)2D3 is able to regulate cell growth and differentiation in a number of different cell types, including cancer cells. However, the clinical usefulness of 1alpha,25(OH)2D3 is limited by its tendency to cause hypercalcaemia. Much effort has therefore been directed to identifying new vitamin D analogues with potent cell regulatory effects, but with weaker effects on the calcium metabolism than those of 1alpha,25(OH)2D3. One of these new synthetic analogues is Seocalcitol (EB 1089). Despite being 50-200 times more potent than 1alpha,25(OH)2D3 with respect to regulation of cell growth and differentiation in vitro as well as in vivo, EB 1089 displays a reduced calcaemic activity in vivo compared to that of 1alpha, 25(OH)2D3. These characteristics make EB 1089 a potentially useful compound for the treatment of cancer. Recent clinical evaluation of EB 1089 has focused mainly on establishing a maximum tolerated dose in cancer patients. Early results confirm that the low calcaemic activity observed in animals can be reproduced in the clinic. Furthermore, EB 1089 has been shown to induce regression of tumours, especially in hepatocellular carcinoma where complete remission has been obtained. In conclusion, the development of EB 1089 as an anti-cancer drug holds promise. However, its final evaluation must await the completion of ongoing controlled clinical trials.

Animals↗

PubMed2000

Effect of a novel vitamin D3 analog, EB1089, on G1 cell cycle regulatory proteins in HL-60 cells.

Progression of cell cycle in eukaryotes is regulated by a series of the cyclin-dependent kinases (CDKs) and cyclin-dependent kinase inhibitors (CDKIs). It has been shown that 1,25(OH)2D3 is able to arrest cell cycle at G1 phase in malignant cells including HL-60 cells. EB1089 is a novel 1,25(OH)2D3 analog that has more potent antileukemic properties with reduced hypercalcemic effect in vitro and in vivo than 1,25(OH)2D3. In the present study, we examined the effect of EB1089 on HL-60 cells at the protein levels of several G1 regulatory proteins. Exposure of HL-60 cells to EB1089 (1x10-8 M) for 3 days showed the G1 block by FACS analysis. The level of p21 was markedly induced in HL-60 cells treated with EB1089 at 24 h, and p27 were progressively increased in a time-dependent manner. The expressions of CDK2 and CDK6 were down-regulated during G1 block of HL-60 cells, and CDK4 is progressively elevated. In addition, level of cyclin D1 was increased in a time-dependent manner, however, no change of cyclin E was noted through the G1 to S traverse. Immunoprecipitation study demonstrated that p27 did not bind to CDK2, CDK4 and CDK6 in EB1089-treated HL-60 cell extracts. In contrast, complexes immunoprecipitated from EB1089-treated HL-60 cells with antibodies CDK2 and CDK6 contained higher amounts of immunodetectable p21 protein compared to untreated HL-60 cells, whereas no detectable change was noted with anti-CDK4 antibody. Furthermore, the kinase activities of CDK2 and CDK6 were decreased while little change was observed in CDK4 activity. These data indicated that p21 protein is a strong candidate for the control of G1 progression in EB1089-treated HL-60 cells, and its major target molecules are CDK2 and CDK6.

Antineoplastic Agents↗

PubMed1999

Enhanced biological activity of 1alpha,25-dihydroxy-20-epi-vitamin D3, the C-20 epimer of 1alpha,25-dihydroxyvitamin D3, is in part due to its metabolism into stable intermediary metabolites with significant biological activity.

1alpha,25-dihydroxy-20-epi-vitamin D3 (1alpha,25(OH)2-20-epi-D3), the C-20 epimer of the natural hormone 1alpha,25(OH)2D3, is several fold more potent than the natural hormone in inhibiting cell growth and inducing cell differentiation. At present, the various mechanisms responsible for the enhanced biological activities of this unique vitamin D3 analog are not fully understood. In our present study we compared the target tissue metabolism of 1alpha,25(OH)2D3 with that of 1alpha,25(OH)2-20-epi-D3 using the technique of isolated perfused rat kidney. The results indicated that the C-24 oxidation pathway plays a major role in the metabolism of both compounds in the rat kidney. However, it was noted that the concentrations of two of the intermediary metabolites of 1alpha,25(OH)2-20-epi-D3, namely, 1alpha,24(R),25(OH)3-20-epi-D3 and 1alpha,25(OH)2-24-oxo-20-epi-D3 in the kidney perfusate, exceeded the concentrations of the corresponding intermediary metabolites of 1alpha,25(OH)2D3. Furthermore, 1alpha,25(OH)2-24-oxo-20-epi-D3 induces the conformation of the vitamin D receptor similar to that induced by its parent analog and is nearly as potent as its parent in inducing transactivation of a gene construct containing the human osteocalcin vitamin D-responsive element. We conclude that 1alpha,25(OH)2-20-epi-D3 by itself is not metabolically stable when compared to 1alpha,25(OH)2D3, but it acquires its metabolic stability because of the reduced rate of catabolism of its intermediary metabolites. Furthermore, 1alpha,25(OH)2-24-oxo-20-epi-D3, the stable bioactive intermediary metabolite plays a significant role in generating the enhanced biological activities ascribed to 1alpha,25(OH)2-20-epi-D3.

Animals↗

PubMed1999

CHS 828, a novel pyridyl cyanoguanidine with potent antitumor activity in vitro and in vivo.

A new class of recently discovered antineoplastic agents, the pyridyl cyanoguanidines, exert a potent antitumor activity in rodents after oral administration. Optimization in vitro and in vivo has resulted in the selection of the lead candidate CHS 828 (N-(6-chlorophenoxyhexyl)-N'cyano-N"-4-pyridylguanidine). CHS 828 was found to exert potent cytotoxic effects in human breast and lung cancer cell lines, with lesser effects on normal fibroblasts and endothelial cells. In a study using a panel of cell lines with different resistance patterns, the effects of CHS 828 showed a low correlation with the activity patterns of known anticancer agents, and no sensitivity to known mechanisms of multidrug resistance was observed. In nude mice bearing human tumor xenografts, CHS 828, at doses from 20 to 50 mg/kg/day p.o., inhibited the growth of MCF-7 breast cancer tumors and caused regression of NYH small cell lung cancer tumors. Oral administration of CHS 828 once weekly improved efficacy without increasing toxicity. CHS 828 was found to compare favorably with established chemotherapeutic agents such as cyclophosphamide, etoposide, methotrexate, and paclitaxel. In mice with NYH tumors, long-term survival (>6 months) was observed after treatment with CHS 828 was stopped. In conclusion, CHS 828 is an effective new antitumor agent, with a potentially new mechanism of action. CHS 828 is presently being tested in Phase I clinical trials in collaboration with the European Organization for Research and Treatment of Cancer.

Animals↗

PubMed1999

Novel 20-epi-vitamin D3 analog combined with 9-cis-retinoic acid markedly inhibits colony growth of prostate cancer cells.

BACKGROUND: 1,25 dihydroxyvitamin D3 (1,25D) and retinoids may play an important role in preventing progression of prostate cancer. METHODS: We examined the ability of four novel 20-epi-vitamin D3 analogs (CB1093, KH1060, KH1266, and CB1267), either alone or in combination with 9-cis retinoic acid (RA) to inhibit colony growth of a human prostate cancer cell line, LNCaP, using soft agar as well as bone marrow stroma. Also, the effect of these analogs on the cell cycle and expression of Ki-67, p21(waf-1), and p27(kip1) in LNCaP cells was examined. RESULTS: The analog CB1267 was the most potent, with 8 x 10(-10) M of the analog inhibiting 50% colony growth (ED50) of LNCaP. 9-cis-RA also inhibited colony growth of LNCaP (ED50, 5 x 10(-7) M). Combined, CB1267 and 9-cis-RA synergistically inhibited colony growth and significantly increased the number of LNCaP cells in G0/G1 phase. Cell cycle arrest was associated with increased levels of p21(waf-1) and p27(kip1) and decreased expression of Ki-67 protein. Pulse-exposure to this combination (5 x 10(-8) M) irreversibly inhibited colony growth, both in soft agar and on normal human bone marrow stroma. CONCLUSIONS: Combination of a new vitamin D3 analog (CB1267) and a retinoid (9-cis-RA) potently inhibited colony formation of LNCaP prostate cancer cells in vitro, suggesting further studies in animal models. This combination may afford an interesting therapeutic approach to low-burden prostate cancer.

Alitretinoin↗

PubMed1999

Combined effect of vitamin D3 analogs and paclitaxel on the growth of MCF-7 breast cancer cells in vivo.

Vitamin D3 analogs and paclitaxel (Taxol) are able to inhibit the in vitro growth of a variety of malignant cells including breast cancer cells. These two compounds decrease growth by different mechanisms and they have nonoverlapping toxicities. We examined the abilities of three vitamin D3 compounds to inhibit growth of a human mammary cancer (MCF-7) in BNX triple immunodeficient mice either alone or with Taxol. Vitamin D3 analogs were 1,25(OH)2D3 (code name, Compound C), 1,25(OH)2-16-ene-23-yne-19-nor-26,27-F6-D3 (Compound LH), and 24a,26a,27a,-trihomo-22,24-diene-1,25(OH)2D3 (EB1089). At the doses chosen, the antitumor effect of vitamin D3 analogs alone was greater than that of Taxol alone, and an additive effect was observed when a vitamin D3 analog and Taxol were administered together. EB1089 was the most potent compound, and the EB1089 plus Taxol was the most active combination, decreasing the tumor mass nearly 4-fold compared to controls. Weight-gain in each of the experimental cohorts at the end of the study was less than the control group, but the gain was significantly less in only two experimental groups (those receiving either EB1089 or Compound C plus Taxol). None of the animals became hypercalcemic, and their complete blood counts, serum electrolyte analyses, and liver and renal functions were all fairly similar and within the normal range. In summary, this combination of a vitamin D3 analog and Taxol has the potential to be a therapy for breast cancer.

Animals↗

PubMed1999

The rat Subcutaneous Air Sac model: a quantitative assay of antiangiogenesis in induced vessels.

A new in vivo experimental model--the Subcutaneous Air Sac (SAS) model-has recently been presented to replace a previous in vivo rabbit cornea assay where neovascularisation was induced by chemical injury of the cornea or by implantation of tumour cells intracorneally, a methodology which is believed to cause severe pain to the animals. In the SAS model, an air sac is induced by injection of air subcutaneously on the back of the animal. After 10-14 days the air sac appears as an almost transparent avascular membrane in which induction of new vessels can be studied. We present recent developments of this technique: In the SAS-tumour technique, vascular endothelial growth factor-producing tumour cells are inoculated subcutaneously directly on the membrane, and the formation of new vessels is measured 8 days later. In the SAS-pellet technique, slow-release pellets containing angiogenic factors, basic fibroblast growth factor or vascular endothelial growth factor are implanted on the subcutaneous membrane by a simple operation. The formation of new vessels is measured 10 days later. The ability of the SAS-tumour- and SAS-pellet techniques to detect an antiangiogenic effect of a systemically administered compound was investigated using the fumagillin analogue TNP-470 (o-chloroacetyl-carbamoyl)-fumagillol) as a positive control given subcutaneously for 7 and 9 days, respectively. At a dose of 10 mg TNP-470/kg/day the angiogenesis was reduced by approximately 70% in the SAS-tumour technique and by 40-60% in the SAS-pellet technique. The animals were unaffected by the SAS methodology. The SAS-tumour and SAS-pellet models are considered complementary and make use of simple and almost similar techniques which facilitate the evaluation.

Air Sacs↗

PubMed1999

Inhibition of prostate cancer metastasis in vivo: a comparison of 1,23-dihydroxyvitamin D (calcitriol) and EB1089.

The steroid hormone 1,25-dihydroxyvitamin D [1,25(OH)2D, also known as calcitriol] is known to inhibit the proliferation and to promote the differentiation of human prostate cancer cells. Additionally, we showed that 1,25(OH)2D markedly inhibits the invasiveness of human prostate cancer cells in vitro (G. G. Schwartz et al., Cancer Epidemiol. Biomark. Prev., 6: 727-732, 1997). These properties support the use of 1,25(OH)2D as differentiation therapy in prostate cancer. However, the use of 1,25(OH)2D in vivo is limited by the risk of hypercalcemia. We therefore compared the effects of 1,25(OH)2D and of EB1089, an analogue of 1,25(OH)2D with reduced calcemic effects, in an in vivo model of androgen-insensitive metastatic prostate cancer, the rat Dunning MAT LyLu prostate cancer model. Tumor growth and metastasis were studied using Copenhagen rats given s.c. injections of MAT LyLu cells. Fifty male rats were divided into five groups of 10 rats each. Four experimental groups received i.p. injections of low and high doses of 1,25(OH)2D and EB1089 (0.5 and 1.0 microg/kg, low and high, respectively). A control group received injections of vehicle only. Tumor volumes were measured three times per week. Rats were weighed weekly. The number of metastases to the lungs and the extent of hypercalcemia were evaluated. Compared with controls, tumor volumes were significantly smaller in all experimental groups. Similarly, the number of lung metastases (number of foci/lung) was reduced markedly by both 1,25(OH)2D and EB1089. Control rats developed 22.7 (+/- 1.98 SE) tumor foci per lung. Rats treated with 1,25(OH)2D and with EB1089 (1.0 microg/kg) developed 10.4 (+/- 2.81) and 7.70 (+/- 1.29) tumor foci, respectively (P < 0.001 and P < 0.0001, respectively; drug versus control). Compared with controls (10.79 +/- 0.1 mg/dl), serum calcium levels were significantly elevated in both 1,25(OH)2D and EB1089-treated rats (P < 0.01). However, EB1089 was significantly less calcemic than 1,25(OH)2D (12.59 +/- 0.21 mg/dl versus 14.47 +/- 0.46 mg/dl; 1.0 microg/kg; P < 0.001). Rats treated with 1,25(OH)2D showed marked weight loss: 20.0 +/- 1.9% and 26.3 +/- 1.7% of their initial weight (low and high doses, respectively, P < 0.001). Weight loss was significantly lower in rats treated with EB1089 at the high dose 8.4 (+/- 2.9) %. Moreover, rats treated with low-dose EB1089 gained 5.2 (+/- 3.7) % of their initial weight. In conclusion, 1,25(OH)2D and EB1089 showed marked and equivalent inhibition of prostate cancer metastasis in vivo. EB1089 was significantly less calcemic than 1,25(OH)2D and did not induce severe weight loss. This is the first report of a vitamin D analogue that significantly inhibits prostate cancer metastasis in vivo and that does so without producing cachexia or unacceptable hypercalcemia.

Animals↗

PubMed1998

Studies on the interaction between the vitamin D receptor and the radiolabelled 20-epi vitamin D analogue GS 1500.

Previous studies have shown that the binding affinity of a vitamin D analogue for the vitamin D receptor (VDR) does not correlate with the biological potency of the compound. In the present investigation the vitamin D analogue GS 1500, which is characterised by an altered stereochemistry at carbon C-20 (20-epi) and an aromatic ring in the side chain, was studied with respect to its interaction with the VDR. Using [3H]-GS 1500 as tracer, the receptor binding properties of GS 1500 were investigated and compared to those of 1,25(OH)2D3. The binding studies did not reveal a different binding site for GS 1500 than the one already established, and the binding affinity was in accordance with previously found values. At the level of VDR interaction with the vitamin D responsive element, GS 1500 did induce a binding complex at a lower concentration than 1,25(OH)2D3, which may help explain the difference in potency.

Animals↗

PubMed1998

EB1089, a synthetic analogue of vitamin D, induces apoptosis in breast cancer cells in vivo and in vitro.

1. Effects of the synthetic vitamin D analogue EB1089 on indices of apoptosis in cultured human breast cancer cells and in nitrosomethylurea-induced rat mammary tumours in vivo were investigated. 2. At a dose of 0.5 microg kg(-1) body weight, EB1089 caused significant inhibition of tumour progression over the 28 day treatment period in the absence of a significant increase in serum calcium concentration. Higher doses of EB1089 (1 and 2.5 microg kg(-1)) produced substantial regression of the experimental tumours which was accompanied by a striking change in the histological appearance of tumours consistent with induction of tumour cell death. 3. Fragmentation of genomic DNA is a characteristic feature of apoptosis. With the terminal transferase (TdT) assay, 3' DNA breaks indicative of DNA fragmentation were detected histochemically in mammary tumour cells from animals treated with EB1089 (2.5 microg kg(-1)) for 14 days. 4. Effects of the vitamin D analogue on induction of apoptosis were examined in vitro using the MCF-7 human breast cancer cell line. Using the TUNEL method, positive nuclear staining indicative of DNA fragmentation was detected in cells treated for 4 days with 10 nM EB1089. Apoptosis was also quantitated using a cell death ELISA which revealed a time and dose dependent induction of apoptosis by EB1089. 5. The effects of EB1089 on the expression of two oncoproteins which may regulate apoptosis, bcl-2 and bax were examined by Western analysis. In MCF-7 cell cultures treated with 1,25(OH)2D3 or EB1089 (1 x 10(-8) M), bcl-2 protein levels were decreased in a time-dependent manner relative to control levels. In contrast bax protein was not markedly regulated by these compounds. Densitometric analyses indicate that the vitamin D compounds lower the bcl-2/bax ratio favouring increased susceptibility of MCF-7 cells to undergo apoptosis. 6. These results suggest that the synthetic vitamin D analogue EB1089 may promote tumour regression by inducing active cell death.

Animals↗

PubMed1998

Apoptotic regression of MCF-7 xenografts in nude mice treated with the vitamin D3 analog, EB1089.

1,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] and its synthetic analog EB1089 induce characteristic morphological features of apoptosis in MCF-7 cells in vitro that coincide with up-regulation of clusterin and cathepsin B, proteins associated with apoptosis in the mammary gland, and with down-regulation of Bcl-2, an antiapoptotic protein. To determine whether vitamin D3 compounds could mediate apoptosis of breast tumors in vivo, we treated nude mice carrying established MCF-7 xenografts with the low calcemic vitamin D3 analog EB1089 via daily injection or sustained release pellets for up to 5 weeks. The volume of tumors from mice treated with 45 pmol/day EB1089 was 4-fold lower than that of tumors from vehicle-treated control mice after 5 weeks. The reduced growth of tumors from EB1089-treated mice was associated with characteristic apoptotic morphology and a marked reduction in the proportion of epithelial cells to stroma. After 5 weeks of treatment with EB1089, MCF-7 tumors exhibited a 6-fold increase in DNA fragmentation (as measured by in situ end labeling) relative to that in control tumors. The enhanced rate of apoptosis in tumors from EB1089-treated mice was coupled to a 2-fold reduction in proliferation (as measured by expression of proliferating cell nuclear antigen) compared with that in tumors from control mice. The antitumor effects of EB1089 were evident at doses that had minimal effects on serum calcium and body weight. EB1089 treatment did not alter the growth of xenografts derived from a vitamin D3-resistant variant of MCF-7 cells (MCF-7(D3Res) cells), which display resistance to EB1089 in vitro, indicating that resistance to EB1089 is maintained in vivo. Tumors derived from both MCF-7 and MCF-7(D3Res) cells underwent apoptotic regression upon estradiol withdrawal, indicating comparable estrogen dependence of tumors with differential sensitivity to vitamin D3 compounds. These are the first studies to demonstrate apoptotic morphology and regression of human breast tumors in response to treatment with a vitamin D3 analog in vivo and support the concept that vitamin D3 compounds can effectively target human breast cancer.

Animals↗

PubMed1998

Down-regulation of laminin-binding integrins by 1 alpha,25-dihydroxyvitamin D3 in human melanoma cells in vitro.

In the present investigation the effect of 1 alpha,25(OH)2D3 on the expression of the integrin laminin receptor on the melanoma cell line SK-MEL-28 has been examined. The SK-MEL-28 cells were shown to contain high-affinity receptors for 1 alpha,25(OH)2D3 and cell proliferation was found to be inhibited in a dose-dependent manner in response to the hormone. Using monoclonal antibodies against the alpha 6-sub-unit of the integrin laminin receptor, immunocytochemistry demonstrated that exposure of cells to 1 alpha,25(OH)2D3 for 5 days caused a reduced staining intensity. This observation was further confirmed by dot blot analysis, where a dose-dependent decline of alpha 6 expression was obtained after treatment of the cells with 1 alpha,25(OH)2D3 for 6 days. FACS-analysis was performed in order to quantify this decline, and it was found that the level of alpha 6-subunits on the cell surface was reduced by more than 40%. Additional investigations including Northern blot analyses of poly(A)+RNA extracts also showed a dose-dependent reduction of alpha 6 mRNA. Interestingly, the decrease of alpha 6 expression on the surface of SK-MEL-28 melanoma cells was accompanied by a reduced ability of the cells to adhere to an artificial basement membrane. In conclusion, the present investigation shows that besides having an antiproliferative effect on the SK-MEL-28 melanoma cells, 1 alpha,25(OH)2D3 is also able to inhibit the surface expression of the alpha 6-subunit of the integrin laminin receptor. Moreover, the results strongly indicate that 1 alpha,25(OH)2D3 exerts its regulatory effect on the alpha 6-subunit at the transcriptional level rather than at the protein level.

Antigens, CD↗

PubMed1998

Novel vitamin D3 analog (CB1093) when combined with paclitaxel and cisplatin inhibit growth of MCF-7 human breast cancer cells in vivo.

Vitamin D3 compounds paclitaxel (Taxol) and cisplatin (CDDP, cis-diamminodichloroplatinum) inhibit growth of a variety of malignant cells. We examined the ability of a novel 20-epi-vitamin D3 analog (code name, CB1093), Taxol and CDDP either alone or in combination to inhibit the growth of a human mammary cancer (MCF-7) growing in BNX triple immunodeficient mice. Tumors in control animals demonstrated infiltrating poorly differentiated adenocarcinomas. At the doses chosen, the antitumor effect of Taxol alone was greater than that of either CB1093 or CDDP alone; and additive effects were observed when either CB 1093 + Taxol or CB 1093 + CDDP + Taxol were administered together. The combination of CB 1093 + Taxol + CDDP was most potent, inhibiting tumor weights by nearly 83% compared to control tumors and producing extensive necrosis of the remaining tumor mass. No additive effect occurred by combining either CB1093 + CDDP or Taxol + CDDP compared to Taxol alone. For all cohorts, their complete hematopoietic blood counts, serum electrolyte analyses including serum calciums as well as their liver and renal functions were within the normal range. Extensive histological analyses of the liver, spleen, kidneys, bone marrow, skin and subcutaneous fat pads from these mice showed no abnormalities. In summary, combined therapy with CB1093 (a potent vitamin D3 analog), Taxol and CDDP, which have non-cross reactive toxicities, holds promise in the treatment of patients with breast cancer.

Animals↗

PubMed1997

Growth inhibition of human breast cancer cells by 1,25-dihydroxyvitamin D3 is accompanied by induction of apolipoprotein D expression.

We have analyzed the effect of 1,25-dihydroxyvitamin D3 on the expression of the gene encoding apolipoprotein D (apoD), a protein component of the human plasma lipid transport system that is overproduced by a specific subset of breast carcinomas. Northern blot analysis revealed that 1,25-dihydroxyvitamin D3 strongly up-regulated apoD mRNA levels in T-47D human breast cancer cells in a time- and dose-dependent manner. The potency of this vitamin as an inducer of apoD expression was stronger than the effect observed for such steroid hormones as androgens and progesterone, described previously as hormonal up-regulators of apoD expression in these cells. A time course study demonstrated that the induction of apoD mRNA reached a level of 5-fold over the untreated cells after 48 h of incubation in the presence of 10(-7) M 1,25-dihydroxyvitamin D3. A dose-response analysis showed that a 10(-6) M concentration of this vitamin consistently induced a maximal accumulation of 7-fold over the control cells. Similar up-regulatory effects on the apoD gene expression were obtained by treatment of T-47D cells with 1,25-dihydroxyvitamin D3 analogues, including MC 903, which is relatively devoid of hypercalcemic side effects in clinical applications. Western blot analysis revealed that the inductive effect of 1,25-dihydroxyvitamin D3 was also reflected at the protein level as an increase of immunoreactive protein in the conditioned media of vitamin-treated cells. This increased expression of apoD was accompanied by an inhibition of cell growth and morphological changes in T-47D cells. By contrast, we did not detect any inductive effect of 1,25-dihydroxyvitamin D3 on apoD gene expression in MDA-MB-231 cells, which are refractory to the growth-inhibitory effects of this compound. On the basis of these results, we propose 1,25-dihydroxyvitamin D3 as an important regulator of the expression of the apoD gene in breast carcinomas. We also suggest that apoD may be of interest as a biochemical marker of the action of 1,25-dihydroxyvitamin D3 derivatives in current studies using these compounds as inhibitors of breast cancer cell growth or as chemotherapeutic agents in the prevention of breast cancer.

Antineoplastic Agents↗

PubMed1997

Effects of potent vitamin D3 analogs on clonal proliferation of human prostate cancer cell lines.

BACKGROUND: Management of prostate cancer that has spread outside of the prostate capsule is a difficult problem. Innovative, non-toxic approaches to the disease are required. New, relatively non-toxic vitamin D3 analogs have recently been synthesized. We report that several of these compounds have marked antiproliferative effects on prostate cells. METHODS: The clonal antiproliferative activity of five novel analogs of 1,25 dihydroxyvitamin D3 [1,25(OH)2D3, (cmpd C)] as well as 1,25(OH)2D3 itself was tested on three human prostate cancer cell lines (PC-3, LNCaP, and DU-145). The analogs were 20-epi-22oxa-24a,26a,27a-tri-homo-1 alpha,25(OH)2D3 (code name: KH 1060); 24a26a27a-tri-homo-22,24-diene-1 alpha,25(OH)2D3 (code name: EB 1089); 1,25(OH)2-16ene-D3 (code name: HM); 1,25(OH)2-16ene-23yne-D3 (code name: V); 1,25(OH)2-20-epi-D3 (code name: MC 1288)]. RESULTS: With the parent compound [1,25(OH)2D3], the effective dose that inhibited 50% clonogenic growth of PC-3 and LNCaP was 10(-8)M and 7 x 10(-9)M, respectively. For these prostate cancer cell lines, KH 1060 was the most potent analog by an order of 25- to 35-fold as compared to cmpd C. The second and third most potent analogs were HM and MC 1288. DU-145 was resistant to all the vitamin D3 analogs. The major side-effect of 1,25(OH)2D3 is the production of hypercalcemia. The relative inhibitory index (RII) was determined by comparing the antiproliferative activity of the analog to its ability to produce hypercalcemia in mice injected intraperitoneally every other day. The KH 1060 had the best RTI: 50- to 70-fold greater than 1,25(OH)2D3 for PC-3 and LNCaP, respectively. CONCLUSIONS: A trial of one or more of these innovative compounds should be considered for treatment of minimal residual disease of prostate cancer.

Animals↗

PubMed1997

Metabolism of the vitamin D analog EB 1089: identification of in vivo and in vitro liver metabolites and their biological activities.

1(S),3(R)-dihydroxy-20(R)-(5'-ethyl-5'-hydroxy-hepta-1'(E),3'(E)-dien -1'-yl)-9,10-secopregna-5(Z),7(E),10(19)-triene (EB 1089) is a novel analog of the vitamin D hormone, calcitriol that has been modified in the side-chain resulting in an increased metabolic stability relative to other side-chain modified analogs (e.g. calcipotriol and 22-oxacalcitriol). To further investigate the metabolism of EB 1089, we set out to study this metabolism both in the rat in vivo as well as in the postmitochondrial liver fractions from rat, man, and minipig in vitro. The same pattern of metabolism was observed in all biological systems employed, both in vivo and in vitro, namely 26- and 26a-hydroxylation of EB 1089. The same metabolites were produced using cultured cell systems (Shankar et al., see this issue). All the possible isomers of 26- and 26a-hydroxy EB 1089 were synthesised and these were compared to biologically generated material using HPLC, NMR, and GC-MS techniques. The predominant natural isomer observed in vitro and in vivo in rats as well as in vitro in humans was identified to be (25S),26R-hydroxy EB 1089. The biological activities of the EB 1089 metabolites on cell growth regulation were 10- to 100-fold lower than that of EB 1089. The effects of the metabolites on calcium metabolism in vivo were comparable to the effect of EB 1089; however, these effects were reduced for the major metabolite in rat and man and for the isomers of 26a-hydroxy EB 1089. We conclude that EB 1089 is metabolised by a different route of side-chain metabolism than calcitriol and that this may explain its relative metabolic stability in pharmacokinetic experiments in vivo compared to that of other vitamin D analogs.

Animals↗

PubMed1997

A vitamin D analog, MC1288, inhibits adventitial inflammation and suppresses intimal lesions in rat aortic allografts.

Certain analogs of vitamin D have been shown to prevent autoimmune diseases and prolong cardiac allograft survival. We transplanted aortic allografts from DA rats to WF rats to investigate the effect of a synthetic vitamin D analog, MC1288, and cyclosporine (CsA), alone or in combination, on acute and chronic rejection (allograft arteriosclerosis) and the mechanism of action of MC1288. The histological changes in the vascular wall were quantitated as point score units (psu). Adventitial inflammation linked with acute rejection at 1 month after transplantation decreased from 10.0+/-0.9 psu to 4.1+/-1.0 psu (P<0.01) when MC1288, 0.1 microg/kg/every other day, and CsA, 5 mg/kg/day, were combined. Intimal thickening decreased from 2.5+/-0.3 psu to 1.1+/-0.4 psu (P<0.05) at 3 months after transplantation. Proliferation of the adventitial lymphoid cells, detected by bromodeoxyuridine labeling, decreased from 140+/-36 to 20+/-19 labeled cells/cross-section. MC1288 alone suppressed interleukin 2 receptor-expressing cells from 156 to 90 positive cells/cross-section. Taken together, MC1288 with CsA effectively suppress T cell proliferation and activation and decrease intimal thickening.

Animals↗

PubMed1997

Synergistic decrease of clonal proliferation, induction of differentiation, and apoptosis of acute promyelocytic leukemia cells after combined treatment with novel 20-epi vitamin D3 analogs and 9-cis retinoic acid.

Patients with acute promyelocytic leukemia (APL) usually relapse after all-trans retinoic acid (RA) treatment because this therapy fails to eradicate the malignant clone. Our data showed that KH 1060 and other 20-epi vitamin D3 analogs alone were potent inhibitors of clonal growth of NB4 cells, an APL cell line (ED50, approximately 5 x 10(-11) M). The combination of KH 1060 and 9-cis-RA synergistically and irreversibly enhanced this effect. Neither KH 1060 nor 9-cis-RA (10(-6) M, 3 d) were strong inducers of differentiation of NB4 cells. However, 98% of the cells underwent differentiation to a mature phenotype with features of both granulocytes and monocytes after exposure to a combination of both compounds. Apoptosis only increased after incubation of NB4 cells with 9-cis-RA alone (28%) or with a combination of 9-cis-RA plus KH1060 (32%). Immunohistochemistry showed that the bcl-2 protein decreased from nearly 100% of the wild-type NB4 cells to 2% after incubation with a combination of KH 1060 and 9-cis-RA, and the bax protein increased from 50% of wild-type NB4 cells to 92% after culture with both analogs (5 x 10(-7) M, 3 d). Western blot analysis paralleled these results. Studies of APL cells from one untreated individual paralleled our results with NB4 cells. Taken together, the data demonstrated that nearly all of the NB4 cells can be irreversibly induced to differentiate terminally when exposed to the combination of KH 1060 and 9-cis-RA.

Antigens, Differentiation↗