vitamin-d-2 and Retinoblastoma

To investigate the effectiveness of the vitamin D analogues 1,25-(OH)(2)-16-ene-23-yne vitamin D(3) (16,23-D(3)) and 1alpha-hydroxyvitamin D(2) (1alpha-OH-D(2)) in inhibiting retinoblastoma growth in large tumors in a xenograft model and with prolonged use in a transgenic model.. For the large-tumor study, the xenograft athymic mouse/human retinoblastoma cell (Y-79) model was used. Subcutaneous tumors were allowed to grow to an average volume of 1600 mm(3). Systemic treatment with 1 of the vitamin D analogues or with vehicle (control groups) was carried out for 5 weeks. For the long-term study, transgenic beta-luteinizing hormone-large T antigen (LHbeta-Tag) mice were systemically treated with 1 of the 2 compounds or vehicle (control groups) for up to 15 weeks. Tumor size and signs of toxicity were assessed.. In the large-tumor study, tumor volume ratios for the 1alpha-OH-D(2) and 16,23-D(3) groups were significantly lower than those for controls (P<.002). No significant differences in tumor volume were seen between the 1alpha-OH-D(2) and 16,23-D(3) groups (P =.15). In the long-term study, the 1alpha-OH-D(2) group showed significantly smaller tumor size compared with its control (P<.001). No significant difference was seen between the 16,23-D(3) group and its control. Some toxic effects related to hypercalcemia were seen in both studies.. In athymic mice in the large-tumor study, both 1alpha-OH-D(2) and 16,23-D(3) were effective in inhibiting tumor growth compared with controls. In the long-term study, 1alpha-OH-D(2) inhibited tumor growth but 16,23-D(3) did not. Effective doses of both compounds caused hypercalcemia and a significant increase in mortality. Clinical Relevance Use of 1alpha-OH-D(2) inhibited tumor growth in large tumors and with long-term treatment compared with controls. Because of hypercalcemia-related toxic effects seen in the present experiments, in clinical trials, serum calcium levels should be carefully monitored. This analogue may require use with drugs that lower serum calcium levels or use of relatively lower doses or skipped doses. The ideal alternative solution would be to identify vitamin D analogues that retain the antineoplastic action without the calcemic activity.

Topics: Animals; Antineoplastic Agents; Calcitriol; Disease Models, Animal; Ergocalciferols; Hypercalcemia; Mice; Mice, Nude; Mice, Transgenic; Retinal Neoplasms; Retinoblastoma; Survival Rate; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

To determine the effectiveness of a vitamin D analog, 1alpha-hydroxyvitamin D(2) (1alpha-OH-D(2)), in inhibiting retinoblastoma in a transgenic retinoblastoma model (LHbeta-Tag mouse) and to evaluate its toxicity.. Experimental study using an animal (LHbeta-Tag transgenic mouse) randomized (controlled) trial.. Two hundred seventeen LHbeta-Tag transgene-positive 8- to 10-week-old mice total; 179 drug-treated animals, 38 control animals.. Mice were fed a vitamin D- and calcium-restricted diet and were randomized to treatment groups receiving control (vehicle), or 0.1, 0.3, 0.5, or 1.0 micro g/day of 1alpha-OH-D(2) via oral gavage 5 times weekly for 5 weeks. Body weight was measured at the start of treatment and twice weekly during treatment. Animals were euthanized on the last day of treatment. The eyes were enucleated, processed histologically, and serially sectioned. Representative sections from the superior, middle, and inferior regions of each globe were examined microscopically and tumor areas were measured using Optimas software. Serum was collected for serum calcium levels. Kidneys were removed for histologic processing and were analyzed microscopically for kidney calcification.. Mean tumor area was measured to determine drug effectiveness. Toxicity was assessed by survival, weight loss over the treatment period, serum calcium, and kidney calcification.. The mean tumor size in each 1alpha-OH-D(2) group was smaller than controls (all P values < 0.02): control, 90,248 micro m(2); 0.1 micro g, 31,545 micro m(2); 0.3 micro g, 16,750 micro m(2); 0.5 micro g, 30,245 micro m(2); and 1.0 micro g, 16,049 micro m(2). No dose-dependent response curve was evident. The survival percentage for each group was as follows: control, 97%; 0.1 micro g, 91%; 0.3 micro g, 88%; 0.5 micro g, 70%; and 1.0 micro g, 63%. Mortality was higher in the 0.5- micro g and 1.0- micro g doses (P values < 0.01) compared with other treatment groups and with the control group. Serum calcium levels were significant in all treatment groups compared with controls (all P values < 0.0001).. In the LHbeta-Tag mouse, 1alpha-OH-D(2) inhibits retinoblastoma with no significant increase in mortality in lower doses (0.1-0.3 micro g). 1alpha-OH-D(2) has approval by the Food and Drug Administration as an investigative drug for cancer treatment, and has shown efficacy with low toxicity in adult cancer trials. 1alpha-OH-D(2) meets the criteria for human clinical trials.

Topics: Animals; Calcinosis; Calcium; Disease Models, Animal; Dose-Response Relationship, Drug; Ergocalciferols; Kidney; Luteinizing Hormone, beta Subunit; Mice; Mice, Transgenic; Retinal Neoplasms; Retinoblastoma; Survival Rate; Transgenes

This lecture honors the memory of Dr. Robert M. Ellsworth, an important figure in the development of current treatments of retinoblastoma (RB), and reviews our studies of vitamin D analogs as treatments for retinoblastoma in two experimental mouse models. We identified vitamin D receptors in retinoblastoma and examined the effectiveness and mechanism of action of these analogs.. Reverse-transcriptase polymerase chain reaction (RT-PCR) amplification was used to detect vitamin D receptor mRNAs in human and mouse retinoblastomas. The effectiveness and toxicity of vitamin D(2), calcitriol, and synthetic analogs were studied in the athymic/Y-79 xenograft and transgenic mouse models of RB. Dosing was 5X/week for five weeks. Dose-response studies focused on tumor inhibition; toxicity studies investigated survival and serum calcium. The mechanism of action of vitamin D was investigated using terminal transferase dUTP labeling 3'-overhang ligation to measure apoptosis; immunohistochemistry measured p53-dependent gene expression and cell proliferation.. Vitamin D receptor mRNAs were detectable in Y-79 RB cells, LH beta-Tag tumors, and human RB specimens using RT-PCR. Calcitriol inhibited cell growth in vitro. Calcitriol and vitamin D(2) inhibited in vivo growth in xenograft and transgenic models, but therapeutic levels were toxic due to hypercalcemia. Two analogs, 16,23-D(3) and 1 alpha-OH-D( 2), inhibited tumors in animal models of RB with reduced toxicity. The mechanism of action appears related to increased p53-related gene expression resulting in increased apoptosis.. 16,23-D(3) and 1 alpha-OH-D(2) are effective in tumor reduction in two mouse models of RB with low toxicity. These results warrant initiating phase 1 and phase 2 clinical studies in children.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Calcitriol; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Disease Models, Animal; DNA Primers; Ergocalciferols; Humans; Immunoenzyme Techniques; Ki-67 Antigen; Mice; Mice, Nude; Mice, Transgenic; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Receptors, Calcitriol; Retinal Neoplasms; Retinoblastoma; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tumor Cells, Cultured; Tumor Suppressor Protein p53

The study objective is to determine the effectiveness of a vitamin D analogue, 1 alpha-hydroxyvitamin D2 (1 alpha-OH-D2), in inhibiting retinoblastoma in a transgenic retinoblastoma model (LH beta-Tag mouse) and to evaluate its toxicity. Previous studies of 1 alpha-OH-D2 in athymic mice with human retinoblastoma xenografts suggested efficacy in tumor suppression and suitability for human treatment.. LH beta-Tag mice (N = 142), 8 to 10 weeks old, were randomly assigned to treatment groups receiving either control (vehicle) or 0.1, 0.3, 0.5, or 1.0 microgram/day of 1 alpha-OH-D2 via oral gavage five times a week for 5 weeks. Animals were then euthanized. The eyes were enucleated, processed histologically, and serially sectioned. Three sections of each eye were microscopically examined, and mean tumor area was measured using Optimus software. Toxicity was assessed by mortality, weight loss, serum calcium levels, and kidney calcification.. The mean tumor size in each 1 alpha-OH-D2 group was smaller than in controls (P values < .02): control, 90,248 microns 2; 0.1 microgram, 31,545 microns 2; 0.3 microgram, 16,750 microns 2; 0.5 microgram, 30,245 microns 2; and 1.0 microgram, 16,049 microns 2. No dose-dependent response curve was evident. Mortality was higher in the groups receiving the 0.5 microgram and 1.0 microgram doses (P values < .01) than in the other treatment groups and the control group.. In the LH beta-Tag mouse, 1 alpha-OH-D2 inhibits retinoblastoma with no increased mortality at lower doses (0.1 to 0.3 microgram). 1 alpha-OH-D2 has been approved by the Food and Drug Administration as an investigative drug for cancer treatment and has shown efficacy with low levels of toxicity in adult cancer trials. 1 alpha-OH-D2 meets the criteria for human clinical trials.

Topics: Animals; Calcium; Disease Models, Animal; Dose-Response Relationship, Drug; Ergocalciferols; Mice; Mice, Transgenic; Retinal Neoplasms; Retinoblastoma

Although calcitriol (1,25-dihydroxycholecalciferol) and vitamin D(2) inhibit retinoblastoma growth in the athymic (nude) mouse xenograft (Y-79 cell line) model of retinoblastoma, they can cause severe toxicity.. To examine the toxicity of and dose-dependent response for the inhibition of tumor growth for 1alpha-hydroxyvitamin D(2) (1alpha-OH-D(2)), an analogue with reduced systemic toxicity, in the athymic Y-79 mouse model.. Mice were randomized into treatment and control groups for 5-week toxicity and dose-response studies. Treatment was via oral gavage 5 times per week. Dose-response studies measured tumor inhibition and drug serum levels. Tumor size and body weight were measured weekly together with various criteria for toxicity. Animals were euthanized at the end of the treatment period. Tumors and kidneys were harvested, and serum was analyzed for calcium and drug levels.. Doses of 0.1 to 1.2 microg/d were selected on the basis of toxicity studies for the dose-response trial. Tumor weight and volume in the 0.2-microg and 0.3-microg doses were significantly lower than in controls. Mortality rates and kidney calcification in mice treated with doses of 0.1 to 0.3 microg were lower than those observed in studies of calcitriol and vitamin D(2).. A vitamin D analogue, 1alpha-OH-D(2), inhibits tumor growth in this xenograft model of retinoblastoma with less toxicity than calcitriol and vitamin D(2).

Topics: Animals; Disease Models, Animal; Dose-Response Relationship, Drug; Ergocalciferols; Humans; Kidney; Mice; Mice, Nude; Random Allocation; Retinal Neoplasms; Retinoblastoma; Transplantation, Heterologous

The vitamin D receptor has been found in several human organs not involved in calcium metabolism and in several malignant neoplasms found in humans. The role of the receptor in these tissues is unclear. There is, however, a relationship between the presence and quantity of the vitamin D receptor in a malignant cell line and the antineoplastic effect of vitamin D on that cell line. We found that Y-79 retinoblastoma cells have receptors specific for calcitriol (1,25-dihydroxycholecalciferol). Scatchard analysis of the receptor data shows a quantity of 56,000 receptors per retinoblastoma cell. These receptors have a dissociation constant of 1.18 nmol/L. Retinoblastoma cells treated with 10(-9) mol/L of calcitriol for nine days had 15% less cell growth than the control cells. Further studies of the effect of vitamin D on retinoblastoma may warrant its inclusion in chemotherapeutic protocols for the treatment of this childhood affliction.

Topics: Calcitriol; Cell Division; Dose-Response Relationship, Drug; Ergocalciferols; Eye Neoplasms; Osmolar Concentration; Receptors, Calcitriol; Receptors, Steroid; Retinoblastoma; Tumor Cells, Cultured

In 1966, Verhoeff suggested that retinoblastomas might be sensitive to vitamin D because they sometimes undergo calcification and spontaneous regression. In recent years, the antineoplastic effect of vitamin D has been established in vitro and in vivo. This study presents evidence that vitamin D2 inhibits the growth of the human retinoblastoma cell line (Y-79) grown in athymic mice. In mice treated with ergocalciferol, the subcutaneous retinoblastomas were smaller and showed increased tumor necrosis and calcification. Unfortunately, the vitamin D caused significant toxic reactions. Further studies that reduce the toxicity of vitamin D will be needed before its use in children with retinoblastomas can be advocated. To our knowledge, this is the first demonstration of the activity of ergocalciferol against a tumor in vivo and it suggests that ergocalciferol or one of its derivatives may be an effective chemotherapeutic agent against retinoblastomas in humans.

Topics: Animals; Calcinosis; Calcium; Cell Line; Dose-Response Relationship, Drug; Ergocalciferols; Eye Neoplasms; Necrosis; Neoplasm Transplantation; Retinoblastoma; Skin Neoplasms; Vitamin D