1-25(oh)2-16-ene-23-yne-d3 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 study the antineoplastic effect of vitamin D analogues in a xenograft model of human retinoblastoma.. Athymic mice were injected subcutaneously with Y79 cells and treated 5 days a week with either mineral oil (control group) or the vitamin D analogues calcitriol or 1,25-dihydroxy-16-ene-23-yne vitamin D(3) (16,23-D(3)). BrdU was injected 1 hour before death. Animals were killed after 1, 2, 3, or 5 weeks. Paraffin-embedded sections of the tumors were studied for cell proliferation by monitoring for BrdU incorporation and cell death by terminal transferase dUTP-nick end labeling (TUNEL), 3'-overhang ligation, and histology. Sections of the tumors were immunostained for p53 and p21.. There was no significant difference in incorporation of BrdU among the three groups, suggesting that cell proliferation is unaffected by vitamin D analogues. TUNEL was increased in tumors treated with vitamin D analogues compared with the control group. This increase was statistically significant for calcitriol in the time frame examined, but not statistically significant for 16,23-D(3). Alternatively, the ratio of proliferation to cell death was significantly different for both calcitriol and 16,23-D(3) compared with control tumors after 3 weeks of treatment. Dying cells contained DNA strand breaks with overhanging nucleotides and nuclear changes characteristic of apoptosis. There was an increase in staining for p53 and p21 in areas associated with cell death in specimens treated with vitamin D analogues.. Vitamin D analogues appear to attenuate retinoblastoma tumor growth in athymic mice by increasing apoptosis. Cell death is associated with the upregulation of both p53 and p21.

Topics: Animals; Antineoplastic Agents; Apoptosis; Calcitriol; Cell Division; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; DNA Replication; DNA, Neoplasm; Female; Humans; In Situ Nick-End Labeling; Mice; Mice, Nude; Neoplasm Transplantation; Retinal Neoplasms; Retinoblastoma; Transplantation, Heterologous; Tumor Suppressor Protein p53; Vitamin D

To evaluate the in vivo efficacy and toxicity of the 1,25-dihydroxy-16-ene-23-yne-vitamin D3 (16,23-D3) analogue in athymic nude mice injected with Y-79 human retinoblastoma cells and to compare the efficacy and toxicity of this compound with those of 1,25-dihydroxycholecalciferol (D3, calcitriol).. Thirty athymic nude mice (4-6 weeks old) were injected subcutaneously with 1 x 10(7) Y-79 human retinoblastoma cells suspended in a 1:1 mixture of Iscove culture medium supplemented with 20% fetal bovine serum and basement membrane matrix suspension. Five days after tumor injection, the mice were randomized to 3 groups of 10 mice each. The first group served as a control group and received intraperitoneal injections of 0.25 mL of mineral oil (vehicle) 5 times a week. The second group received intraperitoneal injections of 0.05 microg of calcitriol in 0.25 mL of mineral oil intraperitoneally 5 times a week. The third group received intraperitoneal injections of 0.5 microg of 16,23-D3 in 0.25 mL of mineral oil 5 times a week. Injections were continued for 5 weeks, during which tumor size and mouse weight were individually measured. Toxicity was assessed by clinical measures such as lethargy, weight loss, and death. The mice were then killed and the size, volume, and weight of each tumor were determined. Also, in representative animals in each group, kidneys were evaluated for calcification and serum calcium concentration was measured.. All experimental and control animals developed tumors subcutaneously. The 16,23-D3-treated mice had significantly smaller average tumor size (1.55 cm3) than the control mice (3.45 cm3) (P = .02), less gain in average body weight from the beginning of treatment (2.4 g vs 5.5 g) (P= .06), and a 40% mortality. The calcitriol-treated mice did not have significantly smaller average tumor size (1.26 cm3) than the 16,23-D3-treated mice (P = .35), had significant body weight loss compared with the control animals (calcitriol-treated mice lost 4.03 g) (P =.001), and had a mortality of 90% by the completion of the experiment. Histologically, there was no difference in the degree of tumor necrosis and calcification between control and experimental mice. Serum calcium concentrations were equivalent between the control (2.15 mmol/L [8.6 mg/dL]) and experimental groups (calcitriol, 1.88 mmol/L [7.5 mg/dL] [P = .97]; 16,23-D3, 2.15 mmol/L [8.6 mg/dL] [P = .42]). Mild bilateral renal tubular calcification occurred in 3 of 4 mice in the calcitriol-treated group and in 2 of 4 mice in the 16,23-D3-treated group.. The growth of subcutaneous Y-79 human retinoblastoma cells in athymic nude mice is significantly reduced by treatment with intraperitoneal injections of 16,23-D3. The antineoplastic effect of calcitriol is not statistically significantly different but is associated with significantly more toxicity. 1,25-Dihydroxy-16-ene-23-yne-vitamin D3 may be a useful chemotherapeutic adjunct in the treatment of retinoblastoma.

Topics: Animals; Antineoplastic Agents; Calcitriol; Calcium; Female; Injections, Intraperitoneal; Kidney; Kidney Calculi; Male; Mice; Mice, Nude; Neoplasm Transplantation; Random Allocation; Retinal Neoplasms; Retinoblastoma; Tumor Cells, Cultured

The vitamin D3 analogue 1,25-(OH)2-16-ene-23-yne vitamin D3 (16,23-D3) in doses with low systemic toxicity has been demonstrated to inhibit retinoblastoma growth in transgenic mice. This study examines the dose-dependent response for inhibition of tumor growth in transgenic mice with retinoblastoma and evaluates the in vivo toxicity of 16,23-D3 in nontransgenic mice. Transgenic 8-10-week-old mice with retinoblastoma (n = 119) were randomly assigned to groups receiving 1.0, 0.75, 0.5, 0.35, 0.2, or 0.05 microg of 16,23-D3 and a vehicle alone (control) group i.p. five times a week for 5 weeks. An additional control group received no injection. Eyes were enucleated one week after the end of treatment, and tumor areas were measured. To determine the toxic dose, transgene-negative littermates received 0.5, 1.0, 1.5, 2.5, 3.5, 4.5, or 5.0 microg of 16,23-D3, and control groups received vehicle alone, 5 days a week for 5 weeks. Serum calcium levels were measured, and necropsies were performed on animals from each group. In the dose-response study, tumor growth inhibition was greatest in the group receiving 0.35 microg (55% inhibition; P = 0.0056) and was also significant in the group receiving 0.5 microg (42% inhibition; P = 0.036). The systemic toxic effects due to hypercalcemia occurred at doses of > or =1.0 microg. 16,23-D3 inhibits tumor growth at doses > or =0.35 microg and shows toxic effects at doses > or =1.0 microg related to hypercalcemia in mice fed an unrestricted diet. No toxicity was observed with lower doses.

Topics: Animals; Calcitriol; Calcium; Dose-Response Relationship, Drug; Female; Male; Mice; Mice, Nude; Mice, Transgenic; Retinoblastoma

To evaluate the in vivo efficacy and clinical toxic effects of the 1,25-dihydroxy-16-ene-23-yne-vitamin D3 analogue in beta-luteinizing hormone-Tag (LH beta-Tag) transgenic mice with heritable retinoblastoma.. Forty-two mice (8-10 weeks old), randomly assigned to experimental (n = 21) or control (n = 21) groups, received intraperitoneal injections of 0.05 microgram of 1,25-dihydroxy-16-ene-23-yne-D3 in 0.5-mL mineral oil vehicle (experimental group) or 0.5 mL of mineral oil vehicle (control group) for 5 weeks. One experimental and 3 control animals died of injection-related trauma. Eyes were enucleated 1 week after treatment and were examined histologically in a masked fashion.. All experimental and control animals showed evidence of tumor. The tumors in the experimental mice showed a significantly smaller cross-sectional area (0.88 +/- 0.08 mm2) compared with that in the control mice (1.12 +/- 0.12 mm2) (P = .02). All mice completed the treatment and showed no clinical evidence of toxic effects.. Tumors in transgenic mice with retinoblastoma treated with 1,25(OH)2-16-ene-23-yne-D3 showed a 21% smaller cross-sectional area compared with that in the control mice, without producing clinically apparent toxic effects. This compound may be useful as adjunctive therapy in the treatment of retinoblastoma.

Topics: Animals; Antineoplastic Agents; Calcitriol; Disease Models, Animal; Eye Neoplasms; Female; Injections, Intraperitoneal; Luteinizing Hormone; Male; Mice; Mice, Inbred ICR; Mice, Transgenic; Retinoblastoma; Transcriptional Activation