1-alpha-24-dihydroxyvitamin-d3 and 1-25-dihydroxyergocalciferol

This study was aimed to determine whether hypocalcemic analogs of active forms of vitamins D modulate expression of genes related to stem-like phenotype in colon cancer cell lines HT-29 and HCT-116 undergoing renewal after the treatment with 5-fluorouracil (5-FU). Both lines express vitamin D receptor, but differ in differentiation stage and vitamin D sensitivity. Cells that resisted the 5-FU exposure were treated with synthetic analog of 1,25-dihydroxyvitamin D2 (PRI-1906) and analogs of 1,25-dihydroxyvitamin D3 (PRI-2191 and PRI-2205). Proliferative activity was more profoundly affected by vitamin D analogs in HT-29/5-FU than in HCT-116/5-FU cells. In HT-29/5-FU cells, analogs PRI-1906 and PRI-2191 downregulated the expression of genes related to survival, re-growth, and invasiveness during renewal, while PRI-2205 increased expression of genes related to differentiation only. In HCT-116/5-FU cells, PRI-2191 decreased the expression of stemness- and angiogenesis-related genes, whereas PRI-1906 augmented their expression. The effects in HCT-116/5-FU cells were observed at higher concentrations of the analogs than those used for HT-29/5-FU cells. Out of the series of analogs studied, PRI-2191 might be used to counteract the renewal of both moderately and poorly differentiated cancer cells following conventional treatment.

Topics: Antimetabolites, Antineoplastic; Calcitriol; Cell Self Renewal; Cell Survival; Colonic Neoplasms; Dihydroxycholecalciferols; Drug Resistance, Neoplasm; Drug Synergism; Epithelial-Mesenchymal Transition; Ergocalciferols; Fluorouracil; Gene Expression; HCT116 Cells; HT29 Cells; Humans; Neoplastic Stem Cells; Neovascularization, Pathologic

Active and less toxic vitamin D analogs could be useful for clinical applications. In the present study, we evaluated the toxicity and antitumor effect of two new synthetic analogs of vitamin D, namely PRI-1906 [(24E)-24a-Homo-(1S)-1,25-dihydroxyergocalciferol] and its side-chain unsaturated homo analog PRI-1907.. The toxicity and calcemic activity, as well as antitumor effect of calcitriol analogs was investigated in vivo. The studies were performed in a mouse mammary 16/C cancer model. Since calcitriol and its analogs inhibited 16/C tumor growth only slightly, we applied them in the combined therapy with cyclophosphamide (CY). Moreover, cell cycle analysis and VDR and p27 expression were investigated.. The LD50 values after five daily subcutaneous (s.c.) injections were 7.8, 10.0 and 2.4 microg/kg per day for calcitriol, PRI-1906 and PRI-1907, respectively. The serum calcium level increased to 40, 23 and 63% over the control for these compounds. We also compare the antitumor activity of the PRI-1906 with the calcitriol and previously studied PRI-2191 (1,24-dihydroxyvitamin D3, tacalcitol). Statistically significant inhibition of tumor growth by calcitriol up to the eighth day was observed in all schedules applied. PRI-1906 inhibited the tumor growth at doses 1 and 5 microg/kg per day, and PRI-2191 only at the dose 5 microg/kg per day.. Addition of vitamin D analogs increased the antitumor effect of CY. PRI-1906 exhibited toxicity higher than PRI-2191 but lower than calcitriol and antitumor activity similar to both PRI-2191 and calcitriol. This new analog seems to be a good candidate for the combined treatment of mammary cancer.

Topics: Animals; Antineoplastic Agents, Alkylating; Antineoplastic Combined Chemotherapy Protocols; Body Weight; Calcitriol; Calcium; Cell Cycle; Cyclophosphamide; Dihydroxycholecalciferols; Ergocalciferols; Female; Lethal Dose 50; Male; Mammary Neoplasms, Animal; Mice; Mice, Inbred C3H; Mice, Inbred DBA; Vitamins

New vitamin D analogs are interesting candidates for anticancer treatment, including squamous cell carcinomas (SCCs), especially in combination with cytostatics. In order to evaluate the effect of combined application of cisplatin, imatinib, or docetaxel and new vitamin D analogs [PRI-1906: (24E)-24a-homo-(1S)-1,25-dihydroxyergocalciferol, and PRI-2191: (24R)-1,24-dihydroxyvitamin D3], against the cells of two human SCCs lines (SCC-25 and FaDu), cytotoxic activity and the effect on cell cycle and apoptosis were determined. The synergistic or additive antiproliferative effect was observed for all cytostatics used after treatment of FaDu cell line with calcitriol or its analogs. Antagonism caused by combination of calcitriol and docetaxel was shown only in the lowest dose. FaDu cells treated with cytostatics and vitamin D analogs cumulated in G0/G1 stage. A statistically significant decrease (2x) in the percentage of apoptotic cells was observed only in combination of imatinib and calcitriol or PRI-1906. On the other hand, when the SCC-25 cell line incubated with cisplatin and imatinib in combination with calcitriol or PRI-2191 (100 nM) was used, the quantitative method of Chou and Talalay indicated antagonism. In the lower doses of calcitriol or PRI-2191 combined with imatinib, the synergistic effect was observed, but in the case of combination with cisplatin or docetaxel only weak additivity was detected. Moreover, a significant decrease (2x) of the percentage of SCC-25 cells undergoing apoptosis induced by docetaxel, cisplatin, and imatinib was observed. The combination of all cytostatic drugs applied with PRI-1906 in all doses caused synergism or additivity. These results might indicate that PRI-1906 is more effective than calcitriol or PRI-2191 as a potential anticancer agent, when used in combination therapy with cytostatic agents. To our knowledge, this is the first observation of interaction with calcitriol or its analogs and imatinib.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzamides; Calcitriol; Carcinoma, Squamous Cell; Cell Cycle; Cell Line, Tumor; Cisplatin; Dihydroxycholecalciferols; Docetaxel; Dose-Response Relationship, Drug; Drug Synergism; Ergocalciferols; G1 Phase; Head and Neck Neoplasms; Humans; Imatinib Mesylate; Piperazines; Pyrimidines; Resting Phase, Cell Cycle; Taxoids

A lipid indistinguishable from 1,24(R)-dihydroxyvitamin D3 [1,24(R)-(OH)2D3] was found in serum and tumor extracts from a hypercalcemic patient with a small cell carcinoma of the lung. The lipid comigrated with authentic 1,24(R)-(OH)2D3 on high performance liquid chromatography using both straight and reverse phase columns and competed with tritiated 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3)] for binding to intestinal 1,25-(OH)2D3 receptor. Increasing doses of the lipid factor from tumor and authentic 1,24(R)-(OH)2D3 gave parallel responses in a bone resorption assay, as assessed by 45Ca release from prelabeled mouse calvaria. The lipid factor from the patient's serum and authentic 1,24(R)-(OH)2D3 had identical biological activities in the receptor binding and bone resorption assays. In addition, the mechanisms of action of this lipid factor and 1,24(R)-(OH)2D3 were indistinguishable. Bone resorption by both was inhibited by calcitonin, and neither the lipid factor nor authentic 1,24(R)-(OH)2D3 affected cAMP content in osteoblast-like bone cells derived from mouse calvaria. The estimated concentrations of the 1,24(R)-(OH)2D3-like lipid, expressed as 1,24(R)-(OH)2D3 were 11 ng/g tumor wet wt by the receptor binding assay and 9.2 ng/g tumor wet wt by the bone resorption assay. The mean serum concentration was 1.4 +/- 0.3 (+/- SD) ng/ml (n = 3) by the receptor binding assay. No activity was detected in either bioassay when extracts of nontumor tissues from this patient or tumor extracts and sera from one hypercalcemic and four normocalcemic cancer patients were tested. The mean serum 1,25-(OH)2D level was low (6.4 +/- 0.5 pg/ml; n = 2), and serum 1,24(R),25-(OH)3D in this patient was high (103 pg/ml) compared to normocalcemic cancer patients, in whom the mean serum 1,25-(OH)2D level was 27 +/- 12 pg/ml (n = 4) and the 1,24(R),25(OH)3D level was 28 +/- 1.3 pg/ml (n = 4). Thus, the 1,24(R)-(OH)2D3-like lipid may be a substrate for metabolic conversion to 1,24(R),25-(OH)3D in vivo. These results provide evidence for the presence of a novel metabolite of vitamin D3, 1,24(R)-(OH)2D3. Detection of this bone-resorbing lipid in both tumor and serum suggests, but does not prove, that the tumor secreted this bioactive lipid into the circulation and that the high level of circulating bone-resorbing lipid was related to the hypercalcemia in this patient.

Topics: Animals; Bone and Bones; Bone Resorption; Calcium; Carcinoma, Small Cell; Chromatography, High Pressure Liquid; Cyclic AMP; Dihydroxycholecalciferols; Ergocalciferols; Humans; Hypercalcemia; In Vitro Techniques; Lipids; Lung Neoplasms; Male; Mice; Middle Aged; Paraneoplastic Endocrine Syndromes; Radioligand Assay