Differentiating and antitumor activities of 1α,25‐dihydroxyvitamin D₃ in vitro and 1α‐hydroxyvitamin D₃ in vivo on human osteosarcoma

Abstract

The differentiating and antitumor activities of 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3) in vitro and 1 alpha-hydroxyvitamin D3 (1 alpha(OH)D3) in vivo were studied with a human osteosarcoma cell line (OST strain). Anti-tumor activity was estimated with the use of 3-(4,5-dimethylthiazol)-2, 5-diphenyltetrazolium bromide (MTT) assay, colony-forming assay, and athymic mouse assay. The intracellular alkaline phosphatase (ALP) activity of tumor cells and production of bone Gla protein (BGP) in culture media were measured to mark osteoblastic differentiation. In addition, the combination of 1 alpha,25(OH)2D3 and cis-dichlorodiammineplatinum(II) (CDDP) was tested by the colony-forming assay and the measurement of ALP activity and BGP production for differentiating and antitumor effects. The assays revealed that 1 alpha,25(OH)2D3 exerted a dose-related, growth-inhibitory influence. In the colony-forming assay, the 1 alpha,25(OH)2D3-treated colonies were smaller than the untreated colonies. The ALP activity and the BGP production also increased in relation to dose. In the assay in athymic mice, the relative weight of tumors treated with 1 alpha(OH)D3 at 2.5 nmol/kg was significantly smaller than that of the controls, and no side effects were observed in the 1 alpha(OH)D3-treated mice. Marked tumor chondrogenesis was observed in human osteosarcoma treated with 1 alpha(OH)D3 in athymic mice. The combination of 1 alpha,25(OH)2D3 at 10(-8) M and CDDP at 2 micrograms/ml significantly enhanced both the differentiation and the growth inhibition in vitro. Our study apparently is the first demonstration that vitamin D3 metabolites have an antitumor and differentiating effect on human osteosarcoma cells in vitro and in athymic mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Apoptosis Induction of POS Canine Osteosarcoma cells by Vitamin D and Retinoids

“…Osteosarcoma is one of the most malignant tumors of animals and humans, and has a high percentage of pulmonary metastasis in its early stages [18]. Canine and human osteosarcoma closely resemble each other in their histological appearance, biological behavior and pathogenesis, hence canine osteosarcoma becomes an excellent model for studying antitumor responses for human osteosarcoma [2,12].While vitamin D and retinoids have been shown to increase the rate at which transformed cells express complex patterns of gene expression, to control cell cycle that leads to differentiation, loss of proliferative capacity and loss of oncogenecity [9,15,17,19] we investigated in the present study whether vitamin D 3 and its derivatives, and the retinoids have the potential for inducing apoptosis in canine osteosarcoma using the POS osteosarcoma cell line.POS canine osteosarcoma cell line, established and characterized directly from a spontaneous osteosarcoma on a femur of a 1.5 year old male mongrel dog [8] were used for this study. These cells were maintained in RPMI-1640 containing 10% heat-inactivated fetal calf serum (FCS), HEPES (2,383 mg/ml), L-glutamine, and antibiotics penicillin (62.5 mg/ml) and streptomycin (100 mg/ml) at 37°C in a humidified atmosphere containing 95% air and 5% CO 2 .…”

“…While vitamin D and retinoids have been shown to increase the rate at which transformed cells express complex patterns of gene expression, to control cell cycle that leads to differentiation, loss of proliferative capacity and loss of oncogenecity [9,15,17,19] we investigated in the present study whether vitamin D 3 and its derivatives, and the retinoids have the potential for inducing apoptosis in canine osteosarcoma using the POS osteosarcoma cell line.…”

“…Vitamin D and retinoids acts through nuclear vitamin D receptor (VDR) and retinoid A receptor (RAR)/retinoid X receptor (RXR) respectively, resulting into a complex cascade of events leading to changes in the cell differentiation, with parallel inhibition of cell proliferation [15,19]. Although hypervitaminosis D and A causing hypercalcemia and hyperkeratosis respectively results from their long term administration in excessive amounts, this new novel vitamin D 3 analogue OCT, is more potent than calcitriol in terms of its differentiation inducing properties, antiproliferative and immunoregulatory activities, but has virtually no calcemic activity [7].…”

1, 25-Dihydroxyvitamin D₃, Recombinant Human Transforming Growth Factor-β₁, and Recombinant Human Bone Morphogenetic Protein-2 Induce In Vitro Differentiation of Canine Osteosarcoma Cells

“…POS53B, 53C, and 53D showed high ALP activity compared with POS14A. 1,25(OH)2D3 was added to the culture medium under the same conditions as described by Tsuchiya et al in which an increase in ALP activity was demonstrated in near-confluent culture [32]. The different responses in ALP activity among cell lines to 1,25(OH)2D3 may therefore be due to their maturity: immature cells with low ALP activity were stimulated and mature cells with high ALP activity were suppressed [18].…”

“…Sci. 61(6): 649-656, 1999 1,25(OH)2D3 also enhanced antitumor chemotherapy both in vitro and in vivo [32]. TGF-β1, one of the most abundant growth regulatory factors in bone matrix, has complex effects.…”