tei-9647 and Osteitis-Deformans

Vitamin D receptor antagonist has attracted significant level of interests because of its potential utility in the treatment of Paget's disease, which is known as the most flagrant example of disordered bone remodeling and the second most common bone disease after osteoporosis in Anglo-Saxons. Recent studies on Paget's disease suggested a specific increase in osteoclasts sensitivity to the differentiation activity of active vitamin D(3) as the principal mechanism for abnormal bone formation. We set out to conduct a structure-activity relationship study on the first VDR antagonists of TEI-9647 and TEI-9648 (25-dehydro-1alpha-hydroxyvitamin D(3)-26,23-lactone) toward improved VDR antagonistic activity. Given that both potent agonists and antagonists must have high affinity for the VDR, we hoped that our accumulated knowledge in VDR agonists would help us identify potent antagonists. First, 2alpha-modified TEI-9647 analogs were synthesized, and then, 24-substitution was next investigated to stabilize its lactone structure under the physiological conditions. Finally, 2alpha-modified 24-methyl-, 24,24-dimethyl-25-dehydro-1alpha-hydroxyvitamin D(3)-26,23-lactone analogs were synthesized. It was found that 2alpha,24,24-trimethyl-TEI-9647 was found to possess approximately 90-fold improved antagonistic activity (IC(50) 0.093 nM) over the original TEI-9647 (IC(50) 8.3 nM).

Topics: Calcitriol; Cholecalciferol; Drug Design; Lactones; Osteitis Deformans; Receptors, Calcitriol; Structure-Activity Relationship

Osteoclast (OCL) precursors from patients with Paget's disease (PD) and normal OCL precursors transduced with the measles virus nucleocapsid protein gene (MVNP) are hyperresponsive to 1alpha,25-dihydroxyvitamin D(3) [1alpha,25-(OH)(2)D(3)] and can form OCLs at physiologic concentrations of 1alpha,25-(OH)(2)D(3). This hyperresponsivity to 1alpha,25-(OH)(2)D(3) is due to increased expression of TATA box-associated factor II-17, a potential coactivator of the vitamin D receptor. Hyperresponsivity to 1alpha,25-(OH)(2)D(3) may permit OCL formation in PD patients with low levels of 1alpha,25-(OH)(2)D(3) and play a role in the pathogenesis of PD. Therefore, we tested the effects of a vitamin D antagonist, (23S)-25-dehydro-1alpha-hydroxyvitamin D(3)-26,23-lactone (TEI-9647), to determine its potential to inhibit the enhanced OCL formation and bone resorption seen in patients with PD. TEI-9647, by itself, was not a vitamin D receptor agonist and did not induce OCL formation in vitro, even at 10(-6) m. However, it dose-dependently (10(-10) m to 10(-6) m) inhibited osteoclast formation induced by concentrations of 1alpha,25-(OH)(2)D(3) (41 pg/ml, 10(-10) m) detected in PD patients by bone marrow cells of patients with PD and MVNP-transduced colony-forming unit-granulocyte macrophage (CFU-GM) cells, which form pagetic-like OCL. Moreover, bone resorption by OCLs derived from MVNP-transduced CFU-GM treated with 10(-9) m 1alpha,25-(OH)(2)D(3) was dose-dependently inhibited by TEI-9647 (10(-9) m to 10(-6) m). Furthermore, 10(-7) m TEI-9647 by itself did not cause 1alpha,25-(OH)(2)D(3)-dependent gene expression but almost completely suppressed expression of the TATA box-associated factor II-17 and 25-hydroxyvitamin D(3)-24-hydroxylase genes induced by 1alpha,25-(OH)(2)D(3) treatment of MVNP-transduced CFU-GM cells. These results demonstrate that TEI-9647 can suppress the excessive bone resorption and OCL formation seen in marrow cultures from patients with PD.

Topics: Bone Marrow Cells; Bone Resorption; Calcitriol; Cells, Cultured; Cytochrome P-450 Enzyme System; Humans; Osteitis Deformans; Osteoclasts; Receptors, Calcitriol; Steroid Hydroxylases; Transcription Factor TFIID; Vitamin D; Vitamin D3 24-Hydroxylase

(23S)-25-Dehydro-1alpha-hydroxyvitamin D(3)-26,23-lactone (TEI-9647) functions an antagonist of the 1alpha,25-dihydroxyvitamin D(3) (1alpha,25-(OH)(2)D(3)) nuclear receptor (VDR)-mediated differentiation of human leukemia (HL-60) cells [J. Biol. Chem. 274 (1999) 16392]. We examined the effect of vitamin D antagonist, TEI-9647, on osteoclast formation induced by 1alpha,25-(OH)(2)D(3) from bone marrow cells of patients with Paget's disease. TEI-9647 itself never induced osteoclast formation even at 10(-6)M, but dose-dependently (10(-10) to 10(-6)M) inhibited osteoclast formation induced by physiologic concentrations of 1alpha,25-(OH)(2)D(3) (41 pg/ml, 10(-10)M) from bone marrow cells of patients with Paget's disease. At the same time, 10(-8)M of TEI-9647 alone did not cause 1alpha,25-(OH)(2)D(3) dependent gene expression, but almost completely suppressed TAF(II)-17, a potential coactivator of VDR and 25-hydroxyvitamin D(3)-24-hydroxylase (25-OH-D(3)-24-hydroxylase) gene expression induced by 10(-10)M 1alpha,25-(OH)(2)D(3) in bone marrow cells of patients with Paget's disease. Moreover, TEI-9647 dose-dependently inhibited bone resorption induced by 10(-9)M 1alpha,25-(OH)(2)D(3) by osteoclasts produced by RANKL and M-CSF treatment of measles virus nucleocapsid gene transduced bone marrow cells. These results suggest that TEI-9647 acts directly on osteoclast precursors and osteoclasts, and that TEI-9647 may be a novel agent to suppress the excessive bone resorption and osteoclast formation in patients with Paget's disease.

Topics: Base Sequence; Bone Marrow Cells; Bone Resorption; Calcitriol; DNA Primers; Gene Expression Regulation; Humans; Osteitis Deformans; Osteoclasts; Vitamin D