A novel nonsecosteroidal VDR agonist (CH5036249) exhibits efficacy in a spontaneous benign prostatic hyperplasia beagle model.

To date, there have been no reports showing the efficacy of nonsecosteroidal vitamin D receptor (VDR) agonists in a benign prostatic hyperplasia (BPH) animal model. To examine the efficacy of CH5036249, a novel nonsecosteroidal VDR agonist, we orally administered the compound at 0.03 microg/kg to a beagle model with spontaneous BPH. Prostate volume was checked by rectal ultrasonic probe periodically during 11 months of administration and the prostate tissues histologically examined. CH5036249 inhibited prostate growth in two out of three dogs compared with vehicle-treated dogs. In the prostate specimens, substantial atrophy of the epithelium was observed in all dogs administered CH5036249. At the dose given, serum calcium levels slightly increased in the CH5036249-treated dogs but stayed within a normal range. We next examined the cell growth inhibition of CH5036249 using human prostate stromal cells and found the cell growth inhibitory activity of CH5036249 to be comparable to that of 1alpha,25(OH)2D3. The bioavailability from oral administration in rats was 95.1% with a t1/2 of 17.6 h. Both micro-AMES and micronucleus tests were negative. Although the results are still preliminary, we consider the novel nonsecosteroidal VDR agonist CH5036249 to be a possible new drug candidate for the treatment of BPH in humans.

Long-term production of erythropoietin after electroporation-mediated transfer of plasmid DNA into the muscles of normal and uremic rats.

The anemia associated with chronic renal failure is one of the best target diseases for erythropoietin (Epo) gene transfer. We previously reported a short-term (1 month) study of continuous rat Epo delivery by muscle-targeted gene transfer of plasmid DNA expressing rat Epo (pCAGGS-Epo) using in vivo electroporation in normal rats. Here, we performed a long-term pharmacokinetic study of continuous Epo delivery by this method in normal rats and uremic five-sixths nephrectomized rats. In normal rats, Epo gene expression and sufficient erythropoiesis occurred with Epo gene transfer in a dose-dependent manner, and persisted for at least 11 weeks. Repeated administration of the plasmid DNA effectively produced erythropoiesis. Similar erythropoiesis was observed in the uremic rats, and persisted for more than 15 weeks. Both normal and uremic rats showed a significant decrease in platelet count. Moreover, the uremic rats showed Epo-induced hypertension, which is the major side-effect of recombinant human Epo. These results demonstrate that muscle-targeted pCAGGS-Epo transfer by in vivo electroporation is a useful procedure for the long-term continuous delivery of Epo in both normal and uremic rats.

Synthesis and pharmacokinetics of 1 alpha-hydroxyvitamin D3 tritiated at 22 and 23 positions showing high specific radioactivity.

A novel synthesis of a radioactive compound of 1 alpha-hydroxyvitamin D3 (1 alpha OHD3) (1) and its pharmacokinetics are described. Radioactive 1 alpha OHD3 tritiated at 22 and 23 positions ([22,23-(3)H4]1 alpha OHD3) (5) was prepared via key reactions of the reduction of acetylenic side chain in the ketone (12) with tritium gas in the presence of palladium-charcoal and the subsequent Wittig reaction with the A-ring synthon (16). [22,23-(3)H4]1 alpha OHD3 (5) showed high specific radioactivity (111.5 Ci/mmol) and was used successfully in pharmacokinetics studies with rats. In the pharmacokinetics studies, the plasma concentration level of the active form of vitamin D3, 1 alpha,25-dihydroxy-vitamin D3 [1 alpha,25(OH)2D3], after oral or intravenous administration of [22,23-(3)H4]1 alpha OHD3 (5), showed longer half-life, lower maximum concentration, and lower area under the curve than those after treatment of 1 alpha,25(OH)2D3 tritiated at 26 and 27 positions (4). These results might suggest a beneficial therapeutic utility of 1 alpha OHD3 (1) over the treatment of 1 alpha,25(OH)2D3 (2).

1Alpha-hydroxyvitamin D3 prevents the decrease of bone mineral density in lactating beagles.

We assessed the change of bone mineral density (BMD) in lactating beagles with dual energy X-ray absorptiometry (DXA) and the preventive effect of 1alpha-hydroxyvitamin D3 (1alpha(OH)D3) on the BMD. Beagles, two to five years old, were used for detecting the time course change of BMD. Since the coefficient of variation (CV(%)) on detecting lumber vertebral (L2-L4) and tibial BMD by DXA was about 0.5%, DXA was useful to detect the change of BMD in beagles. There was a marked decrease in vertebral BMD during lactational period in the control group. The BMD levels after weaning were found to reverse to the initial level at mating. The same tendency was observed in tibial BMD as vertebral BMD, though the BMD changes were not marked. Beagles were administered at a dose of 0.1 microg/kg of 1alpha(OH)D3 three times in a week, and it was found to suppress the decrease in vertebral BMD during the breast feeding period. Also, the administration of 1alpha(OH)D3 promoted the prevention of decreased BMD during lactation both in vertebrae and tibiae. Significant effects of 1alpha(OH)D3 administration on tibial BMD were not observed. No adverse effects, such as hypercalcemia and hypercalciuria, were observed during the experimental period. Therefore, DXA was useful for detecting the changes of BMD in lactating beagles and the change of BMD was marked in lumber vertebrae, which are rich in trabecular bone. The preventive effect of 1alpha(OH)D3 on the decrease of BMD during the lactation period was observed in beagles.

Association of an (A-C)n dinucleotide repeat polymorphic marker at the 5'-region of the aldose reductase gene with retinopathy but not with nephropathy or neuropathy in Japanese patients with Type 2 diabetes mellitus.

AIMS: Recently an (A-C)n dinucleotide repeat polymorphic marker in the 5'-region of the ALR2 gene encoding aldose reductase was found to be associated with diabetic retinopathy in the Chinese population in Hong Kong, and with nephropathy and neuropathy in the British Caucasian population. The present study assessed the association between the polymorphism and microvascular complications in Japanese patients with Type 2 diabetes mellitus. METHODS: DNA from 87 Japanese patients with Type 2 diabetes mellitus and 90 control subjects with normal glucose tolerance were typed for the polymorphic marker by polymerase chain reaction and direct sequencing. RESULTS: Six alleles, namely Z-12, Z-6, Z-4, Z-2, Z, and Z+2 were identified. There was no significant difference in allele distribution between diabetic patients and controls. The Z-2 allele frequency was significantly higher in subjects with diabetic retinopathy than those without retinopathy (0.35 vs. 0.20, P=0.039), suggesting that aldose reductase is involved in the development of diabetic retinopathy. In contrast, the microsatellite marker was not associated with diabetic nephropathy, peripheral or autonomic neuropathy. The discrepancy may be partly attributable to the low frequency of Z+2 allele in the Japanese subjects. CONCLUSIONS: The (A-C)n dinucleotide repeat polymorphism may be a useful genetic marker to screen for patients at high risk of retinopathy.

Polymorphism in the 5'-leader cistron of the beta2-adrenergic receptor gene associated with obesity and type 2 diabetes.

We screened the 5'-untranslated region of the beta2-adrenergic receptor gene from 40 obese subjects by the PCR-direct sequencing technique. Two polymorphic sites were identified; a T-->C substitution at -47 and a T-->C substitution at -20. We further analyzed the association of the polymorphisms with obesity in 574 subjects by PCR and restriction digestion. The substitution at -47 was in tight linkage disequilibrium with that at -20. The polymorphisms were also in linkage disequilibrium with codon 16 and codon 27 polymorphisms. Subjects carrying the -47C/-20C allele had greater body mass index (25.5+/-4.5 vs. 24.4+/-4.1 kg/m2, p=0.007) and higher serum triglyceride levels (166+/-160 vs. 139+/-95 mg/dl, p=0.015) than -47T/-20T homozygotes. The variant allele frequency was significantly higher in obese subjects than in non-obese subjects (0.18 vs. 0.11, p=0.0026). Furthermore, an increased frequency of the variant allele was shown in diabetic patients compared with non-diabetic subjects (0.19 vs. 0.11, p=0.0005). The association may be attributable to the greater proportion of diabetic patients in the obese group. The exchange at -47 may alter the expression level of the beta2-adrenergic receptor gene, because the nucleotide substitution at -47 results in a Cys-->Arg exchange at the C terminal of the leader peptide. The -47C/-20C allele may be associated with genetic predisposition to obesity and obesity-related metabolic disorders.

Essential role of caspase-3 in apoptosis of mouse beta-cells transfected with human Fas.

Several recent studies have indicated that the Fas-Fas ligand system may be critical for pancreatic beta-cell destruction in type 1 diabetes. Although the fundamental roles of caspases in the mammalian apoptotic machinery have been elucidated, it is not known which caspase or caspases play a major role in Fas-mediated apoptosis of beta-cells. In this study, we transfected human Fas cDNA into a mouse beta-cell line (betaTC1) and established a beta-cell clone expressing human Fas. This clone, designated hFas/betaTC1, underwent apoptosis when exposed to anti-Fas, showing hallmarks of apoptosis (chromatin condensation, nucleolar disintegration, internucleosomal DNA fragmentation, and annexin V staining), indicating that the mouse beta-cell line has the intact machinery of Fas-mediated apoptosis. The cross-linking of Fas by anti-Fas resulted in the elevation of caspase-3-like, but not caspase-1-like, protease activity 2-12 h after the addition of the anti-Fas. A caspase-3 inhibitor, Z-Asp-Glu-Val-Asp-fluoromethyl ketone, attenuated the Fas-mediated beta-cell apoptosis, while a caspase-1 inhibitor, acetyl-Tyr-Val-Ala-Asp-chloromethylketone, failed to suppress the apoptosis. Thus the Fas-induced death signal apparently bypassed caspase-1 in the cells. Furthermore, an antisense caspase-3 construct blocked caspase-3 activation and substantially suppressed Fas-triggered apoptosis of hFas/betaTC1 cells. These observations suggest the essential role of caspase-3 in Fas-mediated apoptosis of the beta-cell line.

Association of polymorphisms in the beta2-adrenergic receptor gene with obesity, hypertriglyceridaemia, and diabetes mellitus.

To assess the role of polymorphisms in the beta2-adrenergic receptor gene in the development of obesity and obesity-related metabolic disorders, we analysed Arg16Gly, Gln27Glu, and Thr164Ile polymorphisms in 400 non-obese subjects (body mass index < 27 kg/m2) and 108 obese subjects (body mass index> or =27 kg/m2). The Gln27Glu substitution was twice as common in obese subjects as in non-obese subjects (0.14 vs 0.07, p = 0.001, odds ratio 2.14, 95 % confidence interval 1.35-3.41). The frequency of the Glu27 allele was also higher in patients with Type II (non-insulin-dependent) diabetes mellitus than nondiabetic subjects (0.14 vs 0.07, p = 0.001, odds ratio 2.13, 95% confidence interval 1.34-3.41). Analysis of variance of multiple variables showed an association between 2-h post-load glucose concentrations and body mass index but not with the Glu27 variant, suggesting that the association with diabetes could be secondary to obesity. Obese subjects carrying the variant allele had higher concentrations of serum triglyceride than obese subjects homozygous for the wild type allele (2.68+/-1.90 vs 1.18+/-1.15 mmol/l, p = 0.02). Conversely, the frequency of Gly16 homozygotes was lower in obese women when compared with non-obese women (11% vs 28%, p = 0.01, odds ratio 0.30, 95% confidence interval 0.12-0.75), although the association was not present in male subjects. Thr164Ile substitution was not detected in the subjects of this study. These observations suggest that the amino-terminal polymorphisms of the beta2-adrenergic receptor gene could be involved in the molecular pathogenesis of obesity and hypertriglyceridaemia, and thereby the development of Type II diabetes mellitus.

Sustained osteoblast nuclear receptor binding of converted 1alpha, 25-dihydroxyvitamin D3 after administration of 3H-1alpha-hydroxyvitamin D3: a combined receptor autoradiography and radioassay time course study with comparison to 3H-1alpha, 25-dihydroxyvitamin D3.

The present study was undertaken to clarify the receptor distribution and the pharmacokinetics of 3H-1alpha(OH)D3, and 3H-1alpha,25(OH)2D3 for comparison. Receptor autoradiography was used after intravenous injection to 3-day-old neonatal rats and radioassay-HPLC after oral application to young adult rats. Corresponding results were obtained from both receptor autoradiography and radioassay. After 3H-1alpha(OH)D3 administration, uptake was delayed but sustained over a long period of time and the concentration of silver grains (autoradiography) or recovered 3H-1alpha,25(OH)2D3 (radioassay) peaked at a lower level. After 3H-1alpha,25(OH)2D3 administration, osteoblast nuclear, whole bone uptake and retention of radiolabeled compound were relatively rapid and short in duration. Nuclear uptake in osteoblasts after administration of 3H-1alpha(OH)D3 was abolished in competition studies with 10-fold unlabeled 1alpha,25(OH)2D3. These results indicate that 1alpha(OH)D3 continuously supplies osteoblasts with converted 1alpha,25(OH)2D3 and would not spread to the cells because of the low binding affinity of the receptor. Accordingly, 1alpha(OH)D3 appears to have some therapeutic properties different from 1alpha,25(OH)2D3 because of a relatively slow and sustained accumulation of the receptor and less Cmax (pharmacokinetics) compared with 1alpha,25(OH)2D3.

Identification of a single nucleotide insertion polymorphism in the upstream region of the insulin promoter factor-1 gene: an association study with diabetes mellitus.

Insulin promoter factor 1 (IPF1) is a key factor both for the regulation of insulin gene expression and for the development of the pancreas. In this study 88 patients with non-insulin-dependent diabetes mellitus (NIDDM) who were diagnosed as diabetic at less than 40 years of age, 55 patients with insulin-dependent-diabetes (IDDM), and 67 normal control subjects were analysed for variants in the upstream region of the IPF1 gene by direct sequencing. A novel single nucleotide insertion polymorphism was found in a guanine triplet at 108 bp upstream of the translation start site. The G insertion allele (G4 allele) was found to be common in the Japanese population, at a frequency of 0.50. The prevalence of G3 homozygotes was higher in IDDM patients (35%) and lower in NIDDM patients (17%) than in normal control subjects (28%, p=0.049). In the NIDDM group, the ratio of insulin treatment tended to be higher in subjects homozygous for the G3 allele, although the genotype was not significantly associated with basal C-peptide levels. The polymorphism is unlikely to be a major contributor to the insulin deficiency of diabetes. However, the polymorphic locus, or an unknown mutation which is in linkage disequilibrium with the polymorphism, could be involved in the pathophysiology of diabetes. The high heterozygosity may be useful for genetic linkage studies of other mutations within and near the IPF1 gene.

Beta 3-adrenergic receptor gene polymorphism is not a major genetic determinant of obesity and diabetes in Japanese general population.

To assess the contribution of a replacement of Trp at codon 64 of beta 3-adrenergic receptor by Arg to fat distribution and metabolic disturbances in Japanese general population, we examined the missense mutation in 1122 persons consisting of 817 men aged 50.0 +/- 8.9 years and 305 women aged 50.8 +/- 8.5 years in Kyushu, Japan. The incidence of Arg64 allele was 0.21; no age-dependent decrease of the allele frequency was observed, suggesting that the mutation was not associated with early mortality. The genotype was not significantly correlated with body mass index or the thickness of visceral fat estimated by ultrasonography. Glucose tolerance and glucose-induced insulin secretion were not significantly different among subjects with Trp/Trp, Trp/Arg and Arg/Arg at codon 64. Although in obese persons the ratio of heterozygotes for the mutation tended to be higher in subjects with impaired glucose tolerance than in subjects with normal glucose tolerance, the tendency was not observed in non-obese persons. Furthermore none of 39 non-obese individuals homozygous for the mutation was diabetic, whereas two out of six obese homozygous persons were diabetic. These observations suggest that the missense mutation may not be a main determinant of obesity in populations taking low fat/low energy Japanese-style diet and it may not be deleterious at least in non-obese individuals.

Clinical characteristics of Japanese men with glucokinase gene beta-cell promoter variant.

OBJECTIVE: To study the association between a variant at the position of -30 of beta-cell-specific promoter of the glucokinase gene and glucose tolerance in the Japanese general population and to assess the clinical characteristics of subjects with the variant. RESEARCH DESIGN AND METHODS: The genotype of 657 Japanese men aged 51.0 +/- 8.8 years (mean +/- SD) was analyzed by an allele-specific assay using polymerase chain reaction-restriction fragment length polymorphism. RESULTS: The variant allele frequency was 0.188 in subjects with normal glucose tolerance, 0.211 in subjects with impaired glucose tolerance, and 0.176 in diabetic subjects. In subjects with fasting plasma glucose levels <140 mg/dl, homozygous subjects for the promoter variant had significantly higher plasma glucose levels 60 min after oral glucose administration when compared with subjects without the variant allele. A cross-sectional analysis showed age-related elevation of basal glucose levels only in subjects without the promoter variant. Individuals heterozygous for the variant had significantly lower levels of HDL cholesterol than normal subjects. HDL cholesterol values were lower in homozygous people than in normal and heterozygous subjects, although the differences were not statistically significant. CONCLUSIONS: The beta-cell promoter variant in homozygous state was associated with impaired glucose tolerance, but not with diabetes, and low HDL cholesterol levels in Japanese men. It is unlikely that the glucose intolerance associated with the promoter variant is progressive with age.

Association between Ala54Thr substitution of the fatty acid-binding protein 2 gene with insulin resistance and intra-abdominal fat thickness in Japanese men.

Alanine to threonine substitution at codon 54 of the fatty acid-binding protein 2 (FABP2) gene was recently shown to be associated with insulin resistance in Pima Indians. It has been hypothesized that the mutation may result in enhanced intestinal up-take of fatty acids, and thereby an impairment of insulin action. We analysed the association of the Ala54Thr substitution with insulin sensitivity and abdominal fat thickness in 395 Japanese men aged 50.5 +/- 8.8 years (mean +/- SD) with a body mass index of 24.4 +/- 3.0 kg/m2. The frequency of the Thr54 allele was 0.34. Although the polymorphism was not significantly associated with diabetes or impaired glucose tolerance, subjects homozygous for the Thr54 allele had higher basal insulin levels. Analysis by homeostasis model assessment showed an association between the amino acid substitution and greater insulin resistance, and slightly higher beta-cell function. Oral glucose tolerance tests performed in 392 subjects without fasting hyperglycaemia showed higher 2-h insulin concentrations in individuals homozygous for the Thr54 allele when compared with heterozygotes or homozygotes for the Ala54 allele. No significant association was obtained between the polymorphism of the FABP2 gene and body mass index. However, ultrasound measurements of abdominal fat thickness revealed a greater accumulation of intra-abdominal fat in subjects homozygous for the Thr54 allele, whereas subcutaneous fat thickness was not associated with the polymorphism. These observations suggest that the Ala54Thr substitution in the FABP2 gene is associated with insulin resistance in Japanese men, and that visceral fat accumulation might be involved in the impaired insulin action associated with the substitution.

Combined measurements of GAD65 and ICA512 antibodies in acute onset and slowly progressive IDDM.

Autoantibodies to 65 kD glutamic acid decarboxylase (GADAA) and ICA512 (ICA512AA) were measured by radioimmunoassays using as antigens in vitro transcribed and translated [35S]-methionine-labeled human GAD65 and ICA512 (IA-2). The prevalence of GADAA and ICA512AA in sera from 87 patients with IDDM was 39 and 23%, respectively. The frequency and titer of ICA512AA declined sharply within 5 years after the onset of IDDM. Among patients tested within 4 years after diagnosis, the prevalence of ICA512AA was significantly higher in acute onset IDDM than in slowly progressive IDDM (37 versus 6%, P < 0.025) irrespective of age, while there was no difference in GADAA frequency between acute onset and slowly progressive subtypes (51 versus 63%). A total of two patients out of 121 patients with NIDDM were positive for GADAA, and two other NIDDM patients, who were suffering from sarcoidosis, were positive for ICA512AA. Neither of the antibodies were positive in sera from four atypical NIDDM patients, aged < 20 years, who showed ketosis at onset and required insulin followed by excellent metabolic control with diet restriction alone. These observations suggest that ICA512AA are associated with rapid progression of beta cell damage in IDDM. ICA512 radioassay, in combination with GAD assay may provide a useful diagnostic marker for IDDM especially in youth.

Mouse islet cell lysis mediated by interleukin-1-induced Fas.

This study was conducted to investigate the possible involvement of Fas in beta-cell death in insulitis of Type 1 (insulin-dependent) diabetes mellitus. Although primary cultured Balb/c mouse islet cells did not express Fas mRNA, 4-12 hours of treatment with 10(2)-10(3) U/l of mouse interleukin-1 alpha (IL-1 alpha) induced the expression of Fas mRNA. Surface Fas expression was detected by immunofluorescence flow cytometry using a non-cytolytic anti-Fas monoclonal antibody after 6 or 12 h of incubation with 10(3) U/l of IL-1 alpha. Primary islet cells were resistant to an agonistic anti-Fas monoclonal antibody. However, 12 h pretreatment with IL-1 alpha sensitized islet cells to its cytolytic effect. Significant cell death was observed 24 h after the addition of anti-Fas, and progressively increased until 72 h, when specific 51Cr release was 72 +/- 6%. Agarose gel electrophoresis of DNA extracted from cells exposed to IL-1 alpha and agonistic anti-Fas showed internucleosomal DNA fragmentation, a hallmark of apoptotic cell death. Since the Fas antibody showed no cross-reactive activity of tumour necrosis factor (TNF), the cytotoxic effect was not mediated by TNF receptors. A protein synthesis inhibitor cycloheximide augmented Fas-mediated islet cell death. The Fas-mediated killing of islet cells was not L-arginine-dependent, or blocked by N(G)-monomethyl-L-arginine. beta-TC1 cells also expressed Fas mRNA when exposed to IL-1 alpha or IL-1 alpha plus interferon-gamma. These observations suggest that Fas-mediated apoptosis may be a mechanism of islet cell death in autoimmune insulitis.

A method of measuring dipalmitoylphosphatidylcholine (DPPC) by high-performance liquid chromatography (HPLC): effect of dexamethasone on DPPC secretion in fetal rat alveolar type II cell culture.

OBJECTIVE: To establish a method by which to measure dipalmitoylphosphatidylcholine (DPPC), which is the most prevalent phospholipid in lung surfactant, by high-performance liquid chromatography (HPLC), and to measure DPPC secretion in type-II alveolar cell culture to determine whether glucocorticoid has a direct accerelating effect. METHOD: Type-II alveolar cell suspensions were made with fetal rat lungs and then cultured. Dexamethasone, (10(-9), 10(-8) M) was added to some of the culture dishes. DPPC was extracted from the culture medium, purified, and measured by high-performance liquid chromatography (HPLC). RESULTS: In the measurements of DPPC, the specificity of isolation and measurement parity were excellent [coefficient of variation: intraassay; 5.66% (0.005 mg/ml), 25.37% (0.05 mg/ml): interassay; 8.35% (0.005 mg/ml), 0.08% (0.05 mg/ml)]. The DPPC concentration in the culture dishes of the dexamethasone was not significantly different than that of the control dishes (Student's t-test). CONCLUSION: The above results prove that dexamethasone does not directly stimulate lung alveolar type-II cells.

Relapsing polychondritis associated with subclinical Sjögren's syndrome and phlegmon of the neck.

A 25-year-old woman, diagnosed with Sjögren's syndrome at age 20, presented with painful edema of her left neck. Three days later, she additionally complained of bilateral auricular pain, and her nasal cartilage was tender to palpation. She was diagnosed as having phlegmon on the basis of her neck findings. Anti-human cartilage antibodies were demonstrated by indirect immunofluorescence, and the diagnosis of relapsing polychondritis was established. The patient was administered antibiotics and a non-steroidal anti-inflammatory drug, and her symptoms gradually improved. Relapsing polychondritis is one of the possible complications of autoimmune diseases, and infection might be a precipitating factor for this disease.

Mouse primary osteoblasts express vitamin D3 25-hydroxylase mRNA and convert 1 alpha-hydroxyvitamin D3 into 1 alpha,25-dihydroxyvitamin D3.

We examined whether 1 alpha-hydroxyvitamin D3 (1 alpha(OH)D3) is metabolized into 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3) in bone. Northern blot analysis indicated that the expression of vitamin D3 25-hydroxylase mRNA was highest in the liver, followed by the duodenum, calvaria, lung, kidney, skin and long bone, and lowest in the spleen. Of the bone cell fractions isolated from fetal mouse calvaria by a sequential enzymatic digestion, fraction 3, which consisted of mostly osteoblastic cells, showed the highest expression of vitamin D3 25-hydroxylase mRNA. When either cultured bone cells of fraction 3 or mouse calvaria were incubated with [3H]-1 alpha (OH)D3, a radioactive peak which comigrated at the same position as authentic 1 alpha,25(OH)2D3 was found on an HPLC chromatogram. The radioactive fraction obtained from the conditioned media of fetal mouse calvaria was tentatively identified as 1 alpha,25(OH)2D3 by cochromatography with authentic 1 alpha,25(OH)2D3 on three different HPLC systems and a thermal isomerization analysis. These results indicate that 1 alpha(OH)D3 is hydroxylated at the 25-position in bones, resulting in the local synthesis of 1 alpha,25(OH)2D3 from 1 alpha(OH)D3 in the skeletal tissues.

1α,25-Dihydroxyvitamin D(3) down-regulates pleiotrophin messenger RNA expression in osteoblast-like cells.

Pleiotrophin (PTN)[heparin-binding-growth-associated molecule (HB-GAM), heparin-binding neurite-promoting factor (HBNF)] is a recently identified polypeptide that stimulates growth of fibroblasts and enhances neurite extension. PTN is expressed in many tissues but relatively high level of expression has been observed in brain and bone. We examined hormonal regulation of PTN mRNA expression in several osteoblast-like cell lines including MC3T3-E1 and ROS17/2.8. The levels of PTN mRNA in these cells was significantly reduced by treatment with 10(-8) M: 1α,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) for 24 h. However, PTN mRNA levels were increased when the non-osteoblastic cell line, ROS 25/1, was treated with 1,25(OH)(2)D(3). These effects were observed in a dose-dependent manner in a dose range between 10(-11) M: to 10(-8) M: . This effect was specific to 1,25(OH)(2)D(3), since PTN mRNA levels were not affected by other steroids such as retinoic acid and dexamethasone in MC3T3-E1 or ROS17/2.8 cells. Similar 1,25(OH)(2)D(3) down-regulation of PTN mRNA was also observed in primary cultures of osteoblast-enriched fetal rat calvaria cells as well as cultures of MC3T3-E1 and ROS17/2.8 cells. These observations suggest that PTN expression in osteoblasts is regulated by the calcitropic hormone, 1,25(OH)(2)D(3), and that PTN may play a role in vitamin D-dependent regulation of bone metabolism.

Evidence for the uptake of a vitamin D analogue (OCT) by a human carcinoma and its effect of suppressing the transcription of parathyroid hormone-related peptide gene in vivo.

The present study was undertaken to clarify the pharmacokinetics of 22-oxa-1,25-dihydroxyvitamin D3 (22-oxa-1,25-(OH)2D3, OCT), a vitamin D3 analogue with little calcemic activity, and its effect on the transcription of parathyroid hormone-related peptide (PTHRP) gene in nude mice bearing a human carcinoma (FA-6) associated with humoral hypercalcemia. FA-6 tumor expressed vitamin D receptor (VDR) mRNA, and its nuclear extract contained a specific and saturable 1,25-(OH)2D3 binding activity. Although [3H]OCT administered intravenously into FA-6 tumor-bearing nude mice was cleared from the circulation more rapidly than [3H]1,25-(OH)2D3, the uptake of [3H]OCT into the tumor tissue, relative to the radioactivity in the circulation, was greater than that of [3H]1,25-(OH)2D3. Intravenous or oral administration of OCT reduced the steady-state levels of PTHRP mRNA in FA-6 tumor, and nuclear run-off assays demonstrated that the effect of OCT on PTHRP gene expression occurred at a transcriptional level. RNase mapping analysis revealed that both upstream and downstream promoters of the human PTHRP gene were down-regulated by OCT. Finally, OCT exerted a preventive as well as therapeutic effect on cancer-associated hypercalcemia with a marked prolongation of the survival time in tumor-bearing animals. These results suggest that OCT is effectively taken up by a VDR-positive human carcinoma in vivo and has a therapeutic potential for cancer-associated hypercalcemia through suppression of PTHRP gene transcription.