Cyp19 encodes the key enzyme of estrogen biosynthesis, aromatase cytochrome P450. In mice it is mainly expressed in the ovary and brain, where transcription is directed by a distal, brain-specific promoter (P(br)). In order to map functional sequence elements of P(br), portions of various length (0.2, 1.0, and 1.7[kb]) were fused to a lacZ reporter gene and analyzed in transgenic mice. Numbers of integrated reporter genes varied from 1 to 23 copies in different transgenic lines. These copy numbers however did not show any correlation to the levels of transgene expression. All of the constructs were found being expressed in the olfactory bulb, limbic cortex, amygdala, and hypothalamus. Additional expression in thalamic nuclei, bed nucleus of stria terminalis, and dorsal mesencephalon was found in transgenic lines with constructs 1.0 and 1.7, and expression in septal and preoptic nuclei was only found with construct 1.7. The data demonstrate that 0.2kb of P(br) target reporter gene expression to specific brain areas. The data also strongly suggest that the sequence between 0.2 and 1.7kb upstream, is necessary for expression in additional areas. However even 1.7kb of P(br) are not sufficient to consistently mimic the accurate expression pattern of Cyp19.
In order to test the hypothesis of complete androgen blockade for advanced prostate cancer (D2CaP), an intergroup trial was instituted in 1985 comparing leuprolide (L) alone to the combination of L with flutamide (F). Eligibility requirements included previously untreated histologically confirmed stage D2CaP, measurable bone or soft tissue metastases, performance status (PS) of 3 or better, acceptable renal and hepatic function, no severe cardiac disease, and no prior or concomitant endocrine therapy. Stratification at entry was on the basis of PS and none or minimal disease (MD) versus severe degree (SD) of bone metastases. Six hundred and seventeen patients were entered into this study between March 1985 and April 1986. At the present time, there is a 3-month difference in the median progression-free survival (13.9 vs 16.9 months; P = 0.039) and a 7.1-month difference in survival (27.9 vs 35.01 months; P = 0.035) favoring L + F. In L + F-treated patients with good PS-MD, the median survival recently has been reached and is 51.9 months vs 39.6 months for L + P patients. The 107 black patients in the study had median survival of 26.4 months vs 33.3 months for whites. Discussions of racial differences in survival as well as other prognostic factors will be presented. The combination of L + F is superior to treatment with L alone. The benefits appear greatest in patients with minimal disease.
Both calcitriol and UVB radiation exert potent antipsoriatic effects. We hypothesize that the therapeutical effect of UVB radiation may be attributed at least in part to UVB-triggered cutaneous synthesis of calcitriol. The optimum wavelength for initiation of the vitamin D(3) pathway was found to be in the range of 300+/-5 nm in vitro and in vivo. The narrowband Philips TL-01 lamp which is commonly used as UVB source for phototherapy of psoriasis has maximum spectral irradiance at around 311 nm which is presumed to be, however, of lesser importance in photochemical activation of the vitamin D(3) pathway. The aim of this study was to compare the vitamin D(3) and calcitriol-inducing potential of UVB from the TL-01 lamp with that of monochromatic UVB at 300+/-2.5 nm and 310+/-2.5 nm in organotypic cultures of keratinocytes supplemented with 25 microM 7-DHC. We found that maximum calcitriol-generating capacity of the TL-01 lamp at 500 mJ/cm(2) and 16 h after irradiation still amounts up to 44% of that found after monochromatic irradiation at 300+/-2.5 nm and 30 mJ/cm(2). Thus, the antipsoriatic effect of UVB emitted from the TL-01 lamp may, at least in part, based on the antiproliferative and prodifferentiative action of newly synthesized calcitriol on epidermal keratinocytes.
Male infertility is a multifactorial condition with a strong genetic component. In the last decade a large number of investigations focused on the identification of gene variants affecting spermatogenesis in human. Polymorphisms of the estrogen receptor (ER) genes, have been implicated in male infertility, however, comprehensive data are lacking. We investigated the association between the ER-α gene (ESR1) PvuII and XbaI and ER-β gene (ESR2) RsaI and Alul polymorphisms and the idiopathic male infertility in Iranian males. Polymerase chain reaction (PCR) method and restriction fragment length polymorphism (RFLP) were used to detect the ER-α, and ER-β gene polymorphisms in 164 infertile men and 164 age-matched healthy controls. Reproductive hormones were measured and at least two semen analyses were performed in each subject. Significant differences were observed in the frequency distribution of Pvull and XbaI in the ESR-α gene and RsaI and Alul in the ER-β gene between patients and controls. The presence of the ER-α Pvull TC (OR = 0.56, 95% CI: 0.26-0.80; P = 0.011), ER-α XbaI AG (OR = 0.51, 95% CI: 0.31-0.84; P = 0.017), and ER-β Alul GG (OR = 0.48, 95% CI: 0.265-0.84; P = 0.012) genotypes suggest a protective effect for infertility. The ER-β RsaI AG (OR = 2.32, 95% CI: 1.61-3.22; P = 0.012) and ER-β Alul AG (OR=2.76, 95% CI: 1.64-3.66; P=0.014) genotypes are associated with increased infertility risk. Subjects (both fertile and infertile) with ER-α Pvull TT, ER-α XbaI AA, ER-β RsaI AG, and ER-β Alul AG genotypes had significantly lower levels of serum sex hormone binding globulin (SHBG), and luteinizing hormone (LH), but, higher serum levels of free estradiol and follicle stimulating hormone (FSH). The same genotypes had significantly lower values for sperm density, sperm motility, and percentage of sperm with normal morphology. Our results further suggest a possible role of ESR-α, and ER-β variants on male infertility. Further studies are needed to replicate our findings as well as to better elucidate the biological mechanisms of the modulation of ESR-α, and ER-β on male infertility.
Sex hormone binding globulin (SHBG) is involved in delivering sex hormones to target tissues. We investigated the association between the (TAAAA)n repeat polymorphism, and Asp327Asn polymorphism in the SHBG gene with semen quality and idiopathic male infertility. We studied 168 men with idiopathic infertility [oligoasthenoteratozoospermia (OAT)] and equal number of age-matched normal controls. The serum levels of SHBG, reproductive and thyroid hormones, and Inhibin B were measured. Semen parameters were also assessed. The genotype assays for the SHBG polymorphism were done using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. Baseline SHBG levels tended to be lower in infertile men (21.1±7.2nmol/l) compared to normal fertile men (24.7±7.9nmol/l). SHBG levels tended to be higher among the subjects with the Asn/Asn (25.84±3.6nmol/l) and S/S (24.50±5.4nmol/l) genotypes compared to subjects with the Asp/Asn (24.38±3.2nmol/l) and L/L (18.44±4.2nmol/l) genotypes of the SHBG gene. The genotype frequencies of Asp/Asp were 80.9% in cases and 71.4% in controls (P=0.001). The variant Asp/Asn genotype was associated with a more than 50% reduced risk of infertility (OR: 0.46, 95% CI: 0.25-0.80, P=0.001). Genotype analysis demonstrated six SHBG (TAAAA)n alleles with 6-11 repeats. Long SHBG (TAAAA)n alleles (>8 repeats) were at greater frequency in infertile men than fertile subjects (P=0.001), whereas short SHBG (TAAAA)n alleles (≤8 repeats) tended to be more frequent in fertile men than cases (P=0.001). Men with the 9/X TAAAA repeat genotype displayed a 2.82-fold increased risk of infertility (95% CI: 1.27-4.79, P=0.01). There were strong and significant positive correlations between plasma SHBG and sperm count (r=0.672, P=0.01), sperm motility (r=0.721, P=0.01) and sperm morphology (r=0.574, P=0.02). We concluded that the SHBG Asp237Asn and (TAAAA)n polymorphisms may influence SHBG levels and as a result, male infertility. Multicenter large scale studies are warranted to better elucidate the role of SHBG gene polymorphism in male infertility.
1,1-bis(4-Hydroxyphenyl)-2-phenylpent-1-ene (5) and 1,1,2-tris(4-hydroxyphenyl)pent-1-ene (6) derivatives with terminal CN (5a, 6a), NH(2) (5b, 6b), NHCOCH(3) (5c, 6c), NHCOC(2)H(5) (5d, 6d) groups at the C2-propyl chain were synthesized and assayed in vitro for estrogen receptor (ER) binding affinity (RBA) in a competition experiment with [3H]estradiol and for estrogenic and anti-estrogenic properties in a luciferase assay with ER-positive MCF-7-2a cells, stably transfected with the plasmid ERE(wtc)luc. The CN as well as the NH(2) group reduced the RBA-values (5: 2.09%; 5a: 1.50%; 5b: 0.07%; 6: 4.03%; 6a: 0.67%; 6b: 0.20%) and the antagonistic potency (5: IC(50)=0.05 microM; 5a: IC(50)=0.43 microM; 5b: IC(50)=1.50 microM; 6: IC(50)=0.07 microM; 6a: IC(50)=0.60 microM; 6b: IC(50)=2.00 microM). Derivatization of the amino function with acetic anhydride and propionic anhydride did not change the RBA-value but altered the antagonistic profile (5c: IC(50)=2.50 microM; 5d: IC(50)=not detectable; 6c: IC(50)=0.65 microM; 6d: IC(50)=1.00 microM). Agonistic effects were only detected for the amine 6b (34.2% activation of the luciferase expression). These data document that estrogen receptor binding and the antagonistic effects can be modified by terminal groups at the C2-propyl chain of the pure antagonists 5 and 6. The mode of action is unclear. However, it can be assumed that the elongation of the side chain causes a reorientation in the LBD in order to locate the side chain in a side pocket near the ligand binding domain.
1,1-bis(4-Methoxyphenyl)-2-phenylalkenes (1a-9a) and 1,1,2-tris(4-methoxyphenyl)alkenes (1b-9b) with various C2-substituents (H (1a, 1b), methyl (2a, 2b), ethyl (3a, 3b), propyl (4a, 4b), butyl (5a, 5b), 2-cyanoethyl (6a, 6b), 3-cyanopropyl (7a, 7b), 3-aminopropyl (8a, 8b), 3-carboxypropyl (9a, 9b)) were tested for cytotoxic effects on hormone dependent MCF-7 cells. The effects were correlated with agonistic and antagonist properties determined on the MCF-7-2a cell line stably transfected with the plasmid ERE(wtc)luc. We demonstrated that the antiproliferative effects did not result from an interaction with the estrogen receptor (ER). The most cytotoxic compounds 5,5-bis(4-methoxyphenyl)-4-phenylpent-4-enylamine (8a) and 4,5,5-tris(4-methoxyphenyl)pent-4-enyl (8b) showed cytocidal effects without having significant agonistic and antagonistic properties.
As part of an ongoing program to develop high affinity estrogenic ligands we have synthesized the 11 beta-vinyl, 11 beta-ethyl- and 1,11 beta-ethanoestradiols. Because the 1,11 beta-ethano-estradiol had not been previously reported in the literature, the investigation of its receptor binding characteristics would provide valuable insight into the effect of 1/11 beta-substitution. The data obtained in this study indicate that although significant estrogen receptor affinity is present for the 1,11 beta-ethano derivative, the RBA values, 5-22.4%, were far less than those observed (5-300-fold less) for the corresponding 11 beta-ethyl and 11 beta-vinyl estradiols and less than those for the 1-methyl and 11 beta-methyl estradiols. These results suggest that the orientation that the 11 beta-substituent must occupy is directed away from the A-ring and that substituents in the 1-11 pocket produce a detrimental effect on receptor interactions.
The misuse of anabolic steroids by athletes has been banned by sports organizations and is controlled by the analysis of urine samples obtained from athletes using gas chromatography/mass spectrometry (GC/MS). To extend the retrospectivity of the analytical methods, research is focused on long-term excreted metabolites. Preliminary results concerning the long-term detection of metabolites of the anabolic androgenic steroid 4-chloro-1,2-dehydro-17alpha-methyltestosterone I are presented. A new metabolite 4-chloro-3alpha, 6 beta, 17beta-trihydroxy-17alpha-methyl-5beta-androst-l-en-16-one was isolated by high performance liquid chromatography (HPLC) from urine following a single oral administration of 40 mg of I and characterized. Metabolite II was excreted into urine with a maximum excretion rate at approximately 48 h after administration and could be detected by gas chromatography/high resolution mass spectrometry (GC/HRMS) for up to 14 days. Two further partly characterized metabolites III and IV were confirmed for more than 9 days. The same three metabolites, II-IV, in varying amounts were also detected in urine samples from athletes who administered I.
In the 2-phenylindole system, the side chain at the nitrogen atom dominates the endocrine profile both in respect to the reduction of estrogenic action and the increase of antiestrogenic potency. In previous papers we reported on 2-phenylindoles with aliphatic side chains and various functional groups [Biberger, C. and von Angerer, E., J. Steroid Biochem. Molec. Biol., 1996, 58, 31-43 and references therein]. In this study, we incorporated one or two phenyl rings into the side chain in order to lower the flexibility of the side chain. The sulfone group which was used as a polar function was linked to various positions of a benzyl or a phenyl group attached to the indole moiety. The relative binding affinities (RBA) ranged from 1.5 to 8.4% of estradiol. Agonist and antagonist activities were estimated in transfection assays using transiently transfected HeLa cells (cotransfected with the HEG0 vector) and stably transfected MCF-7/2a human breast cancer cells. The reporter plasmid contained the ERE from the Vitellogenin 2A gene, a viral tk promotor and the luciferase gene. Many of the new derivatives showed no or only very low estrogenic activity except for the compound 4e which contained two benzyl elements in the side chain. The antiestrogenic potency was very variable when concentrations 100-fold higher than that of estradiol were applied. The compound with the para-substituted benzyl fragment (4b) proved to be a pure antagonist in the transfection assays. It antagonized the effect of estradiol (10 nM) with an IC50 value of 10(-7) M. It also inhibited strongly the growth of estrogen-sensitive human MCF-7 mammary carcinoma cells (IC50, 3 nM). Its activity was comparable to the one of the corresponding aliphatic 2-phenylindole derivative ZK 164.015. The data from the transcription and proliferation assays suggest that a phenyl ring can be incorporated into the side chain of pure antiestrogens without reducing their potency, provided the aromatic ring is para-substituted and a methylene group between the indole nitrogen and the phenyl group can act as hinge.
Four ring A steroidal epoxyenones as probable intermediate in the formation of catechol estrogens were synthesized. The isomeric 1 alpha,2 alpha-epoxy-17 beta-hydroxyestr-4-en-3-one (9) and 1 beta,2 beta-epoxy-17 beta-hydroxyestr-4-en-3-one (8) were synthesized from 17 beta-hydroxy-5 alpha-estra-3-one. The isomeric 4 alpha,5 alpha-epoxy-17 beta-hydroxyestr-1-en-3-one (11) and 4 beta,5 beta-epoxy-17 beta-hydroxyestr-1-en-3-one (10) were prepared from 19-nortestosterone. The reaction of 9 and 10 with sodium/ethanethiol resulted in the formation of three types of reactions leading to multiple products: 1,4-addition, opening of epoxide, and epoxide opening followed by dehydration. Reaction of 8 with ethanethiol gave only one compound identified as 2-ethanethio-1,4-estradien-17 beta-ol-3-one, while reaction of 9 with ethanethiol gave an unusual product identified as 4-estren-1 alpha,17 beta-diol-3-one. Unlike reaction of ethanethiol with 9 and 10, reaction with N-acetylecysteine or glutathione results in epoxide opening followed by dehydration leading to the formation of estradiol-4-thioethers.
Angiotensin II acts on adrenal glomerulosa cells to induce the phospholipase C-mediated generation of inositol trisphosphate and sn-1,2-diacylglycerol as the major products of inositol phospholipid breakdown. This last product is known to activate protein kinase C, but its role in the action of angiotensin II on steroidogenesis has not been defined. We report herein that, in bovine adrenal glomerulosa cells, protein kinase C activators, such as phorbol 12,13-dibutyrate, 12-O-tetradecanoylphorbol-13-acetate, mezerein and sn 1,2 oleoyl acetoylglycerol, each failed to increase steroidogenesis. These results contrast with our recent report on the enhancement of aldosterone output by sn-1,2-dioctanoylglycerol (DiC8) [J. Steroid Biochem. 35 (1990) 19-33]. In addition, the difference between DiC8 and the other protein kinase activators was also observed in the pattern of 86Rb efflux from preloaded glomerulosa cells; only DiC8 mimicked the effect of angiotensin II on ion fluxes. Furthermore, staurosporine, a potent inhibitor of protein kinase C, was capable of amplifying the aldosterone output induced by a maximally effective concentration of DiC8 or angiotensin II. These data suggest that the effect of the cell permeant DiC8 on aldosterone biosynthesis either is not mediated by protein kinase C activation, or is mediated by a phorbol ester-insensitive isoenzyme of protein kinase C.
The objective of this study was to assess the pharmacokinetics and bioavailability of 3beta-hydroxy-17-(1H-1,2,3-triazol-1-yl)androsta-5,16-diene (VN/87-1) in normal male mice and in SCID mice bearing human LNCaP tumor xenografts. VN/87-1 is a novel potent steroidal inhibitor of human testicular 17-alpha-hydroxylase/C(17,20)-lyase. The steroid also shows anti-androgenic activity and inhibits the growth of human prostate cancer cell lines (LNCaP) in vitro and in vivo. Male Balb/c mice were given a single oral, subcutaneous (s.c.) or intravenous (i.v.) bolus dose of VN/87-1 (25, 50 or 100 mg/kg). Male SCID mice bearing LNCaP tumor xenografts were injected with a single s.c. dose of VN/87-1 (50 mg/kg). The animals were sacrificed at various times up to 24 h after drug administration and blood was collected. The plasma samples were prepared and analyzed by a reversed phase HPLC system equipped with a diode array detector. A non-compartmental pharmacokinetic approach was used to evaluate the plasma level versus time data. Following i.v. administration of VN/87-1, the plasma levels declined exponentially with an elimination half-life of 1.2+/-0.03 h. The absolute bioavailability of the 50 mg/kg dose after oral or s.c. administration was 12.08+/-2 or 57.2+/-4.5%, respectively. VN/87-1 is a high clearance (5.0+/-1.3 l/h per kg) compound in mice and its volume of distribution was relatively large (6.5+/-1.2 l/kg). The pharmacokinetic parameters of VN/87-1 were not significantly altered in SCID mice bearing human LNCaP tumor xenografts. VN/87-1 is well absorbed from the subcutaneous site compared with absorption from the gastrointestinal tract and shows linear kinetics at doses up to 100 mg/kg.
[1,2,3,4-13C]cortisol was i.v. administered to two sisters aged 11 yr (patient I) and 3 yr (patient II) who suffer from 17 alpha-hydroxylase deficiency. This is the first time that the cortisol production rate (CPR) in patients with 17 alpha-hydroxylase deficiency has been measured with a stable labelled tracer using the urinary method. The urine was collected for 3 days. High-performance liquid chromatography (HPLC) of approximately 100 ml urine extracts was carried out to isolate the small amount of cortisol metabolites excreted. The cortisol metabolites were oxidized to 11-oxo-aetiocholanolone. The isotope dilution in the methyl oxime tert-butyldimethylsilyl ether derivatives was measured by selected ion monitoring gas chromatography/mass spectrometry (GC/MS). The CPR calculated from tetrahydrocortisone (THE) and the cortolones was 765 and 536 nmol/day, respectively in patient I. The CPR in patient II was only calculated from THE and was 62 nmol/day. If radioactive labelled cortisol had been used, much larger quantities of urine would have been needed for isolation of sufficient mass of metabolites, even then purification may have been difficult. Steroid profiling of 1 ml urine samples by GC and identification by GC/MS revealed high concentrations of pregnenolone, progesterone, 11 beta-hydroxy progesterone and corticosterone metabolites. Tetrahydrocorticosterone and 5 alpha-tetrahydrocorticosterone were found in urine at elevated excretions of 2.5 and 5.7, 0.9 and 2.0 mumols/24 h, in patients I and II respectively. No cortisol metabolites were detected by routine GC or GC/MS as the low amounts excreted co-eluted with the relatively abundant corticosterone metabolites.
In a steroid degradation gene cluster of Comamonas testosteroni TA441 consisting of ORF18, 17 and tesIHA2A1DEFG, ORF18 was implicated in encoding a CoA-transferase by database searches, but the matching substrate was not clear. In this study, ORF18 was shown to be necessary for conversion of 9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid, a product of hydrolysis of 4,5-9,10-diseco-3-hydroxy-5,9,17-trioxoandrosta-1(10),2-dien-4-oic acid in steroid degradation by TA441. The ORF18-disrupted mutant accumulates 7-hydroxy-9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid and 7,12-dihydroxy-9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid when incubated with chenodeoxycholic acid and cholic acid, respectively.
Comamonas testosteroni degrades testosterone into 9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid and 2-hydroxyhexa-2,4-dienoic acid via aromatization of the A-ring. The former compound is suggested to be degraded further by β-oxidation, but the details of the process remain unclear. In this study, we identified 9α -hydroxy-17-oxo-1,2,3,4,10,19-hexanorandrost-6-en-5-oic acid as an intermediate compound in the β-oxidation of this compound. ORF32, located in one of the two main steroid degradation gene clusters, was shown to be indispensable for the conversion of this compound. A homology search indicated that ORF32 encodes a hydratase for the CoA-ester, suggesting that ORF32 encodes a hydratase that adds a water molecule to a double bond at C-6 of the CoA-ester of 9α-hydroxy-17-oxo-1,2,3,4,10,19-hexanorandrost-6-en-5-oic acid. From the culture of an ORF32-disrupted mutant incubated with cholic acid for a short period (around two days, when a considerable number of intermediate compounds were detected by HPLC), 7α,12α-dihydroxy-3-oxochola-1,4-dien-24-oic acid, 7α,12α-dihydroxy-3-oxochol-4-en-24-oic acid, 12α-hydroxy-3-oxochola-4,6-dien-24-oic acid, 7α,12α-dihydroxy-3-oxopregna-1,4-diene-20-carboxylic acid, 12α-hydroxy-3-oxopregna-4,6-diene-20-carboxylic acid, 7α,12α-dihydroxy-3-oxopregn-4-ene-20-carboxylic acid, 12α-hydroxy-3-oxopregna- 4,6-diene-20-carboxylic acid, 7α-hydroxy-3-oxopregna-4,17(20)-diene-20-carboxylic acid, and 3-oxopregna-4,6,17(20)-triene-20-carboxylic acid were isolated as intermediate compounds of C-17 side-chain degradation. The presence of these compounds implies that the process of degradation of the C-17 side chain in C. testosteroni will be similar to the process in Pseudomonas. The final two compounds, which have a double bond at the C-17(20) position, are here identified for the first time, to the best of our knowledge, as intermediate compounds in bacterial steroid degradation; their composition suggests that the remaining three carbons at the C-17 position would be removed oxidatively as a propionic acid derivative.
1,24(R)(OH)2D3 is a synthetic analogue of 1,25(OH)2D3 which binds to the same receptors as the physiologic metabolite with a lower affinity. The aim of the present study was to compare the activity of 1,24(R)(OH)2D3 and 1,25(OH)2D3 on several target organs in patients with chronic renal failure. Treatment with 1,24(R)(OH)2D3 at doses of either 1 or 2 micrograms daily was carried out in two groups of 9 patients, with serum creatinine of 4.61 +/- 1.59 and 4.66 +/- 1.46 mg/dl, respectively. Doses of 1,25(OH)2D3 were 0.5 and 1 microgram daily and were administered to 9 and 13 patients, serum creatinine of 4.52 +/- 1.67 and 4.3 +/- 1.16 mg/dl, respectively. Treatment periods were of 2 weeks. Administration of 1,25(OH)2D3, 1 microgram, induced significant increments of intestinal calcium absorption (ICA), ionized calcium, osteocalcin, serum creatinine, urine Ca/GFR, and a decrease in iPTH. 1,25(OH)2D3, 0.5 microgram, induced a significant increase in ICA and osteocalcin and a decrease in iPTH. Similarly 1,24(OH)2D3, 2 micrograms daily, significantly stimulated ICA and raised serum levels of osteocalcin and creatinine while lowering serum iPTH. In addition, 1,24(R)(OH)2D3 administration induced a significant fall of serum 1,25(OH)2D3. Following 1 microgram, only osteocalcin increased. Therefore, the dose of 2 micrograms of 1,24(R)(OH)2D3 has biologic activity similar to 0.5 microgram 1,25(OH)2D3 (4:1). However the activity ratio on osteocalcin production appears to be 2:1. In addition, 1,24(R)(OH)2D3 is able to inhibit renal tubular 1 alpha-hydroxylase. In conclusion 1,24(R)(OH)2D3 may prove to be useful in the treatment of metabolic bone disease.
The active form of Vitamin D(3) has been reported to prevent neuronal damage caused by a variety of insults, however, it may also induce undesirable hypercalcemic effects. In the present study, we evaluated effects of (24R)-1,24-dihydroxycholecalciferol (PRI-2191) on hydrogen peroxide- and excitatory amino acid-induced neuronal damage in human neuroblastoma (SH-SY5Y) cell line. Exposure of SH-SY5Y cells to N-methyl-d-aspartate (NMDA; 5mM), kainate (0.2mM) and hydrogen peroxide (0.1-1mM) significantly enhanced lactate dehydrogenase release. Furthermore, the neurotoxic effects of hydrogen peroxide was dependent on c-Jun N-terminal kinase (JNK)- and p38- mitogen-activated protein kinase (MAPK) activity. Both secosteroids at nanomolar concentrations inhibited neuronal damage, but their efficacy varied depending on the toxic agent. PRI-2191 was equipotent as 1alpha,25-dihydroxyVitamin D(3) in protecting SH-SY5Ycells against NMDA toxicity, and had stronger effect against hydrogen peroxide-induced damage, but was less efficient against kainate-induced injury. The obtained results suggest potential usefulness of PRI 2191 in the treatment of neurodegenerative diseases.
It has been shown that Solanum malacoxylon contains 1 alpha,25-dihydroxyvitamin D3-glycoside. The presence of vitamin D3 and 25-hydroxyvitamin D3 has also been suggested. In the present study vitamin D3 and three of its metabolites, including 1 alpha,25-dihydroxyvitamin D3, were detected in plant leaf extracts preincubated with ruminal fluid (SMRF). Extraction of SMRF with non-polar organic solvents and purification of the lipid extract by TLC followed by HPLC yielded nine ultraviolet-absorbing (264 nm) peaks. Four of them comigrated on a Zorbax-Sil HPLC column with synthetic standards of vitamin D3, 25-hydroxyvitamin D3, 1 alpha,25-dihydroxyvitamin D3 and 1,24R,25-trihydroxyvitamin D3, respectively. These compounds were unequivocally identified by means of mass spectrometry. The results confirm that Solanum malacoxylon contains, in addition to 1 alpha,25-dihydroxyvitamin D3, vitamin D3, 25-hydroxyvitamin D3 and possibly other as yet unidentified derivatives. As 1,24,25-trihydroxyvitamin D3 is absent in plant extracts not incubated with ruminal fluid, the data also indicate that rumen microbes may convert 1 alpha,25-dihydroxyvitamin D3 into 1,24,25-trihydroxyvitamin D3.
The induction of antimicrobial peptides such as the human cathelicidin, CAMP/hCAP18, by 1,25(OH)(2)D(3) provides a very exciting therapeutic approach in boosting immunity against infectious diseases. To explore the range of cell types and expand the number of cell models for studying the regulation of CAMP gene expression by 1,25(OH)(2)D(3), we treated cell lines from various tissue types and determined CAMP gene expression. Also, we tested additional compounds together with 1,25(OH)(2)D(3) to look for possible cooperative activation of the gene. We identified 1,25(OH)(2)D(3)-mediated induction of the CAMP gene in B-cell lymphomas, prostate and endometrial cancer lines and found cooperative activation with the histone deacetylase inhibitor sodium butyrate. The data suggest that regulation of CAMP by 1,25(OH)(2)D(3) is potentially important in a wide range of tissues.
Treatment from weaning until old age with 1,25-dihydroxyvitamin D (1,25(OH)(2)D(3)) prevents diabetes in NOD mice. It is mainly through its actions on dendritic cells (DCs), that 1,25(OH)(2)D(3) changes the function of potentially autoreactive T lymphocytes. In contrast, early life treatment (from 3 to 70 days of age) of NOD mice with vitamin D or 1,25(OH)(2)D(3) did not influence final diabetes incidence at 200 days of age. Also in spontaneous diabetic BB rats, diabetes could not be prevented by early life treatment (from 3 to 50 days of age) with vitamin D (1000 IU per day) or 1,25(OH)(2)D(3) (0.2 microg/kg per day or 1 microg/kg per 2 days). However, when NOD mice were made vitamin D deficient in early life (until 100 days of age), diabetes onset occurred earlier and final incidence was increased. These data further support a role for vitamin D and its metabolites in the pathogenesis of type 1 diabetes in NOD mice.
Although local synthesis of 1,25D has been postulated to regulate parameters of cell growth and differentiation in non-renal cells, the physiological role of 1,25D production in bone cells remains unclear. We used the technique of RNA interference to inhibit the mRNA encoding the enzyme responsible for 1,25D synthesis, 25-hydroxyvitamin D 1alpha-hydroxylase (CYP27B1). Human osteosarcoma (HOS) cells were transfected with siRNA for CYP27B1 or non-silencing RNA before being treated with 25D for 48h under normal growth conditions. De novo synthesis of 1,25D was measured in the media as well as mRNA levels for CYP27B1, osteocalcin (OCN) and 25-hydroxyvitamin D 24-hydroxylase (CYP24). We demonstrated that HOS cells express CYP27B1 mRNA, metabolize 25D and secrete detectable levels of de novo synthesized 1,25D. CYP27B1 mRNA silencing by RNAi, resulted in the suppression of 1,25D production and subsequent reduction of OCN and CYP24 mRNA expression. Our findings suggest that local 1,25D synthesis has paracrine effects in the bone microenvironment implying that vitamin D metabolism in human osteoblasts represents a physiologically important pathway, possibly regulating the maturation of osteoblasts.
The Odd-skipped related genes Osr1 and Osr2 encode closely related zinc finger containing transcription factors that are expressed in developing limb. However, their role in osteoblast proliferation and differentiation remains controversial and little is known about their regulation. In this study we showed that both Osr1 and Osr2 were expressed in several murine and human osteoblast cell lines as well as in primary osteoblast cultures. Moreover, their transcript levels were regulated by a number of osteogenic stimuli in murine pre-osteoblast MC3T3-E1 cells. The most robust regulation of Osr1 and Osr2 mRNA levels was observed after stimulation with 1,25-dihydroxyvitamin D(3). 1,25-dihydroxyvitamin D(3) induced transcript levels of Osr1 and Osr2 and this up-regulation was confirmed in other osteoblast cultures, both from murine and human origin.
Vitamin D depletion in rats causes osteopenia in at least three skeletal sites. However it is unclear whether modulation of dietary calcium intake impacts on the relationship between the level of serum 25-hydroxyvitamin D (25D) and bone loss. Nine-month-old female Sprague-Dawley rats (n=5-6/group) were pair-fed a semi-synthetic diet containing either 0 or 20 IU vitamin D3/day with either low (0.1%) or high (1%) dietary Ca for 6 months. At 15 months of age, fasting bloods were collected for biochemical analyses. Serum 25D levels were lowest in the animals fed 0 IU vitamin D and 0.1% Ca. The animals fed 1% Ca had significantly higher serum 25D levels when compared to animals fed 0.1% Ca (P<0.05). The major determinants of serum 25D were dietary vitamin D and dietary calcium (Multiple R=0.75, P<0.05). Animals fed 0.1% Ca had higher renal CYP27B1 mRNA expression and 12-18-fold increased levels of serum 1,25D. Hence, the reported effects of low calcium diets on bone loss may be, in part, due to the subsequent effects of 25D metabolism leading to reduction in vitamin D status. Such an interaction has significant implications, given the recent evidence for local synthesis of active vitamin D in bone tissue.
The role of MAP kinase pathways in 1,25-dihydroxyvitamin D3 (1,25D)-induced differentiation of myeloid leukemia cells is well established, but the mechanisms by which 1,25D activates these pathways are not entirely clear. Following the finding that kinase suppressors of ras (KSR) 1 and 2 are directly regulated by 1,25D and participate in the monocytic differentiation process, we investigated if the COT1 oncogene (Tpl2 in the rat), known to interact with human KSR2 (hKSR2), is also involved in 1,25D-induced differentiation in leukemia cells. Here we report that the exposure of HL60 and U937 myeloid leukemia cells to 1,25D increases COT1 expression in a concentration-dependent manner. However, COT1 appears to have a differentiation-limiting role in these cells, as an exposure of HL60 and U937 cells to a pharmacological inhibitor of COT1 kinase activity, 4-(3-chloro-4-fluorophenylamino)-6-(pyridin-3-yl-methylamino-3-cyano-[1-7]-naphthyridine, results in increased 1,25D-induced differentiation. These findings provide an additional insight into the 1,25D-regulation of MAPK pathways that contribute to monocytic differentiation process of myeloid leukemia cells.