MYD88 L265P Mutations, But No Other Variants, Identify a Subpopulation of DLBCL Patients of Activated B-cell Origin, Extranodal Involvement, and Poor Outcome

PURPOSE

Mutations in MYD88 are found in different lymphoproliferative disorders associated with particular biologic characteristics and clinical impact. The aim of this study was to analyze the incidence of MYD88 mutations and its clinical impact in diffuse large B-cell lymphoma (DLBCL).

EXPERIMENTAL DESIGN

The incidence, clinicobiological features, and outcome of 213 patients (115 M/98 F; median age, 65 years) with DLBCL treated with immunochemotherapy in a single institution according to MYD88 mutational status as assessed by an allele-specific PCR assay were analyzed. The cell of origin (COO) was determined in 129 cases by gene expression.

RESULTS

MYD88 mutations were found in 47 cases (22%), including L265P in 39 and S219C and M232F in 4 cases, respectively. Patients with MYD88 L265P were older, presenting frequent extranodal involvement, and mostly corresponded to activated B-cell like (ABC) subtype, whereas no preference in COO was observed in patients with other MYD88 mutations. Five-year overall survival (OS) for MYD88 wild-type, MYD88 L265P, and other variants was 62%, 52%, and 75%, respectively (P = 0.05). International Prognostic Index (IPI) (HR, 2.71; P < 0.001) and MYD88 L265P (HR, 1.786; P = 0.023) were independent variables predicting OS in the multivariate analysis. However, MYD88 L265P lost its independent value when COO was included in the model.

CONCLUSIONS

Our findings indicate that MYD88 L265P mutations, but no other variants, identify a subgroup of DLBCL mainly of ABC origin, with extranodal involvement and poor outcome. Clin Cancer Res; 22(11); 2755-64. ©2016 AACR.

Blocking interferon γ reduces expression of chemokines CXCL9, CXCL10 and CXCL11 and decreases macrophage infiltration in ex vivo cultured arteries from patients with giant cell arteritis

Background

Interferon γ (IFNγ) is considered a seminal cytokine in the pathogenesis of giant cell arteritis (GCA), but its functional role has not been investigated. We explored changes in infiltrating cells and biomarkers elicited by blocking IFNγ with a neutralising monoclonal antibody, A6, in temporal arteries from patients with GCA.

Methods

Temporal arteries from 34 patients with GCA (positive histology) and 21 controls were cultured on 3D matrix (Matrigel) and exposed to A6 or recombinant IFNγ. Changes in gene/protein expression were measured by qRT-PCR/western blot or immunoassay. Changes in infiltrating cells were assessed by immunohistochemistry/immunofluorescence. Chemotaxis/adhesion assays were performed with temporal artery-derived vascular smooth muscle cells (VSMCs) and peripheral blood mononuclear cells (PBMCs).

Results

Blocking endogenous IFNγ with A6 abrogated STAT-1 phosphorylation in cultured GCA arteries. Furthermore, selective reduction in CXCL9, CXCL10 and CXCL11 chemokine expression was observed along with reduction in infiltrating CD68 macrophages. Adding IFNγ elicited consistent opposite effects. IFNγ induced CXCL9, CXCL10, CXCL11, CCL2 and intracellular adhesion molecule-1 expression by cultured VSMC, resulting in increased PBMC chemotaxis/adhesion. Spontaneous expression of chemokines was higher in VSMC isolated from GCA-involved arteries than in those obtained from controls. Incubation of IFNγ-treated control arteries with PBMC resulted in adhesion/infiltration by CD68 macrophages, which did not occur in untreated arteries.

Conclusions

Our ex vivo system suggests that IFNγ may play an important role in the recruitment of macrophages in GCA by inducing production of specific chemokines and adhesion molecules. Vascular wall components (ie, VSMC) are mediators of these functions and may facilitate progression of inflammatory infiltrates through the vessel wall.

Genome-wide methylation analyses identify a subset of mantle cell lymphoma with a high number of methylated CpGs and aggressive clinicopathological features

Mantle cell lymphoma (MCL) is a B-cell neoplasm with an aggressive clinical behavior characterized by the t(11;14)(q13;q32) and cyclin D1 overexpression. To clarify the potential contribution of altered DNA methylation in the development and/or progression of MCL, we performed genome-wide methylation profiling of a large cohort of primary MCL tumors (n = 132), MCL cell lines (n = 6) and normal lymphoid tissue samples (n = 31), using the Infinium HumanMethylation27 BeadChip. DNA methylation was compared to gene expression, chromosomal alterations and clinicopathological parameters. Primary MCL displayed a heterogeneous methylation pattern dominated by DNA hypomethylation when compared to normal lymphoid samples. A total of 454 hypermethylated and 875 hypomethylated genes were identified as differentially methylated in at least 10% of primary MCL. Annotation analysis of hypermethylated genes recognized WNT pathway inhibitors and several tumor suppressor genes as frequently methylated, and a substantial fraction of these genes (22%) showed a significant downregulation of their transcriptional levels. Furthermore, we identified a subset of tumors with extensive CpG methylation that had an increased proliferation signature, higher number of chromosomal alterations and poor prognosis. Our results suggest that a subset of MCL displays a dysregulation of DNA methylation characterized by the accumulation of CpG hypermethylation highly associated with increased proliferation that may influence the clinical behavior of the tumors.

Association of NOS2 and potential effect of VEGF, IL6, CCL2 and IL1RN polymorphisms and haplotypes on susceptibility to GCA--a simultaneous study of 130 potentially functional SNPs in 14 candidate genes

OBJECTIVE

Frequent genetic variants may be associated with GCA. Existing studies have analysed a limited number of candidate genes and genetic variants. To expand this information, we performed a case-control study genotyping 130 single nucleotide polymorphisms (SNPs) in 82 biopsy-proven GCA patients and 166 healthy controls from the Spanish population.

METHODS

SNPs in coding and regulatory gene regions of 14 candidate genes (CCL2, CCR7, IL10, IL12A, IL1A, IL1B, IL1RN, IL6, IL8, INFG, LTA, NOS2, TNF and VEGF) were explored using the Illumina Bead Array System. Multivariate methods based on logistic regression were used for statistical analysis.

RESULTS

Nine SNPs located in five genes had significant association with GCA risk (P < 0.05). These SNPs were located in the NOS2 (rs2779251), VEGF (rs1885657, rs2010963, rs699946 and rs699947), IL1RN (rs17207494), IL6 (rs7805828 and rs1546766) and CCL2 (rs1860190) genes. The strongest associations were seen for rs2779251, rs1885657 and rs2010963 (P = 2.3 × 10(-5), P = 0.0078 and P = 0.0097, respectively). The presence of the minor allele of NOS2 variant rs2779251 had a protective effect on the risk for GCA [odds ratio (OR) = 0.27, 95% CI 0.14, 0.52]. Risk alleles for three of the four SNPs in the VEGF gene (rs2010963, rs699946 and rs699947) were associated in homozygosis with increased risk (OR = 4.22, 95% CI 1.38, 12.87; OR = 9.04, 95% CI 1.58, 51.81; and OR = 2.38, 95% CI 1.05, 5.38, respectively), whereas a minor allele for the other SNP (rs1885657) had a protective effect (OR = 0.46, 95% CI 0.26, 0.84).

CONCLUSION

Common genetic variants in NOS2, VEGF, IL6, ILRN1 and CCL2 genes are associated with GCA, indicating a polygenic influence on disease susceptibility.

Effects of bilirubin and sera from jaundiced patients on osteoblasts: contribution to the development of osteoporosis in liver diseases

Low bone formation is considered to be the main feature in osteoporosis associated with cholestatic and end-stage liver diseases, although the consequences of retained substances in chronic cholestasis on bone cells have scarcely been studied. Therefore, we analyzed the effects of bilirubin and serum from jaundiced patients on viability, differentiation, mineralization, and gene expression in the cells involved in bone formation. The experiments were performed in human primary osteoblasts and SAOS-2 human osteosarcoma cells. Unconjugated bilirubin or serum from jaundiced patients resulted in a dose-dependent decrease in osteoblast viability. Concentrations of bilirubin or jaundiced serum without effects on cell survival significantly diminished osteoblast differentiation. Mineralization was significantly reduced by exposure to 50 μM bilirubin at all time points (from -32% to -55%) and jaundiced sera resulted in a significant decrease on cell mineralization as well. Furthermore, bilirubin down-regulated RUNX2 (runt-related transcription factor 2) gene expression, a basic osteogenic factor involved in osteoblast differentiation, and serum from jaundiced patients significantly up-regulated the RANKL/OPG (receptor activator of nuclear factor-κB ligand/osteoprotegerin) gene expression ratio, a system closely involved in osteoblast-induced osteoclastogenesis.

CONCLUSION

Besides decreased cell viability, unconjugated bilirubin and serum from jaundiced patients led to defective consequences on osteoblasts. Moreover, jaundiced serum up-regulates the system involved in osteoblast-induced osteoclastogenesis. These results support the deleterious consequences of increased bilirubin in advanced chronic cholestasis and in end-stage liver diseases, resulting in disturbed bone formation related to osteoblast dysfunction.

A putative "hepitype" in the ATM gene associated with chronic lymphocytic leukemia risk

Chronic lymphocytic leukemia (CLL) cells are characterized by several chromosomal lesions. Some of these aberrations imply chromosome breaks as a result of unrepaired double strand breaks (DSBs) in the DNA. The ATM (ataxia telangiectasia-mutated) protein is the principal integrator of cellular responses to DSBs. ATM deletion is also an adverse prognostic factor in CLL. Taking this into account, we evaluated if genetic and/or epigenetic variation in the ATM gene may modulate the individual susceptibility to develop CLL. Our case-control association study was performed in a large Spanish population of 1,503 individuals, including 742 patients with CLL and 761 controls. We identified one haplotype within the ATM gene that confers an increased risk of CLL development (OR = 1.33; 95% CI: 1.10-1.60). Two polymorphisms of this ATM haplotype eliminated one CpG site each in Introns 15 and 61, causing changes in DNA methylation pattern. These data provide the first evidence for the existence of a putative "hepitype" in the ATM gene associated with CLL risk.

Whole-genome sequencing identifies recurrent mutations in chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL), the most frequent leukaemia in adults in Western countries, is a heterogeneous disease with variable clinical presentation and evolution. Two major molecular subtypes can be distinguished, characterized respectively by a high or low number of somatic hypermutations in the variable region of immunoglobulin genes. The molecular changes leading to the pathogenesis of the disease are still poorly understood. Here we performed whole-genome sequencing of four cases of CLL and identified 46 somatic mutations that potentially affect gene function. Further analysis of these mutations in 363 patients with CLL identified four genes that are recurrently mutated: notch 1 (NOTCH1), exportin 1 (XPO1), myeloid differentiation primary response gene 88 (MYD88) and kelch-like 6 (KLHL6). Mutations in MYD88 and KLHL6 are predominant in cases of CLL with mutated immunoglobulin genes, whereas NOTCH1 and XPO1 mutations are mainly detected in patients with unmutated immunoglobulins. The patterns of somatic mutation, supported by functional and clinical analyses, strongly indicate that the recurrent NOTCH1, MYD88 and XPO1 mutations are oncogenic changes that contribute to the clinical evolution of the disease. To our knowledge, this is the first comprehensive analysis of CLL combining whole-genome sequencing with clinical characteristics and clinical outcomes. It highlights the usefulness of this approach for the identification of clinically relevant mutations in cancer.

Identification of methylated genes associated with aggressive clinicopathological features in mantle cell lymphoma

BACKGROUND

Mantle cell lymphoma (MCL) is genetically characterized by the t(11;14)(q13;q32) translocation and a high number of secondary chromosomal alterations. The contribution of DNA methylation to MCL lymphomagenesis is not well known. We sought to identify epigenetically silenced genes in these tumours that might have clinical relevance.

METHODOLOGY/PRINCIPAL FINDINGS

To identify potential methylated genes in MCL we initially investigated seven MCL cell lines treated with epigenetic drugs and gene expression microarray profiling. The methylation status of selected candidate genes was validated by a quantitative assay and subsequently analyzed in a series of primary MCL (n = 38). After pharmacological reversion we identified 252 potentially methylated genes. The methylation analysis of a subset of these genes (n = 25) in the MCL cell lines and normal B lymphocytes confirmed that 80% of them were methylated in the cell lines but not in normal lymphocytes. The subsequent analysis in primary MCL identified five genes (SOX9, HOXA9, AHR, NR2F2, and ROBO1) frequently methylated in these tumours. The gene methylation events tended to occur in the same primary neoplasms and correlated with higher proliferation, increased number of chromosomal abnormalities, and shorter survival of the patients.

CONCLUSIONS

We have identified a set of genes whose methylation degree and gene expression levels correlate with aggressive clinicopathological features of MCL. Our findings also suggest that a subset of MCL might show a CpG island methylator phenotype (CIMP) that may influence the behaviour of the tumours.

Verification that common variation at 2q37.1, 6p25.3, 11q24.1, 15q23, and 19q13.32 influences chronic lymphocytic leukaemia risk

A recent genome wide association study of chronic lymphocytic leukaemia (CLL) provided evidence that common variation at 2q13 (rs17483466), 2q37.1 (rs13397985), 6p25.3 (rs872071), 11q24.1 (rs735665), 15q23 (rs7176508) and 19q13.32 (rs11083846) affects CLL risk. To verify and further explore the relationship between these variants and CLL risk we genotyped case-control datasets from Spain and Sweden (824 cases, 850 controls). Combined data provided statistically significant support for an association between genotypes at rs13397985, rs872071, rs735665, rs7176508 and rs11083846 and CLL risk. CLL risk increased with increasing numbers of risk alleles (P(trend) = 1.40 x 10(-15)), consistent with a polygenic model of disease susceptibility. These data validate the relationship between common variation and risk of CLL.

The effect of the alendronate on OPG/RANKL system in differentiated primary human osteoblasts

Alendronate is a well-established treatment for osteoporosis and suppresses bone resorption by a direct effect on osteoclasts and their precursors. The effect of alendronate on osteoclasts is produced, at least in part, by the receptor activator of nuclear factor kappaB ligand (RANKL) and the osteoprotegerin (OPG) synthesized by the osteoblasts. This study analyzes the effect of alendronate in cell viability, alkaline phosphatase (ALP) activity and RANKL and OPG expression in primary human osteoblasts (hOB). Alendronate at concentrations lower than 10⁻⁵ M did not have a toxic effect on hOB in vitro and did not modify the ALP activity at least for 72 h. Alendronate did not change OPG expression in basal, 10% fetal bovine serum (FBS), and vitamin D-treated cultures. Similar results were observed at the protein level. Unexpectedly, alendronate at 10⁻⁷ and 10⁻⁵ M concentrations increased the RANKL expression with the presence of vitamin D in differentiated hOB, and this induction of RANKL mRNA levels by alendronate was dose-dependent. However, this effect was not observed in basal and 10% FBS culture conditions. Thus, we conclude that alendronate does not affect the ALP activity and OPG gene expression in differentiated hOB, but may increase RANKL gene expression induced by vitamin D.

The effect of the alendronate on OPG/RANKL system in differentiated primary human osteoblasts

Alendronate is a well-established treatment for osteoporosis and suppresses bone resorption by a direct effect on osteoclasts and their precursors. The effect of alendronate on osteoclasts is produced, at least in part, by the receptor activator of nuclear factor kappaB ligand (RANKL) and the osteoprotegerin (OPG) synthesized by the osteoblasts. This study analyzes the effect of alendronate in cell viability, phosphatase alkaline (ALP) activity and RANKL, and OPG expression in primary human osteoblasts (hOB). Alendronate at concentrations lower than 10(-5) M did not have a toxic effect on hOB in vitro and did not modify the ALP activity at least for 72 h. Alendronate did not change OPG expression in basal, 10% FBS, and vitamin D-treated cultures. Similar results were observed at the protein level. Unexpectedly, alendronate at 10(-7) and 10(-5) M concentrations increased the RANKL expression with the presence of vitamin D in differentiated hOB and this induction of RANKL mRNA levels by alendronate was dose-dependent. However, this effect was not observed in basal and 10% FBS culture conditions. Thus, we conclude that alendronate does not affect the ALP activity and OPG gene expression in differentiated hOB, but may increase RANKL gene expression induced by vitamin D.

Common variants at 2q37.3, 8q24.21, 15q21.3 and 16q24.1 influence chronic lymphocytic leukemia risk

To identify new risk variants for chronic lymphocytic leukemia (CLL), we conducted a genome-wide association study of 299,983 tagging SNPs, with validation in four additional series totaling 2,503 cases and 5,789 controls. We identified four new risk loci for CLL at 2q37.3 (rs757978, FARP2; odds ratio (OR) = 1.39; P = 2.11 x 10(-9)), 8q24.21 (rs2456449; OR = 1.26; P = 7.84 x 10(-10)), 15q21.3 (rs7169431; OR = 1.36; P = 4.74 x 10(-7)) and 16q24.1 (rs305061; OR = 1.22; P = 3.60 x 10(-7)). We also found evidence for risk loci at 15q25.2 (rs783540, CPEB1; OR = 1.18; P = 3.67 x 10(-6)) and 18q21.1 (rs1036935; OR = 1.22; P = 2.28 x 10(-6)). These data provide further evidence for genetic susceptibility to this B-cell hematological malignancy.

Lithocholic acid downregulates vitamin D effects in human osteoblasts

BACKGROUND

Osteoporosis is a common complication in chronic cholestasis. It has been proposed that retained substances such as bile acids may produce a damaging effect on bone cells. This study analyses the effects of lithocholic acid (LCA) on cell survival and vitamin D metabolism in human osteoblasts (hOB).

MATERIALS AND METHODS

Human osteoblasts cultures were performed with or without foetal bovine serum (FBS) or human albumin (HA) at different LCA concentrations and times with or without vitamin D.

RESULTS

Lithocholic acid at concentrations higher than 10(-5 )M decreased cell survival. This effect was partially prevented by the presence of FBS or HA. Vitamin D stimulated CYP24A, BGLAP and TNFSF11 expression in hOB and these effects were modified by nontoxic LCA concentrations. LCA significantly decreased vitamin D stimulation of CYP24A, BGLAP and TNFSF11 gene expression at 72%, 79% and 56% (respectively). LCA alone has an agonistic effect, as has vitamin D, thus partially increasing CYP24A and BGLAP expression, but with no changes on TNFRSF11B expression. Equivalent effects of the LCA were observed by performing gene reporter assays using MG-63 cells transfected with constructs containing CYP24A1 promoter regions.

CONCLUSIONS

Lithocholic acid decreases the stimulatory effect of vitamin D on CYP24A, BGLAP and TNFSF11 expression in hOB. This effect is produced through vitamin D response elements (VDREs), located in the promoter regions of these genes, suggesting that LCA acts as a mild analogous of vitamin D, interacting with the vitamin D receptor. These results may explain the potential deleterious effects of retained bile acids on hOB.

High osteoprotegerin serum levels in primary biliary cirrhosis are associated with disease severity but not with the mRNA gene expression in liver tissue

The influence of osteoprotegerin and RANKL as regulators of osteoclastogenesis and bone remodeling in liver disease and in the development of osteoporosis in primary biliary cirrhosis (PBC) is uncertain. Therefore, 68 women with PBC and 20 healthy females were studied by assessing circulating osteoprotegerin and RANKL. Bone mineral density and markers of bone turnover were measured as well. Osteoprotegerin-mRNA expression was also assessed in liver tissue from 16 patients and 5 controls. Osteoprotegerin was higher in PBC than in controls (5.4 +/- 0.2 vs. 2.9 +/- 0.2 pM/l, P < 0.0001), whilst RANKL was lower in patients than in controls (0.39 +/- 0.06 vs. 1.40 +/- 0.16 pM/l, P < 0.0001). Osteoprotegerin was more elevated in patients with more advanced disease, as defined by bilirubin above 1.2 mg/dl (6.6 +/- 0.6 vs. 5.2 +/- 0.2 pM/l, P = 0.02) or by Mayo over 4 (5.9 +/- 0.3 vs. 4.8 +/- 0.2 pM/l, P = 0.02). Osteoprotegerin and RANKL were unrelated with osteoporosis, and no associations were found with markers of bone remodeling, except for RANKL, which was particularly decreased in patients with low osteocalcin. This marker of bone formation was also higher in patients with elevated circulating osteoprotegerin. Liver osteoprotegerin gene expression was similar in patients and controls, and no correlation was found between liver osteoprotegerin-mRNA and patients' respective circulating levels. In conclusion, osteoprotegerin and RANKL are abnormal in patients with PBC, regardless of osteoporosis. The elevated circulating osteoprotegerin is associated with the severity of disease, but not with gene expression in the liver.

COL1A1, ESR1, VDR and TGFB1 polymorphisms and haplotypes in relation to BMD in Spanish postmenopausal women

INTRODUCTION AND HYPOTHESIS

Genetic studies of osteoporosis have focused on analysing single polymorphisms in individual genes - with inconclusive results. An alternative approach may involve haplotypes and gene-gene interactions. The aim of the study was to test the association between the COL1A1, ESR1, VDR and TGFB1 polymorphisms or haplotypes and bone mineral density (BMD) in Spanish postmenopausal women.

METHODS

Sixteen polymorphisms were analysed in 719 postmenopausal women. ANOVA, ANCOVA and Xi2 tests were used to perform the statistical analysis.

RESULTS

COL1A1 -1997G > T (p=0.04) and TGFB1 Leu10Pro (p=0.02) were found to be associated with adjusted lumbar spine (LS) BMD. Interactions were observed between: the COL1A1 -1997 G/T and Sp1 polymorphisms (p < 0.01 for LS BMD) and the COL1A1 -1663 indelT and VDR ApaI polymorphisms (p < 0.01 for femoral neck (FN) BMD). The COL1A1 GDs and ESR1 LPX haplotypes were associated with FN BMD (p=0.03 and p=0.03).

CONCLUSIONS

Polymorphisms at COL1A1 and TGFB1 and haplotypes at COL1A1 and ESR1 were found to be associated with BMD in a cohort of postmenopausal Spanish women. Moreover, COL1A1 polymorphisms showed significant interactions among them and with the VDR 3' polymorphisms.

[Effect of tobacco smoking on leptin serum levels and its relationship with steroid hormones and bone mineral density]

BACKGROUND AND OBJECTIVE

Leptin is an hormone resulting from the obesity gene. Their actions could be important in the pathogenesis of the osteoporosis. The aim of this study is to analyse the influence of tobacco on serum leptin levels, and its relationship with bone mineral density (BMD) and steroid hormones.

SUBJECTS AND METHOD

A group of healthy volunteers were recruited and classified as smokers or non-smokers. A subgroup of smokers ceased smoking during one month. Serum leptin and steroids hormones levels were analysed, and a baseline BMD was measured. In the abstinent group the analysis was repeated at the end of the study.

RESULTS

Fifty-nine healthy volunteers were included (22 of which were smokers). Fifteen smokers remained abstinent for a month. Both groups were similar except in age, being smokers older. Male smokers had lower lumbar BMD (p = 0.017). After adjusting by age, serum leptin levels were higher in smokers than in non-smokers, with statistical differences in women (p = 0.049). Abstinence increased leptin levels, though not reaching statistical significance. An inverse correlation between leptin levels and androstendione in men (r = -0.622; p = 0.001), and a positive correlation with testosterone in women (r = 0.405; p = 0.019) were found. After adjusting by body mass index, only the correlation of leptin levels with androstendione persisted.

CONCLUSIONS

Leptin negatively correlate with sex hormones in young men and is influenced by smoking in young women. Thus, the hormone could be relevant for bone mass regulation in smoker persons.

Simvastatin and atorvastatin enhance gene expression of collagen type 1 and osteocalcin in primary human osteoblasts and MG-63 cultures

To clarify the mechanism of the stimulatory effect of statins on bone formation, we have assessed the effect of simvastatin and atorvastatin on osteoblast activity by analysing cell proliferation, as well as collagen, osteocalcin, and bone morphogenetic protein-2 (BMP2) gene expression in primary human osteoblast (hOB) and MG-63 cell line cultures. Explants of bone from patients without any metabolic disease under orthopedic hip procedures were used to obtain hOB. Cell cultures were established, synchronized, and different concentrations of simvastatin or atorvastatin were added (10(-9) M, 10(-8) M, 10(-7) M, 10(-6) M) during the experiment. Cell proliferation was analyzed after 24 h. Collagen polypeptide alpha1 type 1 (COL1A1) gene expression, osteocalcin, and BMP2 expression levels were quantified by real-time PCR after 24 h incubation with statins. There was a statistically significant decrease in cell proliferation related to simvastatin or atorvastatin addition at all concentrations in primary hOB compared with those not treated. A significant increase in COL1A1, osteocalcin, and BMP2 gene expression was detected when hOB cultures were treated with simvastatin or atorvastatin at different concentrations. Similar but less significant effects were found on MG-63 cells. After statin treatment we observed both an arrest of proliferation in hOB cells and an increase in collagen, osteocalcin, and BMP2 gene expression, consistent with a stimulatory effect towards mature osteoblast differentiation. These findings support the bone-forming effect of statins, probably through the BMP2 pathway.

The association between common vitamin D receptor gene variations and osteoporosis: a participant-level meta-analysis

BACKGROUND

Polymorphisms of the vitamin D receptor (VDR) gene have been implicated in the genetic regulation of bone mineral density (BMD). However, the clinical impact of these variants remains unclear.

OBJECTIVE

To evaluate the relation between VDR polymorphisms, BMD, and fractures.

DESIGN

Prospective multicenter large-scale association study.

SETTING

The Genetic Markers for Osteoporosis consortium, involving 9 European research teams.

PARTICIPANTS

26,242 participants (18,405 women).

MEASUREMENTS

Cdx2 promoter, FokI, BsmI, ApaI, and TaqI polymorphisms; BMD at the femoral neck and the lumbar spine by dual x-ray absorptiometry; and fractures.

RESULTS

Comparisons of BMD at the lumbar spine and femoral neck showed nonsignificant differences less than 0.011 g/cm2 for any genotype with or without adjustments. A total of 6067 participants reported a history of fracture, and 2088 had vertebral fractures. For all VDR alleles, odds ratios for fractures were very close to 1.00 (range, 0.98 to 1.02) and collectively the 95% CIs ranged from 0.94 (lowest) to 1.07 (highest). For vertebral fractures, we observed a 9% (95% CI, 0% to 18%; P = 0.039) risk reduction for the Cdx2 A-allele (13% risk reduction in a dominant model).

LIMITATIONS

The authors analyzed only selected VDR polymorphisms. Heterogeneity was detected in some analyses and may reflect some differences in collection of fracture data across cohorts. Not all fractures were related to osteoporosis.

CONCLUSIONS

The FokI, BsmI, ApaI, and TaqI VDR polymorphisms are not associated with BMD or with fractures, but the Cdx2 polymorphism may be associated with risk for vertebral fractures.

Effect of smoking and smoking cessation on bone mass, bone remodeling, vitamin D, PTH and sex hormones

OBJECTIVE

To assess the effect of smoking and smoking cessation on bone density, bone remodeling markers, sex hormones, and vitamin D-PTH axis in healthy young subjects.

MATERIALS AND METHODS

We studied 74 healthy people (31 men, 43 women; mean age 32.2 (7) years) divided into 52 never smokers and 22 smokers, 15 of which stopped smoking for one month.

RESULTS

Male smokers compared with never smokers showed lower BMD (0.971 (0.11) g/cm(2) vs. 1.069 (0.09) g/cm(2), P=0.042); higher plasma estrone levels (32.37 (10.13) pg/mL vs. 20.91 (5.46) pg/mL, P=0.001); and lower serum iPTH levels (16.2 (3.5) pg/mL vs. 28.8 (2.0) pg/mL, P=0.008). In women, BMD values were similar in smokers than in never smokers, but 25-hydroxyvitamin D levels were lower in smokers (31.9 (15.1) ng/mL vs. 16.8 (9.9) ng/mL, P=0.002). After adjusting by age and coffee consumption, female smokers had higher urinary-NTX levels than never smokers. After smoking cessation, statistically significant decreases of 25-hydroxyvitamin D and SHBG plasma levels were observed in men and women, respectively.

CONCLUSIONS

Tobacco increases bone resorption and affects bone mass by some alterations in sex hormone metabolism, but also importantly by alterations on the vitamin D-PTH axis.

A new SNP in a negative regulatory region of the CYP19A1 gene is associated with lumbar spine BMD in postmenopausal women

Osteoporosis is a common disease of bone possessing a strong genetic component. Cytochrome P450 aromatase, which is encoded by the CYP19A1 gene, converts androgens to estradiol. Considerable evidence suggests that extragonadal estrogens play an important role in determining bone mineral density (BMD) in postmenopausal women, and, among them, those synthesized in bone cells may also be important for the determination of bone phenotype. Therefore, CYP19A1 is an excellent candidate gene for osteoporosis. Since a region upstream of exon I.3, including exon I.6, was identified as containing repressor elements of promoter pII, we conducted a search for SNPs in this region of CYP19A1. Two SNPs [Aro1(rs4775936) and Aro2] located in exon I.6 and promoter I.6, respectively, were identified and their association with BMD analyzed in a cohort of 256 Spanish postmenopausal women. Aro1(rs4775936), but not Aro2, was associated with lumbar spine BMD (P = 0.029). Homozygotes AA (16% of the women) exhibited significantly higher lumbar spine BMD, compared with GG or GA individuals. Therefore, this study describes the Aro1 polymorphism which lies within a regulatory region and which may be a functional polymorphism, partially responsible for the bone phenotype it is associated with.

Functional analysis of the I.3, I.6, pII and I.4 promoters of CYP19 (aromatase) gene in human osteoblasts and their role in vitamin D and dexamethasone stimulation

OBJECTIVE

Current evidence suggests that extragonadal estrogens play an important role in bone metabolism. Estrogen biosynthesis is catalyzed by P450aromatase, encoded by the CYP19 gene. The aims of this paper were to study CYP19 gene expression in human osteoblasts under several hormone and cytokine treatments and to define promoter regions involved in this regulation.

METHODS

CYP19 transcript levels were measured from primary human osteoblasts and MG-63 cells by real-time PCR in basal conditions, and in response to seven different hormones and cytokines. Four promoters of CYP19 gene were cloned upstream of the luciferase gene and transfected into MG-63 cells. The effect of vitamin D and dexamethasone in these promoter activities was evaluated.

RESULTS

Vitamin D and dexamethasone were potent stimulators of CYP19 transcription, while testosterone and 17beta-estradiol stimulated moderately. Promoter pII proved the most potent in driving transient luciferase expression. Promoter I.4 displayed moderate activity, while promoters I.3 and I.6 were weak. A region upstream of exon I.3, including exon I.6, was identified as containing repressor elements of promoter pII. Promoter I.3 activity was modulated by repressors located within exon I.3, while an enhancer of promoter I.4 was detected within exon I.4. In the absence of fetal calf serum, dexamethasone stimulation was observed on promoters I.3 and I.4, while vitamin D stimulation acted only on promoter I.3.

CONCLUSIONS

Four regulatory regions of promoters pII, I.3 and I.4 are relevant to CYP19 expression in human osteoblasts. Vitamin D and dexamethasone modulate transcription through these regions.

In vitro functional assay of alleles and haplotypes of two COL1A1-promoter SNPs

Osteoporosis is a common disease with a strong genetic component. We previously described two polymorphic sites in the COL1A1 gene promoter, -1997 G/T and -1663indelT, which have been associated with bone mineral density (BMD), a surrogate trait for osteoporosis. Here, we explore the molecular mechanisms underlying this association by performing transient transfections in MG-63 cells of constructs bearing different COL1A1 promoter regions, containing different alleles or haplotypes of the polymorphic sites. These promoter regions drove the transcription of a luciferase reporter gene. The main differences in transcriptional activity relied on an inhibitory region localized to the -1284 to -254 interval. Regarding the polymorphisms, reproducible differences were observed between the alleles of each of them: the G allele at -1997 showed a higher transcriptional activity than the T allele, as did the 7T allele of -1663 as compared with 8T. Accordingly, the T-8T haplotype was the weakest transcriber. A functional interaction was found between the -1997 and -1663 polymorphisms, in that the difference in transcriptional activity between the 7T and 8T alleles was dependent on the allele at -1997. This different transcriptional activity of the two -1663indelT alleles correlated with different binding capacities of the corresponding oligonucleotides to osteoblast nuclear proteins. Supershift assays allowed us to identify one of these proteins as the architectural transcription factor Nmp4/CIZ, a protein known to be an inhibitor of BMP/Smad signalling.