Effect of progesterone on apoptosis of murine MC3T3-E1 osteoblastic cells

Comparative- and network-based proteomic analysis of bacterial chondronecrosis with osteomyelitis lesions in broiler's proximal tibiae identifies new molecular signatures of lameness

Bacterial Chondronecrosis with Osteomyelitis (BCO) is a specific cause of lameness in commercial fast-growing broiler (meat-type) chickens and represents significant economic, health, and wellbeing burdens. However, the molecular mechanisms underlying the pathogenesis remain poorly understood. This study represents the first comprehensive characterization of the proximal tibia proteome from healthy and BCO chickens. Among a total of 547 proteins identified, 222 were differentially expressed (DE) with 158 up- and 64 down-regulated proteins in tibia of BCO vs. normal chickens. Biological function analysis using Ingenuity Pathways showed that the DE proteins were associated with a variety of diseases including cell death, organismal injury, skeletal and muscular disorder, immunological and inflammatory diseases. Canonical pathway and protein-protein interaction network analysis indicated that these DE proteins were involved in stress response, unfolded protein response, ribosomal protein dysfunction, and actin cytoskeleton signaling. Further, we identified proteins involved in bone resorption (osteoclast-stimulating factor 1, OSFT1) and bone structural integrity (collagen alpha-2 (I) chain, COL2A1), as potential key proteins involved in bone attrition. These results provide new insights by identifying key protein candidates involved in BCO and will have significant impact in understanding BCO pathogenesis.

Timing and dosage of and adherence to hormone replacement therapy and fracture risk in women with menopausal syndrome in Taiwan: A nested case-control study

OBJECTIVE

To investigate the association between hormone replacement therapy (HRT) and the risk of bone fracture in menopausal women in Taiwan.

STUDY DESIGN

The longitudinal, population-based, nested case-control study in Taiwan involved 5269 women aged > 45 years with fractures and 21,076 matched randomly selected controls without fractures. A conditional logistic regression model of analysis was employed.

MAIN OUTCOME MEASURES

The association between the risk of bone fracture and various HRT-related parameters, including the timing, dosage, and adherence, was investigated.

RESULTS

Women with menopausal syndrome were protected from fractures when they received hormone drugs at high cumulative defined daily doses (DDDs) (Cumulative DDDs≥360) (odds ratio [OR]: 0.90, 95 % confidence interval [CI]: 0.82-0.99) and when their adherence was high (over 0.5) (OR: 0.70, 95 % CI: 0.60-0.82). The risk of fracture also decreased with high cumulative DDDs and high adherence combined (OR: 0.71, 95 % CI: 058-0.86). Subgroup analyses suggested that estrogen-containing regimens showed a protective effect against fractures at high cumulative DDDs or when adherence was high. Similar results were also observed with progestogen-containing regimens. Past exposure to an estrogen-containing regimen showed a protective effect against fractures when adherence was high. Past exposure to a progestogen-containing regimen showed a protective effect against fractures at high cumulative DDDs and when adherence was high.

CONCLUSIONS

The results indicate that past exposure to estrogen-containing or progestogen-containing regimens exerts protective effects against bone fracture. These effects increased with higher cumulative DDDs and with adherence in a dose-dependent manner.

An UHPLC-MS/MS method for simultaneous determination of ten sex steroid hormones in ovariectomy-induced osteoporosis rat and its application in discovery of sex steroid hormones regulatory components of Xian-Ling-Gu-Bao capsule

Sex steroid hormones could directly affect the bone metabolism by regulating cell physiological functions. In female, it inevitably causes the abnormal levels of sex steroid hormones at post-menopause in vivo. Ovariectomized rats and mice are classic animal models of osteoporosis to better understand the action mechanism of anti-osteoporosis drugs. However, it is not clear whether Xian-Ling-Gu-Bao capsule (XLGB), a kidney-tonifying traditional Chinese medicine prescription, treat osteoporosis via regulating multiple sex steroid hormones. In the present study, a reliable method involving ultra high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC/TQ-XS-MS) was developed for simultaneous quantitative analysis of ten sex steroid hormones (three estrogens, five androgens and two progestogens) in rat and mouse serum. The results of methodology were acceptable. The validated method was then successfully applied in the determination of the levels of sex steroid hormones in ovariectomy-induced osteoporosis rats, as well as drug (17β-estradiol and XLGB) intervened rats. As a result, XLGB could not only significantly increase the level of 17β-estradiol, but also improve the levels of progesterone, 17α-hydroxyprogesterone and androstenedione. Combined with molecular docking results and pharmacokinetic parameters, psoralen, isopsoralen and sweroside were considered as the key effective components of XLGB to activate adenylyl cyclase on promoting the biosynthesis of multiple sex steroid hormones. It is the first time to evaluate the regulatory effect of kidney-tonifying traditional Chinese medicine prescription on the levels of steroids in ovariectomy-induced osteoporosis rat, as well as the potential substance basis and mechanism of steroid hormone regulation.

The apoptotic effects of progesterone on breast cancer (MCF-7) and human osteosarcoma (MG-636) cells

Purpose

Progesterone has been reported to inhibit the proliferation of breast cancer and osteosarcoma cells; however, its inhibitory mechanism has not yet been clarified. The aim of the present study was to clarify the effects of progesterone on apoptosis in breast cancer (MCF-7) and human osteosarcoma (MG-63) cells.

Materials and methods

In this experimental study the cytotoxic effect of progesterone was measured in MCF-7 and MG-63 cells exposed to different concentrations of progesterone using MTT assay, and effective concentrations were identified. The expression levels of the Bax, P53 and Bcl-2 genes were evaluated by real-time PCR, and caspase-3, 8 and 9 activity levels were determined using a colorimetric method. Hoechst staining and flow cytometry were used to confirm apoptosis. The data were statistically analyzed using one-way analysis of variance (ANOVA) and independent-samples t-test.

Results

Compared to the control group, we observed a significant increase in the expression levels of the Bax and P53 genes and the activity levels of caspase-3 and 9, and a significant decrease in the expression level of the Bcl-2 gene in MCF-7 and MG-63 treated with effective concentration of progesterone. The caspase-8 activity level did not change significantly in treated MG-63 but increased in treated MCF-7 cells. Hoechst staining and flow cytometry results confirmed apoptosis in the cells exposed to effective concentration of progesterone.

Conclusions

The cytotoxic effect of progesterone on breast cancer and osteosarcoma cells was mediated by apoptotic pathways. In this context, progesterone triggers the extrinsic and intrinsic apoptotic pathways in MCF-7 cells and induces the intrinsic apoptotic pathway in MG-63 cells.

In vitro effects of progesterone and the synthetic progestin medroxyprogesterone acetate on vascular remodeling

In this work we tested the hypothesis whether progesterone (Pg) or the synthetic progestin medroxyprogesterone acetate (MPA) could be involved in the regulation of events involved in vascular remodeling. Results revealed an enhancement in the capillary-like tubes formation induced by both progestogens. Unlike MPA, Pg acts through VEGF, nitric oxide, PI3K and ERK1/2 signaling pathways. However, the MPA effect depends on platelet activation. Under stress conditions, the proangiogenic action of Pg and MPA was sustained. The progestogens exhibit the ability to prevent vascular smooth muscle cells (VSMC) osteogenic transdifferentiation. Besides this antiosteogenic action, on bone cells the progestogens induced osteoblast maturation and mineralization. The mechanism of action of both steroids on vascular and bone cells involves the participation of progesterone receptor. The data presented in this work provide evidence that the progestogens reduce osteogenic-like transdifferentiation of VSMC and promote angiogenesis with a slight different mechanism of action elicited by each steroid.

Nuclear receptors in bone physiology and diseases

During the last decade, our view on the skeleton as a mere solid physical support structure has been transformed, as bone emerged as a dynamic, constantly remodeling tissue with systemic regulatory functions including those of an endocrine organ. Reflecting this remarkable functional complexity, distinct classes of humoral and intracellular regulatory factors have been shown to control vital processes in the bone. Among these regulators, nuclear receptors (NRs) play fundamental roles in bone development, growth, and maintenance. NRs are DNA-binding transcription factors that act as intracellular transducers of the respective ligand signaling pathways through modulation of expression of specific sets of cognate target genes. Aberrant NR signaling caused by receptor or ligand deficiency may profoundly affect bone health and compromise skeletal functions. Ligand dependency of NR action underlies a major strategy of therapeutic intervention to correct aberrant NR signaling, and significant efforts have been made to design novel synthetic NR ligands with enhanced beneficial properties and reduced potential negative side effects. As an example, estrogen deficiency causes bone loss and leads to development of osteoporosis, the most prevalent skeletal disorder in postmenopausal women. Since administration of natural estrogens for the treatment of osteoporosis often associates with undesirable side effects, several synthetic estrogen receptor ligands have been developed with higher therapeutic efficacy and specificity. This review presents current progress in our understanding of the roles of various nuclear receptor-mediated signaling pathways in bone physiology and disease, and in development of advanced NR ligands for treatment of common skeletal disorders.

The effect of pregnancy on orthodontic tooth movement in rats

Introduction: The purpose of this study was to investigate the effect of pregnancy on orthodontic tooth movement in Wistar rats. Material and Methods: Forty eight female three-month old Wistar rats with an average weight of 250±25 gr were selected and randomly divided into two experimental (pregnant) and control groups (non-pregnant). Maxillary central incisors were tipped distally by insertion of springs exerting 30g force. Two, seven and fourteen days after spring insertion animals were sacrificed. Then the mesioincisal distance between maxillary incisors were measured. Subsequently, histological sections were prepared to count osteoclasts under a light microscope. The data on the extent of orthodontic tooth movement, and the number of osteoclasts were analyzed by independent sample t-test. Results: The results indicated that 2,7 and 14 days after force application there was no significant difference in orthodontic tooth movement between experimental and control groups (p>0.05). The number of osteoclasts were significantly lower in the experimental group 7 and 14 days after spring insertion (p<0.05). Conclusion: Pregnancy may decrease the amount of tooth movement in the linear phase but it is not statistically significant. The number of osteoclasts is significantly decreased during pregnancy.

Key words:Pregnancy, rat, orthodontic tooth movement, osteoclast.

Inhibition of the progesterone nuclear receptor during the bone linear growth phase increases peak bone mass in female mice

Augmentation of the peak bone mass (PBM) may be one of the most effective interventions to reduce the risk of developing osteoporosis later in life; however treatments to augment PBM are currently limited. Our study evaluated whether a greater PBM could be achieved either in the progesterone nuclear receptor knockout mice (PRKO) or by using a nuclear progesterone receptor (nPR) antagonist, RU486 in mice. Compared to their wild type (WT) littermates the female PRKO mice developed significantly higher cancellous and cortical mass in the distal femurs, and this was associated with increased bone formation. The high bone mass phenotype was partially reproduced by administering RU486 in female WT mice from 1–3 months of age. Our results suggest that the inhibition of the nPR during the rapid bone growth period (1–3 months) increases osteogenesis, which results in acquisition of higher bone mass. Our findings suggest a crucial role for progesterone signaling in bone acquisition and inhibition of the nPR as a novel approach to augment bone mass, which may have the potential to reduce the burden of osteoporosis.

The effects of hormonal contraceptives on bone turnover markers and bone health

Sex hormones are important regulators of bone metabolism. As hormonal contraceptives contain either oestrogens or progestins, or a combination thereof, it is conceivable that these widely used agents have an effect on bone metabolism and bone health. The main users of hormonal contraceptives, adolescent girls and young women, are still building bone and accruing bone mass and may therefore be particularly susceptible to the effects of hormonal contraceptives on bone. Despite these concerns, the effects of hormonal contraceptives on bone health are still poorly understood. As biochemical markers of bone turnover have been proven useful tools in the assessment and monitoring of bone metabolism, we reviewed the effects of combined and gestagen-only hormonal contraceptives on bone turnover markers and related effects on bone mineral density and fracture risk in premenopausal women, as documented in the literature until January 2009.

Icaritin induces growth inhibition and apoptosis of human prostatic smooth muscle cells in an estrogen receptor-independent manner

Icaritin has selective estrogen receptor (ER) modulating activity. ERs are expressed in the prostate stroma, and estrogens have an important role in the pathology of benign prostatic hyperplasia (BPH). However, the impact of icaritin on BPH was not studied. Human prostatic smooth muscle cells (PSMCs) were treated with 0-100 microM icaritin, also using 10 microM ICI182780 as a specific ER antagonist. The effects on cell growth and apoptosis were determined by cell counting and sandwich-enzyme-immunoassay. Western blotting was employed to illustrate the possible mechanisms. Cell growth was strongly inhibited by icaritin, and this was accompanied by an augmented apoptosis. Few changes in icaritin-induced growth inhibition and apoptosis were observed after pretreatment in the presence of ICI182780. Consistent with growth inhibition and apoptosis induction, icaritin decreased cyclin D1 and CDK4 expression and increased Bax/Bcl-2 ratio in human PSMCs. Furthermore, icaritin induced sustained phosphorylation of extracellular signal-regulated kinase (ERK) in human PSMCs. PD98059, a specific ERK inhibitor, blocked the activation of ERK by icaritin and abolished the icaritin-induced growth inhibition and apoptosis. The results indicate that icaritin reduces growth and induces apoptosis in human PSMCs via ERK signaling pathway without involvement of ERs.