Citations

Abstract Some studies suggest that estrogen acts on bone by decreasing the production of interleukin-6 (IL-6), a cytokine that increases bone resorption, by osteoblasts or bone marrow cells. However, other studies have not confirmed this, possibly because of a low and variable number of estrogen receptors (ER) in the model systems used. Thus, we employed a recently developed human fetal osteoblast cell line with high levels of ER. Treatment (n = 4 experiments) with 0.01 to 10 nM of 17β-estradiol had no effect on the constitutive production of IL-6. However, stimulated production, induced by treatment with IL-1β plus tumor necrosis factor-α (TNF-α), was reduced in a dose-dependent manner to 74 + 3% (mean + SEM) of control (p < 0.01). This response was blocked by cotreatment with the type II antiestrogen ICI 182,780. Treatment with hydrocortisone (1 μM), a known inhibitor of IL-6 production in many cell types, reduced IL-6 production to 17 + 1% of control (p < 0.001). As assessed by Northern analysis, treatment (n = 3 experiments) with 0.01-10 nM of 17β-estradiol decreased steady-state levels of IL-6 mRNA in a dose-dependent manner. These data support the hypothesis that at least part of the antiresorptive action of estrogen in humans is mediated by decreased production of IL-6 by osteoblastic cells.

Abstract To gain insights into 1,25-dihydroxyvitamin D3 receptor (VDR) function during fetal bone development, we examined fetal rat tissues from gestational days 13–21 for the presence and distribution of VDR using immuno-histochemistry. Prior to ossification, VDR epitopes were observed in the mesenchyme condensing to form skeletal tissues, on day 13 in the developing vertebral column and limbs, and on day 17 of gestation in developing calvaria. Immunostaining for VDR was seen in proliferating and hypertrophic chondrocytes and in osteoblasts of limb buds and the vertebral column by day 17 of gestation. In calvaria, VDR epitopes were observed in osteoblasts by gestational day 19. VDR immunostaining was also evident in the skin of fetal limbs at all gestational ages examined. We show for the first time that the VDR appears very early in the developing fetal rat skeleton, suggesting that the VDR, in concert with its ligand, 1,25-dihydroxyvitamin D3, may play a role in the differentiation of mesenchymal precursors into bone tissue.

Abstract Vertebral fractures are the classic hallmark of osteoporosis, yet little is known of their epidemiology. The incidence of clinically diagnosed vertebral fractures was therefore directly assessed in the predominantly white (European descent) population of Rochester, Minnesota. Altogether, 341 Rochester residents were radiologically diagnosed for the first time with one or more vertebral fractures in the 5 year study period, 1985–1989. The overall age- and sex-adjusted incidence rate was 117 per 100,000 person-years (95% CI, 105 to 130). The age-adjusted rate in women (145 per 100,000 person-years) was almost twice that in men (73 per 100,000 person-years). Of all fractures, 47 (14%) followed severe trauma, 282 (83%) followed moderate or no trauma, and 12 (3%) were pathologic. Incidence rates for fractures following moderate trauma were higher in women than in men and rose steeply with age in both genders. In contrast, fractures following severe trauma were more frequent in men, and their incidence increased less with age. These Rochester rates are greater than those previously reported from studies in Britain and Sweden but lower than the incidence rates extrapolated from a prevalence study in this population.

Abstract Bone mineral density (BMD) was measured at the lumbar spine and cervical and intertrochanteric regions of the proximal femur by dual-photon absorptiometry and bone mineral content was assessed at the distal and midradius by single-photon absorptiometry in an age-stratified random sample of 304 Rochester, Minnesota women aged 30–94 years. Over follow-up extending to 10 years (median 8.3 years), 93 women experienced 163 new fractures. After adjusting for age, these bone mineral measurements predicted the likelihood of any incident fracture due to moderate trauma, with relative hazards varying from 1.4 to 1.6 per SD decrease in baseline bone mineral. A 1 SD decrease in lumbar spine BMD increased the risk of a new vertebral fracture comparably to a 17 year increase in age; a 1 SD decrease in femoral BMD was comparable to a 13–14 year increase in age on the risk of a hip fracture. We conclude that bone mineral measurements made at a variety of skeletal sites can predict the occurrence for at least 8–10 years of moderate trauma fractures of the sort that might be related to osteoporosis.

Abstract We report the establishment of a human fetal osteoblast cell line derived from biopsies obtained from a spontaneous miscarriage. Primary cultures isolated from fetal tissue were transfected with a gene coding for a temperature-sensitive mutant (tsA58) of SV40 large T antigen along with a gene coding for neomycin (G418) resistance. Individual neomycin resistant colonies were screened for alkaline phosphatase (AP)-specific staining. The clone with the highest AP level, hFOB 1.19, was examined further for other osteoblast phenotypic markers. Incubation of hFOB cells at the permissive temperature (33.5°C) resulted in rapid cell division, whereas little or no cell division occurred at the restrictive temperature (39.5°C). Both AP activity and osteocalcin (OC) secretion increased in a dose-dependent manner following dihydroxyvitamin D3 (1,25-D3) treatment when cultured at either temperature. However, AP and 1,25-D3-induced OC levels were elevated in confluent hFOB cells cultured at 39.5°C compared with 33.5°C. Treatment of hFOB cells with 1–34 parathyroid hormone (PTH) resulted in an increase in cAMP levels. Upon reaching confluence, hFOB cultures went through programmed differentiation and formed mineralized nodules as observed by von Kossa staining. Further, immunostaining of postconfluent, differentiated hFOB cells showed that high levels of osteopontin, osteonectin, bone sialoprotein, and type I collagen were expressed. Therefore, the clonal cell line hFOB 1.19 provides a homogeneous, rapidly proliferating model system to study certain stages of human osteoblast differentiation.

Bilateral oophorectomy at the time of hysterectomy for benign disease is commonly practiced in order to prevent the subsequent development of ovarian cancer or other ovarian pathology that might require additional surgery. At present, bilateral oophorectomy is performed in 78% of women aged between 45 and 64 years having a hysterectomy, and a total of approximately 300,000 prophylactic oophorectomies are performed in the USA every year. Estrogen deficiency resulting from pre- and post-menopausal oophorectomies has been associated with higher risks of coronary heart disease, stroke, hip fracture, Parkinsonism, dementia, cognitive impairment, depression and anxiety in many studies. While ovarian cancer accounts for 14,800 deaths per year in the USA, coronary heart disease accounts for 350,000 deaths per year. In addition, 100,000 cases of dementia may be attributable annually to prior bilateral oophorectomy. At present, observational studies suggest that bilateral oophorectomy may do more harm than good. In women who are not at high risk of developing ovarian or breast cancer, removing the ovaries at the time of hysterectomy should be approached with caution.

The importance of mind–body health relationships has been recognized for decades, but only recently has the wider medical and cardiovascular community become engaged in understanding and addressing the complex, bidirectional risk relationship between cardiovascular disease (CVD) and depression. Furthermore, it has become increasingly clear that there are incompletely understood sex differences in incidence and outcomes for both conditions that should guide treatment and future research efforts. This review will explore the role of depression in women as a risk factor for incident CVD, its impact on women already suffering from CVD, proposed psychobiologic mechanisms and links, and the implications of sex differences on diagnosis and treatment.

Abstract Neurofibromatosis type 1 (NF1) is a common cancer predisposition syndrome in which affected individuals develop benign and malignant nerve tumors. The NF1 gene product neurofibromin negatively regulates Ras and mammalian target of rapamycin (mTOR) signaling, prompting clinical trials to evaluate the ability of Ras and mTOR pathway inhibitors to arrest NF1-associated tumor growth. To discover other downstream targets of neurofibromin, we performed an unbiased cell-based high-throughput chemical library screen using NF1-deficient malignant peripheral nerve sheath tumor (MPNST) cells. We identified the natural product, cucurbitacin-I (JSI-124), which inhibited NF1-deficient cell growth by inducing apoptosis. We further showed that signal transducer and activator of transcription-3 (STAT3), the target of cucurbitacin-I inhibition, was hyperactivated in NF1-deficient primary astrocytes and neural stem cells, mouse glioma cells, and human MPNST cells through Ser727 phosphorylation, leading to increased cyclin D1 expression. STAT3 was regulated in NF1-deficient cells of murine and human origin in a TORC1- and Rac1-dependent manner. Finally, cucurbitacin-I inhibited the growth of NF1-deficient MPNST cells in vivo. In summary, we used a chemical genetics approach to reveal STAT3 as a novel neurofibromin/mTOR pathway signaling molecule, define its action and regulation, and establish STAT3 as a tractable target for future NF1-associated cancer therapy studies. Cancer Res; 70(4); 1356–66