Negative association between trunk fat, insulin resistance and skeleton in obese women

AIM

To evaluate the potential interference of trunk fat (TF) mass on metabolic and skeletal metabolism.

METHODS

In this cross-sectional study, 340 obese women (mean age: 44.8 ± 14 years; body mass index: 36.0 ± 5.9 kg/m(2)) were included. Patients were evaluated for serum vitamin D, osteocalcin (OSCA), inflammatory markers, lipids, glucose and insulin (homeostasis model assessment of insulin resistance, HOMA-IR) levels, and hormones profile. Moreover, all patients underwent measurements of bone mineral density (BMD; at lumbar and hip site) and body composition (lean mass, total and trunk fat mass) by dual-energy X-ray absorptiometry.

RESULTS

Data showed that: (1) high TF mass was inversely correlated with low BMD both at lumbar (P < 0.001) and hip (P < 0.01) sites and with serum vitamin D (P < 0.0005), OSCA (P < 0.0001) and insulin-like growth factor-1 (IGF-1; P < 0.0001) levels; (2) a positive correlation was found between TF and HOMA-IR (P < 0.01), fibrinogen (P < 0.0001) and erythrocyte sedimentation rate (P < 0.0001); (3) vitamin D levels were directly correlated with IGF-1 (P < 0.0005), lumbar (P < 0.006) and hip (P < 0.01) BMD; and (4) inversely with HOMA-IR (P < 0.001) and fibrinogen (P < 0.0005).Multivariate analysis demonstrated that only vitamin D was independent of TF variable.

CONCLUSION

In obese women, TF negatively correlates with BMD independently from vitamin D levels. Reduced IGF-1 and increased inflammatory markers might be some important determinants that account for this relationship.

Approach in glucocorticoid-induced osteoporosis prevention: results from the Italian multicenter observational EGEO study

Glucocorticoid-induced osteoporosis (GIO) is the most frequent cause of secondary osteoporosis. GIO is linked to glucocorticoids (GC) daily assumption with maximum effect within first months of treatment and decreasing to basal levels as the therapy is discontinued. In Italy, primary prevention of GIO is suggested when GC therapy (prednisone >5 mg/day or equivalent) is taken for longer than 3 months. Lazio GISMO (Italian Group for Study and Diagnosis of Bone Metabolism Diseases) group organized the GC and Osteoporosis Epidemiology study (EGEO) to evaluate physician's approach in preventing GIO. The study involved 19 osteoporosis centers. Patients taking long-term GC therapy were recruited and information collected: medical history and anthropometric data, GC therapy, primary disease, physician's specialty, osteopororosis screening, and pharmacological intervention. The study included 1334 patients. Mean age was 63 ± 13 yr; 243 (18%) patients had a history of falls from standing position in the previous 12 months, 78 (35%) vertebral fractures, 91 (41%) fractures other than vertebral, 27 (12%) femoral fractures, and 27 (12%) multiple sites fractures. The molecules of GC more often prescribed were prednisone and 6-metil prednisolone. One thousand and forty patients (78%) were taking GC for more than 6 months. GC therapy was prescribed more frequently by rheumatologists (62%). Antiosteoporotic drugs for GIO prevention were prescribed in 431 patients (32%). Among the patients, only 27% (360) received calcium and vitamin D supplements, and 39% (319) treated by rheumatologists received anti-resorptive drugs. In conclusion, our data show that in Italy, as already described elsewhere, only a small subpopulation of GC-treated patients was supported by an anti-osteoporotic therapy, indicating the need to further stimulate awareness of both patients and specialists, prescribing GC therapy, to an appropriate and prompt GIO prevention.

Trunk fat negatively influences skeletal and testicular functions in obese men: clinical implications for the aging male

Osteocalcin (OSCA) seems to act as a negative regulator of energy metabolism and insulin sensitivity. Evidence from male rodents suggests that OSCA may also regulate testosterone (T) synthesis. Using a cross-sectional design, we evaluated OSCA, 25(OH) vitamin D, T, 17 β -estradiol (E2), homeostasis model assessment of insulin resistance (HOMA-IR), and body composition in 86 obese (mean BMI = 34) male subjects (18-69 yr old). Independently from BMI, an inverse relationship between trunk fat percentage and plasma T (r (2) = -0.26, P < 0.01) and between HOMA-IR and OSCA levels (r (2) = -0.22, P < 0.005) was found. OSCA levels, as well as vitamin D, decreased significantly for higher BMI with significant differences above 35 (P < 0.01). A direct correlation between T and bone mineral density at lumbar (BMDL) and neck (BMDH) (P < 0.001, r (2) = -0.20; P < 0.001, r (2) = -0.24) was found, independently from age. An inverse correlation between E2 levels, BMDL, and BMDH (P < 0.001, r (2) = -0.20; P < 0.001, r (2) = -0.19) was observed. These data provide new evidences that a relationship between trunk fat mass, insulin sensitivity, OSCA and T synthesis occurs. This new relationship with skeletal health has relevant implications for the aging male, suggesting OSCA as a novel marker of metabolic and gonadal health status.

Effectiveness of teriparatide treatment on back pain-related functional limitations in individuals affected by severe osteoporosis: a prospective pilot study

INTRODUCTION

Vertebral fractures have been associated with back pain, functional limitations and reduced health-related quality of life (HRQoL). Teriparatide is the first effective anabolic agent that demonstrated to significantly reduce the risk of vertebral fracture by 65%, as compared to placebo. The aims of this study were to evaluate the effectiveness of teriparatide treatment on back pain-related functional limitations and to investigate on patients HRQoL.

MATERIALS AND METHODS

In this prospective observational pilot study osteoporotic patients, who were prescribed teriparatide therapy and a supplementation of calcium and vitamin D, were asked to answer to two self-administered questionnaires: the Spine Pain Index (SPI) and the SF-12 (at the recruitment, after 6, 12, and 18 months).

RESULTS

Fifty-two women were evaluated (mean age of 70.58 yrs). The mean SPI score passed from 50.01 at baseline to 32.20 at 18 months. The mean SF-12 PCS score passed from 30.00 at baseline to 36.79 at 18 months, while the mean SF-12 MCS score was already within the normality range at baseline, constantly improving during the 18 months.

CONCLUSION

In conclusion, 18 months of treatment with teriparatide has to be considered an effective therapeutic option for women with severe osteoporosis and vertebral fractures, in a real-life clinical setting, to improve both back pain related disability and quality of life.

Effects of long-acting testosterone undecanoate on bone mineral density in middle-aged men with late-onset hypogonadism and metabolic syndrome: results from a 36 months controlled study

We evaluated the effects of long-term testosterone replacement therapy (TRT) on the bone mineral density (BMD) in obese patients with metabolic syndrome (MS) and late-onset hypogonadism (LOH). Sixty men (mean age 57 ± 10) with low serum testosterone (T < 320 ng/dL) and MS regardless the presence of osteoporosis were enrolled. Forty men received intramuscular T-undecanoate (TU) four times/year for 36 months and 20 age-matched hypogonadal men with MS in whom T treatment was contraindicated were used as controls. Hormonal, biochemical markers, vertebral and femoral BMD by dual-energy x-ray absorptiometry were measured. At baseline, overall patients had mild osteopenia (lumbar BMD= 0.891 ± 0.097 g/cm(2); femoral BMD= 0.847 ± 0.117 g/cm(2)). TU induced a significant improvement of bone mass after 36 months (lumbar BMD=1.053 ± 0.145 g/cm(2); p < 0.002; femoral BMD=0.989 ± 0.109; p < 0.003 g/cm(2)) with a 5%/year increase and a significant reduction in hs-CRP without changes in body mass index. A direct relationship between serum T and BMD increments at the lumbar (r(2) = 0.66, p < 0.0001) and femoral (r(2) =0.52, p < 0.0001) sites was demonstrated. Study adherence was 50% without serious side effects. Long-term TRT in middle-aged men with LOH and MS determines a significant increase in both vertebral and femoral BMD related to increased serum T levels, probably independently from estradiol modifications.

Concerns about serum androgens monitoring during testosterone replacement treatments in hypogonadal male athletes: a pilot study

INTRODUCTION

A well-tailored testosterone replacement treatment (TRT) in male hypogonadal athletes plays a pivotal role to restore physiological performances, to reduce health risks, and to guarantee the ethic of competition. Few studies evaluated individual androgens profiles during TRT in trained individuals.

AIM

The aim of this article was to verify the efficacy in restoring eugonadal serum and urinary androgens profiles after testosterone enanthate (TE) and gel (TG) administration.

METHODS

Ten male Caucasian-trained volunteers affected by severe hypotestosteronemia (<8 nmol/L) were included. Serum androgens and urinary testosterone metabolites were evaluated, in the same subjects, before and weekly for 5 weeks after both a single intramuscular TE injection (250 mg) and during a daily administration of TG (50 mg/die of testosterone), respectively.

MAIN OUTCOME MEASURES

The main outcome measures of this article were serum total testosterone (TT), dihydrotestosterone (DHT), calculated free and bioavailable testosterone (cFT, cBioT), 17-β-estradiol, and urinary glucuronide testosterone metabolites.

RESULTS

Supraphysiological TT concentrations were observed in 50% of our volunteers until 7 days after TE and in the 4% of total samples after TG. Serum DHT was high both after TE (all volunteers on day 7 and 50% on day 14) and during TG (32% of total samples). A relatively low number of samples showed normal cFT and cBioT both after TE and TG (20-44%, respectively). Urinary metabolites were related to the type of treatment and to serum androgens profile and resulted in the normal ranges from 15% to 60% of total samples.

CONCLUSION

Besides well-known variations of mean serum TT, we showed a high percentage of serum and urinary samples with abnormal androgens, being TG safer than TE. We conclude that monitoring TRT with TT only may be inaccurate because of abnormal fluctuations of other circulating androgens. Further studies to identify the appropriate markers of eugonadism during TRT are highly warranted both in athletes and in non-athletes.

Cadmium-induced apoptosis and necrosis in human osteoblasts: role of caspases and mitogen-activated protein kinases pathways

Cadmium is a widespread environmental pollutant which induces severe toxic alterations, including osteomalacia and osteoporosis, likely by estrogen receptor-dependent mechanisms. Indeed, cadmium has been described to act as an endocrine disruptor and its toxicity is exerted both in vivo and in vitro through induction of apoptosis and/or necrosis by not fully clarified intracellular mechanism(s) of action. Aim of the present study was to further investigate the molecular mechanism by which cadmium might alter homeostasis of estrogen target cells, such as osteoblast homeostasis, inducing cell apoptosis and/or necrosis. Human osteoblastic cells (hFOB 1.19) in culture were used as an in vitro model to characterize the intracellular mechanisms induced by this heavy metal. Cells were incubated in the presence/ absence of 10-50 μM cadmium chloride at different times and DNA fragmentation and activation of procaspases- 8 and -3 were induced upon CdCl(2) treatment triggering apoptotic and necrotic pathways. Addition of caspase-8 and -3 inhibitors (Z-IETD-FMK and Z-DQMD-FMK) partially blocked these effects. No activation of procaspase-9 was observed. To determine the role of mitogen-activated protein kinases (MAPK) in these events, we investigated c-jun N-terminal kinase (JNK), p38 and extracellular signal-regulated protein kinase (ERK1/2) phosphorylation which were activated by 10 μM CdCl(2). Chemical inhibitors of JNK, p38, and ERK1/2, SP600125, SB202190, and PD98059, significantly reduced the phosphorylation of the kinases and blunted apoptosis. In contrast, caspase inhibitors did not reduce the cadmium-induced MAPK phosphorylation, suggesting an independent activation of these pathways. In conclusion, at least 2 pathways appear activated by cadmium in osteoblasts: a direct induction of caspase-8 followed by activation of caspase-3 and an indirect induction by phosphorylation of ERK1/2, p38, and JNK MAPK triggering activation of caspase-8 and -3.

Is obesity in women protective against osteoporosis?

The belief that obesity is protective against osteoporosis has recently come into question. The latest epidemiologic and clinical studies have shown that a high level of fat mass might be a risk factor for osteoporosis and fragility fractures. Further, increasing evidence seems to indicate that different components of the metabolic syndrome, ie, hypertension, increased triglycerides, reduced high-density lipoprotein cholesterol, are also potential risk factors for the development of low bone mineral density and osteoporosis. This review considers both the older and more recent data in the literature in order to evaluate further the relationship between fat tissue and bone tissue.

Baseline characteristics of the population enrolled in the Italian Observational Study on Severe Osteoporosis (ISSO)

OBJECTIVES

Baseline characteristics of the population enrolled in the ISSO study, designed to evaluate the incidence of vertebral and non-vertebral fractures in Italian patients with severe osteoporosis treated according to clinical practice over 24 months observation.

METHODS

Prospective observational study in 783 post-menopausal women and men entering 18-month treatment with teriparatide in a community setting at 57 centres in Italy. Characterisation included demographics, fracture risk factors, bone mineral density, fracture status, Health-Related Quality of Life (HRQoL) measured by the European Quality of Life Questionnaire, EQ-5D, and back pain assessed by VAS.

RESULTS

Most patients were elderly women (90.5%), mean age±SD was 72.9±8.8 years. Nearly all (91.3%) had experienced ≥ 1 vertebral fracture (mean±SD, 3.6±2.2 per patient), 37.5% had ≥ 1 non-vertebral fracture (mean±SD, 1.4±0.7 per patient). Nearly all patients were suffering from back pain (94.9%), which had significantly restricted their daily activities (51.7%) and had likely or very likely been caused by vertebral fractures (29.2% and 55.8%, respectively). Mean EuroQoL EQ-5D index value was 0.58±0.25 and VAS score 49.2±23.6. Non-vertebral fractures, back pain and multiple vertebral fractures were associated with lower HRQoL (EuroQoL-5D Index both p<0.001, EQ-5D VAS score p=0.025 and p<0.016, respectively). Many patients were physically inactive (81.1%). One third (34.7%) of population had co-morbidities and 60.5% were on chronic concomitant treatments. Few subjects reported a maternal history of osteoporosis (15.5%), regular consumption of alcohol (13.3%) or were current smokers (11.5%). Nearly two-thirds (71.5%) had already been treated for osteoporosis, mainly with bisphosphonates. Calcium and vitamin D supplements were taken by 13% and 15.5% of the total population, respectively.

CONCLUSIONS

At enrollment, the population of ISSO study mostly consisted in aging women, who had osteoporosis with high fracture risk, poor HRQoL and suffered from significant back pain. Most of them had already been treated by bisphosphonates but without calcium and vitamin D supplements. Back pain, as well as non-vertebral and multiple vertebral fractures, were associated with lower HRQoL.

Differential characteristics of bone quality and bone turnover biochemical markers in patients with hip fragility fractures and hip osteoarthritis: results of a clinical pilot study

BACKGROUND AND AIMS

Bone density and quality alterations worsen the ability of osteoporotic bone to support prosthetic implants. The aim of our study was to evaluate potential differences in bone quality and bone turnover markers in aged individuals undergoing surgery for hip fragility fracture or hip osteoarthritis.

METHODS

Eighteen subjects with hip fragility fractures (Hip Fracture Group), 35 subjects with osteoarthritis of the hip (Hip Osteoarthritis Group) and 19 subjects with normal femoral bone mineral density (Control Group) were evaluated. Serum and urinary bone markers were assayed preoperatively in all surgical patients, and within 48 hours after fracture in the Hip Fracture, Osteoarthritis and Control groups. Histomorphometric analysis was performed on surgical samples.

RESULTS

A significant alteration in calcium and PTH serum levels with hyperparathyroidism was observed in the Hip Fracture Group compared with Hip Osteoarthritis and Control Groups. C-Terminal telopeptides of type I-collagen (CTx) and tartrate resistant-acid phosphatase (TRAP), markers of bone resorption, were increased in the Hip Fracture Group compared with both Osteoarthritis and Control Groups (CTx: p<0.0007 and p<0.0039 respectively; TRAP: p<0.002 and p<0.0007). All subjects were vitamin D3-deficient, but no differences were found among the different groups. In addition, histomorphometric data showed better maintained connectivity in the Osteoarthritis Group compared with the Hip Fracture Group (p<0.0001).

CONCLUSIONS

Our data show significant differences in bone turnover markers in patients undergoing hip prosthesis for fragility fractures, compared with patients operated for hip osteoarthritis.

Exposure to phosphodiesterase type 5 inhibitors stimulates aromatase expression in human adipocytes in vitro

INTRODUCTION

Prolonged tadalafil administration in men with erectile dysfunction is associated with increased testosterone (T): estradiol (E(2)) ratio mainly related to reduction of E(2) levels.

AIM

To investigate the presence of phosphodiesterase type 5 (PDE5) isoenzyme in primary human visceral adipocytes and whether different PDE5 inhibitors (PDE5i) could directly modulate aromatase (ARO) expression in differentiated human visceral adipocytes in culture.

MAIN OUTCOME MEASURES

PDE5 mRNA and protein expression in primary human visceral adipocytes as well as mRNA and protein expression of ARO, with functional activity after selective PDE5 blockade by tadalafil and sildenafil.

METHODS

Purified primary human visceral pre-adipocytes were differentiated ex vivo and were exposed to tadalafil or sildenafil (1 µM) for different intervals of time (6-12-24-96 hours). ARO mRNA content and expression were measured by Western Blot and quantitative reverse transcription-polymerase chain reaction (qRT-PCR), respectively. T and E(2) in supernatants were measured by ELISA also in the presence of letrozole.

RESULTS

Differentiated adipocytes were found to express detectable levels of PDE5 transcripts. Acute exposure (6 hours) to both PDE5i tadalafil and sildenafil increased ARO mRNA expression by 4.7- and 2.8-fold, respectively (P < 0.001). ARO mRNA and protein levels were increased by the treatment with PDE5i in a time- and dose-dependent manner. Such effect was mimicked by 8-bromo-cGMP but was lost after 24 and 96 hours; differently, the PDE3B specific inhibitor milrinone (1 µM), displayed no effect. Accordingly, long-term exposure (24 and 96 hours) to PDE5i caused a significant increase in E(2) concentrations in the supernatant (1.7 and 2 fold, respectively; P < 0.001), with a parallel reduction of T (15% and 30%, respectively; P < 0.001). Such effect was reversed by the co-incubation with the specific ARO-inhibitor letrozole.

CONCLUSIONS

Our results demonstrate that PDE5 is expressed in human visceral adipocytes and that acute exposure to PDE5i selectively stimulates ARO expression, which is related to a specific PDE5 blockade. We speculate that modulation of ARO activity by PDE5i could be one of the mechanisms responsible, at least in part, for the beneficial effects of PDE5i on endothelial and metabolic functions.

[Guidelines for the diagnosis, prevention and treatment of osteoporosis]

The guidelines for the osteoporosis management were first drafted by a working group and then critically evaluated by the board of SIOMMMS. The most relevant points are:

DEFINITION

Osteoporosis is defined as a quantitative and qualitative deterioration of bone tissue leading to increased risk of fracture. Postmenopausal and senile osteoporosis are defined as primitive.

DIAGNOSIS

The cornerstone for the diagnosis of osteoporosis is the measurement of bone mineral density (BMD) by DXA (dual-energy X-ray absortiometry) at the femoral neck with T-score values <-2.5, following the WHO definition. Other DXA sites or technologies for measuring bone mass are also acceptable when the former is not accessible. A BMD evaluation is recommended to all women above 65 years of age. At younger age or in man the bone assessment is recommended only in subjects with specific risk factors. A control of bone mass measurement is seldom required before 2 years.

DIFFERENTIAL DIAGNOSIS

A few biochemical tests such as serum and urinary calcium, protein electrophoresis, serum creatinine and ESR are usually sufficient to exclude most secondary types of osteoporosis. The value of the so called bone turnover markers for the diagnosis and follow-up of osteoporosis remains uncertain. Several secondary forms of osteoporosis require a specific diagnostic and therapeutic management.

PREVENTION

The osteoporosis prevention should be based on the elimination of specific risk factors such as inadequate calcium and vitamin D intake, smoking and sedentary life. The use of pharmacological agents in subjects with BMD values >-2.5 is usually not justified. Pharmacological intervention: The use of drugs registered for the treatment of osteoporosis are recommended when the benefits overcome the risk. This is the case only when the risk of fracture is rather high. FRAX is recognized as a useful tool for easily estimate the long-term fracture risk. SIOMMMS with these guidelines is committed to validate and further develop this diagnostic tool.

Expression of parathyroid hormone-related protein in human inflamed dental pulp

INTRODUCTION

The aim of this study was to investigate the presence and the role of the parathyroid hormone-related protein (PTH-rP) in the inflamed pulp.

MATERIALS AND METHODS

Thirty-four pulp tissue specimens (24 inflamed and 10 normal pulps) from extracted third molars were studied. The presence of PTH-rP was observed by using immunohistochemistry. Negative controls were performed using non immunized rabbit or mouse serum, omitting the primary antibody.

RESULTS

The analysis of all the sections of normal pulps showed the presence of PTHrP positive cells only in the odontoblastic zone and in few fibroblasts. Instead all inflamed pulps showed PTHrP positive cells both in vascular zone and in pulp stroma, as well as in the odontoblastic and subodontoblastic zone.

CONCLUSION

Several works proved that this peptide plays a role even in angiogenesis process, but its function is controversial. It is possible to hypothesize that PTHrP stimulates angiogenesis, but it is recommended to further conduct research on this area.

Is obesity protective for osteoporosis? Evaluation of bone mineral density in individuals with high body mass index

BACKGROUND

Obese individuals often present comorbidities while they appear protected against the development of osteoporosis. However, few and contradictory data are now available on skeletal modifications in obese patients. The aim of this study was to characterise bone mineral density (BMD) in overweight (BMI > 25 < 29.9) and obese (BMI > 30) patients.

METHODS

We selected 398 patients (291 women, 107 men, age 44.1 + 14.2 years, BMI 35.8 + 5.9 kg/m(2)) who underwent clinical examination, blood tests and examination of body composition. Subjects with chronic conditions or taking medications interfering with bone metabolism, hormonal and nutritional status and recent weight loss were excluded.

RESULTS

Interestingly, 37% (n = 146) of this population showed a significantly lower than expected lumbar BMD: 33% (n = 98) of women showed a T-score -1.84 +/- 0.71, and 45% (n = 48) of men showed a T-score -1.88 +/- 0.64. When the population was divided into subgroups based on different BMI, it was noted that overweight (BMI > 25 < 29.9) was neutral or protective for BMD, whereas obesity (BMI > 30) was associated with a low bone mass, compatible with a diagnosis of osteoporosis. No differences were observed in hormones and lipid profiles among subgroups.

CONCLUSIONS

Our results indicate that a subpopulation of obese patients has a significant low lumbar BMD than expected for age. Thus, a careful characterisation of skeletal metabolism might be useful in all obese individuals to avoid fragility fractures later in life.

Management of glucocorticoids-induced osteoporosis: role of teriparatide

Glucocorticoids (GC)-induced osteoporosis (GIOP) is the most common cause of secondary osteoporosis, which leads to an increased fracture risk in patients. The normal bone turnover depends on a balance between osteoblasts and osteoclasts activity and GC can cause a rapid bone loss, decreasing bone formation and increasing bone resorption. The decreased bone formation is mainly due to the GC-induced apoptosis of both osteoblasts and osteocytes, while the increased bone resorption is due to the increased life-span of pre-existing osteoclasts. Bisphosphonates are clearly effective in preventing and treating GIOP but anabolic therapeutic strategies are the new promising therapeutic alternative. Experimental and clinical studies indicate that teriparatide, the active (1–34) parathyroid hormone (PTH) molecule, is efficacious for the treatment of GIOP, being able to induce an increase in bone mass in these patients. Intermittent administration of human PTH (1–34) stimulates bone formation by increasing osteoblast number. Additionally, human PTH (1–34) modulates the level and/or activity of locally produced growth factors and cytokines. Teriparatide has been demonstrated in several clinical studies to significantly decrease the incidence of fractures in patients affected by GIOP. It has recently received an indication for GIOP and its label indication has also been expanded.

Glucocorticoid-induced osteoporosis: an osteoblastic disease

It is well-known that glucocorticoid-induced osteoporosis (GIO) is the most common form of secondary osteoporosis. It is estimated that 30% to 50% of patients receiving chronic glucocorticoid therapy suffer vertebral or hip fractures, which are often asymptomatic. Vertebral fractures occur early after exposure to glucocorticoids, at a time when bone mineral density (BMD) declines rapidly. Glucocorticoids impair osteoblast homeostasis and induce apoptosis of both osteoblasts and osteocytes, leading to suppression of bone formation. Glucocorticoids also favor osteoclastogenesis and, as a consequence, increase bone resorption. The end-point of these alterations is a net decrease in BMD and alterations in bone quality. Bisphosphonates have been approved for both prevention and treatment of GIO. At the present time, anabolic therapeutic agents are still under investigation.

Osteoblast-conditioned medium promotes proliferation and sensitizes breast cancer cells to imatinib treatment

Inhibition of platelet-derived growth factor receptor (PDGFR) signaling restricts the growth of human breast cancer in the bone of nude mice. We hypothesized that osteoblast-secreted substances may alter the response capacity of breast cancer cells to the PDGFRs tyrosine kinase inhibitor imatinib mesylate. We found that osteoblast-conditioned medium (OCM) increases the proliferation rate of the estrogen receptor negative (ER-) MDA-MB-231 and of the ER+ MCF-7 human breast cancer cell lines and the growth-promoting effect on ER+ cells is independent from estrogen. OCM significantly improved the dose- and the time-dependent sensitivity of the tumor cells to the anti-proliferative effect of imatinib. We also found that MDA-MB-231 and MCF-7 cells express the two PDGFRs subtypes, PDGFR-alpha and PDGFR-beta, and OCM treatment increases the expression of the PDGFRs. Furthermore, imatinib inhibited the phosphorylation rate of its target tyrosine kinase receptors. We conclude that bone microenvironment, through osteoblast-secreted substances may cause estrogen-independent proliferation of breast cancer cells by a mechanism mediated by the induction of PDGFRs expression. The enhanced sensitivity of OCM-treated breast cancer cells to imatinib would justify investigation on the efficacy of imatinib in bone breast cancer metastasis.

Cadmium induces mitogenic signaling in breast cancer cell by an ERalpha-dependent mechanism

Breast cancer (BC) is linked to estrogen exposure. Estradiol (E2) stimulates BC cells proliferation by binding the estrogen receptor (ER). Hormone-related cancers have been linked to estrogenic environmental contaminants. Cadmium (Cd) a toxic pollutant, acts as estrogens in BC cells. Purpose of our study was to evaluate whether Cd regulates MCF-7 cell proliferation by activating ERK1/2, Akt and PDGFRalpha kinases. Cd increased cell proliferation and the ER-antagonist ICI 182,780 blunted it. To characterize an ER-dependent mechanism, ERalpha/beta expression was evaluated. Cd decreased ERalpha expression, but not ERbeta. Cd also increased ERK1/2, Akt and PDGFRalpha phosphorylation while ICI blocked it. Since stimulation of phosphorylation was slower than expected, c-fos and c-jun proto-oncogenes, and PDGFA were analyzed. Cd rapidly increased c-jun, c-fos and PDGFA expression. Cells were also co-incubated with the Cd and specific kinases inhibitors, which blocked the Cd-stimulated proliferation. In conclusion, our results indicate that Cd increases BC cell proliferation in vitro by stimulating Akt, ERK1/2 and PDGFRalpha kinases activity likely by activating c-fos, c-jun and PDGFA by an ERalpha-dependent mechanism.

Effect of titanium carbide coating on the osseointegration response in vitro and in vivo

Titanium has limitations in its clinical performance in dental and orthopaedic applications. This study describes a coating process using pulsed laser deposition (PLD) technology to produce surfaces of titanium carbide (TiC) on titanium substrates and evaluates the biological response both in vitro and in vivo. X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of 18.6-21.5% TiC in the surface layer, accompanied by oxides of titanium 78.5-81.4% in the following concentrations: 11.1-13.0% Ti(2)O(3), 50.8-55.8% TiO(2), 14.5-14.7% TiO. Expression of genes central to osteoblast differentiation (alkaline phosphatase, A2 pro-collagen type 1, osteocalcin, BMP-4, TGFbeta and Cbfa-1) were up-regulated in all cell lines (primary human osteoblasts, hFOB1.19 and ROS.MER#14) grown on TiC compared with uncoated titanium when measured by semiquantitative PCR and real time-PCR, whilst genes involved in modulation of osteoclastogenesis and osteoclast activity (IL-6 and M-CSF) were unchanged. Bone density was shown to be greater around TiC-coated implants after 2 and 4 weeks in sheep and both 4 and 8 weeks in rabbits compared to uncoated titanium. Rapid bone deposition was demonstrated after only 2 weeks in the rabbit model when visualized with intravital staining. It is concluded that coating with TiC will, in comparison to uncoated titanium, improve implant hardness, biocompatibility through surface stability and osseointegration through improved bone growth.

The differential effects of bisphosphonates, SERMS (selective estrogen receptor modulators), and parathyroid hormone on bone remodeling in osteoporosis

Osteoporosis is a skeletal metabolic disease characterized by a compromised bone fragility, leading to an increased risk of developing spontaneous and traumatic fractures. Osteoporosis is considered a multifactorial disease and fractures are the results of several different risk factors both extra- and intraskeletal. Thus bone fragility can be the end point of several different causes: a) failure to reach an optimal peak bone mass during growth; b) excessive bone resorption resulting in decreased bone mass and microarchitectural deterioration; c) inadequate formation upon an increased resorption during the process of bone remodeling. The pharmacological therapeutical options, available to date, are directed on prevention of fractures. The aim of this paper is to describe the activities and the mechanisms of action, as known at present, of the most used therapies for osteoporosis and their clinical implications. Improvement of knowledge in this field will allow us to further improve therapeutical choices and pharmacological interventions.

Modulation of human estrogen receptor alpha F promoter by a protein kinase C/c-Src-dependent mechanism in osteoblast-like cells

The human estrogen receptor alpha (ERalpha) gene is driven by multiple promoters, of which the F promoter alone is found to be active in primary osteoblasts. The study was aimed at identifying new regulatory pathways affecting transcription of the receptor in this cell lineage. We generated human osteoblast-like cells, Saos-2, stably transfected with a luciferase-reporter gene downstream of the human ERalpha F promoter (Saos F-Luc), and assayed the reporter response to differentiation-related signals. Over-confluence, shown to stimulate osteoblast differentiation, caused a time-dependent increase of F-promoter activity and correlated with an inactivation of protein kinase C alpha (PKCalpha ). PKC downregulation, obtained by long-term treatment with phorbol 12-myristate 13-acetate (PMA), resulted in promoter stimulation at similar levels in sub-confluent cells. The F promoter contains a putative PMA-responsive AP-1 site, but AP-1 activation was unremarkable in over-confluent cells. Treatment with PP1, a specific inhibitor of the non-receptor tyrosine-kinase c-Src, which is a negative regulator of osteoblast differentiation, showed that the activity of this kinase inhibits the F promoter. In PP1-treated cells, F-promoter activity was not further increased by PMA. Treatment with the generic kinase inhibitor 4-dimethylaminopyridine (DMAP) resulted in a dose-dependent induction of the promoter, which matched a parallel decrease of active c-Src. The effect was c-Src dependent, as DMAP caused no further promoter induction in PP1-treated cells. Overexpression of exogenous human ERalpha resulted in modest promoter stimulation, which required the ligand-independent activator function 1 of the receptor. In murine primary osteoblasts, additional ERalpha signal was observed upon induction of F promoter. In conclusion, we demonstrated a robust PKC/c-Src-dependent and estrogen-independent mechanism modulating transcription of ERalpha in osteoblasts, probably affecting estrogen responsiveness during cell differentiation.

Clinical, genetic, and cellular analysis of 49 osteopetrotic patients: implications for diagnosis and treatment

BACKGROUND

Osteopetrosis, a genetic disease characterised by osteoclast failure, is classified into three forms: infantile malignant autosomal recessive osteopetrosis (ARO), intermediate autosomal recessive osteopetrosis (IRO), and autosomal dominant osteopetrosis (ADO).

METHODS

We studied 49 patients, 21 with ARO, one with IRO, and 27 with type II ADO (ADO II).

RESULTS

Most ARO patients bore known or novel (one case) ATP6i (TCIRG1) gene mutations. Six ADO II patients had no mutations in ClCN7, the only so far recognised gene implicated, suggesting involvement of yet unknown genes. Identical ClCN7 mutations produced differing phenotypes with variable degrees of severity. In ADO II, serum tartrate resistant acid phosphatase was always elevated. Bone alkaline phosphatase (BALP) was generally low, but osteocalcin was high, suggesting perturbed osteoblast differentiation or function. In contrast, BALP was high in ARO patients. Elevated osteoclast surface/bone surface was noted in biopsies from most ARO patients. Cases with high osteoclasts also showed increased osteoblast surface/bone surface. ARO osteoclasts were morphologically normal, with unaltered formation rates, intracellular pH handling, and response to acidification. Their resorption activity was greatly reduced, but not abolished. In control osteoclasts, all resorption activity was abolished by combined inhibition of proton pumping and sodium/proton antiport.

CONCLUSIONS

These findings provide a rationale for novel therapies targeting pH handling mechanisms in osteoclasts and their microenvironment.

Raloxifene modulates interleukin-6 and tumor necrosis factor-alpha synthesis in vivo: results from a pilot clinical study

Raloxifene (RAL), a selective estrogen receptor modulator, is indicated for the prevention and treatment of postmenopausal osteoporosis. RAL, by decreasing bone turnover, prevents bone loss and microarchitecture damage, reducing the incidence of osteoporotic fractures. Our previous in vitro data demonstrated that RAL modulates osteoclast activity by, at least in part, an IL-6- and TNF-alpha-dependent mechanism. In this study we evaluated the effects of RAL treatment (60 mg/d) on circulating levels of these cytokines in 14 postmenopausal women with osteoporosis. Lumbar bone density (determined by dual energy x-ray absorptiometry) and IL-6 and TNF-alpha levels were measured before and after 6 and 24 months of therapy. After 24 months, RAL increased bone density. IL-6 and TNF-alpha expression, elevated before treatment, significantly decreased (50% and 30%, respectively) after 6 months. This effect was sustained up to the end of the treatment (75% and 35%, respectively). Thus, our data show that RAL can modulate circulating levels of cytokines involved in osteoclastogenesis and bone resorption, suggesting that modulation of soluble factors could play a pivotal role in the mechanisms of the osteoprotective effect of RAL.

Reduction of risk factors for cardiovascular diseases in morbid-obese patients following biliary-intestinal bypass: 3 years' follow-up

BACKGROUND

Obese patients are often affected by hypertension, dyslipidaemia, impaired glucose metabolism, and suffer from cardiovascular disease (CVD), related to the characteristic metabolic alterations.

AIM OF THE STUDY

To evaluate reduction of risk factors for CVDs in morbid-obese patients (body mass index (BMI)>40 kg/m2) after weight loss upon bariatric surgery intervention of biliary-intestinal bypass.

SUBJECTS

45 (17 men, 28 women) morbid-obese patients (age: 19-49 y, BMI>40 kg/m2). All patients were selected on the basis of medical history, physical and biochemical evaluation and of psychiatric tests, which were performed on all individuals admitted to our Day Hospital to verify the safety of surgical intervention.

MEASUREMENTS

Body weight, body composition (by dual X-ray absorptiometry, DXA), blood pressure, lipid profile, fibrinogen and glucose metabolism were monitored at baseline and 1, 3, 6, 9, 12, 24 and 36 months after surgery.

RESULTS

A significant and persistent weight loss was present in all patients at the end of the 3 y follow-up period (P<0.001), with a progressive reduction of total and trunk fat mass as evaluated by means of DXA. Additionally, a parallel significant reduction in systolic (P<0.001) and diastolic (P<0.001) blood pressure was observed. Total and LDL cholesterol were significantly reduced (P<0.001), while HDL showed no modifications; triglycerides declined progressively during the 3 y follow-up (P<0.001). Fibrinogen decreased from 364.5+/-82.4 to 266.4+/-45.7 mg/dl at the end of the period (P<0.001). Fasting glucose levels and glucose levels 120 min after an oral glucose tolerance test were reduced from 95.1+/-20.3 to 78.6+/-9.1 mg/dl (P<0.001) and from 116.9+/-34.7 to 77.6+/-15.5 mg/dl (P<0.001), respectively, at baseline and at the end of the study. Moreover, fasting insulin decreased from 30.0+/-20.4 to 8.6+/-2.9 microUI/ml (P<0.001) after 3 y, while insulin levels after (120 min) oral glucose load decreased from 105.5+/-61.5 to 12.0+/-6.0 microUI/ml (P<0.001).

CONCLUSION

Our results show that biliary-intestinal bypass may represent a valid and alternative therapeutic approach in patients with morbid obesity since it induces a significant and stable reduction of body weight and obesity-related risk factors for CVD.

Imbalance of osteoclastogenesis-regulating factors in patients with celiac disease

Celiac disease is an autoimmune disorder characterized by atrophy of the intestine villi triggered by ingestion of gluten in genetically susceptible individuals. The association between celiac disease and low BMD has been recognized, but the mechanisms of disturbance are poorly understood. We show imbalance of cytokines relevant to bone metabolism in celiac patients' sera and the direct effect of these sera on in vitro bone cell activity.

INTRODUCTION

Celiac disease is associated with mineral metabolism derangement and low BMD. We investigated whether imbalance of serum factors in celiac patients could affect human bone cell activity in vitro.

MATERIALS AND METHODS

We studied two groups of celiac patients--one on a gluten-free diet and another before the diet--both with decreased bone mass. Patients were investigated for bone turnover markers, and their sera were used for culturing bone cells from healthy donors and evaluate changes in cell activity.

RESULTS

The N-terminal telopeptide of procollagen type I and interleukin (IL)-6 were higher than normal in patients not on the gluten-free diet. IL-1beta and TNF-alpha/beta were normal in all patients. IL-12 was reduced in all patients, whereas IL-18 was reduced only in patients on the diet. The RANKL/osteoprotegerin (OPG) ratio was increased in patients not on the gluten-free diet. Persistently increased osteoclast numbers were obtained from peripheral blood mononuclear cells of healthy donors on incubation with sera of patients not on the gluten-free diet versus control sera and sera from patients on the diet. In human osteoblasts from healthy individuals, IL-18 was reduced on incubation with sera from all patients, whereas OPG expression was lower when sera from patients not on the diet were used. Proliferation, alkaline phosphatase, and nodule mineralization were increased in osteoblast cultures containing sera from all celiac patients, either on or not on the gluten-free diet.

CONCLUSIONS

We conclude that bone loss in celiac disease might also be caused by a cytokine imbalance directly affecting osteoclastogenesis and osteoblast activity.

In vivo bone metastases, osteoclastogenic ability, and phenotypic characterization of human breast cancer cells

Mouse bone marrow cells cultured with human breast cancer MCF-7 cell-conditioned media showed osteoclastogenesis with an increment of bone resorption, although conditioned media from an adriamycin-selected MCF-7 clone (MCF-7ADR) had no effect. Consistently, MCF-7 cells induced 5-fold more in vivo experimental osteolytic bone metastases, with no soft tissue lesions, compared to MCF-7ADR cells. Paracrine factors stimulating (interleukin (IL)-6, IL-1beta, tumor necrosis factor-alpha (TNF-alpha)) or inhibiting (IL-12, IL-18, granulocyte macrophage-colony stimulating factor (GM-CSF)) osteoclastogenesis were significantly increased in MCF-7ADR relative to MCF-7 cells, suggesting that the inhibitory cytokines could selectively overwhelm the effects of the stimulatory ones. Treatment of osteoblast primary cultures with MCF-7-conditioned medium induced a selective upregulation of IL-6 expression, suggesting an indirect stimulation of osteoclastogenesis via the osteoblasts. MCF-7 and MCF-7ADR showed no difference in proliferation rate. However, a higher ability to migrate and invade gelatin and matrigel was observed in MCF-7ADR. Enhanced invasiveness might result from increased metalloproteinase (MMP) activity and cytoskeleton rearrangement. MCF-7ADR cells expressed higher levels of c-Src, focal adhesion kinase (FAK), and protein tyrosine kinase 2 (PYK2) involved in cell adhesion and motility. MCF-7 and MCF-7ADR expressed high and faint levels of functional estrogen receptor alpha (ERalpha), respectively. MCF-7ADR also showed significantly higher levels of the protein kinase C (PKC) alpha and beta2 and a selective activation of PKC compared to MCF-7, where the most abundant isoforms were beta1 and delta. Heat shock protein 27 (Hsp27) was more abundant in MCF-7 cells, but failed to translocate to the nucleus in response to heat shock. In conclusion, we have demonstrated that despite the fact that MCF-7ADR cells showed a more invasive phenotype relative to MCF-7, they have low potential to induce osteolytic bone lesions and stimulate osteoclastogenesis and osteoclast activity. Therefore, we believe that reduced aggressiveness of breast carcinomas could correlate with a greater osteolytic activity featuring their bone metastases.

Type II benign osteopetrosis (Albers-Schönberg disease) caused by a novel mutation in CLCN7 presenting with unusual clinical manifestations

A 16-year-old male patient with type II autosomal dominant benign osteopetrosis (ADO) was genotyped and found to harbor a novel mutation in exon 25 of the gene encoding for the osteoclast-specific chloride channel, CLCN7, inherited from the father, who was asymptomatic. The patient had normal biochemical findings and acid-base balance, except for increased serum levels of creatine kinase, lactic dehydrogenase, and the bone formation markers bone alkaline phosphatase isoenzyme, osteocalcin and N-terminal type I collagen telopeptide/creatinine ratio. Unusual generalized osteosclerosis was observed together with a canonical increase in vertebral and pelvis bone mass. An affected first grade cousin presented with normal biochemical findings and a milder osteosclerotic pattern of the pelvis. At the cellular level, cultured osteoclasts from the patient showed increased motility, with lamellipodia, membrane ruffling and motile pattern of podosome distribution, all of which could have contributed to functional impairment of bone resorption. The present report documents a novel mutation of the CLCN7 gene causing osteopetrosis in a radiologically uncertain form of the diseases, with apparent incomplete penetrance.

Interaction of estrogen receptor alpha with protein kinase C alpha and c-Src in osteoblasts during differentiation

In cultured osteoblasts, protein kinase C (PKC) activity increases and estrogen receptor alpha (ERalpha) binding capacity decreases upon confluence. We investigated potential interactions between ERalpha and PKC isoforms and their confluence-induced modulations in clonal ROS.SMER#14 cells and primary osteoblasts. In sub-confluent ROS.SMER#14 cells, which express an exogenous plus small amounts of the endogenous ERalpha gene, the receptor appeared as two main bands of approximately 66 and approximately 46 kDa. In over-confluent, more differentiated cells, the cytosolic approximately 66 kDa ERalpha appeared decreased and the approximately 46 kDa variant increased. Enhanced expression and/or membrane translocation of PKCalpha and PKCepsilon, but not PKCzeta, was evidenced at over-confluence, along with transient increases in expression and kinase activity of c-Src, accompanied by membrane translocation of the kinase-activated enzyme. In contrast, negligible membrane translocation of PKCalpha and/or activated c-Src was observed in parental ROS 17/2.8 cells, which express low levels of full-length ERalpha. PKCalpha from over-confluent cells phosphorylated p60c-Src in vitro, suggesting functional interaction between the two kinases. ERalpha co-immunoprecipitated c-Src and PKCalpha, mostly in its cleaved form (PKMalpha). An analogous interaction was observed in primary osteoblasts. However, in these cells, much more PKCalpha/PKMalpha was ERalpha-co-immunoprecipitated at over-confluence, a condition in which the shorter, approximately 46 kDa ERalpha variant is increased. This interaction was enhanced by estradiol treatment or PKC down-regulation, but was unaffected by c-Src inhibition. These data highlight direct PKCalpha-c-Src-ERalpha interactions, which may be crucial in the modulation of estrogen responsiveness and the differentiation process in osteoblasts.

Reduction of c-Src activity by substituted 5,7-diphenyl-pyrrolo[2,3-d]-pyrimidines induces osteoclast apoptosis in vivo and in vitro. Involvement of ERK1/2 pathway

We employed potent and selective c-Src inhibitors to investigate the functional and molecular consequences of inhibited c-Src tyrosine kinase activity in osteoclasts. These pyrrolopyrimidine derivatives reduced osteoclast numbers and induced osteoclast disruption in vivo. In vitro, they inhibited resorption pit formation and osteoclastogenesis, impaired adhesion ability and actin ring organization, and induced programmed cell death in mature osteoclasts. The cell death receptor Fas and p53 were insensitive to c-Src modulation. The expression of the cyclin-dependent kinase (CDK)-inhibitor p21WAF1/CIP1 was markedly reduced, but neither Bcl-2 nor Bcl-xL or Bax were modulated by c-Src inhibition. Caspase-9, and to a lesser extent caspase-3, but not caspase-8, were transiently cleaved (activated) by treatment with the c-Src inhibitors. c-Src inhibition stabilized p38 mitogen-activated protein kinase (MAPK), whereas the c-Jun N-terminal kinase (JNK) pathway did not appear to be modulated by our compounds. Most interestingly, transient extracellular signal regulated kinase (ERK1/2) dephosphorylation followed by sustained remarkable rephosphorylation overwhelming control levels was observed in response to c-Src inhibition. Blockade of ERK1/2 rephosphorylation by PD98059 reduced osteoclast nuclear disruption, suggesting the involvement of this pathway in apoptosis. Collectively, these data demonstrate that small pyrrolopyrimidine derivatives impair osteoclast function and induce cell damage suggestive of apoptosis in vivo and in vitro, with mechanisms presumably involving selective sustained ERK1/2 phosphorylation.

Pyrrolopyrimidine c-Src inhibitors reduce growth, adhesion, motility and invasion of prostate cancer cells in vitro

Two bona fide c-Src inhibitors, denominated CGP77675 and CGP76030, reduced in a time- and concentration-dependent manner (i) the proliferation of the PC3 prostate carcinoma cell line, as assessed by the [3H]-thymidine incorporation test, (ii) the capacity of PC3 cells to adhere and spread on Matrigel substrate, as determined by crystal violet staining, (iii) the ability of PC3 cells to migrate through a gelatine boundary and invade a Matrigel substrate. The latter effect was not due to a decrease of urokinase-type plasminogen activator (uPA), nor of metalloproteinase-2 (MMP-2) activities. The MMP-9 activity, along with the expression of the Tissue Inhibitor of Metalloproteinases (TIMP)-1 and TIMP-2, were reduced by the two inhibitors, consistent with the ability of c-Src to enhance MMP-9 and TIMP expression levels. Collectively, these data demonstrate that the pyrrolopyrimidine-derived c-Src inhibitors significantly reduced PC3 cell activities associated with their malignant phenotype.

Isoflavones and skeletal health: are these molecules ready for clinical application?

A review of the recent literature on the effects of isoflavones was undertaken to determine whether molecules such as genistein and daidzein, aglycone derivatives of soybeans, might have benefit in the prevention and treatment of osteoporosis. The current standard for science-based medicine is the documentation of efficacy of an agent under controlled, randomized, prospective conditions. A few short clinical investigations have been undertaken using isoflavones (along with soy protein), but they had limitations in study design, and the numbers of women studied were small. Other evidence from animal models, in vitro experiments, and epidemiological reports suggest that the isoflavones have skeletal benefits in women with little or no ovarian estrogen production. A clear need exists for prospective human trials, using the required conditions of randomized clinical trials and designs, to satisfy objectively the needs for science-based medicine and for appropriate clinical applications.

Genotype-phenotype relationship in human ATP6i-dependent autosomal recessive osteopetrosis

Autosomal-recessive osteopetrosis is a severe genetic disease caused by osteoclast failure. Approximately 50% of the patients harbor mutations of the ATP6i gene, encoding for the osteoclast-specific a3 subunit of V-ATPase. We found inactivating ATP6i mutations in four patients, and three of these were novel. Patients shared macrocephaly, growth retardation and optic nerve alteration, osteosclerotic and endobone patterns, and high alkaline phosphatase and parathyroid hormone levels. Bone biopsies revealed primary spongiosa lined with active osteoblasts and high numbers of tartrate-resistant acid phosphatase (TRAP)-positive, a3 subunit-negative, morphologically unremarkable osteoclasts, some of which located in shallow Howship lacunae. Scarce hematopoietic cells and abundant fibrous tissue containing TRAP-positive putative osteoclast precursors were noted. In vitro osteoclasts were a3-negative, morphologically normal, with prominent clear zones and actin rings, and TRAP activity more elevated than in control patients. Podosomes, alphaVbeta3 receptor, c-Src, and PYK2 were unremarkable. Consistent with the finding in the bone biopsies, these cells excavated pits faintly stained with toluidine blue, indicating inefficient bone resorption. Bone marrow transplantation was successful in all patients, and posttransplant osteoclasts showed rescue of a3 subunit immunoreactivity.

The role of the alphaVbeta3 integrin in the development of osteolytic bone metastases: a pharmacological target for alternative therapy?

Common cancers frequently develop bone metastases, which are often osteolytic in nature due to activation of osteoclast differentiation and bone resorption. This may result from direct stimulation of these cells by the metastasis, or may be due to indirect enhancement of osteoclast activity by osteoblasts. A further feature of the bone metastasis is an extensive medullary angiogenesis which supports tumor growth. The alphaVbeta3 integrin is highly expressed in bone metastatic cells, as well as in osteoclasts and in the activated endothelium, where it plays a major role in cell function. In contrast, this receptor is barely expressed in other cell types. Our hypothesis is that inhibition of this mechanism, which is not widespread in most tissues and at the same time is common to several steps of cancer-induced osteolysis (i.e., homing, growth, and survival of metastatic cells, osteoclast bone resorption, and angiogenesis), should represent a suitable target to block the development of bone spreading of metastatic tumors. We extend this hypothesis to downstream signalling molecules activated by ligation of the alphaVbeta3 integrin, some of which (i.e., Src, PYK2, and Shc) could have similar specific roles in tumor cells, activated endothelium and osteoclasts, but not in other cell types.

Characterization of the osteoblast-like cell phenotype under microgravity conditions in the NASA-approved Rotating Wall Vessel bioreactor (RWV)

Weightlessness induces bone loss in humans and animal models. We employed the NASA-approved Rotating Wall Vessel bioreactor (RWV) to develop osteoblast-like cell cultures under microgravity and evaluate osteoblast phenotype and cell function. Rat osteoblast-like cell line (ROS.SMER#14) was grown in the RWV at a calculated gravity of 0.008g. For comparison, aliquots of cells were grown in conventional tissue culture dishes or in Non-Rotating Wall Vessels (N-RWV) maintained at unit gravity. In RWV, osteoblasts showed high levels of alkaline phosphatase expression and activity, and elevated expression of osteopontin, osteocalcin, and bone morphogenetic protein 4 (BMP-4). In contrast, the expression of osteonectin, bone sialoprotein II and BMP-2 were unaltered compared to cells in conventional culture conditions. These observations are consistent with a marked osteoblast phenotype. However, we observed that in RWV osteoblasts showed reduced proliferation. Furthermore, DNA nucleosome-size fragmentation was revealed both morphologically, by in situ staining with the Thymine-Adenine binding dye bis-benzimide, and electrophoretically, by DNA laddering. Surprisingly, no p53, nor bcl-2/bax, nor caspase 8 pathways were activated by microgravity, therefore the intracellular cascade leading to programmed cell death remains to be elucidated. Finally, consistent with an osteoclast-stimulating effect by microgravity, osteoblasts cultured in RWV showed upregulation of interleukin-6 (IL-6) mRNA, and IL-6 proved to be active at stimulating osteoclast formation and resorbing activity in vitro. We conclude that under microgravity, reduced osteoblast life span and enhanced IL-6 expression may result in inefficient osteoblast- and increased osteoclast-activity, respectively, thus potentially contributing to bone loss in individuals subjected to weightlessness.

The selective estrogen receptor modulator raloxifene regulates osteoclast and osteoblast activity in vitro

Raloxifene is a selective estrogen receptor modulator (SERM) that prevents bone loss. Although it is largely used for the treatment of osteoporosis, the mechanisms by which this compound modulates the activity of bone cells are still poorly understood. In this study we investigate whether raloxifene affects osteoclast and osteoblast activity in vitro. Bone marrow cultures were established from neonatal mice and treated with 1,25(OH)(2) vitamin D(3) (VitD(3), 10(-8) mol/L) to induce osteoclast generation. Similar to 17beta-estradiol, raloxifene significantly reduced the number of osteoclasts in a concentration-dependent manner, with maximal inhibition at 10(-11) mol/L (-48%). However, as for 17beta-estradiol, at a high concentration (10(-7) mol/L), the inhibitory effect of raloxifene was abolished. In a pit assay, raloxifene inhibited bone resorption. A maximal effect was observed at 10(-9) mol/L, and maintained at a high concentration, indicating that inhibition of osteoclast formation and inhibition of bone resorption may be due to activation of, at least in part, different pathways. Osteoblasts from neonatal mice calvariae were also exposed to raloxifene. In these cells, this compound induced a concentration-dependent increase of proliferation, which was blocked by the estrogen-receptor antagonist ICI 164,384. Raloxifene also increased the osteoblast-specific transcription factor Cbfa1/Runx2 and alpha2 procollagen type I chain mRNAs, with a pattern that only partially coincided with that of 17beta-estradiol. Consistent with decreased osteoclastogenesis, raloxifene inhibited the mRNA expression of interleukin (IL)-1beta and IL-6 at a low concentration, but not at a high concentration, whereas 17beta-estradiol had similar effects on IL-6 and inhibited IL-1beta at both concentrations. Furthermore, both compounds were able to inhibit tumor necrosis factor (TNF)-alpha-induced IL-1beta, but not IL-6, increase. In conclusion, these data show that raloxifene negatively modulates osteoclasts, and positively affects osteoblasts, suggesting not only an antiresorptive role, but also an osteoblast stimulatory role.

Apparent cure of a newborn with malignant osteopetrosis using prednisone therapy

A newborn girl with hemorrhagic purpura, suspected neonatal sepsis, and pale and dry skin was lethargic with remarkable hepatosplenomegaly, convergent strabismus, severe anemia, and elevated alkaline phosphatase activity. Radiographs showed a generalized increase in bone density, small medullary cavities, sclerosis of the skull and vertebrae, transverse wavy stripes of sclerotic bone in the metaphyses, and bone-in-bone appearance in phalanges of hands and feet. On this basis, she was diagnosed with malignant infantile osteopetrosis. On the first day of life, the infant was given a blood transfusion and vitamin K (1 mg intravenously [iv]). Corticosteroid therapy was started with prednisone (2 mg/kg per day). She showed marked improvement of symptoms. On the 26th day and 42nd day of life, she received additional blood transfusions. On the 49th day, the patient was discharged and corticosteroid therapy was continued at a regimen of 5 mg/day. Subsequent blood sample analyses revealed normal values for age. At 1 year of life, a bone marrow sample showed normal white and red cell lineages. X-ray confirmed attenuation of the bone sclerosis; therefore, bone marrow transplantation (BMT) was not implemented. At the age of 1.5 years, prednisone therapy was discontinued gradually and withdrawn before the age of 2 years. Subsequent follow-up showed normalization of all radiological and hematologic parameters. At present, the patient is 3 years old and appears healthy with apparently complete regression of the disease.

Reduced growth and skeletal changes in zinc-deficient growing rats are due to impaired growth plate activity and inanition

We investigated the effects of dietary zinc deficiency on skeletal metabolism in an animal model. Thirty 21-d-old male Sprague-Dawley rats were fed for 28 d either a zinc-deficient (ZD) diet (1 mg zinc/kg) or a normal diet ad libitum (AL, 50 mg zinc/kg) or in the same quantity as the ZD (pair-fed, PF). Only in the ZD group were general physical signs of zinc deficiency observed. Compared with the AL and PF rats, ZD rats showed significantly lower mean values in ponderal growth rate, femur weight and length, circulating levels of insulin-like growth factor-I, bone mechanical properties and concentration of zinc and, on histomorphometry, a decrease in the thicknesses of the overall growth plate and hypertrophic cartilage. In contrast, although bone volume was significantly lower in the ZD and PF rats than in the AL rats, no difference was observed between the ZD and PF rats. Osteoclast surface/bone surface and osteoclast number/bone surface ratios were significantly greater in PF rats than in the other two groups and not different in ZD and AL rats. Collectively, these data indicate that zinc deficiency has profound effects on the skeletal system of growing rats. In particular, the effects of zinc deficiency on bone growth and mass are the result of the reduced activity of the growth plate, likely mediated by impairment in the insulin-like growth factor-I system. We did not demonstrate an effect on bone mass via increased bone resorption.

Melanoma cells stimulate osteoclastogenesis, c-Src expression and osteoblast cytokines

Malignant melanomas metastasise to the bone and enhance osteoclast bone resorption. We demonstrated that a 48-h-B16 melanoma cell conditioned media (B16CM) induced osteoclastogenesis in mouse bone marrow cultures, without the requirement of B16 cell-bone marrow cell co-culture. B16 cells transcriptionally expressed detectable levels of TGFbeta1, IL-6, M-CSF, GM-CSF and TNFalpha mRNAs, albeit to a lower extent compared with levels in osteoblasts, and failed to express PTHrP, OPGL, OPG and IL-1beta. Interestingly, B16CM greatly upregulated IL-1beta, IL-6 and GM-CSF, and modestly enhanced TNFalpha and OPGL mRNA expression in osteoblasts, suggesting a potential indirect stimulation of osteoclastogenesis via the osteogenic lineage. B16CM barely upregulated c-Fos, but strongly and time-dependently enhanced c-Src expression in the total bone marrow cultures during osteoclast differentiation. Moreover, c-Src expression was enhanced in differentiated and purified osteoclast preparations to higher levels than in stromal cells. In conclusion, melanoma induces osteoclast generation with a paracrine mechanism independent of cell-cell contact, specifically upregulating c-Src in osteoclasts and cytokine expression in osteoblasts.

Decreased c-Src expression enhances osteoblast differentiation and bone formation

c-src deletion in mice leads to osteopetrosis as a result of reduced bone resorption due to an alteration of the osteoclast. We report that deletion/reduction of Src expression enhances osteoblast differentiation and bone formation, contributing to the increase in bone mass. Bone histomorphometry showed that bone formation was increased in Src null compared with wild-type mice. In vitro, alkaline phosphatase (ALP) activity and nodule mineralization were increased in primary calvarial cells and in SV40-immortalized osteoblasts from Src(-/-) relative to Src(+/+) mice. Src-antisense oligodeoxynucleotides (AS-src) reduced Src levels by approximately 60% and caused a similar increase in ALP activity and nodule mineralization in primary osteoblasts in vitro. Reduction in cell proliferation was observed in primary and immortalized Src(-/-) osteoblasts and in normal osteoblasts incubated with the AS-src. Semiquantitative reverse transcriptase-PCR revealed upregulation of ALP, Osf2/Cbfa1 transcription factor, PTH/PTHrP receptor, osteocalcin, and pro-alpha 2(I) collagen in Src-deficient osteoblasts. The expression of the bone matrix protein osteopontin remained unchanged. Based on these results, we conclude that the reduction of Src expression not only inhibits bone resorption, but also stimulates osteoblast differentiation and bone formation, suggesting that the osteogenic cells may contribute to the development of the osteopetrotic phenotype in Src-deficient mice.

Qualitative assessment of natural apatite in vitro and in vivo

Among the natural and synthetic materials investigated as bone graft substitutes, much interest has been focused on natural apatite obtained from low temperature heat-deproteinated compact bone. Previous research demonstrates that, when treated at a temperature below 500 degrees C, this material maintains its characteristic ultrastructural features, with a high surface/volume ratio, while as an implant material, it offers the host tissue a large surface of interaction. In vitro and in vivo tests showed that natural apatite is well tolerated and is a good osteoconducing material. The present in vivo study in rabbits was carried out to first investigate the behavior and capacity of natural apatite implants to stimulate bone ingrowth, and then to analyze the cells located at the bone/material interface. Synthetic hydroxyapatite was used as a control material. In a parallel in vitro study, we investigated the activity of differentiated osteoblasts and periosteal cells obtained from rats and new-born rabbits, incubated with natural apatite and synthetic hydroxyapatite. The in vivo study showed that natural apatite allows osteoblasts to form new bone tissue, adhering to the implant with ingrowth into the implant structure. In the presence of synthetic hydroxyapatite, a less pronounced osteoblastic activity was observed. In agreement with these observations, the in vitro study showed that natural apatite is more effective in attracting cells, favoring their proliferation and stimulating alkaline phosphatase activity. These findings suggest that natural apatite is more suitable for bone filling or bone regeneration than synthetic hydroxyapatite.