Uric acid-lowering effects of sodium-glucose cotransporter 2 inhibitors for preventing cardiovascular events and mortality: A systematic review and meta-analysis.

BACKGROUND: To evaluate the effect of a 1 mg/dl reduction in uric acid (UA) on cardiovascular events and mortality in patients treated with sodium-glucose cotransporter 2 (SGLT2) inhibitors. RESEARCH DESIGN AND METHODS: We performed a systematic review of the MEDLINE and EMBASE databases searched up to 30 June 2023 (PROSPERO, CRD42022355479) to identify large-scale SGLT2 inhibitor trials. Random-effects meta-analyses were used to pool the estimates. RESULTS: In total, five SGLT2 inhibitor trials (31 535 patients, 54% with heart failure) were analysed. Over a median follow-up of 2.2 years, the mean reduction in UA was -0.79 mg/dl (95% confidence interval (CI), -1.03 to -0.54). Every 1 mg/dl reduction in UA was associated with a significantly lower risk of a composite of cardiovascular death and hospitalization for heart failure [hazard ratio, 0.64 (95% CI, 0.46-0.88)] and hospitalization for heart failure (0.68; 95% CI, 0.62-0.74), with a similar risk of mortality. CONCLUSIONS: SGLT2 inhibitors reduced UA levels and cardiovascular events independently of heart failure status.

Characteristics of human metapneumovirus infection in adults hospitalized for community-acquired influenza-like illness in France, 2012-2018: a retrospective observational study.

OBJECTIVES: To describe the prevalence, clinical features and complications of human metapneumovirus (hMPV) infections in a population of adults hospitalized with influenza-like illness (ILI). METHODS: This was a retrospective, observational, multicenter cohort study using prospectively collected data from adult patients hospitalized during influenza virus circulation, for at least 24 h, for community-acquired ILI (with symptom onset <7 days). Data were collected from five French teaching hospitals over six consecutive winters (2012-2018). Respiratory viruses were identified by multiplex reverse transcription polymerase chain reaction (RT-PCR) on nasopharyngeal specimens. hMPV + patients were compared with hMPV- patients, influenza+ and respiratory syncytial virus (RSV)+ patients using multivariate logistic regressions. Primary outcome was the prevalence of hMPV in patients hospitalized for ILI. RESULTS: Among the 3148 patients included (1449 (46%) women, 1988 (63%) aged 65 and over; 2508 (80%) with chronic disease), at least one respiratory virus was detected in 1604 (51%, 95% confidence interval (CI) 49-53), including 100 cases of hMPV (100/3148, 3% 95% CI 3-4), of which 10 (10%) were viral co-infection. In the hMPV + patients, mean length of stay was 7 days, 62% (56/90) developed a complication, 21% (14/68) were admitted to intensive care unit and 4% (4/90) died during hospitalization. In comparison with influenza + patients, hMPV + patients were more frequently >65 years old (adjusted odds ratio (aOR) = 3.3, 95% CI 1.9-6.3) and presented more acute heart failure during hospitalization (aOR = 1.8, 95% CI 1.0-2.9). Compared with RSV + patients, hMPV + patients had less cancer (aOR = 0.4, 95% CI 0.2-0.9) and were less likely to smoke (aOR = 0.5, 95% CI 0.2-0.9) but had similar outcomes, especially high rates of respiratory and cardiovascular complications. CONCLUSIONS: Adult hMPV infections mainly affect the elderly and patients with chronic conditions and are responsible for frequent cardiac and pulmonary complications similar to those of RSV infections. At-risk populations would benefit from the development of antivirals and vaccines targeting hMPV.

Seasonal influenza vaccination among people with diabetes: influence of patients' characteristics and healthcare use on behavioral changes.

Annual seasonal influenza vaccination (SIV) is recommended for people with diabetes, but vaccine coverage remains low. We estimated the probabilities of stopping or starting SIV, their correlates, and the expected time spent in the vaccinated state over 10 seasons for different patient profiles. We set up a retrospective cohort study of patients with diabetes in 2006 (n = 16,026), identified in a representative sample of beneficiaries of the French National Health Insurance Fund. We followed them up over 10 seasons (2005/06-2015/16). We used a Markov model to estimate transition probabilities and a proportional hazards model to study covariates. Between two consecutive seasons, the probabilities of starting (0.17) or stopping (0.09) SIV were lower than those of remaining vaccinated (0.91) or unvaccinated (0.83). Men, older patients, those with type 1 diabetes, treated diabetes or more comorbidities, frequent contacts with doctors, and with any hospital stay for diabetes or influenza during the last year were more likely to start and/or less likely to stop SIV. The mean expected number of seasons with SIV uptake over 10 seasons (range: 2.6-7.9) was lowest for women <65 years with untreated diabetes and highest for men ≥65 years with type 1 diabetes. Contacts with doctors and some clinical events may play a key role in SIV adoption. Healthcare workers have a crucial role in reducing missed opportunities for SIV. The existence of empirical patient profiles with different patterns of SIV uptake should encourage their use of tailored educational approaches about SIV to address patients' vaccine hesitancy.

Bariatric surgery and the perioperative management of type 2 diabetes: Practical guidelines.

BACKGROUND: Metabolic surgery is now considered as a therapeutic option in type 2 diabetes (T2D). However, few data are available regarding perioperative management of T2D. OBJECTIVES: To assess current practice among bariatric teams regarding perioperative management of T2D in order to propose guidelines. METHODS: A two-round Delphi method using online surveys was employed among bariatric teams experts (surgeons, diabetologists, anesthetists, nutritionists): first round, 63 questions covering 6 topics (characteristics of experts/teams, characteristics of patients, operative technique, pre/postoperative management, diabetes remission); second round, 44 items needing clarification. They were discussed within national congress of corresponding learned societies. Consensus was defined as ≥66% agreement. RESULTS: A total of 170 experts participated. Experts favored gastric bypass to achieve remission (76.7%). Screening for retinopathy, cardiac ultrasound, and reaching an HbA1c<8% are required in the pre-operative period for 67%, 75.3% and 56.7% of experts, respectively. After surgery, insulin pump should not be stopped, basal insulin should be halved, and bolus insulin should be stopped except if severe hyperglycemia. DPP-IV inhibitors and metformin are preferred after surgery. Patients should be seen by a diabetologist within one month if on oral antidiabetic agents (71.8% of experts), 2 weeks if on injectable treatments (77.1% of experts), and immediately after surgery if on insulin pump (93.5% of experts). Long-term monitoring of HbA1c is necessary even if diabetes remission (100%). CONCLUSION: Rapid postoperative modifications of blood glucose require a close monitoring and a prompt adjustment of diabetes medications.

Rhythmic abilities and musical training in Parkinson's disease: do they help?

Rhythmic auditory cues can immediately improve gait in Parkinson's disease. However, this effect varies considerably across patients. The factors associated with this individual variability are not known to date. Patients' rhythmic abilities and musicality (e.g., perceptual and singing abilities, emotional response to music, and musical training) may foster a positive response to rhythmic cues. To examine this hypothesis, we measured gait at baseline and with rhythmic cues in 39 non-demented patients with Parkinson's disease and 39 matched healthy controls. Cognition, rhythmic abilities and general musicality were assessed. A response to cueing was qualified as positive when the stimulation led to a clinically meaningful increase in gait speed. We observed that patients with positive response to cueing (n = 17) were more musically trained, aligned more often their steps to the rhythmic cues while walking, and showed better music perception as well as poorer cognitive flexibility than patients with non-positive response (n = 22). Gait performance with rhythmic cues worsened in six patients. We concluded that rhythmic and musical skills, which can be modulated by musical training, may increase beneficial effects of rhythmic auditory cueing in Parkinson's disease. Screening patients in terms of musical/rhythmic abilities and musical training may allow teasing apart patients who are likely to benefit from cueing from those who may worsen their performance due to the stimulation.

Clinical characteristics and outcome of respiratory syncytial virus infection among adults hospitalized with influenza-like illness in France.

OBJECTIVES: The aim of this study was to analyse characteristics and outcome of respiratory syncytial virus (RSV) infection in adults hospitalized with influenza-like illness (ILI). METHODS: Patients hospitalized with ILI were included in this prospective, multicentre study carried out in six French hospitals during three consecutive influenza seasons (2012-2015). RSV and other respiratory viruses were detected by multiplex PCR in nasopharyngeal swabs. Risk factors for RSV infection were identified by backward stepwise logistic regression analysis. RESULTS: A total of 1452 patients hospitalized with ILI were included, of whom 59% (861/1452) were >65 years and 83% (1211/1452) had underlying chronic illnesses. RSV was detected in 4% (59/1452), and influenza virus in 39% (566/1452). Risk factors for RSV infection were cancer (adjusted OR 2.1, 95% CI 1.1-4.1, p 0.04), and immunosuppressive treatment (adjusted OR 2.0, 95% CI 1.1-3.8, p 0.03). Patients with RSV had a median length of stay of 9 days (6-25), and 57% of them (30/53) had complications, including pneumonia (23/53, 44%) and respiratory failure (15/53, 28%). Fifteen per cent (8/53) were admitted to an intensive care unit, and the in-hospital mortality rate was 8% (4/53). Pneumonia was more likely to occur in patients with RSV than in patients with RSV-negative ILI (44% (23/53) versus 26% (362/1393), p 0.006) or with influenza virus infection (44% versus 28% (157/560), p 0.02). CONCLUSION: RSV is an infrequent cause of ILI during periods of influenza virus circulation but can cause severe complications in hospitalized adults. Risk factors for RSV detection in adults hospitalized with ILI include cancer and immunosuppressive treatment. Specific immunization and antiviral therapy might benefit patients at risk.

Moderate influenza vaccine effectiveness against hospitalisation with A(H3N2) and A(H1N1) influenza in 2013-14: Results from the InNHOVE network.

We conducted a multicentre test negative case control study to estimate the 2013-14 influenza vaccine effectiveness (IVE) against hospitalised laboratory confirmed influenza in 12 hospitals in France, Italy and Spain. We included all ≥18 years hospitalised patients targeted by local influenza vaccination campaign reporting an influenza-like illness within 7 days before admission. We defined as cases patients RT-PCR positive for influenza and as controls those negative for all influenza virus. We used a logistic regression to calculate IVE adjusted for country, month of onset, chronic diseases and age. We included 104 A(H1N1)pdm09, 157 A(H3N2) cases and 585 controls. The adjusted IVE was 42.8% (95%CI: 6.3;65;0) against A(H1N1)pdm09. It was respectively 61.4% (95%CI: -1.9;85.4), 39.4% (95%CI: -32.2;72.2) and 19.7% (95%CI:-148.1;74.0) among patients aged 18-64, 65-79 and ≥80 years. The adjusted IVE against A(H3N2) was 38.1% (95%CI: 8.3;58.2) overall. It was respectively 7.8% (95%CI: -145.3;65.4), 25.6% (95%CI: -36.0;59.2) and 55.2% (95%CI: 15.4;76.3) among patients aged 18-64, 65-79 and ≥80 years. These results suggest a moderate and age varying effectiveness of the 2013-14 influenza vaccine to prevent hospitalised laboratory-confirmed influenza. While vaccination remains the most effective prevention measure, developing more immunogenic influenza vaccines is needed to prevent severe outcomes among target groups.

2012/13 influenza vaccine effectiveness against hospitalised influenza A(H1N1)pdm09, A(H3N2) and B: estimates from a European network of hospitals.

While influenza vaccines aim to decrease the incidence of severe influenza among high-risk groups, evidence of influenza vaccine effectiveness (IVE) among the influenza vaccine target population is sparse. We conducted a multicentre test-negative case-control study to estimate IVE against hospitalised laboratory-confirmed influenza in the target population in 18 hospitals in France, Italy, Lithuania and the Navarre and Valencia regions in Spain. All hospitalised patients aged ≥18 years, belonging to the target population presenting with influenza-like illness symptom onset within seven days were swabbed. Patients positive by reverse transcription polymerase chain reaction for influenza virus were cases and those negative were controls. Using logistic regression, we calculated IVE for each influenza virus subtype and adjusted it for month of symptom onset, study site, age and chronic conditions. Of the 1,972 patients included, 116 were positive for influenza A(H1N1)pdm09, 58 for A(H3N2) and 232 for influenza B. Adjusted IVE was 21.3% (95% confidence interval (CI): -25.2 to 50.6; n=1,628), 61.8% (95% CI: 26.8 to 80.0; n=557) and 43.1% (95% CI: 21.2 to 58.9; n=1,526) against influenza A(H1N1) pdm09, A(H3N2) and B respectively. Our results suggest that the 2012/13 IVE was moderate against influenza A(H3N2) and B and low against influenza A(H1N1) pdm09.

Effect of a high dose of simvastatin on muscle mitochondrial metabolism and calcium signaling in healthy volunteers.

Statin use may be limited by muscle side effects. Although incompletely understood to date, their pathophysiology may involve oxidative stress and impairments of mitochondrial function and of muscle Ca(2+) homeostasis. In order to simultaneously assess these mechanisms, 24 male healthy volunteers were randomized to receive either simvastatin for 80 mg daily or placebo for 8 weeks. Blood and urine samples and a stress test were performed at baseline and at follow-up, and mitochondrial respiration and Ca(2+) spark properties were evaluated on a muscle biopsy 4 days before the second stress test. Simvastatin-treated subjects were separated according to their median creatine kinase (CK) increase. Simvastatin treatment induced a significant elevation of aspartate amino transferase (3.38±5.68 vs -1.15±4.32 UI/L, P<0.001) and CK (-24.3±99.1±189.3 vs 48.3 UI/L, P=0.01) and a trend to an elevation of isoprostanes (193±408 vs 12±53 pmol/mmol creatinine, P=0.09) with no global change in mitochondrial respiration, lactate/pyruvate ratio or Ca(2+) sparks. However, among statin-treated subjects, those with the highest CK increase displayed a significantly lower Vmax rotenone succinate and an increase in Ca(2+) spark amplitude vs both subjects with the lowest CK increase and placebo-treated subjects. Moreover, Ca(2+) spark amplitude was positively correlated with treatment-induced CK increase in the whole group (r=0.71, P=0.0045). In conclusion, this study further supports that statin induced muscular toxicity may be related to alterations in mitochondrial respiration and muscle calcium homeostasis independently of underlying disease or concomitant medication.

The PKCθ pathway participates in the aberrant accumulation of Fra-1 protein in invasive ER-negative breast cancer cells.

Fra-1 is aberrantly expressed in a large number of cancer cells and tissues, and emerging evidence suggests an important role for this Fos family protein in both oncogenesis and the progression or maintenance of many tumour types. Here, we show that the concentration of Fra-1 is high in invasive oestrogen receptor (ER)-negative (ER-) breast cancer cell lines, regardless of their Ras pathway status. All of the ER- cells express high levels of activated PKCθ, and the inhibition of PKCθ activity using RNA interference or the expression of a dominant-negative mutant results in a dramatic reduction in Fra-1 abundance. Conversely, the ectopic expression of constitutively active PKCθ leads to Fra-1 phosphorylation and accumulation in poorly invasive ER+ cells. This accumulation is due to the stabilisation of the Fra-1 protein through PKCθ signalling, whereas other members of the PKC family are ineffective. Both Ste20-related proline-alanine-rich kinase (SPAK) and ERK1/2, whose activities are upregulated by PKCθ, participate in PKCθ-driven Fra-1 stabilisation. Interestingly, their relative contributions appear to be different depending on the cell line studied. ERK1/2 signalling has a major role in ER- MDA-MB-231 cells, whereas Fra-1 accumulation occurs mainly through SPAK signalling in ER- BT549 cells. Fra-1 mutational analysis shows that the phosphorylation of S265, T223 and T230 is critical for PKCθ-driven Fra-1 stabilisation. Phosphorylation of the protein was confirmed using specific antisera against Fra-1 phosphorylated on T223 or S265. In addition, Fra-1 participates in PKCθ-induced cell invasion and is necessary for PKCθ-induced cell migration. In summary, we identified PKCθ signalling as an important regulator of Fra-1 accumulation in ER- breast cancer cells. Moreover, our results suggest that PKCθ could participate in progression of some breast cancers and could be a new therapeutic target.

In peripubertal girls, artistic gymnastics improves areal bone mineral density and femoral bone geometry without affecting serum OPG/RANKL levels.

UNLABELLED: Peripubertal artistic gymnasts display elevated areal bone mineral density at various bone sites, despite delayed menarche and a high frequency of menstrual disorders, factors that may compromise bone health. The concomitant improvement in femoral bone geometry and strength suggested that this type of physical activity might have favourable clinical impact. INTRODUCTION: The purpose of this study is to evaluate the effect of artistic gymnastics (GYM) on areal bone mineral density (aBMD), femoral bone geometry and bone markers and its relationship with the osteoprotegerin (OPG)/rank-ligand (RANKL) system in peripubertal girls. METHODS: Forty-six girls (age 10-17.2 years) were recruited for this study: 23 elite athletes in the GYM group (training 12-30 h/week, age at start of training 5.3 years) and 23 age-matched (± 6 months; leisure physical activity ≤ 3 h/week) controls (CON). The aBMD at whole body, total proximal femur, lumbar spine, mid-radius and skull was determined using dual-X-ray absorptiometry. Hip structural analysis (HSA software) was applied at the femur to evaluate cross-sectional area (CSA, cm(2)), cross-sectional moment of inertia (CSMI, cm(4)), and the section modulus (Z, cm(3)) and buckling ratio at neck, intertrochanteric region and shaft. Markers of bone turnover and OPG/RANKL levels were also analysed. RESULTS: GYM had higher (5.5-16.4%) non-adjusted aBMD and adjusted aBMD for age, fat-free soft tissue and fat mass at all bone sites, skull excepted and the difference increased with age. In the three femoral regions adjusted for body weight and height, CSA (12.5-18%), CSMI (14-18%), Z (15.5-18.6%) and mean cortical thickness (13.6-21%) were higher in GYM than CON, while the buckling ratio (21-27.1%) was lower. Bone markers decreased with age in both groups and GYM presented higher values than CON only in the postmenarchal period. A similar increase in RANKL with age without OPG variation was observed for both groups. CONCLUSION: GYM is associated not only with an increase in aBMD but also an improvement in bone geometry associated with an increase in bone remodelling. These adaptations seem to be independent of the OPG/RANKL system.

[Definitions, epidemiology, risk factors]. / Définitions, épidémiologie, facteurs de risque.

Gestational diabetes mellitus is defined as carbohydrate intolerance that begins or is first recognized during pregnancy. Its prevalence, generally situated between 2-6%, may reach 10-20% in high-risk populations, with an increasing trend across most racial/ethnic groups studied. Among classical risk factors, previous gestational diabetes, older maternal age and obesity have the most important impact on gestational diabetes risk. Racial/ethnic origin and family history of type 2 diabetes have a significant but moderate impact (except for type 2 diabetes in siblings). Several non classical factors have been recently characterized, either physiological (low birth weight and short maternal height) or pathological (polycystic ovaries). The multiplicity of risk factors and their interactions results in a low reliability of risk prediction on an individual basis.

Definition, epidemiology, risk factors.

Gestational diabetes mellitus is defined as glucose intolerance that begins or is first recognized during pregnancy. Its prevalence, generally situated between 2-6%, may reach 10-20% in high-risk populations, with an increasing trend across most racial/ethnic groups studied. Among traditional risk factors, previous gestational diabetes, advanced maternal age and obesity have the highest impact on gestational diabetes risk. Racial/ethnic origin and family history of type 2 diabetes have a significant but moderate impact (except for type 2 diabetes in siblings). Several non traditional factors have been recently characterized, either physiological (low birthweight and short maternal height) or pathological (polycystic ovaries). The multiplicity of risk factors and their interactions results in a low reliability of risk prediction on an individual basis.

Optimizing the outcome of pregnancy in obese women: from pregestational to long-term management.

The obesity epidemic is of some concern in women of reproductive age. Maternal obesity is associated with many pregnancy complications, especially gestational diabetes and hypertensive disorders of pregnancy. Delivery in obese women is characterized by a high caesarean-section rate and an increased risk of anaesthetic and postoperative complications. Weight retention after birth may increase the risk of type 2 diabetes in the long term. Foetal risks include macrosomia, malformations and increased perinatal mortality, with the long-term infant health marked by a higher risk of obesity and metabolic disorders. Optimal management includes preconception counselling, pregravid weight-loss programmes, monitoring of gestational weight gain, repeated screening for pregnancy complications and long-term follow-up to minimize the social and economic consequences of pregnancy in overweight women.

Direct rosiglitazone-induced modifications in insulin secretion, action and clearance: a single-dose hyperglycaemic clamp study.

AIMS/HYPOTHESIS: In addition to the improvement in insulin sensitivity, it has been shown that thiazolidinediones modulate beta cell function and insulin clearance in type 2 diabetic subjects. However, interactions between all these actions, and confounding factors due to co-morbidities and co-treatments in diabetic individuals, complicate the identification of specific effects. The aim of this pilot study was to investigate the potential acute effects of rosiglitazone on beta cell function and insulin sensitivity by the hyperglycaemic clamp technique in healthy volunteers. SUBJECTS AND METHODS: Twelve healthy men were included in a randomised, double-blind crossover study. Rosiglitazone (8 mg) or placebo was given orally 45 min before the hyperglycaemic clamp (10 mmol/l for 2 h). RESULTS: The second phase of the insulin response was significantly decreased by rosiglitazone: 13,066 +/- 1,531 vs 16,316 +/- 2,813 pmol l(-1) 110 min in controls (p < 0.05), without change in the first phase. Serum C-peptide was not modified. Rosiglitazone treatment significantly increased insulin clearance (molar ratio of the C-peptide to insulin AUCs: 12.80 +/- 1.34 vs 11.38 +/- .33, p < 0.05) and the insulin sensitivity index (12.0 +/- 1.5 vs 8.5 +/- 1.1 micromol m(-2) min(-1) pmol(-1)l, p < 0.01). CONCLUSIONS/INTERPRETATION: The present results show that a single dose of rosiglitazone rapidly increases insulin clearance and insulin sensitivity index in healthy volunteers, with no direct effect on insulin secretion. The precise mechanisms mediating these actions remain to be determined.

Resting energy expenditure and fuel metabolism following laparoscopic adjustable gastric banding in severely obese women: relationships with excess weight lost.

BACKGROUND: Although adjustable gastric banding is increasingly proposed for massively obese patients, little is known about the modifications of resting metabolic rate and substrate oxidation or about metabolic determinants of weight loss following this type of bariatric surgery. OBJECTIVES: To evaluate the relationships between excess weight loss, resting metabolic rate (RMR) and substrate oxidation, and to identify metabolic predictive factors of weight loss after adjustable gastric banding. SUBJECTS: Seventy-three obese nondiabetic women aged 39.1+/-10.4 years (18.4-64.8). DESIGN: Resting metabolic rate and substrate oxidation (indirect calorimetry), body composition (bio-impedance), lipid profile and insulin sensitivity indexes were assessed before and after (13.3+/-6.0 months, range 6.0-31.1) adjustable gastric banding. Patients were classified according to postsurgery time: group A (6-12 months, n=39); group B (12-18 months, n=21); group C (>18 months, n=13). Metabolic parameters associated with the percentage of excess weight lost (EWL) 1 year after surgery were analyzed in univariate and multivariate regressions. RESULTS: Mean weight loss was 26.2+/-11.4 kg. Mean fat mass loss was 17.3+/-8.1 kg. All biological parameters associated with excess weight improved after surgery. Excess weight lost at 1 year was 45.9+/-17.1% in group A, 47.4+/-17.1% in group B and 51.4+/-18.5% in group C (P=NS). Resting metabolic rate/fat-free mass (FFM) slightly decreased (28.9+/-3.26 vs 30.3+/-2.8, P<0.00001) and RMR/body weight slightly increased (18.5+/-2.8 vs 17.3+/-1.9, P<0.00001) after surgery. Respiratory quotient (0.81+/-0.06 vs 0.82+/-0.05) and FFM-adjusted lipid oxidation (1.10+/-0.41 vs 1.05+/-0.33 mg/min/kg FFM) were not significantly modified after surgery. In multiple linear regression analysis, difference in RMR/body weight, difference in energy sparing, baseline BMI and postsurgery time, were significantly and independently correlated with EWL (total R2=72.5%). CONCLUSIONS: Adjustable gastric banding promotes gradual but sustained weight loss and is associated with long-term conservation of lipid oxidation and energy expenditure. The individual variability in energy sparing mechanisms predicts weight loss during the first year after surgery.

Anti-growth factor activities of benzothiophenes in human breast cancer cells.

We have tested the effects of two Eli-Lilly compounds, LY 117, 018 and raloxifene, on E2-regulated and IGF-I-induced proliferation or AP-1 activity in human breast cancer cells. We now demonstrate that both molecules have strong antiestrogenic and anti-growth factor inhibitory effects in MCF7 cells. They were as potent as ICI 182, 780 and more efficient than OH-Tam to prevent estradiol action whereas their inhibition on IGF-I stimulation was less than with ICI 182, 780 and equivalent to that of OH-Tam. Moreover, raloxifene was the most efficient molecule to prevent IGF-I-induced AP-1 activity, with a significant effect observed with a concentration as low as 5 x 10(-11)M in the presence of IGF-I alone. Similar dose-response curves were obtained with a combined treatment of IGF-I and E2 with a 2log shift. Their action on IGF-I-induced proliferation was completely abrogated in MCF7 transfectants in which the expression of an antiestrogen-regulated protein tyrosine phosphatase, PTPL1, was abolished by antisense RNA transfection. Accordingly, they were both able to dose-dependently regulate the expression of PTPL1 and to interfere with the PI3-K/Akt pathway by drastically decreasing Akt phosphorylation exclusively in wild-type PTPL1 expressing cells. Our data altogether demonstrate that raloxifene has a potent inhibitory effect on IGF-I action, with a drastic effect on AP-1 triggered responses as well as on Akt phosphorylation, suggesting that it might be a useful therapeutic agent in tumors in which these signalling pathways become constitutively active.

Characterization of the physical interaction between estrogen receptor alpha and JUN proteins.

Activated estrogen receptor alpha (ERalpha) modulates transcription triggered by the transcription factor activator protein-1 (AP-1), which consists of Jun-Jun homodimers and Jun-Fos heterodimers. Previous studies have demonstrated that the interference occurs without binding of ERalpha to DNA but probably results from protein.protein interactions. However, involvement of a direct interaction between ERalpha and AP-1 is still debated. Using glutathione S-transferase pull-down assays, we demonstrated that ERalpha bound directly to c-Jun and JunB but not to FOS family members, in a ligand-independent manner. The interaction could occur when c-Jun was bound onto DNA, as shown in a protein-protein-DNA assay. It implicated the C-terminal part of c-Jun and amino acids 259-302 present in the ERalpha hinge domain. ERalpha but not an ERalpha mutant deleted of amino acids 250-303 (ER241G), also associated with c-Jun in intact cells, in the presence of estradiol, as shown by two-hybrid and coimmunoprecipitation assays. We also show that ERalpha, c-Jun, and the p160 coactivator GRIP1 can form a multiprotein complex in vitro and in intact cells and that the ERalpha.c-Jun interaction could be crucial for the stability of this complex. VP16-ERalpha and c-Jun, which both interact with GRIP1, had synergistic effect on GAL4-GRIP1-induced transcription in the presence of estradiol, and this synergistic effect was not observed with the ERalpha mutant VP16-ER241G or when c-Fos, which bound GRIP1 but not ERalpha, was used instead of c-Jun. Finally, ER241G was inefficient for regulation of AP-1 activity, and an ERalpha truncation mutant encompassing the hinge domain had a dominant negative effect on ERalpha action. These results altogether demonstrate that ERalpha can bind to c-Jun in vitro and in intact cells and that this interaction, by stabilizing a multiprotein complex containing p160 coactivator, is likely to be involved in estradiol regulation of AP-1 responses.