Metformin impairs Rho GTPase signaling to induce apoptosis in neuroblastoma cells and inhibits growth of tumors in the xenograft mouse model of neuroblastoma

Metformin has been shown to inhibit tumor growth in xenograft rodent models of adult cancers, and various human clinical trials are in progress. However, the precise molecular mechanisms of metformin action are largely unknown. In the present study we examined the anti-tumor activity of metformin against neuroblastoma, and determined the underlying signaling mechanisms. Using human neuroblastoma xenograft mice, we demonstrated that oral administration of metformin (100 and 250 mg/kg body weight) significantly inhibited the growth of tumors. The interference of metformin in spheroid formation further confirmed the anti-tumor activity of metformin. In tumors, the activation of Rac1 (GTP-Rac1) and Cdc42 (GTP-Cdc42) was increased while RhoA activation (GTP-RhoA) was decreased by metformin. It also induced phosphorylation of JNK and inhibited the phosphorylation of ERK1/2 without affecting p38 MAP Kinase. Infection of cells by adenoviruses expressing dominant negative Rac1 (Rac1-N17), Cdc42 (Cdc42-N17) or constitutively active RhoA (RhoA-V14), or incubation of cells with pharmacological inhibitors of Rac1 (NSC23766) or Cdc42 (ML141) significantly protected neuroblastoma cells from metformin-induced apoptosis. Additionally, inhibition of JNK activity along with Rac1 or Cdc42 attenuated cytotoxic effects of metformin. These studies demonstrated that metformin impairs Rho GTPases signaling to induce apoptosis via JNK pathway.     

Positive link between variant Toll-like receptor 4 (Asp299Gly and Thr399Ile) and colorectal cancer patients with advanced stage and lymph node metastasis

Toll-like receptors (TLRs) are considered as major endotoxin-signaling receptor and as crucial sensors of innate immunity. TLRs recognize pathogen-associated molecular patterns; induce effectors genes involving inflammatory cytokines and therefore initiation of adaptative immune responses against pathogens. Recently, it has been shown that TLRs are involved in tumor progression. In fact, increased level of TLR4 is associated with progression of colon malignancies. Even, TLR4 polymorphism has been shown associated with susceptibility to have colorectal cancer. Our study aimed to investigate an association between TLR4 Asp299Gly (D299G) and Thr399Ile (T399I) polymorphisms in Tunisian patients with colorectal cancer. Using a primer extension method (SNaPshot), we genotyped two variants of TLR4 D299G and T399I in 100 patients with colorectal cancer and 140 healthy controls in Tunisian population. Interesting, we noted a significant association between T399I polymorphism and tumor differentiation (p?=?0.027) and tumor architecture (p?=?0.02) in colorectal cancer (CRC) patients. We also showed a significant association of D299G with an increased risk of advanced stage (p?=?0.03). Finally, we observed a positive link between D299G and T399I polymorphisms and CRC patients with lymph node (p?=?0.00024; p?=?0.0005, respectively) and metastasis (p?=?0.001; p?=?0.002, respectively). However, we found no evidence to support a significant association between TLR4 D299G and T399I polymorphisms and colorectal cancer susceptibility. Our findings suggest that TLR4 D299G and T399I polymorphisms are significantly associated with clinical features variables. TLR4 polymorphisms may serve as biomarker of disease progression. Therefore, our results need confirmation in even larger studies.     

Immunohistochemical expression pattern of MMR protein can specifically identify patients with colorectal cancer microsatellite instability

The microsatellite instability (MSI) pathway is found in most cases of hereditary nonpolyposis colorectal cancer (HNPCC) and in 12 % of sporadic colorectal cancer (CRC). It involves inactivation of deoxyribonucleic acid mismatch repair (MMR) genes MLH1, MSH2, PMS2, and MSH6. MMR germline mutation detections are an important supplement to HNPCC clinical diagnosis. It enables at-risk and mutation-positive relatives to be informed about their cancer risks and to benefit from intensive surveillance programs that have been proven to reduce the incidence of CRC. In this study, we analyzed for the first time in Tunisia the potential value of immunohistochemical assessment of MMR protein to identify microsatellite instability in CRC. We evaluate by immunohistochemistry MMR protein expression loss in tumoral tissue compared to positive expression in normal mucosa. Immunohistochemistry revealed loss of expression for MLH1, MSH2, MSH6, and PMS2 in 15, 21, 13, and 15 % of cases, respectively. Here, we report a more elevated frequency of MSI compared to data of the literature. In fact, by immunohistochemistry, 70 % of cases were shown to be MSS phenotype, whereas 30 % of cases, in our set, were instable. Moreover, according to molecular investigation, 71 % of cases were instable (MSI-H) and remaining cases were stable (29 %). Thus, we found a perfect association between MMR immunohistochemical analyses and MSI molecular investigation. Immunohistochemical analysis of MMR gene product expression may allow one to specifically identify MSI phenotype of patients with colorectal carcinomas.     

Diet Composition,Glucose Homeostasis,and Weight Regain in the YoYo Study

Based on several randomized clinical trials, it has been suggested that baseline glucose homeostasis interacts with the influence of diet composition on weight loss and weight loss maintenance. In this secondary analysis of the YoYo study, a study investigating predictors of weight loss maintenance, we tested the hypothesis that (self-selected) dietary carbohydrate and/or fibre intake interact with the glucose homeostasis parameters for weight loss maintenance. Sixty-one overweight or obese individuals lost around 10 kg of body weight on an energy-restricted diet and were then followed for 9 months. During this period, participants were advised to maintain their body weight and eat a healthy diet without further recommendations on calorie intake or diet composition. Contrary to our hypothesis, carbohydrate intake showed no positive association with weight regain after weight loss, and no interaction with baseline fasting glucose concentration was found. There was a non-significant negative association between fibre intake and weight regain (B = −0.274, standard error (SE) 0.158, p = 0.090), but again, no interaction with fasting plasma glucose was found. In conclusion, the data from the YoYo study do not support a role for baseline glucose homeostasis in determining the association between self-reported carbohydrate and/or fibre intake and weight regain after weight loss.     

Comparison of Micronutrient Intervention Strategies in Ghana and Benin to Cover Micronutrient Needs: Simulation of Bene-Fits and Risks in Women of Reproductive Age

Overlapping micronutrient interventions might increase the risk of excessive micronutrient intake, with potentially adverse health effects. To evaluate how strategies currently implemented in Benin and Ghana contribute to micronutrient intake in women of reproductive age (WRA), and to assess the risk for excess intakes, scenarios of basic rural and urban diets were built, and different on-going interventions were added. We estimated micronutrient intakes for all different scenarios. Four types of intervention were included in the scenarios: fortification, biofortification, supplementation and use of locally available nutrient-rich foods. Basic diets contributed poorly to daily micronutrient intake in WRA. Fortification of oil and salt were essential to reach daily requirements for vitamin A and iodine, while fortified flour contributed less. Biofortified products could make an important contribution to the coverage of vitamin A needs, while they were not sufficient to cover the needs of WRA. Iron and folic acid supplementation was a major contributor in the intake of iron and folate, but only in pregnant and lactating women. Risk of excess were found for three micronutrients (vitamin A, folic acid and niacin) in specific contexts, with excess only coming from voluntary fortified food, supplementation and the simultaneous overlap of several interventions. Better regulation and control of fortification and targeting of supplementation could avoid excess intakes.     

Motor and parietal cortex stimulation for phantom limb pain and sensations

Limb amputation may lead to chronic painful sensations referred to the absent limb, ie phantom limb pain (PLP), which is likely subtended by maladaptive plasticity. The present study investigated whether transcranial direct current stimulation (tDCS), a noninvasive technique of brain stimulation that can modulate neuroplasticity, can reduce PLP. In 2 double-blind, sham-controlled experiments in subjects with unilateral lower or upper limb amputation, we measured the effects of a single session of tDCS (2 mA, 15 min) of the primary motor cortex (M1) and of the posterior parietal cortex (PPC) on PLP, stump pain, nonpainful phantom limb sensations and telescoping. Anodal tDCS of M1 induced a selective short-lasting decrease of PLP, whereas cathodal tDCS of PPC induced a selective short-lasting decrease of nonpainful phantom sensations; stump pain and telescoping were not affected by parietal or by motor tDCS. These findings demonstrate that painful and nonpainful phantom limb sensations are dissociable phenomena. PLP is associated primarily with cortical excitability shifts in the sensorimotor network; increasing excitability in this system by anodal tDCS has an antalgic effect on PLP. Conversely, nonpainful phantom sensations are associated to a hyperexcitation of PPC that can be normalized by cathodal tDCS. This evidence highlights the relationship between the level of excitability of different cortical areas, which underpins maladaptive plasticity following limb amputation and the phenomenology of phantom limb, and it opens up new opportunities for the use of tDCS in the treatment of PLP.     

Lymphovascular invasion is a significant predictor for distant recurrence in patients with early-stage endometrial endometrioid adenocarcinoma

To evaluate the value of lymphovascular invasion (LVI) in endometrial endometrioid adenocarcinoma (EEA) as a predictor for distant recurrence, we analyzed the histopathologic features of 513 consecutive cases of nonsurgically staged EEA limited to the uterus. Grade, myoinvasion, cervical involvement, and LVI were evaluated. With a median follow-up of 28 months (range, 2-144 months), 67 cases (13.1%) recurred, 37 (7.2%) had locoregional recurrence, and 30 (5.8%) developed distant recurrence. LVI was identified in 116 cases (22.6%) cases and was the only adverse histopathologic finding in 23 cases; 5 (22%) of the 23 recurred. Multivariate analysis demonstrated a significant association between any type of recurrence and cervical involvement (hazard ratio [HR], 2.760; 95% confidence interval [CI], 1.621-4.698) and LVI (HR, 2.717; CI, 1.568-4.707). Multivariate analysis revealed LVI as the only independent predictor for distant recurrence (HR, 2.841; CI, 1.282-6.297). Studies to examine the role of adjuvant systemic therapy in patients with early-stage disease should be considered.     

Altered cord blood gammadelta T cell repertoire in Nigeria: possible impacts of environmental factors on neonatal immunity

Infectious diseases during pregnancy can impact the development of fetal immunity, leading to reduced neonatal resistance to infection and decreased responses to pediatric vaccines. Plasmodium falciparum causes placental infection in low parity pregnant women and is among the pathogens that affect fetal immunity. Recognizing the relationship between malaria and gammadelta T lymphocytes in adults, we asked whether neonatal gammadelta T cells would be altered in malaria-endemic regions as a marker for changes in fetal immunity. Our initial studies compared cord blood gammadelta T cells from deliveries to HIV- mothers in Jos (Nigeria) where malaria is endemic, or in Rome (Italy). We noted substantial differences in the Vgamma2 repertoire for cord blood collected in Jos or Rome; differences were consistent with a negative selection mechanism operating on the fetal Vgamma2 chain repertoire in neonates from Jos. A specific disruption affected the fraction of gammadelta T cells that we expect will respond to Bacille Calmette-Guerin (BCG). Fetal gammadelta T cell depletion might be a mechanism for impaired neonatal immunity and lowered responses to pediatric vaccines.