Spatio-Temporal Regulation of Rac1 Mobility by Actin Islands

Rho GTPases play important roles in many aspects of cell migration, including polarity establishment and organizing actin cytoskeleton. In particular, the Rho GTPase Rac1 has been associated with the generation of protrusions at leading edge of migrating cells. Previously we showed the mobility of Rac1 molecules is not uniform throughout a migrating cell (Hinde E et. al. PNAS 2013). Specifically, the closer a Rac1 molecule is to the leading edge, the slower the molecule diffuses. Because actin-bound Rac1 diffuses slower than unbound Rac1, we hypothesized that regions of high actin concentration, called “actin islands”, act as diffusive traps and are responsible for the non-uniform diffusion observed in vivo. Here, in silico model simulations demonstrate that equally spaced actin islands can regulate the time scale for Rac1 diffusion in a manner consistent with data from live-cell imaging experiments. Additionally, we find this mechanism is robust; different patterns of Rac1 mobility can be achieved by changing the actin islands’ positions or their affinity for Rac1.     

MicroRNA-182-5p targets a network of genes involved in DNA repair

MicroRNAs are noncoding regulators of gene expression, which act by repressing protein translation and/or degrading mRNA. Many have been shown to drive tumorigenesis in cancer, but functional studies to understand their mode of action are typically limited to single-target genes. In this study, we use synthetic biotinylated miRNA to pull down endogenous targets of miR-182-5p. We identified more than 1000 genes as potential targets of miR-182-5p, most of which have a known function in pathways underlying tumor biology. Specifically, functional enrichment analysis identified components of both the DNA damage response pathway and cell cycle to be highly represented in this target cohort. Experimental validation confirmed that miR-182-5p-mediated disruption of the homologous recombination (HR) pathway is a consequence of its ability to target multiple components in that pathway. Although there is a strong enrichment for the cell cycle ontology, we do not see primary proliferative defects as a consequence of miR-182-5p overexpression. We highlight targets that could be responsible for miR-182-5p-mediated disruption of other biological processes attributed in the literature so far. Finally, we show that miR-182-5p is highly expressed in a panel of human breast cancer samples, highlighting its role as a potential oncomir in breast cancer.     

Characterization of the inhibitory effects of hyperprolactinaemia on the mechanism controlling LH secretion in chronically ovariectomized rats

The time-course of the inhibitory effect of hyperprolactinaemia on LH secretion was delineated. Hyperprolactinaemia was induced in ovariectomized rats with injections of domperidone or ovine prolactin and circulating LH levels were measured from 1 h to 9 days after the treatment. Inhibition of LH secretion occurred within 2-4 h after treatment, and was maintained (provided that serum prolactin remained elevated) for a period of 6 days only. Thereafter LH levels increased to become insignificantly different from control levels on Day 9. A reduction in pituitary responsiveness was not associated with the acute or sub-chronic inhibition of LH secretion, although a significant fall in responsiveness was observed simultaneously with the return of serum LH levels to control values. No changes in hypothalamic LH-RH content was found. It is concluded that an impairment of pituitary function is not responsible for the inhibitory action of prolactin on LH secretion.     

Data on the effect of sub-epithelial connective tissue graft with hydroxyl-apatite for furcation treatment in Indians

Grade II furcation defect has a great potential for regeneration. Attempts have been made to regenerate lost periodontium in furcation defects through variety of approaches. A total of 22 patients with Grade II furcation defect were examined. The patients were sequentially grouped into three groups namely, (Group A) subepithelial connective tissue graft as a barrier membrane, (Group B) bovine bone graft material Bio-OssTM and (Group C) with the combination of the two. The treatment modalities show that there was a strong improvement in the resolution of the grade II furcation defects. The reduction in horizontal furcation defect measurement was 20.63% for group A. The change was found to be moderate (p=0.023*). The % change is 20.97% for group B and it is statistically significance (p = 0.001**). The % change was 20.78% in Group C with a good statistical significance (p=0.003**). Complete obliteration of the defect clinically and radio-graphically was observed for grade II furcation defect. Thus, the effect of sub-epithelial connective tissue graft with hydroxyl-apatite for furcation treatment in Indians is documented in this report.     

Acacetin exerts antioxidant potential against atherosclerosis through Nrf2 pathway in apoE−/− Mice

Oxidative stress has a considerable influence on endothelial cell dysfunction and atherosclerosis. Acacetin, an anti-inflammatory and antiarrhythmic, is frequently used in the treatment of myocarditis, albeit its role in managing atherosclerosis is currently unclear. Thus, we evaluated the regulatory effects of acacetin in maintaining endothelial cell function and further investigated whether the flavonoid could attenuate atherosclerosis in apolipoprotein E deficiency (apoE^−/−) mice. Different concentrations of acacetin were tested on EA.hy926 cells, either induced or non-induced by human oxidized low-density lipoprotein (oxLDL), to clarify its influence on cell viability, cellular reactive oxidative stress (ROS) level, apoptotic ratios and other regulatory effects. In vivo, apoE^−/− mice were fed either a Western diet or a chow diet. Acacetin pro-drug (15 mg/kg) was injected subcutaneously two times a day for 12 weeks. The effects of acacetin on the atherosclerotic process, plasma inflammatory factors and lipid metabolism were also investigated. Acacetin significantly increased EA.hy926 cell viability by reducing the ratios of apoptotic and necrotic cells at 3 μmol/L. Moreover, 3 μmol/L acacetin clearly decreased ROS levels and enhanced reductase protein expression through MsrA and Nrf2 pathway through phosphorylation of Nrf2 and degradation of Keap1. In vivo, acacetin treatment remarkably attenuated atherosclerosis by increasing reductase levels in circulation and aortic roots, decreasing plasma inflammatory factor levels as well as accelerating lipid metabolism in Western diet-fed apoE^−/− mice. Our findings demonstrate the anti-oxidative and anti-atherosclerotic effects of acacetin, in turn suggesting its potential therapeutic value in atherosclerotic-related cardiovascular diseases (CVD).     

Linking periodontal disease with obesity and blood glucose

It is of interest to evaluate the association of obesity and blood glucose level with periodontitis. Patients (150 with age range 26-68 years) were included based on WHO obesity criteria, undiagnosed for periodontitis, with Body Mass Index (BMI) ≥ 30 and systemically healthy. These patients underwent periodontal examination followed by blood analysis for lipid profile and blood sugar level. The periodontal status was determined using parameters such as Plaque index (PI), gingival index (GI), Probing depth (PPD) and Clinical attachment loss (CAL). 103 (68.7%) patients had >190 of triglyceride values. Data shows that periodontitis has no statistical significance with total cholesterol, HDL, LDL and moderate significance with VLDL, triglycerides. Glycemic control of the patients is assessed using postprandial blood sugar (PPBS) and Fasting Blood Sugar (FBS). Data shows that 129(86.6%) had FBS (mg/dl) <100 and 21 (14.0%) had FBS (mg/dl) >100. So the number of patients with FBS (mg/dl) < 100 were more i.e., 129 (86.6%). The PPBS values were in 136 (90.7%) had PPBS (mg/dl) <140 and only 14(9.3%) had PPBS (mg/dl) >140 group of patients were said have glucose intolerance. Thus, there is no change in lipid profile with established periodontitis in obese individuals. However, altered glycemic control is observed.     

Using the MCF10A/MCF10CA1a Breast Cancer Progression Cell Line Model to Investigate the Effect of Active,Mutant Forms of EGFR in Breast Cancer Development and Treatment Using Gefitinib

Background

Basal-like and triple negative breast cancer (TNBC) share common molecular features, poor prognosis and a propensity for metastasis to the brain. Amplification of epidermal growth factor receptor (EGFR) occurs in ~50% of basal-like breast cancer, and mutations in the epidermal growth factor receptor (EGFR) have been reported in up to ~ 10% of Asian TNBC patients. In non-small cell lung cancer several different mutations in the EGFR tyrosine kinase domain confer sensitivity to receptor tyrosine kinase inhibitors, but the tumourigenic potential of EGFR mutations in breast cells and their potential for targeted therapy is unknown.

Materials and Methods

Constructs containing wild type, G719S or E746-A750 deletion mutant forms of EGFR were transfected into the MCF10A breast cells and their tumorigenic derivative, MCF10CA1a. The effects of EGFR over-expression and mutation on proliferation, migration, invasion, response to gefitinib, and tumour formation in vivo was investigated. Copy number analysis and whole exome sequencing of the MCF10A and MCF10CA1a cell lines were also performed.

Results

Mutant EGFR increased MCF10A and MCF10CA1a proliferation and MCF10A gefitinib sensitivity. The EGFR-E746-A750 deletion increased MCF10CA1a cell migration and invasion, and greatly increased MCF10CA1a xenograft tumour formation and growth. Compared to MCF10A cells, MCF10CA1a cells exhibited large regions of gain on chromosomes 3 and 9, deletion on chromosome 7, and mutations in many genes implicated in cancer.

Conclusions

Mutant EGFR enhances the oncogenic properties of MCF10A cell line, and increases sensitivity to gefitinib. Although the addition of EGFR E746-A750 renders the MCF10CA1a cells more tumourigenic in vivo it is not accompanied by increased gefitinib sensitivity, perhaps due to additional mutations, including the PIK3CA H1047R mutation, that the MCF10CA1a cell line has acquired. Screening TNBC/basal-like breast cancer for EGFR mutations may prove useful for directing therapy but, as in non-small cell lung cancer, accompanying mutations in PIK3CA may confer gefitinib resistance.