Myc controls a distinct transcriptional program in fetal thymic epithelial cells that determines thymus growth

Interactions between thymic epithelial cells (TEC) and developing thymocytes are essential for T cell development, but molecular insights on TEC and thymus homeostasis are still lacking. Here we identify distinct transcriptional programs of TEC that account for their age-specific properties, including proliferation rates, engraftability and function. Further analyses identify Myc as a regulator of fetal thymus development to support the rapid increase of thymus size during fetal life. Enforced Myc expression in TEC induces the prolonged maintenance of a fetal-specific transcriptional program, which in turn extends the growth phase of the thymus and enhances thymic output; meanwhile, inducible expression of Myc in adult TEC similarly promotes thymic growth. Mechanistically, this Myc function is associated with enhanced ribosomal biogenesis in TEC. Our study thus identifies age-specific transcriptional programs in TEC, and establishes that Myc controls thymus size

Effects of selected food phytochemicals in reducing the toxic actions of TCDD and p,p′-DDT in U937 macrophages

To assess the effectiveness of selected food phytochemicals in reducing the toxic effects of the environmental toxicants, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and p,p′-DDT (DDT), we tested the potencies of auraptene, nobiletin, zerumbone, and (±)-13-hydroxy-10-oxo-trans-11-octadecenoic acid (13-HOA) in reversing the inflammatory action of these toxicants in U937 human macrophages. Using quantitative RT–PCR as the initial screening assay, we identified antagonistic actions of zerumbone and auraptene against the action of TCDD and DDT in up-regulating the mRNA expressions of COX-2 and VEGF. The functional significance of the inhibitory action of zerumbone on COX-2 expression was confirmed by demonstrating its suppression of TCDD-induced activation of COX-2 gene expression in mouse MMDD1 cells. We tested auraptene on DDT-induced reactive oxygen species (ROS) formation in U937 macrophages and found that auraptene is a powerful agent antagonizing this action of DDT. To confirm the significance of these actions of zerumbone and auraptene at the cellular level, we assessed their influence on TCDD-induced apoptosis resistance in intact U937 macrophages and found that they are capable of reversing this action of TCDD. In conclusion, zerumbone and auraptene were identified to be the most effective agents in protecting U937 macrophages from developing these cell toxic effects of TCDD and DDT

Overexpression of Batf induces an apoptotic defect and an associated lymphoproliferative disorder in mice

Activator protein-1 (AP-1) is a dimeric transcription factor composed of the Jun, Fos and Atf families of proteins. Batf is expressed in the immune system and participates in AP-1 dimers that modulate gene expression in response to a variety of stimuli. Transgenic (Tg) mice overexpressing human BATF in T cells were generated using the human CD2 promoter (CD2-HA (hemagglutinin antigen) - BATF). By 1 year of age, over 90% of the mice developed a lymphoproliferative disorder (LPD). The enlarged lymph nodes characteristic of this LPD contain a polyclonal accumulation of T cells with a CD4+ bias, yet efforts to propagate these tumor cells in vitro demonstrate that they do not proliferate as well as wild-type CD4+ T cells. Instead, the accumulation of these cells is likely due to an apoptotic defect as CD2-HA-BATF Tg T cells challenged by trophic factor withdrawal in vitro resist apoptosis and display a pro-survival pattern of Bcl-2 family protein expression. As elevated levels of Batf expression are a feature of lymphoid tumors in both humans and mice, these observations support the use of CD2-HA-BATF mice as a model for investigating the molecular details of apoptotic dysregulation in LPD

Antioxidative and Chemopreventive Properties of Vernonia amygdalina and Garcinia biflavonoid

Recently, considerable attention has been focused on dietary and medicinal phytochemicals that inhibit, reverse or retard diseases caused by oxidative and inflammatory processes. Vernonia amygdalina is a perennial herb belonging to the Asteraceae family. Extracts of the plant have been used in various folk medicines as remedies against helminthic, protozoal and bacterial infections with scientific support for these claims. Phytochemicals such as saponins and alkaloids, terpenes, steroids, coumarins, flavonoids, phenolic acids, lignans, xanthones, anthraquinones, edotides and sesquiterpenes have been extracted and isolated from Vernonia amygdalina. These compounds elicit various biological effects including cancer chemoprevention. Garcinia kola (Guttiferae) seed, known as “bitter kola”, plays an important role in African ethnomedicine and traditional hospitality. It is used locally to treat illnesses like colds, bronchitis, bacterial and viral infections and liver diseases. A number of useful phytochemicals have been isolated from the seed and the most prominent of them is the Garcinia bioflavonoids mixture called kolaviron. It has well-defined structure and an array of biological activities including antioxidant, antidiabetic, antigenotoxic and hepatoprotective properties. The chemopreventive properties of Vernonia amygdalina and Garcinia biflavonoids have been attributed to their abilities to scavenge free radicals, induce detoxification, inhibit stress response proteins and interfere with DNA binding activities of some transcription factors

FOXP3+ Tregs and B7-H1+/PD-1+ T lymphocytes co-infiltrate the tumor tissues of high-risk breast cancer patients: Implication for immunotherapy

<p>Abstract</p> <p>Background</p> <p>Recent studies have demonstrated a direct involvement of B7-H1, PD-1 and FOXP3 molecules in the immune escape of cancer. B7-H1 is an inhibitory molecule that binds to PD-1 on T lymphocytes, while FOXP3 is a marker for regulatory T cells (T_regs). We have previously demonstrated the association of B7-H1-expressing T infiltrating lymphocytes (TIL) with high-risk breast cancer patients while other studies reported the involvement of FOXP3+ T_regsas a bad prognostic factor in breast tumors. Although the co-existence between the two types of cells has been demonstrated <it>in vitro </it>and animal models, their relative infiltration and correlation with the clinicopathological parameters of cancer patients have not been well studied. Therefore, we investigated TIL-expressing the B7-H1, PD-1, and FOXP3 molecules, in the microenvironment of human breast tumors and their possible association with the progression of the disease.</p> <p>Methods</p> <p>Using immunohistochemistry, tumor sections from 62 breast cancer patients were co-stained for B7-H1, PD-1 and FOXP3 molecules and their expression was statistically correlated with factors known to be involved in the progression of the disease.</p> <p>Results</p> <p>A co-existence of B7-H1⁺T lymphocytes and FOXP3⁺T_regswas evidenced by the highly significant correlation of these molecules (<it>P </it>< .0001) and their expression by different T lymphocyte subsets was clearly demonstrated. Interestingly, concomitant presence of FOXP3⁺T_regs, B7-H1⁺and PD-1⁺TIL synergistically correlated with high histological grade (III) (<it>P </it>< .001), estrogen receptor negative status (<it>P </it>= .017), and the presence of severe lymphocytic infiltration (<it>P </it>= .022).</p> <p>Conclusion</p> <p>Accumulation of TIL-expressing such inhibitory molecules may deteriorate the immunity of high-risk breast cancer patients and this should encourage vigorous combinatorial immunotherapeutic approaches targeting T_regsand B7-H1/PD-1 molecules.</p

Modelling prognostic factors in advanced pancreatic cancer

Pancreatic cancer is the fifth most common cause of cancer death. Identification of defined patient groups based on a prognostic index may improve the prediction of survival and selection of therapy. Many prognostic factors have been identified often based on retrospective, underpowered studies with unclear analyses. Data from 653 patients were analysed. Continuous variables are often simplified assuming a linear relationship with log hazard or introducing a step function (dichotomising). Misspecification may lead to inappropriate conclusions but has not been previously investigated in pancreatic cancer studies. Models based on standard assumptions were compared with a novel approach using nonlinear fractional polynomial (FP) transformations. The model based on FP-transformed covariates was most appropriate and confirmed five previously reported prognostic factors: albumin, CA19-9, alkaline phosphatase, LDH and metastases, and identified three additional factors not previously reported: WBC, AST and BUN. The effects of CA19-9, alkaline phosphatase, AST and BUN may go unrecognised due to simplistic assumptions made in statistical modelling. We advocate a multivariable approach that uses information contained within continuous variables appropriately. The functional form of the relationship between continuous covariates and survival should always be assessed. Our model should aid individual patient risk stratification and the design and analysis of future trials in pancreatic cancer