Oncogenic and tumor suppressor pathways in subchronic aflatoxicosis in rats: Association with serum and urinary aflatoxin exposure biomarkers

In this study, the changes in oncogenic and tumor suppressor signaling pathways in liver and their association with serum and urinary biomarkers of aflatoxin exposure were evaluated in Wistar rats fed diets containing aflatoxin B1 (AFB1) for 90 days. Rats were divided into four groups (n = 15 per group) and assigned to dietary treatments containing 0 (control), 50 (AFB50), 100 (AFB100) and 200 μg AFB1 kg-1 diet (AFB200). Multiple preneoplastic foci of hepatocytes marked with glutathione-S-transferase-placental form (GST-P) were identified in AFB100 and AFB200 groups. Hepatocellular damage induced by AFB1 resulted in overexpression of cyclin D1 and β-catenin. The liver expression of retinoblastoma (Rb) and p27Kip1 decreased in AFB100 and AFB200 groups, confirming the favorable conditions for neoplastic progression to hepatocellular carcinoma. All samples from rats fed AFB1-contaminated diets had quantifiable AFB1-lysine in serum or urinary AFM1 and AFB1-N7-guanine, with mean levels of 20.42-50.34 ng mL-1, 5.31-37.68 and 39.15-126.37 ng mg-1 creatinine, respectively. Positive correlations were found between AFB1-lysine, AFM1 or AFB1-N7-guanine and GST-P+, β-catenin+ and cyclin D1+ hepatocytes, while Rb + cells negatively correlated with those AFB1 exposure biomarkers. The pathways evaluated are critical molecular mechanisms of AFB1-induced hepatocarcinogenesis in rats.

Aflatoxin B1 residues in human livers and their relationship with markers of hepatic carcinogenesis in São Paulo, Brazil

In this study, hepatic biopsies from autopsy cases in São Paulo, Brazil, showing hepatocellular carcinoma (HCC, n = 8), cirrhosis associated with viral hepatitis (VC, n = 20), cirrhosis associated with alcoholism (AC, n = 20), and normal livers (NL or controls, n = 10) were subjected to determination of aflatoxin B1 (AFB1) and its main metabolites, and of markers of hepatic carcinogenesis Only non-metabolized AFB1 was detected in 13 samples (27.1%, N = 48) of liver disorders (HCC, VC and AC), at levels between 10.0 and 418.0 pg/g (mean: 76.6 ± 107.7 pg/g). Immuno-labeling of p53, cyclin D1, p21, β-catenin, and Prohibitin (PB) increased mainly in HCC patients, in relation to the controls. AFB1+ samples of HCC presented higher expressions of p53, cyclin D1, p21, and β-catenin compared with AFB1-livers. In contrast, p27, p16, and Rb immuno-labeling decreased in HCC, VC, and AC samples, compared with NL, with lowest values in AFB1+ samples for all liver disorders. Compared with NL, gene expression of cyclin D1 and PB in AFB1+ samples of HCC and AC were also higher, along with higher gene expression of p21 in VC and AC AFB1+ livers. Results indicated that patients with liver disorders were exposed to dietary aflatoxins, and that residual AFB1 in liver negatively affected the p53 and protein Rb pathways in HCC. Moreover, the presence of AFB1 in cirrhotic livers warrants concern about the potential contribution of dietary aflatoxin to disease progression during VC and AC.

Congenital Zika Virus Infection Induces Severe Spinal Cord Injury

We report 2 fatal cases of congenital Zika virus (ZIKV) infection. Brain anomalies, including atrophy of the cerebral cortex and brainstem, and cerebellar aplasia were observed. The spinal cord showed architectural distortion, severe neuronal loss, and microcalcifications. The ZIKV proteins and flavivirus-like particles were detected in cytoplasm of spinal neurons, and spinal cord samples were positive for ZIKV RNA.

Inhibition of Hepatocarcinogenesis by ArtinM via Anti-proliferative and Pro-apoptotic Mechanisms

ArtinM is a d-mannose-binding lectin found in the seeds of Artocarpus heterophyllus (jackfruit) that interacts with N-glycans, that is associated with receptors on the surface of phagocytic cells and induces the production of inflammatory mediators. Some of them are especially important because they may be required for antitumor immune response. This study aimed to evaluate the effect of ArtinM on hepatocellular preneoplastic foci. Wistar rats received 50 mg/kg of diethyl-nitrosamine (DEN) intraperitoneal weekly for 12 weeks. From the 14th week, the treated animals received 50 μg/kg of ArtinM subcutaneous every 2 weeks until the 18th week, whereas control animals were injected with vehicle alone. Preneoplastic-related factors were estimated using histological, western blotting and RT-PCR analysis. In comparison to the groups exposed to DEN, the ArtinM-treated rats showed diminution of preneoplastic foci, decreased expression of proliferating cell nuclear antigen (PCNA), increased number of nuclear p21 and p27 stained cells, augmented number of apoptotic cells, increased expression of p53, p42/44 MAPK and p21 proteins, reduced cyclin D1 (CCND1) protein levels and increased expression of TNFα and IFNγ genes. No difference was observed in interleukin 12 (IL12) protein levels. These findings indicate that ArtinM may provide protection against hepatocarcinogenesis as a result of the induction of cell-cycle blockage and pro-apoptotic mechanisms.

Specificity of modified Drosophila mariner transposons in the identification of Leishmania genes

Genetic manipulation of the protozoan Leishmania has led to a better understanding of the survival and development of these pathogens within their hosts. The association of the Leishmania genome sequencing information with the ability of transposons to introduce or destroy phenotypes allows a global perspective on the role and importance of genes in cellular pathways. Herein we report the construction and testing of mariner transposable elements carrying the neomycin phosphotransferase, green fluorescent protein, or beta-glucuronidase genes as reporters for translational fusion events. We demonstrate that the expression of the reporter genes will occur only when the genes are inserted in-frame within predicted genes. Our results not only add to the mariner toolkit for gene manipulation but also strengthen the evidence that the mariner system is a reliable means for the study of gene expression in Leishmania.