Effect of Snake Venom Metalloprotease Desintegrin in Hepatocarcinoma Tumor Cells

Hepatocellular carcinoma is the third leading cause of cancer-related death in the world. This cancer is associated with cirrhosis following the hepatitis B or C virus infection, alcohol addiction, metabolic liver disease and exposure to dietary toxins such as aflatoxins and aristolochic acid. Studies demonstrate the integration of the HBV genome into liver cell DNA, including cases of patients with HBV-negative serology. Despite advances in prevention techniques, screening, and technology in cancer diagnosis and treatments, the incidence and mortality remain worrisome. Therefore, this research is significant due to the contribution of the development of new biological agents that can be used as monotherapy or adjuvant chemotherapy. Jararhagin, a snake toxin isolated from Bothrops jararaca venom, has been the subject of many studies seeking alternatives for the treatment of cancer. This protein contains the cysteine-rich disintegrin-like metalloproteinase domains and desirable functions to combat tumor cells, such as promoting acute inflammation, damaging the vascular endothelium through the zinc-dependent catalytic domain (responsible for hemorrhagic function) and enzymatically degrading the constituents of the endothelial basement membrane. Due to the antitumor effects of jararhagin presented in previous research, this study aimed to describe the possible antitumor effects of this snake metalloprotease in the murine liver tumor, intending to propose a new therapeutic option in the human liver tumor.

Gut bitter taste receptor signalling induces ABCB1 through a mechanism involving CCK

T2Rs (bitter taste-sensing type 2 receptors) are expressed in the oral cavity to prevent ingestion of dietary toxins through taste avoidance. They are also expressed in other cell types, including gut enteroendocrine cells, where their physiological role is enigmatic. Previously, we proposed that T2R-dependent CCK (cholecystokinin) secretion from enteroendocrine cells limits absorption of dietary toxins, but an active mechanism was lacking. In the present study we show that T2R signalling activates ABCB1 (ATP-binding cassette B1) in intestinal cells through a CCK signalling mechanism. PTC (phenylthiocarbamide), an agonist for the T2R38 bitter receptor, increased ABCB1 expression in both intestinal cells and mouse intestine. PTC induction of ABCB1 was decreased by either T2R38 siRNA (small interfering RNA) or treatment with YM022, a gastrin receptor antagonist. Thus gut ABCB1 is regulated through signalling by CCK/gastrin released in response to PTC stimulation of T2R38 on enteroendocrine cells. We also show that PTC increases the efflux activity of ABCB1, suggesting that T2R signalling limits the absorption of bitter tasting/toxic substances through modulation of gut efflux membrane transporters.

Worldwide Survey of Fumonisin Contamination of Corn and Corn-Based Products

As part of a comprehensive risk assessment study for fumonisins, reliable data on exposure of populations to these dietary toxins must be obtained. To assess the extent of worldwide exposure, the published literature on the contamination of food and feed supplies has been reviewed and supplemented with unpublished material from various international sources. Fumonisin contamination of corn and corn-based products occurs in many countries. Animal mycotoxicoses such as equine leukoencephalomalacia and porcine pulmonary edema are caused by heavily contaminated animal feeds. For example, as much as 330 μg/g fumonisin B1 (FB1) has been found in swine feed. Although commercially available refined corn products for human consumption are generally contaminated at levels below 1 μg/g FB1, individual products in certain countries can reach far higher levels. Health risks associated with consumption of these products depend on the extent to which they are consumed in a varied diet. Home-grown corn in certain rural areas, where it also constitutes the staple diet, can be contaminated at >100 μg/g. Consumption of corn contaminated at these high levels has: been associated with a high incidence of esophageal cancer in these areas.