Selenium prevents tumor development in a rat model for chemical carcinogenesis

Abstract

Previous studies in animals and humans have shown that selenium compounds can prevent cancer development. In this work we studied the tumor preventive effect of selenium supplementation, administrated as selenite, in the initiation, promotion and progression phases in a synchronized rat model for chemically induced hepatocarcinogenesis, the resistant hepatocyte model. Selenite in supra-nutritional but subtoxic doses (1 and 5 p.p.m.) was administrated to the animals through the drinking water. Such supplementation during the initiation phase did not have a tumor preventive effect. However, selenite treatment during the promotion phase decreased the volume fraction of pre-neoplastic liver nodules from 38% in control animals to 25 (1 p.p.m.) and 14% (5 p.p.m.) in the selenite-supplemented groups. In addition the cell proliferation within the nodules decreased from 42% in the control to 22 (1 p.p.m.) and 17% (5 p.p.m.). Immunohistochemical staining for the selenoenzyme thioredoxin reductase 1 revealed an increased expression of the enzyme in liver nodules compared with the surrounding tissue. The activity was reduced to 50% in liver homogenates from selenium-treated animals but the activity of the selenoenzyme glutathione peroxidase was essentially unaltered. Selenite treatment (5 p.p.m.) during the progression phase resulted in a significantly lower volume fraction of liver tumors (14 compared with 26%) along with a decrease in cell proliferation within the tumors (34 compared with 63%). Taken together our data indicate that the carcinogenetic process may be prevented by selenium supplementation both during the promotion and the progression phase.

Sodium selenite-induced activation of DAPK promotes autophagy in human leukemia HL60 cells

“…Sodium selenite is commonly used as a source of selenium in biological research. Accumulating evidences confirmed the application of selenite in studies of cell proliferation and cancer (3,4). Previous results suggested supranutritional doses of selenite promoted cell death through mitochondria-or ER stress-mediated apoptotic pathway in human leukemia cell lines (5,6).…”

Role of Nigella sativa and a number of its antioxidant constituents towards azoxymethane‐induced genotoxic effects and colon cancer in rats

“…This could be due to the presence of selenium as one of its constituents. Diets high in selenium have been shown to suppress carcinogenesis in animal models (Baines et al, 2000;Bjorkhem-Bergman et al, 2005). Selenium levels above the RDA are required for the inhibition of genetic damage and cancer in both rodents and humans (El-Bayoumy, 2001).…”

Oxidative Stress and Antioxidant Status in Hypo- and Hyperthyroidism

“…Thus, H2O2 is carcinogenic and has been found to play a role in several human cancers (7) even if it may not be sufficient [49]. Conversely, selenium, the essential constituent of protective enzymes, prevents tumor development in rats submitted to chemical carcinogenesis [50]. Lack of protective systems in knockout mice such as lack of peroxiredoxin or glutathione (GSH) peroxidases indeed leads to malignant cancers [51,52].…”