This experiment was designed to compare the effect of two
selenium sources at the dosage of therapeutic level on hepatocarcinogenesis and angiogenic
cytokines in DEN-induced hepatocarcinoma rats to further approach their possible anticancer's mechanism. One hundred and seventy-eight Sprague-Dawley (SD) rats (average weight being 100-120g) were randomly divided into 5 groups (I-V). Animals in group I, group II and group III served as the negative control,
sodium selenite control (SS) and positive controls respectively, and received 0.1, 3.0, and 0.1mg/kg
selenium from
sodium selenite supplemented diets during the whole experimental time. Rats in group IV and group V were fed with
selenium from
selenium-enriched malt (SEM) and
sodium selenite (SS) supplemented diets (3mg/kg respectively). To balance the nutritional content among each group, normal malt which was not treated with
selenium was added into the diets of the challenge groups. The nutrition contents, except the
selenium of the diet in each group, were similar and in accordance with NRC standards. Rats in groups III-V were treated by aqueous
diethylnitrosamine solution (100mg/L) at the dosage of 10mg/kg
body weight every day for 16 weeks to induce hepatocarcinoma, and drank sterilized water for an additional two weeks. Rats in group I and group II drank sterilized water throughout the experiment. At 4th, 8th, 12th, 16th week, five rats in each group were then sacrificed by cervical
decapitation. At the termination of the study, at 18th week, the surplus rats were sacrificed by cervical
decapitation. Feed was withheld from the rats for 12h before sampling. The number of
hepatoma nodules in liver and mortality of rats were calculated. The values of the following items, including α-
fetoprotein (AFP), gamma-glutamyltranspeptidase (GGT),
tumor necrosis factor-α (TNF-α),
insulin-like growth factors-II (
IGF-II),
nitric oxide (NO) and total
nitric oxide synthase (T-NOS) in plasma were determined. At the same time, the positive numbers of
vascular endothelial growth factor (
VEGF) and
protein kinase C-α (PKCα) staining cells in
tumor tissue were analyzed by immunohistochemistry using the Envision two step methods with a kit. The results indicated that SEM could significantly decrease the mortality of rats and the number of
hepatoma nodules, values of GGT and AFP, and the levels of
IGF-II, NO and NOS and lessen the positive numbers of
VEGF and PKCα staining cells in
tumor tissue. Moreover, SEM could increase the levels of TNF-α in the initiated time of hepatocarcinogenesis, whereas, decrease the levels of TNF-α in the progressive time of hepatocarcinogenesis. SS could only significantly inhibit the positive numbers of PKCα staining cells in
tumor tissue, decrease the levels of GGT, AFP and TNF-α at minority sampling times, and increase the levels of NO. In conclusion, SEM could reduce the mortality. It might be related to deaden significantly the lesion of liver, delay the cause of hepatocarcinogenesis, and inhibit the progress of angiogenesis to increase the livability of DEN-induced hepatocarcinoma rats. SS at the same therapeutic dosage had less effect on the hepatocarcinogenesis by inhibiting angiogenesis and relative
cytokines to some extent.