RESUMEN
Resveratrol (RES) can inhibit the growth and proliferation of liver cancer cells. However, its role in the precancerous stage is still unclear. This paper aims to study the effect and mechanism of RES on the precancerous stage of liver cancer in rats induced by diethylinitrosamine (DEN). SD rats were divided into normal control group, RES treatment group, DEN treatment group and RES-DEN treatment group. The results showed that after the rats were treated with DEN for 8 weeks, the total expression level of proliferating cell nuclear antigen (PCNA) of hepatocytes increased to 2-fold (P<0.05), and the expression level of PCNA protein in the nucleus increased to 3-fold (P<0.001). However, the expression levels of total PCNA (P<0.05) and nuclear PCNA protein (P<0.001) in hepatocytes of rats treated with RES-DEN decreased, suggesting that RES could significantly inhibit the liver malignant proliferation of cells. Through non-targeted metabolomics and KEGG metabolic pathway enrichment analysis, the results showed that the level of glycolysis did not increase significantly in the hepatocytes of RES-DEN-treated rats, although the transition from the pentose phosphate pathway to the glycolysis pathway was enhanced when compared with the DEN group rats. This finding suggested that the metabolic pathway of phosphoenolpyruvate-pyruvate-lactate was inhibited. Further verification found that the protein expression levels of key enzymes M2-type pyruvate kinase (PKM2) and lactate dehydrogenase (LDHA) in this metabolic pathway were inhibited (P<0.05). RES can reprogram glucose metabolism and inhibit DEN-induced excessive proliferation of rat hepatocytes in the precancerous stage of liver cancer, providing an experimental basis for RES to prevent liver cancer.
RESUMEN
To clarify the role of stem cells in hepatocarcinogenesis, CD44 expression was investigated in mouse livers as well as embryonic cell lineages treated with diethylnitrosamine (DEN). Liver tumors induced by DEN were analyzed by immunohistochemisty for CD44. Liver tissues were sampled at 6, 24, and 48 hr after treatment with saline or DEN. Mouse embryonic stem cells (ESCs), hepatic progenitor cells (HPCs), and hepatocyte like cells (HCs), representing 0, 22, and 40 days of differentiation, respectively, were treated with DEN at four doses (0, 1, 5, and 15 mM, respectively) for 24 hr, after which CD44 expression levels were examined by relative quantitative real-time PCR. CD44 expression was weakly detected in tumor cells as well as in some hepatocytes surrounding the tumor cells. However, CD44 expression was not detected in liver tissue treated with DEN at early time points. The CD44 mRNA expression level was significantly different among cells treated with 5 mM DEN at day 22 (P<0.01) as well as 1, 5, and 15 mM DEN at day 40 (P<0.01) compared with control. Taken together, CD44 expression slightly increased in mouse DEN-induced tumors. Furthermore, expression of CD44 in embryonic cell lineages treated with various doses of DEN significantly differed among embryo stem cells and derived hepatic lineage cells. This suggests that CD44 expression may be modulated in the progeny of stem cells during their differentiation toward hepatocytes, and its expression may increase in the tumor stage but not during early carcinogenesis.