Signal transducer and activator of transcription 3 promotes the Warburg effect possibly by inducing pyruvate kinase M2 phosphorylation in liver precancerous lesions.

BACKGROUND: Study shows that signal transducer and activator of transcription 3 (STAT3) can increase the Warburg effect by stimulating hexokinase 2 in breast cancer and upregulate lactate dehydrogenase A and pyruvate dehydrogenase kinase 1 in myeloma. STAT3 and pyruvate kinase M2 (PKM2) can also be activated and enhance the Warburg effect in hepatocellular carcinoma. Precancerous lesions are critical to human and rodent hepatocarcinogenesis. However, the underlying molecular mechanism for the development of liver precancerous lesions remains unknown. We hypothesized that STAT3 promotes the Warburg effect possibly by upregulating p-PKM2 in liver precancerous lesions in rats. AIM: To investigate the mechanism of the Warburg effect in liver precancerous lesions in rats. METHODS: A model of liver precancerous lesions was established by a modified Solt-Farber method. The liver pathological changes were observed by HE staining and immunohistochemistry. The transformation of WB-F344 cells induced with N-methyl-N'-nitro-N-nitrosoguanidine and hydrogen peroxide was evaluated by the soft agar assay and aneuploidy. The levels of glucose and lactate in the tissue and culture medium were detected with a spectrophotometer. The protein levels of glutathione S-transferase-π, proliferating cell nuclear antigen (PCNA), STAT3, and PKM2 were examined by Western blot and immunofluorescence. RESULTS: We found that the Warburg effect was increased in liver precancerous lesions in rats. PKM2 and p-STAT3 were upregulated in activated oval cells in liver precancerous lesions in rats. The Warburg effect, p-PKM2, and p-STAT3 expression were also increased in transformed WB-F344 cells. STAT3 activation promoted the clonal formation rate, aneuploidy, alpha-fetoprotein expression, PCNA expression, G1/S phase transition, the Warburg effect, PKM2 phosphorylation, and nuclear translocation in transformed WB-F344 cells. Moreover, the Warburg effect was inhibited by stattic, a specific inhibitor of STAT3, and further reduced in transformed WB-F344 cells after the intervention for PKM2. CONCLUSION: The Warburg effect is initiated in liver precancerous lesions in rats. STAT3 activation promotes the Warburg effect by enhancing the phosphorylation of PKM2 in transformed WB-F344 cells.

[Dynamic changes of TGF-α and TGF-ß1 in rats with liver cirrhosis induced by multiple pathogenic factors].

OBJECTIVE: To explore the dynamic changes of transforming growth factor-α (TGF-α) and transforming growth factor-ß1 (TGF-ß1) of liver cirrhosis induced by multiple pathogenic factors in rats. METHODS: Animals in the cirrhosis group were fed a mixture of maize flour, lard, cholesterol and alcohol plus subcutaneously injection with carbon tetrachloride (CCl4), the CCl4(0.5 ml/100 g · w) was injected at the first day of experiment and the 40% CCl4oil solution (0.3 ml /100 g · w) was injected at an interval of three days. The thirty-six male SD rats were randomly divided into liver cirrhosis group of the 4th, 6th and 8 th week, and normal control group of the 4th, 6th and 8th week. The contents of alanine transferase (ALT), endotoxin, tumor necrosis factor-α (TNF-α) and homocysteine (Hcy) in plasma were evaluated. Histopathological changes of the liver were observed under microscope with the staining of HE. The expressions of TGF-α and TGF-ß1 were analyzed by the method of immunohistochemistry. RESULTS: Compared with the corresponding normal control group, the levels of ALT, endotoxin, TNF-α and Hcy in plasma were gradually significantly increased in liver cirrhosis group of the 4th, 6th and 8th week (P < 0.05); the expression of TGF-α in the liver tissues was significantly increased at the 4th week (P < 0.05); the expression of TGF-ß1 in the liver tissues was gradually significantly increased in every model group (P < 0.05). CONCLUSION: In the formation process of cirrhosis, the expression of TGF-α was increased in liver of cirrhosis group at the 4th week, and later it was suppressed; the expression of TGF-ß1 was continuously increased. The characteristic dynamic changes of TGF-α and TGF-ß1 might be related to sustained endotoxemia, the high level of TNF-α and hyperhomocysteinemia.

Effect of artesunate supplementation on bacterial translocation and dysbiosis of gut microbiota in rats with liver cirrhosis.

AIM: To evaluate the effect of artesunate (AS) supplementation on bacterial translocation (BT) and gut microbiota in a rat model of liver cirrhosis. METHODS: Fifty-four male Sprague-Dawley rats were randomly divided into a normal control group (N), a liver cirrhosis group (M) and a liver cirrhosis group intervened with AS (MA). Each group was sampled at 4, 6 and 8 wk. Liver cirrhosis was induced by injection of carbon tetrachloride (CCl4), intragastric administration of 10% ethanol, and feeding a high fat diet. Rats in the MA group were intragastrically administered with AS (25 mg/kg body weight, once daily). Injuries of the liver and intestinal mucosa were assessed by hematoxylin-eosin or Masson's trichrome staining. Liver index was calculated as a ratio of the organ weight (g) to body weight (g). The gut microbiota was examined by automated ribosomal intergenic-spacer analysis of fecal DNA. BT was assessed by standard microbiological techniques in the blood, mesenteric lymph nodes (MLNs), liver, spleen, and kidney. RESULTS: Compared to group N, the body weight was reduced significantly in groups M and MA due to the development of liver cirrhosis over the period of 8 wk. The body weight was higher in group MA than in group M. The liver indices were significantly elevated at 4, 6 and 8 wk in groups M and MA compared to group N. AS supplementation partially decreased the liver indices in group MA. Marked histopathologic changes in the liver and small intestinal mucosa in group M were observed, which were alleviated in group MA. Levels of pro-inflammatory interleukin-6 and tumor necrosis factor-α were significantly elevated at 8 wk in ileal homogenates in group M compared to group N, which were decreased after AS supplementation in group MA. The dysbiosis of gut microbiota indicated by the mean diversity (Shannon index) and mean similarity (Sorenson index) was severe as the liver cirrhosis developed, and AS supplementation had an apparent intervention effect on the dysbiosis of gut microbiota at 4 wk. The occurrence of BT was increased in the liver of group M compared to that of group N. AS supplementation reduced BT in group MA at 8 wk. BT also occurred in the MLNs, spleen, and kidney, which was reduced by AS supplementation. BT was not detected in the blood in any group. CONCLUSION: Dysbiosis of gut microbiota, injury of intestinal mucosal barrier and BT occurred as liver cirrhosis progressed, which might enhance inflammation and aggravate liver injury. AS may have other non-antimalarial effects that modulate gut microbiota, inhibit BT and alleviate inflammation, resulting in a reduction in CCl4, alcohol and high fat-caused damages to the liver and intestine.