RESUMO
BACKGROUND: There are strong links between obesity, diabetes and hepatocellular carcinoma (HCC), but molecular mechanisms remain unclear. AIM: We tested the proposed involvement of NF-κB, IL-6/STAT3 and Akt/mTORC1 before onset (at 3 months) and at onset (6 months) of accelerated hepatocarcinogenesis in DEN-injected obese and diabetic foz/foz compared to lean wildtype (Wt) mice, and also studied the hepatocyte proliferative response to DNA damage between the obese and lean lines. METHODS: Male foz/foz and Wt littermates fed normal chow were DEN-injected (10mg/kg i.p.) at age 12-15 days. To test the effect of mTOR inhibitor on growth of dysplastic hepatocytes, a separate cohort of DEN-injected foz/foz mice was administered rapamycin (4 mg/kg body weight/day). RESULTS: foz/foz mice developed obesity, hyperinsulinemia, diabetes, adipokine dysregulation and fatty liver, without increased serum or liver TNF-α or serum IL-6. All DEN-injected foz/foz mice developed HCC by 6 mths vs. 0/10 lean Wt. At 3 mths, there were more dysplastic hepatocytes in DEN-injected foz/foz than Wt, with increased liver injury (serum ALT), hepatocyte apoptosis (M30-positive cells) and proliferation (cyclin D1, cyclin E, PCNA), but neither NF-κB nor STAT3 activation. foz/foz livers exhibited upregulation of DNA damage sensors ATM and ATR, with inadequate cell cycle checkpoint controls (CHK1, CHK2, p53, p21). Akt and mTORC1 were highly activated in livers from foz/foz vs. Wt mice. Despite such activation, rapamycin failed to reduce growth of dysplastic hepatocytes. CONCLUSIONS: Accelerated DEN-induced HCC in obese/diabetic mice is linked to enhanced growth of dysplastic hepatocytes that cannot be attributed to NF-κB or IL-6/STAT3 activation, nor to sustained mTORC1 activation. The critical mechanism for obesity-enhanced hepatocarcinogenesis lies in the disconnection between hepatocellular injury with DNA damage, and an unrestrained proliferative response. RELEVANCE FOR PATIENTS: This study supports the epidemiological data linking obesity, diabetes and fatty liver disease with increased risk for developing HCC. The findings also suggest that mTORC1 inhibition may not be beneficial in the prevention of obesity-related hepatocarcinogenesis.
RESUMO
Patients with Barrett's esophagus are at high risk of progression to adenocarcinoma. A growing, but conflicting body of evidence implicates bile reflux as a contributor to Barrett's esophagus. To investigate whether duodenogastric reflux was associated with an increased risk of Barrett's esophagus, a case-control study of incident Barrett's esophagus was performed. Cases (n=72) were identified by new histologically-confirmed diagnosis of specialized intestinal metaplasia (indicative of Barrett's esophagus) following upper endoscopy for refractory gastroesophageal reflux between October 1997 and September 2000. Cases were compared to gastroesophageal reflux patients without specialized intestinal metaplasia (controls; n=72). There was no difference in total bile acid concentrations between cases and controls. Risk of Barrett's esophagus did not significantly vary with increasing concentrations of total or free bile acids, respectively (OR 0.35 (95% CI 0.12, 1.02) and 0.60 (95% CI 0.22, 1.66)). Low gastric fluid pH (toxic range 3-5), was associated with a non-significant increase in the risk of Barrett's esophagus. In conclusion, no significant association between Barrett's esophagus and total or free bile acids in gastric refluxate was found. Patients with low gastric fluid pH (3-5) may represent a subset of patients at high risk of developing Barrett's esophagus.
