OBJECTIVE

To establish an apolipoprotein E (ApoE) and low-density lipoprotein receptor (LDLR) double-knockout (ApoE(-/-)/LDLR(-/-)) mouse model of nonalcoholic steatohepatitis (NASH)-related hepatocellular carcinoma (HCC) induced by high-fat and high-cholesterol (HFHC) diet.

METHODS

ApoE(-/-) knockout mice were crossed with LDLR(-/-) knockout mice to obtain ApoE(-/-)/LDLR(-/-) mice. The ApoE(-/-)/LDLR(-/-) mice mated with each other, and the offspring were injected with low-dose streptozotocin (STZ) at 2-3 days after birth. Some mice were fed with HFHC diet after weaning as the model group (n = 15), and some mice were fed with normal diet as the control group (n = 15). Mice were sacrificed at the end of weeks 10, 16, and 20 (5 mice at each time point). The body weight was measured. Liver tissue and blood were collected to measure biochemical parameters, evaluate the pathological changes in the liver tissue by HE staining, oil red O staining, and Masson staining, and detect the expression of glypican-3 (a marker of HCC) by immunohistochemical staining.

RESULTS

The model group had significantly higher levels of fasting blood glucose and total cholesterol than the control group (P < 0.01). Serum levels of alanine aminotransferase, aspartate aminotransferase, and total triglyceride gradually increased with time in the model group; at week 20, there were significant differences in above three indices between the two groups (P < 0.05). HE staining showed that compared with the control group at the corresponding time point, the model group developed sequential histological changes: NASH at week 10, dysplastic nodules at week 16, and early HCC at week 20. Oil red O staining showed that in the model group, the degree of liver steatosis increased within 10 weeks and gradually decreased later. Masson staining demonstrated that the model group developed pathological changes: mild perisinusoidal fibrosis at week 16 and bridging fibrosis around tumors at week 20. HE staining, oil red O staining, and Masson staining showed that no histological or pathological changes were found in the control group. Glypican-3 was detected in the nodules at week 16 and in the cytoplasm of HCC cells at week 20 in the model group.

CONCLUSION

The mouse model of NASH-related HCC can be developed by giving STZ injection to neonatal ApoE(-/-)/LDLR(-/-) mice and feeding them with HFHC diet after weaning for 20 weeks. Early HCC may develop directly from NASH.