The Animal Model For Studying The Effect Of Fatty Liver On Liver Metastasis In Breast Cancer

Breast cancer is the leading cause of tumour-related mortality in women,and patients generally die from distant metastasis.Recently,as the changes in human lifestyle and diet structure,the incidence rates of liver metabolic disorders such as non-alcoholic fatty liver disease is increasing,and its incidence is closely related to metabolic diseases such as obesity and type 2 diabetes.Although obesity and obesity-related inflammation are considered to be the risk factors for the onset,development,recurrence,and metastasis of breast cancer,and fatty liver has been shown to be closely related to liver metastases in some kind of cancer such as hepatocellular carcinoma colorectal cancer and lung cancer,there are rare studies on the relationship between fatty liver and breast cancer liver metastasis.The clinical data study of the relationship between fatty liver and breast cancer completed by our research group demonstrated that breast cancer patients who had non-alcoholic fatty liver disease(NAFLD)were significantly less likely to develop metastasis of their cancer to the liver.This was an surprising finding but does not confirm that having NAFLD reduces liver metastasis as the clinical data only reveal a correlation between these two events.Further experimental research is needed to determine whether fatty liver is a factor that inhibits liver metastasis.Aim:To study the impact of NAFLD on liver metastasis of breast cancer by inducing liver metastasis model with fatty liver in mice normal immune function.Methods:1,From the Balb/c mouse cell lines 67NR,66c14,4T 1.2 CH A5,EMT 6.5 and C57BL/6 mouse cell lines EO 771 LMB,AT-3,the liver metastatic tumor was selected to form the best cell strain;2,The Balb/c mice were assigned to experimental group and control group randomly.Mice from experimental group were fed with high fat diet containing 46%of the total energy from lipids and the control mice fed with normal chow including 16%energy from lipids for 9-15 weeks.3 livers of the mice in each group were taken to pathologically detect the fatty liver at the 9th,12th,and 15th weeks of the experimental diet,respectively.In the 9th and 12th weeks of diet,breast cancer cells were injected into the mice by intrasplenic injection,and mice were harvested 3 weeks after injection.The livers of mice were taken for detecting relative tumor burden by RT-PCR.3,The C57BL/6 mice were assigned to experimental group and control group randomly Mice from experimental group were fed with high fat diet containing 46%of the total energy from lipids and the control mice fed with normal chow including 16%energy from lipids for 9 weeks.3 livers of the mice in each group were taken to pathologically detect the fatty liver at 9 weeks of the experimental diet.At 9 weeks of diet,breast cancer cells were injected into the mice by intrasplenic injection,and mice were harvested 3 weeks after injection.The livers of mice were taken for detecting relative tumor burden by RT-PCR.Results:1,All the Balb/c mouse cell lines(67NR,66c14,4T1.2 CH A5,EMT6.5)and C57BL/6 mouse cell lines(EO 771 LMB,AT-3)can develop liver metastases after intrasplenic injection.However,only about 1 in 2 mice found liver metastasis after intrasplenic injection with both E0771 LMB and AT-3 cells.4T1.2 chA5 were selected as the Balb/c cell strain and E0771 LMB were chose as the C57BL/6 cell strain for the further experiment.2,Balb/c mice in high fat diet did not put on weight and develop NAFLD significantly at 9,12,and 15 weeks of diet feeding compared to those mice fed with normal diet,and there were no significant difference in liver relative tumor burden between two groups.3,High-fat fed C57BL/6 mice found more lipids accumulation and detected higher tumor burden in liver after 9 weeks of diet compared to the mice fed with normal diet,but whether it was lipids accumulation or tumor burden,there was no significant difference between the experimental group and the control group.Conclusion:1.Intrasplenic injection could induce the breast cancer liver metastases successfully both in Balb/c nd C57BL/6 mice.2,Balb/c mice with a short-term high fat diet can not put on weight and form NAFLD significantly,and a high fat diet can not promote or inhibit liver metastasis of breast cancer in Balb/c mice.Therefore,Balb/c mice is not suitable for studying the effects of fatty liver on liver metastasis of breast cancer.3,High-fat fed C57BL/6 mice trended to develop NAFLD and decrease liver metastases after 9 weeks of diet compared to the mice fed with normal diet.Further study is warranted to verify the relationship of NAFLD and breast cancer liver metastasis and elucidate the mechanism of protective effect in patients with NAFLD.