The Effect Of Ethanol Consumption On The Progression And Metastasis Of Murine Mammary Tumor

Breast cancer is the most common malignant tumor in women worldwide. Theoccurrence of breast cancer is considered to be resulted from multiple risk factors, suchas genetic/familial, reproductive/hormonal, environmental factors and lifestyle-relatedunhealthy living habits. Alcohol consumption may effect on many tumor’s progression:First, epidemiological studies indicate that alcohol consumption increases breast cancerrisk in a dose-dependent manner. Second, clinical studies show that chronic ethanolconsumption is related to tumor aggressiveness and poor survival of tumor patient.Moreover, experimental research find that alcohol may also enhance the growth ofexisting breast tumors and increase the aggressiveness of breast cancer cells to invadeand metastasize. Nevertheless, the potential mechanism by which alcohol effects onbreast cancer development is remain unclear.Tumor growth and metastasis depend on angiogenesis. In our previous study, we havedemonstrated that alcohol could increase tumor angiogenesis and help tumor growthand metastasis which is correlated with MCP-1. Moreover, vascular endothelial growthfactor (VEGF) is one of the most important known factors that can induce angiogenesisin vivo. Many studies have proved VEGF plays an important role in the process oftumor angiogenesis through promoting proliferation, migration, stabilization, andsurvival of endothelial cells and tumor cell as well. It has been demonstrated that thelevel of VEGF mRNA and protein in breast cancer tissue are significantly higher thanthe adjacent normal tissues. More interestingly, recently, some study found that chronic alcohol consumption could up-regulate the expression of VEGF in the melanoma andpromoted tumor angiogenesis and progression of melanoma in mice. This indicatesVEGF is acquired in the course of malignant transformation and suggests it plays a rolein breast cancer development and/or progression.In this study, we set up a mouse model of ethanol exposed first. Female C57BL/6micewere divided into two groups and fed with standard chaw ad libitum. The mice inethanol-exposed group (n=15) were given2%ethanol in drinking water for a12hour-period during the night, starting at8:00pm and then replaced with regular waterwithout ethanol at8:00am for the remaining12hours each day for3weeks. The micein control group (n=15) were provided with regular drinking water only. During thetest, we detected the change of water intake、weight and the blood ethanol concentration(BEC). Then, combined this model with a direct xenograft model of mammary tumor,E0771cells (2.5x105in100μl PBS) were injected into the secondary mammary padof mice. The mice were continually provided with2%ethanol in drinking water orregular drinking water without ethanol. Then, we researched the effect of ethanol on thegrowth and metastasis of mammary tumor, and we sought to determine whether alcoholcould induce the expression of VEGF in breast cancer cells and we investigated the roleof VEGF in alcohol-promoted malignant progression of mammary tumor. Results showthat alcohol could advanced the growth/metastasis of mammary tumor in vivo. Usinghistological and immunological analysis and western blotting, we detected alcoholincreased tumor angiogenesis and increased the expression of VEGF in breast cancer.In the other hand, we use a three-dimensional (3D) tumor/endothelial cell co-culturesystem to study the effect of ethanol on the form of angiogenesis in vitro. Wedemonstrated that ethanol promoted angiogensis induced by breast cancer E0771cellsin vitro which is significantly suppressed by VEGFR inhibitor (SU5416). These results suggest that the overexpression of VEGF induced by ethanol is one of thepotential mechanisms by which alcohol contributes to breast tumor angiogenesis andtumor progression. Moreover, alcohol consumption also could effect on the secretion ofleptin, estrogens or insulin etc. We known the risk of breast cancer is associated withestrogens, so we detected whether alcohol consumption effect on the secretion ofestrogen in mice. We used the enzyme-linked immunosorbent assay (ELASA), the levelof estrogen in mice were quantified. The result showed that alcohol consumptionincreased the level of estrogen in mice.In short, our present results demonstrated that ethanol advanced the growth;metastasisand increased tumor angiogenesis of mammary tumor, and one of the potentialmechanisms is the overexpression of VEGF induced by ethanol. Moreover, weidentified that ethanol could increase the level of estrogen which may be relevant withthe growth and metastasis of breast cancer.