Why Alcohol Consumption Increases Breast Cancer Risk, New Animal Study

Alcohol (EtOH) consumption -- even moderate -- is a well-established risk factor for breast cancer in women. A recent study showed that 60 percent of female breast cancers worldwide were attributable to alcohol consumption. Nevertheless, the mechanisms of alcohol-induced breast cancer are poorly understood.
The definitive biological effects and molecular mechanisms of EtOH on progression and malignancy of breast cancer have not been investigated using a mammalian breast cancer model that mimics the human disease. Scientists have suggested that the possible mechanisms involved include the agitation of estrogen metabolism and response; cell mutation by the EtOH metabolite acetaldehyde; oxidative damage; and one-carbon metabolism pathways through reduced folic acid.

Methodology

To date, there has not been an animal model that faithfully mimics the human disease with respect to characteristics of breast cancer, immunocompetence, and physiologically relevant EtOH intake. The researchers addressed and overcame the obstacles and developed a novel mouse breast cancer model. The model mimics human breast cancer disease in which the estrogen receptor-positive breast adenocarcinoma cells were subcutaneously injected near the pad of the fourth mammary gland of female immunocompetant mice (C57BL/6). The six-week-old female mice were fed with moderate EtOH (one percent in drinking water) for four weeks, the equivalent of two drinks per day in humans. The control mice received regular drinking water only.

In the second week of the experiment, mouse breast cancer cells (5x105 E0771) were injected at cite referenced above. At the end of the experiment, the tumors were isolated to measure tumor size, examine intratumoral microvessel (IM) density via CD 31 immunohistochemistry staining, and assessing VEGF protein levels via ELISA. These steps were taken to determine the effects of EtOH intake in physiologically relevant doses on tumor growth and angiogenesis in mouse breast cancer.