Effect of Common Bean Consumption on the Gut Associated Microbiome in an In Vivo Screening Model for Breast Cancer ^†

Population data indicate that consumption of common bean reduces breast cancer risk, an effect replicated in a well characterized rodent model of mammary carcinogenesis. However, low molecular weight fractions of bean failed to inhibit growth of established breast cancer cell lines. Given that cell culture screens for anticancer activity are designed to detect a decrease in cell number accumulation, we reasoned that it might be possible to create a cell number accumulation assay for screening foods such as common bean in vivo by using an oncogene driven model for breast cancer. A benefit of this approach is that it permits simultaneous detection of systemic effects in the host and their potential mediation by the gut microbiome. We report an in vivo mammary cell accumulation assay driven by the polyoma middle T antigen (PyMT) oncogene and show that bean feeding reduced the accumulation of cells in developing mammary pathologies. As a candidate mediator, we report the impact of bean consumption on the gut associated microbiome. Differences were observed between common bean and the control diet in microbial phylogenetic diversity, beta diversity, abundance of various taxa, and predicted functional activity.