Breast cancer causes 15% of cancer deaths in women worldwide. The roles of genetic mutations in breast cancer risk are well known. Recent studies have shown that there is a diversity of microbes in breast tissues. However, the role of the tumor microbiome in influencing breast cancer is not fully understood.

We analyzed RNA sequencing data from The Cancer Genome Atlas (TCGA) breast cancer project and observed that breast cancer types can be segregated by microbiome content. We also identified a bacterial enzyme that resembles the HER2 protein, which is a drug target in breast cancer, and showed that this bacterial protein increases the growth of breast cancer cell lines. We are currently testing the effect of this bacterial protein on drug response.