Abstract 2007: Ischemic And Non-ischemic Cardiovascular Events Differentially Regulate Cross Disease Communication With Cancer

Cancer and cardiovascular disease (CVD) are the top two leading causes of death worldwide, exhibiting cross-disease communication that increases morbidity. Cancer patients are at significantly increased risk for CVD and recent studies by our lab and others indicate that CVDs like myocardial infarction (MI) or heart failure can in turn accelerate tumor growth. We previously showed this occurs through changes in the innate immune system or via tumor-promoting factors secreted from the damaged myocardium, which together have established the nascent field of Reverse CardioOncology. We hypothesized that ischemic and non-ischemic CVD injuries have distinctly different mechanisms underlying mammary tumor growth. To mimic these events, we modeled non-cardiac hind limb ischemic injury by femoral artery ligation (FAL) and non-ischemic cardiac injury by cardiac cryoinjury (CCI). To test our hypothesis, we introduced primary E0771 mouse mammary cancer cells into the mammary fat pad three days prior to FAL or CCI. Measurements of tumor over time showed significant increases in tumor growth after both FAL and CCI when compared to sham surgeries. However, only the ischemic injury, FAL, induced similar changes in immune cells to what we observed after MI (induced by left anterior descending coronary artery LAD ligation). This included significant increases in myeloid populations and decreased lymphocytes within the circulation. Additionally, flow cytometry of immune cells within tumors of mice exposed to FAL showed significantly increased myeloid cells and macrophages, as well as increased immunosuppressive T-regulatory cells. In contrast, while CCI showed significantly increased tumor burden and circulating leukocytes, there were no differences in the above-mentioned subsets of immune cells within the circulation or within the tumor. These data suggest that ischemic injury, via FAL or LAD, induces an immunosuppressive environment within the tumor that accelerates cancer growth that is distinct from the non-ischemic cardiac injury induced by CCI. Taken together, our data suggest that the immune reprogramming after ischemic CVDs is a risk factor for tumor growth and these data help to elucidate the mechanisms that underlie cancer risk in CVD patients.