High expression levels of cyclooxygenase 2 expression and infiltration by regulatory T cells (Tregs) are often associated with tumor progression. In human breast cancer patients, the percentage of Tregs at the tumor site is positively correlated with disease progression to normal tissue to ductal carcinoma in situ (DCIS), and from DCIS to invasive carcinoma. Despite the correlation between Treg accumulation and worsened disease outcome, the mechanisms by which Tregs promote tumor progression remain unclear. Of note, the levels of cyclooxygenase 2 (COX2) and of its main product prostaglandin E2 (PGE2) have also been associated to poor outcome in many tumor models and clinical studies. Although reports have correlated the upregulation of COX2 with increased levels of Tregs in breast cancer, no mechanistic data on this observation was available.
Karavitis J, Zhang M. COX2 regulation of breast cancer bone metastasis. Oncoimmunology. 2013;2(3):e23129. doi:10.4161/onci.23129.