Prostaglandin E2 down-regulates sirtuin 1 (SIRT1), leading to elevated levels of aromatase, providing insights into the obesity–breast cancer connectionObesity increases the risk of hormone receptor–positive breast cancer in postmenopausal women. Levels of aromatase, the rate-limiting enzyme in estrogen biosynthesis, are increased in the breast tissue of obese women. Both prostaglandin E2 (PGE2) and hypoxia-inducible factor 1α (HIF-1α) contribute to the induction of aromatase in adipose stromal cells (ASCs). Sirtuin 1 (SIRT1) binds, deacetylates, and thereby inactivates HIF-1α. Here, we sought to determine whether SIRT1 also plays a role in regulating aromatase expression.
Hsp90 and PKM2 Drive the Expression of Aromatase in Li-Fraumeni Syndrome Breast Adipose Stromal CellsLi-Fraumeni syndrome (LFS) patients harbor germ line mutations in the TP53 gene and are at increased risk of hormone receptor-positive breast cancers. Recently, elevated levels of aromatase, the rate-limiting enzyme for estrogen biosynthesis, were found in the breast tissue of LFS patients. Although p53 down-regulates aromatase expression, the underlying mechanisms are incompletely understood. In the present study, we found that LFS stromal cells expressed higher levels of Hsp90 ATPase activity and aromatase compared with wild-type stromal cells.