Aromatase and prostaglandin inter-relationships in breast adipose tissue: significance for breast cancer development

The role of prostaglandins in the development of breast cancer is a topic of growing interest. Stimulation of aromatase expression within the breast has been proposed as a mechanism whereby prostaglandins could influence breast cancer growth. In the present study, we show that PGE₂ is a powerful stimulator of aromatase expression in human breast adipose stromal cells. Moreover, TNF, which also stimulates aromatase expression in breast adipose stromal cells, acts to increase the secretion of PGE₂ by these cells, as well as the expression of COX 2 and PGE synthase, but not that of COX 1. On the other hand, class I cytokines had no effect, either by themselves or in the presence of estradiol. These factors had little influence on secretion of 15-deoxy-^12,14-PGJ₂, which is inhibitory of aromatase expression by breast adipose stromal cells. These results further substantiate an important role for PGE₂ to stimulate estrogen biosynthesis within the local environment of the breast.