We also demonstrate that cigarette smoke induces the expression of cyclooxygenase-2 and microsomal prostaglandin E synthase-1 and reduces 15-hydroxyprostaglandin dehydrogenase, resulting in prostaglandin E<sub>2</sub> release in human breast cancer.
Mice deficient in mPGES-1 were crossed with a strain in which breast cancer is driven by overexpression of human epidermal growth factor receptor 2 (HER2/neu).
Although not detectable in normal epithelial cells, expression was noted in areas of fibrocystic change and in situ carcinoma. mPGES-1 expression was noted in 79% of breast cancer tissues.