Expression of the jun family of genes in human ovarian cancer and normal ovarian surface epithelium.

The jun genes (c-jun, jun-B and jun-D) play a role in critical cell functions such as proliferation, differentiation and apoptosis. We documented jun expression at the mRNA and protein level in human ovarian cancer tissues (n=28), surface epithelial cells of normal ovaries (n=14) and ovarian cancer cell lines (n=6). Almost all of ovarian tumors as well as normal ovaries concomitantly express c-jun, jun-B, and jun-D mRNA. Immunohistochemistry was less sensitive and revealed nuclear c-Jun and Jun-B proteins in the malignant epithelial cells of respectively 38% and 11% of ovarian tumors and in the surface epithelium of a normal premenopausal ovary. In cultured ovarian cancer cells, c-jun and jun-B expression is inducible by serum and TPA and is therefore not constitutive. The c-jun and jun-B proteins therefore play a role both in differentiation of the normal ovarian surface epithelium, as well as in the proliferation of epithelial ovarian cancer cells. High jun-B expression relates to a more malignant phenotype both in vitro and in vivo. The jun-D gene is suppressed in ovarian cancer cells as compared to normal ovarian surface epithelial cells in situ and in vitro. Downregulation of jun-D might therefore be part of the malignant ovarian epithelial cell phenotype.