Elafin as a biomarker and growth factor for ovarian cancer. Free

B140

Ovarian cancer (OvCa) is a leading cause of cancer-related death of women in the United States and Europe. Three-quarters of patients have locally advanced or disseminated disease at the time of diagnosis. Cures are rare at advanced clinical stages, placing emphasis on early detection to reduce mortality. A sensitive and specific screening test that could detect OvCa at a curative stage has yet to be developed. We previously identified a locus on chromosome 20q13 that encompasses 14 genes with homology to whey acidic protein (WAP). This locus resides within one of the most frequently amplified chromosomal regions in OvCas. In fact, we previously reported that a member of this gene WAP cluster, HE4, is overexpressed and secreted by OvCa cells. This led us to investigate whether other members of the WAP cluster might also be involved in this disease. A collection of OvCa cell lines was analyzed by RT-PCR for WAP gene expression. In addition to HE4, two other WAP genes are overexpressed compared to normal ovarian surface epithelium: SLPI and Elafin. Western blot analysis of conditioned media from cultured and primary tumor lines showed that these proteins, like HE4, are also secreted. High-density OvCa tissue microarrays and whole tissue sections demonstrated that Elafin expression varies from diffuse to very focal staining, with most tumor cases exhibiting a focal pattern with scattered single positive glands and cells. In non-cancerous tissues, expression of Elafin and SLPI is induced under the conditions of inflammation and wound healing. These processes are also implicated in the pathophysiology of OvCa. Putative transcription factors binding sites for AP1 and NF-kB, two factors involved in mediating inflammatory signals, were identified in the Elafin promoter. To address whether Elafin expression in OvCa cells is linked to inflammation, we treated various lines that do not express Elafin with TNFalpha and IL-1beta. As early as 6 hours after treatment with IL-1beta, Elafin expression was dramatically elevated. To determine whether NF-KB activation is required for the IL-1beta-mediated Elafin expression, chromatin immunoprecipitation (ChIP) with anti-NF-KB antibodies was done in the absence or presence of cytokine. Our results strongly suggest that NF-KB plays a major role in directing expression of Elafin in ovarian cancer cells in response to inflammatory mediators. To determine whether Elafin contributes to OvCa cell growth, Hey-A8 cells were incubated with rElafin for 72 hours and cell viability was monitored by MTS assay. Compared to controls, rElafin induced a 150% increase in proliferation in these cells, suggesting that Elafin can promote the growth or survival of these cells in culture. Therefore, Elafin is a member of a trio of WAP genes that is overexpressed and secreted by ovarian carcinomas. Induced by Inflammatory mediators, Elafin expression may confer a proliferative advantage to OvCa cells.