This study was to determine the expression of Toll-like receptor 4 (TLR-4) in ovarian serous adenocarcinoma tissues.

TLR-4 expression was evaluated at the RNA level by real-time quantitative RT-PCR, in 24 fresh frozen ovarian serous adenocarcinoma tissues and 9 normal ovarian tissues. TLR-4 expression was also evaluated by immunohistochemistry (IHC) in each three ovarian carcinoma tissues and normal ovarian tissues.

Positive immunoreactivity for TLR-4 was observed in the normal ovarian tissues but not in the ovarian carcinoma tissues. The staining was localized in the cytoplasm as well as on the cell surface. Real-time quantitative RT-PCR revealed that TLR-4 expression was significantly lower in tumors than in normal ovarian tissues (p=0.0003). There were no significant correlations between clinical parameters and the expression level of TLR-4 mRNA in ovarian serous adenocarcinomas. However, tumors without LN metastasis (p=0.068) and lower grade (p=0.075) showed trends of higher TLR-4 mRNA expression.

TLR-4 expression was significantly lower in ovarian serous adenocarcinoma tissues than in normal ovarian tissues, and further studies on TLR-4 signaling pathway in ovarian carcinoma are needed.