Protein levels and gene expressions of the epidermal growth factor receptors, HER1, HER2, HER3 and HER4 in benign and malignant ovarian tumors.

The epidermal growth factor receptors, HER1, HER2, HER3 and HER4 play a key role in the growth of malignant tumors. The receptors of the EGF receptor family are not cancer-specific proteins since these receptors are expressed to some extent in both normal and benign tissue, but this is not elucidated in detail in ovarian tissue. High tumor-to-normal-tissue concentration ratios would be favorable for molecular targeted anti-cancer treatment. The primary aim of the study was to analyze the potential differential protein content and gene expression of the four receptors in benign and malignant ovarian tumors. Tissue from 207 patients (101 malignant, 19 borderline, 64 benign ovarian tumors and 23 normal ovaries) were analyzed by quantitative ELISA for HER1-HER4 protein concentrations and by real-time PCR for HER1-HER4 gene expression. HER2 was also analyzed by immunohistochemistry. The HER2-4 receptor protein content and the median gene expression level was significantly higher in ovarian cancer patients compared to patients with benign ovarian tumors and normal ovaries (p<0.0000001). The protein content of the HER1 receptor was significantly lower in ovarian cancer compared to borderline tumors (p=0.012), benign ovarian tumors (p=0.049) and to normal ovaries (p=0.000069). A sound correlation between the protein levels and gene expressions was documented. In conclusion, decreased concentration of HER1 protein and increased HER2, HER3 and HER4 protein concentration were observed, as also elevated HER2-HER4 gene expression levels in ovarian cancer patients with barely any overlap of the HER3 and HER4 expression in malignant ovarian tumors compared to benign ovarian tissues.