Reduced expression of epidermal growth factor receptor-related protein in hepatocellular carcinoma: Implications for cancer growth

Background/Aims: The mitogenic signaling pathway of epidermal growth factor receptor (EGFR) is activated in a variety of cancers, including hepatocellular carcinoma (HCC). The recently cloned EGFR-related protein (ERRP) has been proposed to be a negative regulator of EGFR. The expression of ERRP in non-malignant liver cells and in HCC, and its relation to cell proliferation, have not been examined. Methods: Paraffin sections of formalinfixed HCC specimens of 51 HCCs and 10 normal liver specimens were immunostained with anti-ERRP and anti-p53 antibodies. To determine the relationship between ERRP expression and cell proliferation, we performed double staining for ERRP and proliferating cell nuclear antigen (PCNA) in the same HCC specimens. Results: In normal liver, ERRP was expressed in 100% of specimens, while in non-malignant liver tissue from HCC, ERRP expression was present in 50% of the specimens (p < 0.001). In contrast, ERRP expression was present only in 14% of the HCC specimens. The expression of ERRP in cancer cells was inversely correlated with proliferative activity and tumor size (p < 0.001, p < 0.05, respectively). No significant correlation was found between p53 expression and the expression of ERRP. Conclusions: Human HCC, which has been shown to be associated with increased activation of EGFR, exhibits a substantial reduction in ERRP expression. The inverse relationship between ERRP expression, proliferative activity of tumor cells and tumor size suggests that in some HCC, ERRP is a negative regulator of HCC growth.