The effect of epiregulin on epidermal growth factor receptor expression and proliferation of oral squamous cell carcinoma cell lines

Background: Epiregulin (EPR) is a novel member of the epidermal growth factor (EGF) family. It has been shown to promote wound healing in oral epithelium, enhance proliferation of other epithelial tissues, and is involved in several epithelial-related malignancies such as colorectal, lung, and bladder carcinoma. More recently, EPR transcripts were found to be high in a study on archival oral squamous cell carcinoma (OSCC) specimens. This implies that EPR may be responsible for the progression of OSCC. The aim of this was to elucidate the effects of EPR on (i) cell morphological changes, (ii) cell proliferation and (iii) receptor expression of the H-series OSCC cell lines. Methods: The clinicopathological origin and the expression of the epidermal growth factor receptor (EGFR) and ErbB4 receptors of the H-series cell lines were initially characterised. Based on these parameters, two of the H-series cell lines, namely H103 and H357 were selected for downstream experiments. The cell lines were treated with 1 ng/ml, 10 ng/ml, and 20 ng/ml of EPR for 24 and 48 hours in all subsequent experiments. Untreated cells acted as the control which was used for comparison with each treated group. The cell morphological changes, cell proliferation and receptor expression of the OSCC cell lines were evaluated using phase contrast microscopy, 5-bromo-2'-deoxy-uridine (BrdU) assays and flow cytometry respectively. The results were compared and analysed using the student t-test. Results: There were no appreciable morphological changes in the cells regardless of the dose of EPR tested nor between the different timelines. There were no significant changes in cell proliferation after EPR treatment. As for the effect of EPR on receptor expression, 20 ng/ml of EPR significantly reduced the density of EGFR expression (p value = 0.049) in the H103 cell line after the 24-hour treatment. No other statistically significant changes were detected. Conclusions: The results show that EPR had no effect on the morphology and proliferativity of OSCC cells. However, the significant decline in EGFR expression after EPR treatment suggests that EPR might play an important role in the regulation of EGFR expression and hence OSCC progression.