Expression of EGFR, HER2, phosphorylated ERK and phosphorylated MEK in colonic neoplasms of familial adenomatous polyposis patients.
Wang J., Hollingshead J., El-Masry N., Horncastle D., Talbot I., Tomlinson I., Alison MR., El-Bahrawy M.
PURPOSE: The expression of epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2) is associated with poor prognosis in sporadic colorectal carcinoma (CRC). EGFR inhibitors are approved for the treatment of refractory CRC. The aim of this study was to investigate the expression of EGFR and HER2 and downstream extracellular signal regulated kinase (ERK) and mitogen activated protein kinase (MAPK) in non-neoplastic colonic mucosa, adenomas and carcinomas from familial adenomatous polyposis coli (FAP) patients, exploring the expression along the adenoma-carcinoma sequence. METHODS: The expression of EGFR, HER2, phosphorylated MAPK/ERK kinase (pMEK) and phosphorylated ERK (pERK) proteins was studied by immunohistochemistry in samples of colonic non-neoplastic mucosa (n = 65), adenomas (n = 149) and adenocarcinomas (n = 16) from each of the 16 FAP patients. RESULTS: For HER2, only weak cytoplasmic expression was seen in 8% of adenomas, 6% of carcinomas and 3% of the non-neoplastic mucosa. EGFR was expressed in non-neoplastic mucosa, adenomas and carcinomas with a statistically significant increase in expression in adenomas compared with non-neoplastic mucosa (p