Significance of Gene Amplification and Expression of HER2/neu in Colon Carcinoma, SAMI A. MOHAMMED, MOHEBAT HELMI, NASHWA M. EMARA, MAGDA H. BAKER and ABD EL-LATIF M. EL-BALSHY
Abstract
Introduction: Colorectal cancer is a major worldwide health problem with an annual incidence of 1.2 million and an annual mortality of over 600,000 people. Her2/neu oncogen is one of four epidermal growth factor receptors. It's located on chromosome 17q21 and encodes a 185 transmembrane protein with tyrosine kinase activity that functions as a growth factor receptor. Clinically, amplification and/or overexpression of Her2/neu has been associated with poor prognosis in a number of tumor types such as breast and ovarian cancer. Conflicting data exist about the prevalence of HER-2/neu overexpression in colorectal cancer ranging from 0 to 83%.
Aim of the Work: The aim of this study were to compare qRT-PCR and immunohistochemical expression of HER-2/neu oncogene in colorectal carcinoma and their correlation to other clinicopathological parameters.
Material and Methods: This work involved 50 cases of surgically resected colorectal cancers. HER2/neu immuno-histochemistry was performed using the C-erbB-2 gene product.
Results: Out of 50 studied cases, 40 cases (80%) were HER-2/neu negative (scor 0 and 1+) and 10 cases (20%) were positive (scor 2+ and 3+). No statistically significant correlation were found between IHC expression HER2 and clinicopatho-logical parameters. Among the examined 50 cases, 44 cases (88%) were over expression of HER-2/neu by qRT-PCR (>2) and 6 cases (12%) were under expression of HER-2/neu by qRT-PCR (<2). A significant correlation were found between expression of HER-2/neu by qRT-PCR HER2 and clinico-pathological parameters and no correlation with IHC expression HER2.
Conclusion: Q-RT-PCR is now considered the gold stan-dard for mRNA quantitative evaluation, and its application to HER2 status evaluation could contribute to method stan-dardization and reduce reports of variability.