RET Protein Expression in Colorectal Cancer; An Immunohistochemical Assessment

BACKGROUND: RET (rearranged during transfection) is a transmembrane receptor tyrosine kinase and a receptor for the GDNF-family ligands. It plays the role of a tumor suppressor in colorectal cancer. Therefore, it is expected that RET gene becomes downregulated in colorectal cancer (CRC). In this study, we evaluated immuno-histochemical expression of RET in CRC and assessed its correlation with some of the clinicopathological features to study the prognostic value in CRC. MATERIALS AND METHODS: In total, 60 cases of colorectal cancer (CRC) from the patients who underwent surgical gastroenterology operations were randomly selected. The samples included one tumor-rich section per case and one adjacent tumor-free section as the normal control for that case. Then, immunohistochemistry (ICH) was performed for RET on all the samples and the expression of RET was analyzed. Furthermore, the correlation of RET with clinicopathological features including age, gender, location of the tumor, grade, and stage was evaluated. RESULTS: The expression of RET caused significant downregulation in cancer samples compared to the normal control ones (P = 0.002). This downregulation increased in correlation to both grade and metastasis to lymph nodes (P = 0.03 & 0.02 respectively). However, no correlation was found between the expression of RET and gender as well as location of the tumor. CONCLUSION: RET may be considered as a protein marker in CRC detection and prognosis.