Increased Expression of RelA/Nuclear Factor-κB Protein Correlates with Colorectal Tumorigenesis

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Abstract
Objective: To identify the role of RelA/nuclear factor-ĸB, an important inhibitor of apoptosis in colorectal tumorigenesis, we examined the expression of RelA in normal colorectal mucosa (n = 10), colorectal adenomas (n = 30) and colorectal adenocarcinomas (n = 30). Furthermore, the association of RelA expression with tumor cell apoptosis, proliferation, and expression of Bcl-2/Bcl-xL was also studied. Methods: Paraffin sections were stained with monoclonal antibodies directed against RelA, Bcl-2, Bcl-xL, and Ki-67 to assess protein expression patterns in normal, adenomatous and colon cancer tissue. Apoptotic cells were detected by terminal deoxynucleotidyl-transferase-mediated dUTP-biotin nick end labeling (TUNEL) using an in situ detection kit. Results: The results of immunohistochemical staining revealed that expression of RelA, Bcl-2, Bcl-xL, and Ki-67 labeling index (LI) significantly increased in the transition from adenoma with low dysplasia to adenocarcinoma. This transition was associated with a significant decrease in the apoptotic index (AI) and a significant increase in the Ki-67 LI. The expression of RelA correlated inversely with the AI and correlated positively with the expression of Bcl-2, Bcl-xL, and Ki-67 LI in the transition from low-grade dysplasia to adenocarcinoma. Conclusion: Our results suggest that increased expression of RelA/nuclear factor-ĸB plays an important role in the transition from colorectal adenoma with low-grade dysplasia to adenocarcinoma in the pathogenesis of colon cancer in humans.