Introduction: The NF-κB transcription factor protein family has diverse cellular and biological functions, and posttranslational modification is important to regulate these functions. An important site of phosphorylation of NF-κB p65 subunit is at serine-536 (phospho-Ser536-p65), and this phosphorylation is involved in regulation of transcriptional activity, nuclear localization, and protein stability.
Patients and methods: In this study, we investigated expression of phospho-Ser536-p65 in colorectal cancers and its relationships with clinicopathological factors. The expression of phospho-Ser536-p65 was examined by immunohistochemistry in 203 primary colorectal cancers, 156 normal mucosa specimens, and 18 metastases in the lymph nodes.
Results: The expression of phospho-Ser536-p65 increased from normal mucosa to primary tumor (p < 0.0001). Further, the increased expression of phospho-Ser536-p65 in the cytoplasm of the primary tumors correlated with worse survival of the patients independently of gender, age, tumor location, stage, and differentiation (p = 0.04; hazard ratio, 1.89; 95% CI 1.03-3.47).
Conclusion: The NF-κB p65 subunit phosphorylated at serine-536 is an independent prognostic factor in colorectal cancer patients.