Objectives
Nuclear Factor-Kappa Beta (NF-κB)is a protein transcription factor that functions as a central regulator within the cell by enhancing the transcription of a wide variety of genes, including cytokines, growth factors, adhesion molecules, and immunoreceptors. Several pro-inflammatory cytokines, including IL-6 and Tumor Necrosis Factor which are encoded by target genes of IKK-B dependant NF-κB activation pathway and are associated with tumor development and progression in humans. NF-κB is central to the regulation of genes encoding for mediators of the local and systemic immunoinflammatory responses. Activation of lymphocytes occurs subsequent to surgery, and the aim of this study was to assess NF-κB response in lymphocytes, and cytokine activity, subsequent to neoadjuvant therapy and surgery for oesophageal and rectal carcinoma.
Methods
Thirty-five patients were studied (23 oesophageal; 12 rectal) for NF-κB activation. Lymphocytes were isolated at time points 0 (pre-operatively), following the first and final cycles of neoadjuvant chemoradiation, and on days 1, 3, 7, 14,21, and 28 post operatively. NF-κB p50 subunit activity was analysed on nuclear extracts by the Active Motif NF-κB TransAm assay, which comprised a 96-well plat to which oligonucleotide containing an NF-κB consensus binding site has been immobilised. IκB-a expression was examined by Western blotting. Cytokine immunoassays were performed on 55 oesophageal and 20 rectal cancer patients using the Evidence Investigator.
Results
The oesophageal multimodal cohort had significantly higher levels of NF-κBp50 subunit expression following the second cycle of neoadjuvant therapy (p<0.05) compared to preoperative levels. NF-κBp50 lymphocyte expression was significantly elevated (p0.05) in the oesophageal cohort post operatively compared to the rectal cohort. Activation of NF-κB was corroborated by IκB-a expression. No significant changes occurred after rectal cancer resection compared with either preoperative values or the oesophageal group. Interleukin-6 and Vasccularised Endothelial Growth Factor were significantly elevated p (0.05) and differential patterns of response were observed in the other cytokines analysed.
Conclusion
Prolonged activation of NF-κB occurs following oesophageal neoadjuvant chemoradiotherapy and surgery. NF-κB has pleiotropic roles in immune regulation, and these data suggest a sustained drive for local and systemic immuno-inflammation after oesophageal resection. The impact of these findings on clinical outcomes demands further study.