PO-513 The alternative NF-κB pathway in colorectal cancer. from genetic polymorphisms through mRNA to protein levels

Abstract

IntroductionIn colorectal cancer (CRC), there is scarce information regarding the alternative NF-κB pathway which regulates different aspects of immune functions.Material and methodsFormalin-fixed paraffin-embedded (FFPE) tissue samples from 116 patients with CRC were analysed with IHC to assess NF-κB2, Bcl3, RelB and NIK protein expression in tumour (T), adjacent non-neoplastic (adjNN) and non-neoplastic (NN) tissues. Gene expression was assessed with real time RT-PCR. Genotyping for BCL3 rs8100239, NFKB2 rs7897947 and rs12769316 and NIK rs7222094 was performed with High Resolution Melting Curve analysis.Results and discussionsNF-κB2 and NIK proteins were found mainly in the cytoplasm, whereas Bcl3 and RelB exhibited cytoplasmic and nuclear expression. T cells exhibited higher cytoplasmic expression of each of the four proteins compared to adjNN and NN tissue from a more distant to the tumour site (p=0.000, for all proteins). Protein levels were variably correlated with mRNA levels. The four molecules presented similar mRNA levels between T and NN tissue except for RELB(p=0.002). Particular protein and mRNA levels and SNPs provided prognostic value regarding PFS and OS. Patients who were rs8100239 A carriers (HR=0.356, 95% CI: 0.148–0.862, p=0.022) or exhibited high RELB T cytoplasmic or nuclear expression (HR=0.276 95% CI: 0.104–0.732, p=0.010 and HR=0.260, 95% CI: 0.081–0.834, p=0.023, respectively) presented with improved OS in both single and multiparametric analysis. Moreover, a longer time to progression was noted for patients who were carriers of the rs7897947 G allele (HR=0.362 95% CI: 0.136–0.960, p=0.041) or the rs8100239 A allele (HR=0.292 95% CI: 0.135–0.631, p=0.002). Similarly, patients with high T mRNA levels of each molecule under study or with high cytoplasmic T RelB (HR=0.165 95% CI: 0.060–0.459, p=0.001) or cytoplasmic T NIK (HR=0.133 95% CI: 0.045–0.395, p=0.000) or nuclear T Bcl3 expression (HR=0.329 95% CI: 0.114–0.947, p=0.039) had longer PFS.ConclusionThe alternative NF-κB pathway is deregulated in CRC. Selected genotypes, mRNA and protein levels of NF-κB2, Bcl3, RelB and NIK appear to have prognostic value.