NF-_κB signalling proteins p50/p105, p52/p100, RelA, and IKK_ε are over-expressed in oesophageal squamous cell carcinomas

Aims: Nuclear factor-kappa B (NF-_κB) activation has been recognised as an important mechanism in the development of cancers. However, expression status of NF-_κB-related proteins in oesophageal squamous cell carcinoma (ESCC) tissues is largely unknown. In this study, we analysed expressions of NF-_κB members (p50/105, p52/p100 and RelA) and IKK_ε in ESCC tissues. Methods: We analysed the expression of p50/105, p52/p100, RelA and IKK_ε in 58 ESCC patients' tissues by immunohistochemistry using a tissue microarray (TMA) method. Results: Normal oesophageal squamous cells expressed p50/105, p52/p100 and RelA in 5%, 79% and 10% of the tissues in cytoplasm, respectively; however, only p52/p100 was expressed in the nuclei (12%). The cancer tissues expressed p50/105, p52/p100 and RelA in 93%, 95% and 95% in cytoplasm and/or nuclei, respectively. Nuclear immunostainings of NF-_κB members p50/105, p52/p100 and RelA, which are considered activation of NF-_κB signalling, were observed in 34%, 60% and 26% of the cancers, respectively. IKK_ε is expressed in cytoplasm in 50% of the normal squamous tissues and 84% of the cancer tissues. However, none of the expression of p50/105, p52/p100, RelA or IKK_ε was associated with pathological characteristics, including differentiation, depth of invasion and TNM stage. Conclusion: The increased nuclear expressions of p50/105, p52/p100 and RelA as well as increased cytoplasmic expression of IKK_ε in the ESCC tissues compared to the normal squamous cells suggested that over-expression of these proteins may be related to activation of the NF-_κB pathway and might play a role in the development of ESCC.