BBC3 is down-regulated with increased tumor size independently of p53 expression in head and neck cancer

The study focuses on BBC3 gene expression in primary head and neck squamous cell carcinomas (HNSCC) in relation to pTNM classification. We used quantitative real-time PCR on 35 biopsy samples of HNSCC tumor samples to evaluate differences of BBC3 expression depending on tumor size, regional lymph node involvement, location and tumor staging. In order to confirm the model of BBC3-mediated apoptosis, we used immunohistochemistry to determine the expression of apoptotic proteins p53, p63, Bcl-2 and Bax. We also used publicly available cDNA microarray datasets. Our results show a general down-regulation of BBC3 in tumor tissue compared to adjacent normal tissue. The expression was significantly altered among different groups of patho-histologically evaluated tumor sizes, but not in relation to tumor location, regional lymph node involvement or tumor stage. That suggests the potential use of BBC3 as a new tumor size marker in HNSCC. Through protein expression analysis combined with publicly available cDNA microarray datasets of apoptotic factors, we confirmed the model of BBC3-mediated apoptosis, which can be activated with or without p53.