Evaluation of MAGE A1 in oral squamous cell carcinoma

Abstract

MAGE A1 is a cancer testis antigen (CTA) described in a variety of human cancers. CTAs exhibit a highly restricted tissue expression and by virtue of their immunogenic potential, these genes are promising target molecules for cancer vaccines. DNA hypomethylation is associated with gene regulation in several types of tumours. The aim of this project was to identify the presence of MAGE A1 in oral squamous cell carcinoma (OSCC) samples and to investigate the hypomethylation profile of CpG islands situated in the promoter region of this gene. The expression of MAGE A1 in OSCC and healthy oral mucosal samples was determined by real-time quantitative and conventional endpoint PCR and also by immunohistochemistry staining. In addition, to investigate the hypomethylation profile of promoter MAGE A1 CpG islands, we performed bisulphite sequencing. Real-time quantitative and endpoint PCR assays demonstrated a lower level of MAGE A1 transcription. Endpoint PCR showed expression of MAGE A1 in 10% (2/20) of OSCCs. Sodium bisulphite sequencing analysis of MAGE A1 CpG islands did not reveal a difference between OSCC and normal oral mucosal samples. We further assessed MAGE A1 protein immunoexpression and found 80% (16/20) of immunopositivity in OSCCs. We did not observe a correlation between the presence of MAGE A1 protein and lower levels of transcripts. Identification of MAGE A1 protein in OSCCs and absence of immunoexpression in normal oral mucosa support the idea that this protein can be used as a biomarker for detection of OSCC; however, it is not associated with hypomethylation or high expression of the MAGE A1 gene.