Topoisomerase IIa protein expression analysis in oral squamous cell carcinoma

Topoisomerases represent a super-family of nucleic enzymes involved in the DNA replication, transcription, recombination, and also chromosome topological formation. Topoisomerase II alpha (Topo IIa-gene location 17q21) is a critical gene associated with response to chemotherapeutic agents such as anthracyclines especially in breast adenocarcinoma. Our aim was to investigate the role of aberrant Topo IIa protein expression in oral squamous cell carcinoma (OSCC). Fifty formalin-fixed, paraffin-embedded primary OSCCs tissue sections were used. Immunohistochemistry was performed using an anti- Topo IIa antibody. Digital image analysis was implemented for evaluating objectively the protein expression levels on the corresponding stained nuclei. Topo IIa protein overexpression (moderate to high immunostaining intensity values) was observed in 29/50 (58%) tissue cores, whereas low expression rates were detected in the remaining cases (21/50;42%). Topo IIa overall expression was strongly associated with the differentiation grade of the examined tumors (p=0.037) and also with human papillomavirus (HPV) positivity (p=0.029). No other statistical correlations were identified. Topo IIa overexpression is observed in significant subsets of OSCCs correlated with the grade of differentiation. Additionally, HPV persistent infection is associated with increased Topo IIa protein expression levels. Topo IIa expression analysis should be critical for identifying patients eligible for applying specific chemotherapeutic strategies based on anti-Topo IIa agents.