Background & objective: Base excision repair (BER) genes play important roles in maintaining genomic stability and their abnormal expression are associated with several cancers. This study was to investigate the expression of 7 important BER genes (hOGG1, ADPRT, APE1, MBD4, POLB, XRCC1 and LIG3) in nasopharyngeal carcinoma (NPC) and non-tumor nasopharyngeal tissues, and evaluate their clinical significance.
Methods: The expression of hOGG1, ADPRT, APE1, MBD4, POLB, XRCC1 and LIG3 in 24 specimens of NPC and 24 specimens of non-tumor nasopharyngeal tissues was detected by reverse transcription-polymerase chain reaction (RT-PCR). The differential expression of hOGG1 and ADPRT was further detected by immunohistochemistry in 99 specimens of NPC and 28 specimens of non-tumor nasopharyngeal tissues.
Results: hOGG1, ADPRT, APE1, MBD4, POLB, XRCC1 and LIG3 were expressed in both NPC and non-tumor nasopharyngeal tissues. Among them, the mRNA levels of hOGG1 and ADPRT were significantly lower in NPC than in non-tumor nasopharyngeal tissues (P<0.001). The protein levels of hOGG1 and ADPRT in NPC were also reduced. The high expression rates of hOGG1 were 50.5% in NPC and and 92.8% in non-tumor nasopharyngeal tissues (P<0.001), and those of ADPRT were 53.5% and 96.4%, respectively (P<0.001). However, the expression levels of hOGG1 and ADPRT had no correlations to the clinical stage and prognosis of NPC.
Conclusion: The decreased expression of hOGG1 and ADPRT might be closely related to the development of nasopharyngeal carcinoma.