Methylation Inactivation Mechanism of Parkin Gene mRNA Expression in Nasopharyngeal Carcinoma

Abstract

Objective: To investigate the methylation inactivation and the clinical significance of Parkin gene mRNA expression in nasopharyngeal carcinoma (NPC). Methods: The methylation-specific PCR (MSP) and semi-quantitative reverse transcription PCR (RT-PCR) were used to detect methylation and the mRNA expression level of Parkin gene in 54 cases of NPC tissues and 16 cases of normal nasopharyngeal epithelial (NNE) tissues. The mRNA expression of Parkin gene in two NPC cell lines (CNE1 and CNE2) were detected before and after treatment with the methyltransferase inhibitor 5-aza-2-deoxycytidine so as to analyze the effects of Parkin gene methylation and demethylation on Parkin gene mRNA expression and the relationship between Parkin gene mRNA expression and clinical factors. Results: The methylation frequency of Parkin gene in human NPC tissues was 62.96% (34/54), but didn't happen in any of 16 cases of NNE tissues. The mRNA expression level was (0.3430±0.4947) in 54 cases of NPC tissues and (1.0052±0.4911) in NNE tissues, showing that the mRNA expression level of NPC tissues was significantly down-regulated (P ＜ 0.01). There was significant difference in Parkin mRNA expression of NPC tissues between 34 cases of methylation (0.0942±0.2309) and 20 cases of unmethylation (0.7660±0.4369) (P ＜ 0.01). The Parkin mRNA expression in CNE1 and CNE2 increased after 5-aza-2-deoxycytidine treatment. Parkin gene mRNA expression had no obvious relationship with age, gender, T staging, TNM staging and pathogenic pattern (P ＞ 0.05), but was closely related to lymph node metastasis (P ＜ 0.05). Conclusion: Parkin gene mRNA expression, serving as a cancer suppressor gene in the occurrence and development of NPC, is inactivated and regulated by methylation, which also has a negative correlation with lymph node metastasis and could be considered as the judgment of predictive index of clinical prognosis of NPC