Methylation-specific PCR Test for Early Screening and Early Diagnosis of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma is one of the most common malignant tumors in China, with the progress of radiochemical comprehensive treatment, early stage The 5-year survival rate of nasopharyngeal cancer is more than 95%. However, due to the hidden site of nasopharyngeal carcinoma and the lack of obvious early clinical symptoms, more than 70% of the 87,000 newly diagnosed cases each year belong to the advanced stage of nasopharyngeal carcinoma, and the 5-year survival rate of advanced nasopharyngeal carcinoma is only about 70%. Therefore, early screening and diagnosis and early treatment are the key to improve the survival of patients with nasopharyngeal cancer. Selecting a sensitive and accurate biomarker for nasopharyngeal cancer and relying on a simple and feasible examination method for sampling detection will greatly improve the early diagnosis rate of nasopharyngeal cancer.

DNA methylation is a form of chemical modification of DNA that can be done without altering the DNA sequence changes in genetic expression. The main role of DNA methylation is to regulate gene expression. Tumor suppressor genes play the functions of regulating cell differentiation, maturation and programmed death. However, if methylation of promoter region occurs, the expression of tumor suppressor genes is inhibited and the function is lost, resulting in cells remaining in the stage of low differentiation and proliferation, inhibition of apoptosis, formation of blood vessels by cluster cells, loss of cell adhesion, and formation of tumors. It can be seen that DNA methylation occurs in the early stage of tumor, and this biological feature makes it a strong application prospect in early tumor screening.

There are many methods to detect DNA Methylation, among which methylation-specific PCR (MSP) can easily and quickly determine the methylation status of a specific gene, meeting the affordable, convenient, and easy to generalize characteristics required for screening tests. In combination with previous MSP experiments and previous reports, we found that the methylation levels of promoter fragments of H4C6, Septin9 and RASSF1A genes in nasopharyngeal carcinoma tissues were significantly higher than those in healthy human nasopharyngeal tissues. This suggests that methylation of these three genes may be used as biomarkers for early screening and diagnosis of nasopharyngeal carcinoma.

Therefore, this study intends to detect the methylation status of H4C6, Septin9 and RASSF1A genes based on MSP method with simple operation and low cost. Using clinicopathological diagnosis as the gold standard, the value of this gene methylation index in early screening and early diagnosis of nasopharyngeal cancer was verified, providing a new detection index and method for improving the early diagnosis rate of nasopharyngeal cancer.