Objective: To study the methylation status of retinoic acid receptor β2 (RARβ2) and p16(INK4α) genes in peripheral blood and tumor tissues and the perioperative dynamic changes of free RARβ2 and p16(INK4α) in the peripheral blood, and to investigate the relationship between RARβ2 and p16(INK4α) methylation in peripheral blood and clinicopathological characteristics of esophageal squamous cell carcinoma (ESCC) and their value in evaluating the completeness of surgical resection.
Methods: Real-time methylation specific polymerase chain reaction (real-time MSP) technique was used to detect the methylation status of RARβ2 and p16(INK4α) in tumor tissue, adjacent normal tissue and peripheral blood perioperatively in 76 cases of ESCC. Sixty age-matched healthy volunteers were randomly selected as a control.
Results: RARβ2 and p16(INK4α) hypermethylation presented in both tumor tissue [72.4% (55/76) and 86.8% (66/76)] and peripheral blood [63.2% (48/76) and 71.1% (54/76)] in the ESCC patients, showing a good agreement between them. RARβ2 and p16(INK4α) hypermethylation was significantly related with pathological stage, lymph node metastasis, and invasion of nerves and vessels (P < 0.05). The DNA methylation rate in peripheral blood was increasing first and then decreasing in the preoperative, intraoperative and postoperative periods. Moreover, the RARβ2 methylation in peripheral blood was shown to be significantly associated with family history of cancer (P = 0.023).
Conclusion: RARβ2 and p16(INK4α) methylation in the peripheral blood in ESCC patients may reflect the tumor-bearing status in the body, and may serve as a valuable marker in assessment of the degree of completeness of surgical resection in ESCC patients.