Correlation Analysis Of Promoter Methylation Of Foxp3 Gene In Sentinel Lymph Nodes And Non-sentinel Lymph Nodes In Patients With Colorectal Cancer

Objective: To observe the changes of DNA methylation of the Cp G fragment of the Foxp3 gene promoter region in sentinel lymph node and non-sentinel lymph node tissues of colorectal cancer patients,combined with the analysis of the association between the methylation changes in the promoter region of Foxp3 gene and the clinicopathological features of colorectal cancer,to explore the possible role of promoter-specific DNA methylation in sentinel lymph nodes in the development of colorectal cancer.Methods: Sentinel lymph node tissue and non-sentinel lymph node tissue of 32 patients with colorectal cancer were selected as match paired tissue samples;and the protein expression of Foxp3 in the paired tissues was detected by immunohistochemistry;quantitative analysis of DNA methylation at 7 Cp G sites in the Foxp3 gene promoter region of paired samples using matrix-assisted laser desorption ionization time-of-flight mass spectrometry.Correlation analysis of DNA methylation changes between paired sites of paired tissues were done.Association analysis of methylation changes of paired tissues with clinicopathological features of colorectal cancer were done.Results: There were no significant differences in the number of cells expressing Foxp3 in the paired lymph node tissues selected in the experiment.The 7 sites of Cp G in the promoter region of Foxp3 gene in both sentinel lymph node and non-sentinel lymph node tissues had methylation performance,there was a difference in the total methylation rate(total methylation degree)between the two.Compared with the 7 methylation change sites in the tissues,while the single Cp G?2(P=0.00)and Cp G?8(P=0.00)sites in SLN showed higher levels of methylation,and the difference was statistically significant;the methylation levels of Cp G?1(P=0.01),Cp G?2(P=0.02),Cp G?6.7(P=0.03),and Cp G?8(P=0.02)sites between pairs of tissues were closely related;further analysis revealed that the methylation status of Foxp3 gene promoter region was related to the patient's age(P=0.02),tumor sizes(P=0.00),and tumor infiltration depth(P=0.00).Conclusion: The change of specific methylation sites in the promoter region of Foxp3 gene may be related to the early anti-tumor immunity of SLN and disease progression in CRC.