Detection Of Methylation Of DACH1 Gene In Breast Cancer And Peripheral Blood And Its Clinical Significance

Background&objective:Although the 5-year survival rate of breast cancer has been significantly improved compared with other cancers in the past decade,there are also significant differences in the prognosis of breast cancer patients with different molecular types.How to diagnose breast cancer early,it is necessary to explore the application of new tumor molecular markers in clinical practice.Because the detection of DNA methylation,an efficient and sensitive molecular marker,can improve the rate of tumor diagnosis,it has become a hot spot in the field of oncology.As a tumor suppressor gene,aberrant methylation of cell fate determining factor(Dachshund homolog 1,DACH1)is one of the important mechanisms in the occurrence and progression of many kinds of tumors(including esophageal cancer,gastric cancer,colon cancer,endometrial cancer,prostate cancer,etc.)and has a significant relationship with the prognosis of patients.The epigenetic changes and regulatory mechanism of DACH1 in breast cancer still need to be further explored.The purpose of this study was to investigate the methylation of DACH1 gene in circulating DNA in breast cancer tissue and corresponding plasma,and to compare whether there are differences in clinical features between DACH1 and breast cancer patients,and to provide theoretical basis for clinical search for new molecular biological markers by detecting the methylation status of DACH1 gene in peripheral blood.Methods:The pathological tissue samples of 55 cases of Northern Jiangsu People’s Hospital 2019.12-2020.12 breast cancer were collected,and the preoperative plasma samples of breast cancer were 20 ml,and the plasma samples of 23 cases of benign tumors in the control group were collected.All the samples in this experiment were collected freshly and did not do any treatment before operation.After DNA was extracted from corresponding tissues and plasma,the methylation status of DACH1 was detected by real-time quantitative PCR methylation,and compared with the corresponding clinicopathological parameters to explore its clinical significance and correlation with pathological diagnosis.At the same time,the sensitivity and specificity of preoperative serum CA153,and combined peripheral blood DACH1 methylation in the diagnosis of breast cancer were analyzed,so as to provide clinical value for the early diagnosis of breast cancer by DACH1.Results: 1.The mean and standard deviation of methylation degree in cancer tissues and corresponding paracancerous tissues in 55 patients with breast cancer were(0.22,0.19)and(0.04,0.09),respectively,which were significantly different from each other(P < 0.05).There was no significant difference between DACH1 methylation level and patient’s age,tumor location,lymph node metastasis,status of ER,status of Her-2,status of PR and Ki-67 level in breast cancer tissue,but it was correlated with tumor size,tumor pathological type and TNM stage.Among them,there was significant difference between tumor T1(≤ 2cm)group and tumor in T2(2～5cm)group(P < 0.011),there was no significant difference in tumor between T2(2～5cm)group and tumor T3(>5cm)group(P < 0.375),and there was significant difference between tumor T1(≤ 2cm)group and tumor T3(> 5cm)group(P < 0.039),so it can be considered that the methylation degree of DACH1 in tumor T1(≤ 2cm)group was lower than that in tumor T2(2～5cm)group and tumor T3(> 5cm)group;2.Correlation analysis between the degree of methylation of DACH1 gene in cancer tissues of breast cancer patients and the detection rate of DACH1 in blood was analyzed by Kendall and Spearman two non-parametric tests.The result coefficients were 0.378 and 0.454,respectively,were less than 0.5,and the P values were both less than 0.05.It is suggested that there is a significant correlation between DACH1 methylation status and the detection rate of DACH1 methylation in paired blood of breast cancer patients;3.The sensitivity of peripheral blood DACH1 single index detection for the diagnosis of breast cancer was 80%(44/55),the specificity was 78.3%(18/23),the positive predictive value was 89.8%(44/49),and the negative predictive value was 62.1%(18/29),the consistency analysis test with pathological diagnosis,namely Kappa test,the result was 0.542,the diagnostic consistency was moderate,P<0.001,the Kappa value was statistically significant;4.The Kappa value of serum CA153 index detection and pathological diagnosis consistency analysis was 0.256,and the Kappa value of combined diagnosis and pathological diagnosis consistency analysis was 0.699,which was significantly different from that of pathological diagnosis(P < 0.05).Conclusion: 1.The degree of DACH1 methylation in breast cancer tissues is significantly higher than that of adjacent tissues,which is closely related to the patient’s tumor size,tumor pathological type,and TNM staging;2.The DACH1 methylation status in breast cancer tissues is correlated to a certain degree with the peripheral blood DACH1 methylation status,the methylation status in breast cancer tissue can be reflected by detecting peripheral blood DACH1;3.The expression level of DACH1 methylation in peripheral blood has certain clinical significance in the diagnosis of early breast cancer,but multi-sample data is still needed for further demonstration;4.There is a certain correlation between the detection of DACH1 methylation in peripheral blood and pathological diagnosis,and the positive rate is significantly higher than that of serum CA153.The combined diagnosis can improve the diagnosis rate and has a certain value in early screening of breast cancer.