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Objective Plasma circulating DNA can be em-ployed in place of bone marrow examination for the auxiliary diagnosis of leukemia.This study aimed to explore the clinical application of the plasma DNA level in evaluating the effect of chemotherapy on chronic leukemia. Methods We collected blood samples from 52 patients with chronic myelogenous leukemia (CML) (33 in the chronic phase, 7 in the acceleration phase, and 12 in the blast phase) , 85 with chron-ic lymphocytic leukemia (CLL) (28 with complete remission, 27 with partial remission, and 30 with no remission), 4 patients with hairy cell leukemia (HCL), and 80 healthy subjects.We simultaneously obtained plasma DNA and recombinant plasmid DNA using the BI-LATEST DNA Kit and examined the human β-actin gene and the level of plasmid DNA by real-time quantitative PCR. Results Before chemotherapy, the median value of plasma DNA was 149.46(30.63-496.91)ng/ml in the CML and 101.54(69.10-258.14) ng/ml in the CLL patients, both significantly higher than in the healthy controls (19.05[12.67-25.92]ng/ml) (P<0.01).After chemotherapy, the plasma DNA level of the CML patients was remarkably decreased, but still higher than that of the controls ( P<0.01).The CML patients in the chronic phase showed a markedly higher level of plasma DNA (302.89[93.33-541.52]ng/ml) than those in the blast phase (43.19[23.54-70.03]ng/ml) and acceleration phase (28.11[16.21-92.07]ng/ml) (P<0.05).The CLL patients with CR exhibited a significantly lower level of plasma DNA (24.29[14.64-30.74]ng/ml) than those with PR (106.88 [96.23-143.25]ng/ml) and NR (460.73[284.57-653.38〗ng/ml) (P<0.01), but all dramatically higher than that of the healthy controls (P<0.01) Conclusion The quantification of plasma DNA has a clinical application value in evaluating the effect of chemo-therapy on chronic leukemia.
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Background and purpose:Aberrant DNA methylation that leads to the inactivation of tumor suppressor genes plays important roles in development and progression of breast cancer. Clinically, related gene methylation is considered to be a promising biomarker for tumor diagnosis and prognosis. This study aimed to investigate the methylation status ofSox17 gene in breast cancer tissue and its corresponding plasma circulating DNA, as well as to investigate its value in breast cancer early diagnosis and prognosis.Methods:TheSox17 gene promoter methylation status was detected by MSP in 86 cases of breast cancer, 36 normal breast tissues and its paired plasma DNA, the results were analyzed with corresponding clinical and pathological features.Results:The frequency ofSox17 gene methylation rate among 86 breast cancer tissues was 77.9%(67/86), and was 61.6%(53/86)in plasma circulating DNA, however, noSox17 gene methylation was found in normal breast tissues.Sox17 gene promoter methylation in plasma circulating DNA was signiifcantly associated with the methylation status in tumor tissues (r=0.502,P=0.000). In breast cancer tissue specimens,Sox17 methylation status was significantly correlated with tumor stage (χ2=6.18,P=0.041) and lymph node metastasis (χ2=13.54,P=0.001);Sox17 gene methylation rate was signiifcantly correlated with tumor stage (χ2=27.06,P=0.000), tumor size (χ2=9.65,P=0.007) and lymph node metastasis (χ2=20.80,P=0.000) in plasma samples, and there was no signiifcant difference ofSox17 gene methylation between patient age, histological grade and ER, PR, HER-2/neu status.Conclusion:Sox17 gene promoter methylation plays an important role in the carcinogenesis and development of breast cancer, and may be associated with the prognosis of breast cancer. Furthermore, methylatedSox17 gene may be a useful tumor biomarker in plasma circulating DNA for breast cancer detection and disease monitoring.