[ZO-1 gene methylation status and its clinical significance in children with non-Hodgkin lymphoma].

Objective To investigate the methylation status of zonula occludens-1(ZO-1) gene promoter and its clinical significance in children with stage IV non-Hodgkin lymphoma(NHL) and to provide a basis for further etiological study and early diagnosis of this disease. Methods Fifty-five children with a confirmed diagnosis of stage IV NHL(40 cases of T-NHL and 15 cases of B-NHL) were selected as the case group, and 20 children with diseases other than hematologic malignancies were selected as the control group. Bone marrow samples were collected from these subjects. Methylation-specific PCR(MS-PCR) was applied to evaluate the methylation status of ZO-1 gene promoter, and the integrated optical density(IOD) was determined. RT-PCR was used to measure the mRNA expression of ZO-1. Results MS-PCR showed that the methylated bands of ZO-1 gene promoter were found in 39(70.9%) of 55 patients in the case group before treatment, while no ZO-1 gene promoter methylation was detected in the control group. With close tracking of 47 cases in the study group, consisting of 32 cases of T-NHL and 15 cases of B-NHL, the rates of ZO-1 gene promoter methylation prior to treatment were 72% and 67%, respectively,(P0.572). The cases of T-NHL and B-NHL showed no significant changes in methylation rate in the early and middle phases of chemotherapy(P0.05), but they showed significant changes in methylation rate in the late phase of chemotherapy(P0.05). RT-PCR showed that theNHL cases carrying methylated ZO-1 gene had no mRNA expression of ZO-1, while all children in the control group had mRNA expression of ZO-1. There was no linear relationship between the total number of peripheral blood leukocytes and ZO-1 gene IOD(r=0.093, P=0.575); a positive correlation was found between the number of malignant cells in bone marrow and ZO-1 gene IOD(r=0.669, P0.001). Conclusions ZO-1 gene shows a hypermethylation status in children with NHL, and the methylation level is positively correlated with the number of malignant cells in bone marrow. ZO-1 may be used as a novel molecular marker in early diagnosis, outcome assessment, prognostic evaluation, and detection of minimal residual disease.