The Mutation And Expression Of Human Telomerase Reverse Transcriptase In Children’s Hematological Diseases

Objective: To study the gene mutation and expression of catalyticsubunit of telomerase in children’s hematological diseases, deepenunderstanding of telomere disease (telomeropathy), and gain a furtherinsight about the relationship between telomerase and hematologicaldiseases in children.Methods:1. It has been reported that the15th exon of hTERT is particularly highrisk of mutation in adult acute myeloid leukemia, so we focused on thisregion in children’s hematological diseases.71hospitalized in hematological department patients were enrolled inthis study. Among them,47cases were diagnosed with acute leukemia, andother23cases were non-leukemic patients including2aplastic anemia cases.The whole genome DNA was purified from peripheral blood ofpatients. And then the15th exon of hTERT gene was amplified, PCRproduct was sequenced in Huada Gene company and analyzed thesequencing results. 2. The gene expression of hTERT in acute leukemia of childrenreceived chemotherapy60hospitalized in hematological department patients were enrolled inthis study. Among them,37cases were diagnosed with acute leukemia andreceived standard chemotherapy, and other23cases were non-leukemicpatients.The total RNA were purified from peripheral blood of patients, andreversely transcribed it into cDNA. The relative hTERT expression toGAPDH was detected by using fluorescence quantitative real-time PCR.The results were statistically analyzed in dimidiated and multiply groupedwith nonparametric Mann-Whitney and Kruskall-Wallis tests via SPSS17.0,respectively.Results:1. Mutations analysis of the15th exon of hTERT: Only2patients withaplastic anemia were carried with C＞A mutation on the1254714site of5thchromosome, which lies upstream91bp away from the15th exon of hTERT.However, the rest21non-leukemic cases and47cases of children acuteleukemia were without mutations in this region.2. Gene expression of hTERT: There were significant differences ofhTERT expression among B-ALL, Pre-ALL, and T-ALL phenotype groups,PreB-ALL＜B-ALL＜T-ALL. However, no diversities of hTERTexpression were found between or among other groups, including between leukemic and non-leukemic groups, between AML and ALL groups, amonghigh, mediate and standard risk groups, among WBC≥100×109/L,50×109/Lto100×109/L, and＜50×109/L groups, between normal and abnormalkaryotype groups, or between older than10years and in between1-10yearsgroups.Conclusions:There are differences between childhood and adult acute leukemia inhTERT gene mutations. The high mutational site in adult AML was low inchildren’s acute leukemia. Only2aplastic anemia patients carried with thesame mutation in the1254714site of chromosome5, suggesting thismutation site might be correlated with aplastic anemia and deserve furtherstudy.There is no significant difference of hTERT expression betweenchildren with acute leukemia received chemotherapy and achieved completeremission and the non-leukemic patients. There are significant differencesamong B-ALL, Pre-ALL, and T-ALL phenotypes, however, no morediversities were found in other risk groups. Taken together, hTERTexpression may provide as a molecular marker for complete remission ofchildren’s acute leukemia.