Study On The Molecular Markers PHF6 And DNM2 In Adult T Cell Acute Lymphoblastic Leukemia

Part I Mutations of PHF6 in adult T-cell acute Lymphoblastic LeukemiaObjective:T-cell acute lymphoblastic leukemia (T-ALL) is caused by a collaboration of multiple genetic abnormalities in the transformation of T-cell progenitors.Plant homeodomain ringer 6 (PHF6) has recently been established as a key tumor suppressor, and is mutated in T-ALL.This study was aimed to investigate the mutations and expression of PHF6 gene in adult T-ALL.Methods:Exon 2-10 of PHF6 were amplified,cloned and sequenced in adult T-ALL patients to identify the frequency,position and types of PHF6 mutation.Quantitative real-time polymerase chain reaction was used to detect PHF6 mRNA expression of adult T-ALL patients.The co-existing of PHF6 mutations and abnormal mRNA expression with NOTCH1 mutations were explored.Statistical analysis was carried out using the SPSS (Version 20.0).The differences between groups in quantitative data such like white blood cell(WBC),hemoglobin(Hb),platelet(PLT),and lactate dehydrogenase (LDH) were performed in nonparametric Mann-Whitney test.Comparisons of frequencies in qualitative data were made with Pearson s chi-square test or Fisher s exact test.Kaplan-Meier curves were used to assess overall survival(OS),event-free survival(EFS)and differences between groups were compared using the log-rank test. P values below 0.05 were considered statistically significant.Results:We detected 27.1%(16/59) PHF6 mutations including 10 novel mutations in Chinese adult T-ALL. Six of the PHF6 mutations induce the frame-shift of the gene, indicating PHF6 is dysfuncted in the patients.Moreover, we found significantly lower expression of PHF6 in T-ALL patients.Importantly, we found that PHF6 mutations were significantly associated with older age, lower hemoglobin,higher frequency of CD 13 positive,and higher incidence of splenomegaly or lymphadenopathy. Furthermore, PHF6 mutations are also significantly correlated with NOTCH1 mutations.The T-ALL patients with co-existence of the two mutations have significantly shorter event-free survival (EFS).Conclusion:Our results indicated that PHF6 was inactivated in adult T-ALL due to its low expression and mutations.PHF6 mutation co-existed with NOTCH1 mutations, and patients with co-existed PHF6 and NOTCH1 mutations had a poor prognosis. Our data indicated synergistic oncogenic effect of PHF6 and NOTCH1 mutations and co-existence of the two genes mutations may be a potential prognostic marker in adult T-ALL.Part Ⅱ Mutations of DNM2 in adult T-cell acute Lymphoblastic LeukemiaObjective:Dynamin 2(DNM2)gene is a transcription factor,involved in a wide range of cellular functions, including endocytosis, phagosome formation, intracellular trafficking, interaction with the actin and microtubule networks, and promotion of apoptosis. This study was aimed to investigate the mutations of DNM2 gene in adult T-cell acute lymphoblastic leukemia(T-ALL).Methods:Exon 2-10、12-14 and 16-22 of DNM2 were amplified and sequenced in adult T-ALL patients to identify the frequency,position and types of DNM2 mutation. The interactions of DNM2 mutations with NOTCH1 or PHF6 mutations were explored. Statistical analysis was carried out using the SPSS (Version 20.0). The differences between groups in quantitative data such like white blood cell (WBC), hemoglobin (Hb) and platelet (PLT) were performed in nonparametric Mann-Whitney test. Comparisons of frequencies in qualitative data were made with Pearson’s chi-square test or Fisher s exact test. P values below 0.05 were considered statistically significant.Results:All of the DNM2-mutated samples in this study harbored concomitant mutations in NOTCHl,and the co-existed NOTCH1 mutations located in HD-N,HD-C and PEST domains.In addition,co-existing mutations with PHF6 were identified in 3 of 4 cases located in exon 4、5、8.We also found that DNM2 gene had synonymous amino acid mutations in the patients,exon4(1/42,2.38%), exon6(1/42, 2.38%),exon22(1/42,2.38%)were observed.And there was a high rate of exon20 (35/42,83.33%) synonymous amino acid mutations, including two types, Ala713Ala and Asp720Asp.One of them, A713A, had a high rate of incidence (73.81%,31/42), and the mutation also occured in B-cell acute lymphoblastic leukemia (B-ALL) and healthy persons with the rate above 80%.Conclusion:The phenomenon of co-existed DNM2 and NOTCH1/PHF6 mutations may play an important role in the progress of T-ALL.