Study On The Molecular Markers FBXW7 And PTEN In Adult Patients With Acute Lymphoblastic Leukemia

PartⅠ Mutations of FBXW7 in adult T-cell acute Lymphocytic LeukemiaObjectives: F-Box and WD40 domain containing protein 7 gene( FBXW7) is part of the E3 ubiquitin ligase complex that controls the turnover of various proteins including NOTCH1, c-MYC and cyclin E. This study was aimed to investigate the mutations of FBXW7 gene in adult T-cell acute lymphoblastic leukemia( T-ALL).Methods: Exon 5- 12 of FBXW7 were amplified, cloned and sequenced in 54 adult T-ALL patients to identify the frequency, position and types of FBXW7 mutation. The co-existing of mutations with NOTCH1 and relevant prognostic significance were explored as well. 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: FBXW7 mutations were identified in 11.1% of adult T-ALL patients. A total of 5 types of point mutations( R465 H, R465 L, R479 P, R505 C and S546 X)and one deletion/insertion mutation were observed, and all of them located in WD40 domain of FBXW7. In addition, co-existing mutations with NOTCH1 were identified in 5 of 6 cases with FBXW7 mutation. Notably, the co-existed NOTCH1 mutations, including three point mutations( L1574 P, L1596 H and L1600P) and two deletion/insertion mutations located in HD domain. Furthermore, patients with FBXW7 mutation only had significantly longer overall survival compared with those without mutation( 9.5 months vs. 6.5 months, P=0.049).Conclusion: FBXW7 mutations may play an important role in NOTCH1 mediated pathogenesis in T-ALL.Part Ⅱ Mutations and expression of PTEN gene and relevant clinical significance in adult T-cell acute Lymphocytic LeukemiaObjectives: Phosphatase and tensin homolog( PTEN) is a classical tumor suppressor gene implicated in tumor initiation and progression, which possesses lipid and protein phosphatase activities. PTEN function is commonly lost in a large proportion of human cancers. This study was aimed to investigate the mutations and expression of PTEN gene in adult T-cell acute lymphoblastic leukemia( T-ALL).Methods: Exon 1- 9 of PTEN were amplified, cloned and sequenced in adult T-ALL patients to identify the frequency, position and types of PTEN mutation. Quantitative polymerase chain reaction was used to detect PTEN m RNA expression of adult T-ALL patients. The co-existing of PTEN mutations and abnormal m RNA expression with NOTCH1/FBXW7 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: PTEN mutations were identified in 10.4% of adult T-ALL patients. All of them included deletion/insertion mutations in the C2 domain of PTEN. All of the PTEN-mutated samples in this study harbored concomitant mutations in NOTCH1/FBXW7. PTEN expressions were higher in CR cases compared with newly diagnosed and relapsed cases( 11.000 vs. 0.576, P=0.021; 11.000 vs. 0.426, P=0.029). Low PTEN expression levels may mostly generated in cases with NOTCH1 HD mutations( 73.9% vs.30.0%,P=0.026). Furthermore, compared with high PTEN expression group, patients with low PTEN expression possessed lower 6-month OS rate and 12-month OS rate(43.5% vs. 90.0%, P=0.021; 26.1% vs. 70.0%, P=0.026).Conclusion: Loss-of-function mutations in PTEN may play an important role in NOTCH1 mediated pathogenesis in T-ALL.