Genetic variants and clinical significance of pediatric acute lymphoblastic leukemia.

BACKGROUND: Acute lymphoblastic leukemia (ALL), the most common childhood malignancy, is characterized by molecular aberrations. Recently, genetic profiling has been fully investigated on ALL; however, the interaction between its genetic alterations and clinical features is still unclear. Therefore, we investigated the effects of genetic variants on ALL phenotypes and clinical outcomes. METHODS: Targeted exome sequencing technology was used to detect molecular profiling of 140 Chinese pediatric patients with ALL. Correlation of genetic features and clinical outcomes was analyzed. RESULTS: T-cell ALL (T-ALL) patients had higher initial white blood cell (WBC) count (34.8×109/L), higher incidence of mediastinal mass (26.9%), more relapse (23.1%), and enriched NOTCH1 (23.1%), FBXW7 (23.1%) and PHF6 (11.5%) mutations. Among the 18 recurrently mutated genes, SETD2 and TP53 mutations occurred more in female patients (P=0.041), NOTCH1 and SETD2 mutants were with higher initial WBC counts (≥50×109/L) (P=0.047 and P=0.041), JAK1 mutants were with higher minimal residual disease (MRD) level both on day 19 and day 46 (day 19 MRD ≥1%, P=0.039; day 46 MRD ≥0.01%, P=0.031) after induction chemotherapy. Multivariate analysis revealed that initial WBC counts (≥50×109/L), MLLr, and TP53 mutations were independent risk factors for 3-year relapse free survival (RFS) in ALL. Furthermore, TP53 mutations, age (<1 year or ≥10 years), and MLLr were independently associated with adverse outcome in B-cell ALL (B-ALL). CONCLUSIONS: MLLr and TP53 mutations are powerful predictors for adverse outcome in pediatric B-ALL and ALL. Genetic profiling can contribute to the improvement of prognostication and management in ALL patients.

[Cytogenetic characteristics of 163 children with acute lymphoblastic leukemia].

OBJECTIVE: To further understand the cytogenetic characteristics of pediatric acute lymphoblastic leukemia (ALL). METHODS: Cytogenetic abnormalities of 163 children with newly diagnosed ALL (0-17 years of age) were evaluated by conventional cytogenetic analysis and fluorescent in situ hybridization findings. RESULTS: Chromosome abnormalities were detected in 87.7% of patients (143/163). The ploidy levels most frequently observed among ALL patients were high hyperdiploidy (51-67 chromosomes) (45 cases, 27.6%), Chromosomes X and 21 were gained in 100% of these cases. The most common genetic alterations were t(12;21)/ETV6/RUNX1 (26 cases, 16.0%), followed by t(1;19)/TCF3/PBX1 (13 patients, 8.0%), t(4;11)/MLL rearrangement and t(8;14) IGH/MYC (6 cases, 3.7%), t(9;22)/BCR/ABL(2 cases, 1.2%), and iAMP21 (1 patient, 0.6%). The no-classical structural abnormalities included dup(1q) in 20.2%, del(6q) and del(9p) in 10.4%, del(12p) in 12.9% and del(13q) in 5.5%. The incidences of t(12;21), t(1;19), t(9;22) and high hyperdiploidy were consistent with reports in Western children (P>0.25). The incidence of (9;22) seemed to be much lower in our study than that in Korea (1.5% vs 9.5%, P<0.005). CONCLUSION: Cytogenetic findings of childhood ALL patients are similar to that of Western countries, it seems no more adverse risk factors.

[Knockdown of proteasome subunit α7 with small interfering RNA inhibits cell proliferation of K562 cell line].

OBJECTIVE: To study the effect of human proteasome subunit Α7(PSMA7)gene silencing by small interfering RNA(siRNA)on human myeloid leukemia cell line K562. METHODS: PSMA7 gene-specific siRNA was chemically synthesized and transfected into K562 cell line by HiPerFect. The expression level of PSMA7 protein was detected by Western blot analysis. Cell proliferation was determined by MTS and cell counting. Cell cycle distribution was measured by flow cytometry. The expressions of Cyclin A, D, and E were detected by Western blot analysis. The apoptotic ratio was determined by flow cytometry. RESULTS: PSMA7 protein was evidently silenced 48 hours after transfection of the PSMA7-specific siRNA into K562 cell line. The proliferation of the cells was markedly inhibited, and the percentage of S phase cells decreased. However, no apoptosis was observed. The expressions of Cyclin A and E were down-regulated. CONCLUSION: Knockdown of PSMA7 down-regulates the expression of Cyclin A and E and thus decreases the proportion of cells in S phase as a result, the proliferation of K562 cell line is inhibited.