Serum miR-133 as a novel biomarker for predicting treatment response and survival in acute myeloid leukemia.

OBJECTIVE: MiRNA-133 (miR-133) has been identified as a tumor suppressor in many types of human cancers. However, its clinical significance in acute myeloid leukemia (AML) is still unclear. The purpose of this study was to assess the correlation of miR-133 expression with clinical variables and prognosis in AML patients. PATIENTS AND METHODS: Quantitative Reverse Transcriptase-Polymerase Chain Reaction (qRT-PCR) was performed to analyze blood samples from 145 patients with AML and 70 healthy volunteers. RESULTS: Decreased miR-133 levels were observed in AML patients and closely associated with aggressive clinical parameters, such as white blood cells and poor Karyotype subgroups. In addition, receiver operator characteristic (ROC) analysis revealed that serum miR-133 could efficiently screen AML patients from normal controls with high sensitivity and specificity. More interestingly, serum miR-133 levels were remarkably elevated in the patients with favorable response after standard induction chemotherapy or achieving a complete remission. Furthermore, patients in the high serum miR-133 expression group had better overall survival and recurrence-free survival than those in the low serum miR-133 expression group. Meanwhile, multivariate analysis identified serum miR-133 as a significant independent predictor for survival. CONCLUSIONS: Low miR-133 expression was a common event and correlated with worse clinical outcome in AML, suggesting that serum miR-133 might serve as a promising indicator for the early detection and prognosis evaluation of AML.

[Effect of TSC2 gene expression downregulation by lentivirus induced RNA interference on U937 cell line and its mechanism].

Objective: To investigate the effect of biology and mTOR pathway activity of down-regulated TSC2 gene expression on U937 leukemia cells. Methods: Gene expression was down-regulated by lentivirus induced RNA interference on TSC2 high expressed U937 cell line; the proliferation, apoptosis and differentiation were detected by CCK-8 assay, colony formation assay and flow cytometry; the gene expression level and protein kinase activity were detected by qRT-PCR and Western blot. Results: Down-regulated expression of TSC2 gene promoted U937 cell proliferation and colony formation ability (P<0.05) . The proportion in G(0)/G(1) phase of TSC2 down-regulated U937 cell was much lower than that of the control cells [ (52.53±3.75) % vs (75.10±4.33) %, t=6.829, P=0.002], the S phase [ (22.43±1.00) % vs (15.47±1.20) %, t=-5.581, P=0.019] and G(2)/M phase [ (25.03±4.34) % vs (14.33±0.91) %, t=-5.413, P=0.013] was remarkably higher than that of the control cells (P<0.05) . There were no statistically significant differences in cell apoptosis and differentiation (P>0.05) . Down-regulation of TSC2 led to the increased activity of mTOR, 4EBP1 and S6K1, but did not influence the activity of AKT. The expressions of proliferation related cyclinD1, c-myc and PTEN were also up-regulated after TSC2 silenced, but the expressions of P27KIP and BCL-XL were not changed. Conclusion: Downregulation of TSC2 could promote the proliferation of U937 cells through up-regulation of mTOR activity.

[Frequency and clinical features of ASXL2 gene mutation in acute myeloid leukemia patients with AML1- ETO fusion gene positive].

OBJECTIVE: To investigate frequency and clinical features of additional sex combs-like 2 (ASXL2) gene mutation in acute myeloid leukemia (AML) patients with AML1-ETO fusion gene and to analyze the relationship between ASXL2 gene mutation and c- kit gene mutation. METHODS: Mutation analysis of exon 11 and 12 of ASXL2 gene in 59 de novo AML patients was performed by using polymerase chain reaction (PCR) followed by sequence analysis. The clinical features, survival curve and c-kit gene mutation in ASXL2 gene mutation positive and negative patients were compared. RESULTS: In a total of 59 AML patients with AML1-ETO fusion gene positive, 11.9% (7/59) patients harboured ASXL2 gene mutations. The hemoglobin levels of patients with mutated ASXL2 gene [56.2 (38.0- 72.0) g/L] were significantly lower than those with wild type ASXL2 [69.0(37.2-154.0) g/L] (P=0.038). Differences were not observed in white blood cell counts, platelet counts, the proportion of acidophilic cell, and the proportion of primitive cell in the marrow between patients with mutant ASXL2 and ones without mutant ASXL2 (P>0.05). None of all 59 patients suffered from liver, spleen, central nervous system metastases in both groups. Moreover, enlarged lymph nodes was similar between patients with mutant ASXL2 and ones without mutant ASXL2 (P=0.859). Immunophenotypic analysis: in positive group CD33 positive expression was significantly lower than that of negative group (P=0.033). cCD3 was not expressed in both groups. Expression levels of CD117, cMPO, HLA-DR, CD34, CD38, CD13, CD44, CD15, CD64, CD11b, CD56, CD19, cCD79a and CD7 were similar between patients with mutant ASXL2 and ones without mutant ASXL2 (P>0.05). All of 59 patients were in remission (P=0.577). Overall survival was similar between patients with mutant ASXL2 and ones without mutant ASXL2 (P=0.631). The mutation rates of c- kit in positive group and negative group were 14.3% and 29.4%, without statistical significance (P= 0.697). CONCLUSIONS: ASXL2 mutation may be a new event that can cooperate with AML1-ETO to induce leukemia. Patients in AML1- ETO positive AML with ASXL2 mutation show specific clinical characteristics of hemoglobin levels and expression level of CD33. ASXL2 gene mutations and c-kit gene mutations may not have a specific correlation between them.

[Discovery of a novel spliceosome of ABL gene (ABL(Δexon7+35INS)) and its association with TKIs resistance in chronic myeloid leukemia].

OBJECTIVE: To explore whether the ABL(Δexon7) and ABL(35INS) spliceosome contributed to TKIs resistance. METHODS: Screening ABL(Δexon7) and ABL(35INS) in 74 normal people and 76 CML patients (53 patients in remission and 23 patients with TKIs resistance) by using polyacrylamide gel electrophoresis combined with cloning sequencing. RESULTS: A novel spliceosome ABL(Δexon7+ 35INS) (ABL(Δexon7) and ABL(3)5INS existed at the same time) was identified and the mutation was detected in 8 (10.8%) of 74 normal people, 4 (7.5%) of 53 remission patients and 2 (8.7%) of 23 resistant patients. While 47 (63.5%) cases expressed ABL(Δexon7) and 8 (10.8% ) cases expressed ABL(35INS) in 74 healthy people, 30 (56.6%) cases expressed ABL(Δexon7) and 5 (9.4% ) cases expressed ABL(35INS) in 53 remission patients, 12 (52.2%) cases expressed ABL(Δexon7) and 3(13.0%) cases expressed ABL(35INS) in 23 resistant patients. Three kinds of spliceosome in all groups had no statistical difference. CONCLUSION: ABL(Δexon7+ 35INS), ABL(Δexon7) and ABL(35INS) may be not uncommon in ABL gene and were unrelated to resistance in CML with TKIs treatment. ABL(35INS) were often accompanying with exon 7 deletion.