[Show abstract][Hide abstract] ABSTRACT: Mutations at arginine 132 of isocitrate dehydrogenase 1/2 (IDH1/2) have recently been demonstrated to be recurrent gene alterations in acute myeloid leukemia (AML). Subsequently, this mutation was also found in a variety of other hematologic malignancies, including myelodysplastic syndromes, myeloproliferative diseases, and non-Hodgkin lymphoma. Only a few cases were so far identified in acute lymphoblastic leukemia (ALL). To study the IDH status in ALL patients, we analyzed 54 adult and 34 pediatric ALL samples' IDH1/2 gene.
Three adult cases and no pediatric case with an isocitrate dehydrogenase 1 (IDH1) mutation were identified. No isocitrate dehydrogenase 2 (IDH2) mutation was identified in the total of 88 samples. The frequency of the IDH1 mutation in adult ALL was 5.5%. Among the three IDH1-mutated patients, two had normal karyotype and expressed the myeloid lineage markers. All three patients with an IDH1 mutation relapsed or died within 6 months.
The results suggested that the IDH1 R132 mutation might be a recurrent gene alteration in ALL; patients carrying the mutation have a trend to aberrantly express myeloid antigen and the mutation may imply a dismal outcome.
No preview · Article · Jul 2012 · Genetic Testing and Molecular Biomarkers
[Show abstract][Hide abstract] ABSTRACT: iASPP was an inhibitory member of ASPP family and could specifically inhibit the apoptotic function of p53. iASPPsv was identified by our lab as the short isoform of iASPP, which encoded a 407 aa protein and highly matched the carboxyl terminus of iASPP. In this study, iASPPsv was stably transfected into the breast cancer cell line MCF-7 by means of lentivirus to explore the effects of iASPPsv on biological functions of MCF-7. Thymocytes from iASPP/iASPPsv transgenic mice were also used to explore the effects of iASPP/iASPPsv on cell biological function. The results demonstrated that iASPPsv antagonized the growth inhibition induced by etoposide (VP-16) in MCF-7 cells. iASPPsv also down-regulated proapoptotic genes (Bax, Puma and Noxa) expression to inhibit apoptosis caused by VP-16. Moreover, iASPP and iASPPsv could both help the thymocytes of transgenic mice to resist the growth inhibition and apoptosis caused by dexamethasone (Dex) or VP-16. At the same time, DNA double strand break damage accumulated in either iASPPsv MCF-7 cells or iASPP/iASPPsv thymocytes. These findings showed that iAPSS/iASPPsv reduced the growth inhibition and apoptosis induced by Dex or VP-16, with DNA damage accumulating which might promote the pathogenesis and/or progression of cancer.
No preview · Article · Jul 2012 · Biochemical and Biophysical Research Communications
[Show abstract][Hide abstract] ABSTRACT: Wt1 is a dual-function gene involved in hematopoiesis, leukemogenesis and prognosis for leukemia. This gene is highly expressed in acute myeloid leukemia (AML) and the progression of chronic myelogenous leukemia (CML). It was reported elsewhere that high level of wt1 expression indicated worse prognosis for leukemia. Wt1 gene functions are different due to its subcellular localization. This study was aimed to investigate the expression and localization of wt1 mRNA and WT1 protein, and explore the effects of wt1 inhibitor, curcumin, on K562 cell proliferation, cell cycle and its possible mechanisms. MTT method was used to detect cell proliferation; flow cytometry was used to analyze the alteration of cell cycle, and the immunofluorescence and Western blot technology were performed to observe the subcellular localization of WT1 protein. The transcripts of wt1 and bcr/abl p210 was analyzed by real-time PCR. The results showed that wt1 mRNA and its protein were both highly expressed in K562 cells. The curcumin and imatinib (Glevec) both inhibit the cell proliferation resulting in the G(2)/M and G(0)/G(1) phase arrest respectively. Meanwhile, the transcripts of wt1 and bcr/ablp210 genes decreased greatly after being treated with the two inhibitors above. It is concluded that the alteration of wt1 gene affects the biological characteristics of Ph(+) K562 cells, such as cell proliferation, cell cycle and so on. Gene wt1 is expected to be further studied as a new therapy target in Ph(+) leukemias.
No preview · Article · Jun 2010 · Zhongguo shi yan xue ye xue za zhi / Zhongguo bing li sheng li xue hui = Journal of experimental hematology / Chinese Association of Pathophysiology
[Show abstract][Hide abstract] ABSTRACT: Self-renewal and drug resistance are key features of leukemic stem cells (LSC). To clarify the mechanism of maintaining LSC properties, the CD34(+) leukemic cell line KGla was used as study model to elucidate the role of N-cadherin in self-renewal and drug resistance. N-cadherin positive and N-cadherin negative KG1a cell groups were sorted by flow cytometry. Self-renewal and the half maximal inhibitory concentration (IC(50)) of VP16 in two groups of KG1a cells were determined by colony formation assay and MTT assay. The results showed that cell colony formation ability of N-cadherin positive KG1a cells was significantly higher than that of N-cadherin negative KG1a cells. After treated with VP16, N-cadherin positive KG1a cells showed higher chemoresistance than N-cadherin negative KG1a cells with IC(50) of 220 micro mol/L for N-cadherin positive cells and 151 micro mol/L for N-cadherin negative cells (p = 0.04). The results also showed that N-cadherin mediated adhesion participated in the chemoresistance of N-cadherin positive cells. It is concluded that N-cadherin plays an important role in maintaining the self-renewal and drug resistance properties of LSC.
No preview · Article · Jan 2010 · Zhongguo shi yan xue ye xue za zhi / Zhongguo bing li sheng li xue hui = Journal of experimental hematology / Chinese Association of Pathophysiology
[Show abstract][Hide abstract] ABSTRACT: To investigate the effects of AML1B and AML1/ETO fusion gene on the transcription activity of TSC1 and TSC2 promotor and to explore its role in leukemogenesis.
The luciferase reporter plasmids of TSCs gene promoter containing a AML1 binding site were constructed, and cotransfected into CV-1 cells with AML1B or AML1/ETO expression plasmids separately. The transactivity of TSCs gene promoter was assayed by luminometer.
AML1B exhibited a transactivity to TSC2 gene promoter in a dosage-dependant manner, but showed no significant transactivity to TSC1's. The transactivity to TSC2 gene promoter showed 8.55 fold increase as companed with control group at 75 ng of pCMV5-AML/B. AML1/ETO showed a significant transactivity to TSC1, but no transactivity to TSC2's. However, AML1/ETO antagonized the effect of AMLlB to TSC2 gene promoter.
AML1B and AML1/ETO can regulate the transcription of TSC genes.
No preview · Article · Dec 2009 · Zhonghua xue ye xue za zhi = Zhonghua xueyexue zazhi
[Show abstract][Hide abstract] ABSTRACT: A single nucleotide polymorphism (SNP) in the promoter of MDM2 gene, SNP309 T>G (a T-G exchange at nucleotide 309 in the first intron), can increase the expression level of MDM2, thereby causing an impairment of p53 tumor suppressor activity. A G-C exchange at p53 codon 72 polymorphism results in a substitution of proline (Pro) for arginine (Arg) in the transactivation domain, which was shown to alter the primary structure of the p53 protein. Both polymorphisms have been implicated in cancer. To investigate whether that MDM2 SNP309 and p53 codon 72 polymorphism should be at least partially responsible for genetic susceptibility to acute myeloid leukemia (AML), both polymorphisms were determined in a case-control study consisting of 231 AML patients and 128 normal individuals. The MDM2 SNP309G allele was associated with increased risk of AML. Furthermore, the p53 codon 72 and MDM2 SNP309 polymorphisms did not associate with age of onset and any other clinical parameters studied. When the p53 and MDM2 polymorphisms were combined, no multiplicative joint effect between the MDM2 GG and p53 Pro/Pro genotypes exists in the risk of developing AML. These results suggest that the MDM2 SNP309 homozygous GG genotype may be a genetic susceptibility factor in the pathogenesis of AML.
No preview · Article · May 2009 · Leukemia research
[Show abstract][Hide abstract] ABSTRACT: The tuberous sclerosis (TSC) genes, TSC1 and TSC2, encode hamartin and tuberin, respectively, and are putative tumor suppressor genes that were originally identified due to their involvement in the inherited autosomal dominant disorder tuberous sclerosis. It has been elucidated that the two proteins form an intracellular heterodimer participating in signaling pathway of the mammalian Target of Rapamycin (mTOR). Recent studies showed that mTOR pathway was frequently activated in blasts from acute myeloid leukemia (AML) patient and associated with proliferation, survival, and drug-resistance of these cells. These phenomena led us to hypothesize that TSC gene might be involved in acute leukemia (AL). In this study, we investigated the TSC1 and TSC2 mRNA expression in 104 newly diagnosed AL patients and 29 healthy controls using real-time quantitative PCR (RQ-PCR) and explored the potential mechanisms of the aberrant expression through methylation-specific PCR (MSP). The results showed that the expression of TSC2 was downregulated in AL patients and the TSC2 promoter was hypermethylated which might be an important mechanism for the downregulation of TSC2 expression.
No preview · Article · Mar 2009 · Leukemia research