ANALYSIS OF Lyl1 EXPRESSION AS A FREQUENT PARTNER OF LMO2 IN T-CELL LEUKEMOGENESIS IN HUMAN

Objective： To identify aberrant gene expression in primary human T-cell acute lymphoblastic leukemia （T-ALL） and to evaluate the differently expressed level of Lyll and LMO2 genes in human LMO2 positive/TALl negative T-ALL tumors. Methods： Three methods, representational difference analysis （RDA） of cDNA, cDNA microarrays and RT-PCR were used to detect if Lyll and LMO2 genes were differently expressed in human LMO2 positive/tall negative T-ALL tumors. Results： The results of cDNA RDA and cDNA array shown that Lyll and LMO2 genes are differently expressed in human T-cell tumors. The result of RT-PCR also shown Lyll and LMO2 are high expressed in human T-cell tumors and very low level or no expressed in normal group. Conclusion： We have found that cDNA RDA and cDNA microarray can be successfully used to identify aberrant gene expression in T-ALL cells. In the study described in this manuscript we found that Lyll and LMO2 are aberrantly expressed in human T-ALL LMO2 positive/TALl negative T-ALL tumors.

Overexpression or knock-down of runt-related transcription factor 1 affects BCR-ABL-induced proliferation and migration in vitro and leukemogenesis in vivo in mice

Background Runt-related transcription factor 1 （Runxl） plays a crucial role in hematogenesis and its dysfunction may contribute to leukemogenesis. However, it is not clear whether or not abnormal expression of Runxl will induce leukemia and how the change of Runxl expression level could affect BCR-ABL-induced leukemogenesis. In the present study, we aimed to analyze if abnormal expression of Runxl in BaF3 cells alone would induce teukemogenesis. And we also wanted to know if abnormal expression of Runxl in leukemic cells would affect leukemogenesis. Furthermore, we investigated whether overexpression or knock-down of Runxl in BaF3 cells would induce leukemogenesis. Methods Plasmids containing full-length Runxl cDNA were transduced into BaF3 cells and BaF3-P185wt cells （BCR-ABL transformed BaF3 cells） by electroporation. Plasmids containing a short hairpin RNA of Runxl were transduced into BaF3 cells and BaF3-P185wt cells by electroporation. Runxl expression level was quantified by Western blotting and quantitative real-time PCR. The effects of overexpression or knock-down of Runxl on proliferation, apoptosis and migration of cells were detected in vitro. Then, using MSCV-P185wt-EGFP as a control, we transplanted MSCV-P185wt-Runx1 cells or MSCV-P185wt-shRNA cells into Balb/c mice through tail vein and observed tumorgenesis of the different phenotypes. Results In vitro analysis revealed that overexpression of Runxl in P185wt cells could inhibit cell proliferation and slow down cell migration; while knock-down of Runxl could promote cell proliferation and speed up cell migration. In vivo analysis indicated that mice transplanted with MSCV-P185wt-Runx1 survived longer than controls. In contrast, mice transplanted with MSCV-P185wt-shRNA survived shorter than the control group. Gross pathological analysis revealed that the MSCV-P185wt-Runx1 group had less severe splenomegaly and hepatomegaly compared to the control group, and the MSCV-P185wt-shRNA group had more severe splenomegaly and hepatomegaly. No splenomegaly or hepatomegaly was detected in mice transplanted with MSCV-BaF3-Runxl cells or MSCV-BaF3-shRNA cells. Both the mice of MSCV-BaF3-Runxl group and MSCV-BaF3-shRNA group were healthy with no sign of leukemia for up to three months. Conclusions Overexpression or knock-down of Runxl gene in BaF3 cells alone could not induce leukemogenesis. However, in BaF3-P185wt cells, alteration of Runxl expression could affect BCR-ABL-induced proliferation and migration in vitro and leukemoaenesis in vivo.

PML nuclear body biogenesis and oligomerization-driven leukemogenesis

PML nuclear bodies(NBs),which are increasingly recognized as the central hub of many cellular signaling events,are superassembled spherical complexes with diameters of 0.1–2mm.Recent studies reveal that RING tetramerization and B1-box polymerization are key factors to the overall PML NBs assembly.The productive RBCC oligomerization allows subsequent PML biogenesis steps,including the PML auto-sumoylation and partners recruitment via SUMO–SIM interactions.In promyelocytic leukemia,the oncoprotein PML/RARa(P/R)inhibits PML NBs assembly and leads to a full-fledged leukemogenesis.In this review,we review the recent progress in PML and acute promyelocytic leukemia fields,highlighting the protein oligomerization as an important direction of future targeted therapy.

Super enhancers:Pathogenic roles and potential therapeutic targets for acute myeloid leukemia(AML)

Acute myeloid leukemia(AML)is a malignant hematological tumor with disordered oncogenes/tumor suppressor genes and limited treatments.The potent anti-cancer effects of bromodomain and extra-terminal domain(BET)inhibitors,targeting the key component of super enhancers,in early clinical trials on AML patients,implies the critical role of super enhancers in AML.Here,we review the concept and characteristic of super enhancer,and then summarize the current researches about super enhancers in AML pathogenesis,diagnosis and classification,followed by illustrate the potential super enhancer-related targets and drugs,and propose the future directions of super enhancers in AML.This information provides integrated insight into the roles of super enhancers in this disease.

Transcriptional addiction in mixed lineage leukemia: new avenues for target therapies

Mixed lineage leukemia(MLL)is an aggressive and refractory blood cancer that predominantly occurs in pediatric patients and is often associated with poor prognosis and dismal outcomes.Thus far,no effective target therapy for the treatment of MLL leukemia is available.MLL leukemia is caused by the rearrangement of MLL genes at 11q23,which generates various MLL chimeric proteins that promote leukemogenesis through transcriptional misregulation of MLL target genes.Biochemical studies on MLL chimeras have identified that the most common partners exist in the superelongation complex(SEC)and DOT1L complex,which activate or sustain MLL target gene expression through processive transcription elongation.The results of these studies indicate a transcription-related mechanism for MLL leukemogenesis and maintenance.In this study,we first review the history of MLL leukemia and its related clinical features.Then,we discuss the biological functions of MLL and MLL chimeras,significant cooperating events,and transcriptional addiction mechanisms in MLL leukemia with an emphasis on potential and rational therapy development.Collectively,we believe that targeting the transcriptional addiction mediated by SEC and the DOT1L complex will provide new avenues for target therapies in MLL leukemia and serve as a novel paradigm for targeting transcriptional addiction in other cancers.