Search

Abstract: The frequency of extramedullary infiltration (EMI) in acute myeloblastic leukemia (AML) is reported up to 40% and most prevalent in myelo-monoblastic and monoblastic subtypes of AML (M4 and M5 according to FAB classification). The majority of patients with EMI suffered poor prognosis. To explore mechanism underlying EMI, we analyzed SHI-1 cells, a highly invasive human acute monocytic leukemia cell line, and found their strong expression of matrix metalloproteinase 2 (MMP-2), membrane type 1 MMP (MT1-MMP) and tissue inhibitor of metalloproteinase 2 (TIMP-2). SHI-1 cells showed higher invasive ability to traverse reconstituted basement membranes (Matrigel) and stronger activation of proMMP-2 than other leukemia cell line such as NB4, K562, U937 and THP-1 cells. When co-cultured with bone marrow stromal cells (BMSCs), the invasive capacity and proMMP-2 activation of SHI-1 cells enhanced remarkably. Furthermore, the inhibition of MMP-2, MT1-MMP, or TIMP-2 by small interfering RNA (siRNA) substantially impaired SHI-1 cells invasion and decreased proMMP-2 activation. In the contrast, up-regulated expression of TIMP-2 for 2–3 folds level increased cell invasion and proMMP-2 activation. These results demonstrated that constitutively high expression of MMP-2, MT1-MMP and TIMP-2 in SHI-1 cells facilitated cell invasion by promoting proMMP-2 activation. Moreover, up-regulation of TIMP-2 exhibited not a repressive but an activating effect on SHI-1 cells invasion. Our study indicated that increasing TIMP-2 in AML patients with EMI may potentially cause adverse effects, particularly in patients containing high levels of MMP-2 and MT1-MMP. [Copyright &y& Elsevier]

Abstract: CCAAT/enhancer binding proteins (C/EBPs) are a family of transcription factors that have been implicated in diverse cellular functions such as cellular differentiation and proliferation, and inflammatory processes. C/EBPζ, also known as GADD153, CHOP10, and DDIT3 has been found associated with the development of myxoid liposarcoma and the progression of melanoma. To investigate the correlation of C/EBPζ transcript levels with the development of leukemia, samples from 187 patients with myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and chronic myeloid leukemia (CML) were examined for C/EBPζ mRNA using real-time quantitative PCR (RQ-PCR). RQ-PCR analysis demonstrated the median levels of C/EBPζ were significantly decreased in MDS, AML, and CML patients compared with normal controls (1.40, 0.96, 2.60 versus 14.69, P <0.0001). Significant differences were also observed between patients with CML and with AML or MDS. These results suggest that the insufficient dosage of C/EBPζ might be involved in the development of leukemia. [Copyright &y& Elsevier]

Background BCL11A encodes a C2H2 type zinc-finger protein. During normal haematopoietic cell differentiation BCL11A expression is down-regulated. Data in mice suggest up-regulation of BCL11A is involved in the pathogenesis of myeloid leukaemias. BCL11A expression in persons with acute myeloid leukaemia (AML) is not systematically studied. Objective Interrogate associations between BCL11A expression at diagnosis and clinical and laboratory valuables and outcomes in newly-diagnosed persons with AML. Methods We determined BCL11A mRNA levels in bone marrow and blood mononuclear cells in 292 consecutive newly-diagnosed subjects with AML by reverse transcript and real-time polymerase chain reaction. Data were compared to mRNA levels in bone marrow cells of normals. Results Subjects with BCL11A transcript levels at diagnosis exceeding the median value of 2.434 (±3.423 SD; 25th–75th inter-quartile range, 1.33–4.29) had higher WBC levels, a greater proportion of bone marrow myeloblasts, were more likely to be FAB M 0 subtype, less likely to be FAB M 3 subtype, more likely to be in the intermediate cytogenetic risk cohort, less likely to have a complex karyotype and more likely to have DNMT3A R882 and FLT3 -ITD mutations than subjects with transcript levels below the median value. In 89 subjects receiving conventional induction chemotherapy the complete remission rate was 54% (95% confidence interval [CI]; 33, 75%) in the lower BCL11A cohort and 65% (45, 85%; P = 0.26) in the higher BCL11A cohort. 3 year survival was 33% (2, 65%) in the lower BCL11A cohort and 15% (0, 39%; P = 0.35) in the high BCL11A cohort. Conclusion BCL11A transcript levels at diagnosis was significantly associated with several clinical and laboratory variables. There were also non-significant associations with complete remission rate and survival. These data suggest a possible role for BCL11A expression in AML biology. [ABSTRACT FROM AUTHOR]