Yeonsook Moon

Modeling de novo leukemogenesis from human cord blood with MN1 and NUP98HOXD13

Leukemic transformation of human cells is a complex process. Here we show that forced expression of MN1 in primitive human cord blood cells maintained on stromal cells in vitro induces a transient, but not serially transplantable, myeloproliferation in engrafted mice. However, cotransduction of an activated HOX gene (NUP98HOXD13) with MN1 induces a serially transplantable acute myeloid leukemia (AML). Further characterization of the leukemic cells generated from the dually transduced cells showed the activation of stem cell gene expression signatures also found in primary human AML. These findings show a new forward genetic model of human leukemogenesis and further highlight the relevance of homeobox transcription factors in the transformation process.

A Case of Blastic Plasmacytoid Dendritic Cell Neoplasm Initially Mimicking Cutaneous Lupus Erythematosus

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare disease. The prognosis is poor in most cases with rapid progression despite administering chemotherapy. A 67-year-old man complained of skin rashes on his back and this spread to the trunk, face, arms and thighs, and he was initially diagnosed with cutaneous lupus erythematosus according to the skin biopsy. The skin rashes then became aggravated on a trial of low dose methylprednisolone for 3 months. Repeated skin biopsy revealed a diffuse infiltration of lymphoid cells with medium sized nuclei, positive for CD4 and CD56, negative for Epstein-Barr virus (EBV), indicating a diagnosis of BPDCN. Further workups confirmed stage IVA BPDCN involving the skin, multiple lymph nodes, the peripheral blood and the bone marrow. He was treated with six cycles of combination chemotherapy consisting of ifosphamide, methotrexate, etoposide, prednisolone and L-asparaginase, and he achieved a partial response. Herein we report on a rare case of BPDCN that was initially misinterpreted as cutaneous lupus erythematosus.

Cell Fate Decisions in Malignant Hematopoiesis: Leukemia Phenotype Is Determined by Distinct Functional Domains of the MN1 Oncogene

Extensive molecular profiling of leukemias and preleukemic diseases has revealed that distinct clinical entities, like acute myeloid (AML) and T-lymphoblastic leukemia (T-ALL), share similar pathogenetic mutations. It is not well understood how the cell of origin, accompanying mutations, extracellular signals or structural differences in a mutated gene determine the phenotypic identity of leukemias. We dissected the functional aspects of different protein regions of the MN1 oncogene and their effect on the leukemic phenotype, building on the ability of MN1 to induce leukemia without accompanying mutations. We found that the most C-terminal region of MN1 was required to block myeloid differentiation at an early stage, and deletion of an extended C-terminal region resulted in loss of myeloid identity and cell differentiation along the T-cell lineage in vivo. Megakaryocytic/erythroid lineage differentiation was blocked by the N-terminal region. In addition, the N-terminus was required for proliferation and leukemogenesis in vitro and in vivo through upregulation of HoxA9, HoxA10 and Meis2. Our results provide evidence that a single oncogene can modulate cellular identity of leukemic cells based on its active gene regions. It is therefore likely that different mutations in the same oncogene may impact cell fate decisions and phenotypic appearance of malignant diseases.

Extrinsic signals determine myeloid-erythroid lineage switch in MN1 leukemia

OBJECTIVE Transcriptional control of hematopoietic lineage fate relies on the integration of many intra- and extracellular signals. To test whether the microenvironment impacts on leukemic phenotype, we exploited the MN1 model of acute myeloid leukemia under defined genetically modified microenvironmental conditions. MATERIALS AND METHODS The requirement of both FLT3 and c-Kit signaling for MN1 leukemias was investigated using retroviral infection of bone marrow cells from wild-type, c-Kit-mutated (W41), and Flt3-ligand knockout cells, and bone marrow transplantation into wild-type, c-Kit-mutated, or Flt3-ligand knockout mice. RESULTS Genetic disruption of both FLT3 and c-Kit signaling in the MN1-leukemia model was dispensable for MN1-induced leukemogenesis. However, it induced a switch from myeloid to erythroid phenotype that was preserved, when FLT3 signaling was restored by secondary transplantation of leukemic cells into wild-type recipients. CONCLUSIONS Our findings underscore the importance of microenvironmental signals for lineage choice in leukemia and identify signals that are important in myeloid-erythroid lineage decisions.

Aberrant cystatin‑C expression in blood from patients with breast cancer is a suitable marker for monitoring tumor burden

The present study was performed to evaluate the efficacy of circulating cystatin-C as a tumor monitoring biomarker at different clinical time points in patients with breast cancer over a long-term follow-up period. In addition, the secretory rate of circulating cystatin-C from cancer tissue was investigated by comparing the blood and tissue expression levels of cystatin-C. Blood samples from healthy volunteers (40 males and 40 females) were obtained at yearly health examinations if laboratory and imaging abnormalities were not detected. Blood samples from 34 patients with breast cancer were obtained at 205 different time points of clinical progression. Blood levels of cystatin-C were measured using ELISA and the tissue levels were measured using immunohistochemistry. No age-associated effect was observed in male and female blood cystatin-C levels. The positivity rate was 46% in patients (38/83) and 40% in samples collected at different time points (82/205). Blood cystatin-C levels were lowest following surgery compared with patients with systemic metastasis (P<0.001). The sensitivity, specificity and accuracy rates of ELISA were 53.6, 63.6 and 53.9%, respectively. The concordance rate between blood and tissue expression was 38%. The main reason for discordance between tissue and serum expression of cytostatin-C came from low serum positivity in samples showing tissue cytostatin-C (3/11, 27%). The specificity between cytostatin-C and CA-125 was highest in tumor absence state. In conclusion, elevated blood levels of cystatin-C were observed in 40% of breast cancer cases and were tumor-volume dependent. However, the concordance rate between tissue and blood was quite low, suggesting tumor heterogeneity of cystatin-C expression or co-acting pathway activation, such as cathepsin D. As one-third of breast cancer tissues express cystatin-C without cancer antigen 15-3 elevation, cystatin-C may represent a good tumor-monitoring marker in breast cancer.

The 2016 WHO versus 2008 WHO Criteria for the Diagnosis of Chronic Myelomonocytic Leukemia

The 2016 WHO diagnostic criteria for chronic myelomonocytic leukemia (CMML) require both absolute and relative monocytosis (≥1×109/L and ≥10% of white blood cell counts) in peripheral blood. Moreover, myeloproliferative neoplasm (MPN) features in bone marrow and/or MPN-associated mutations tend to support MPN with monocytosis rather than CMML. We assessed the impact of the 2016 WHO criteria on CMML diagnosis, compared with the 2008 WHO criteria, through a retrospective review of the medical records of 38 CMML patients diagnosed according to the 2008 WHO classification. Application of the 2016 WHO criteria resulted in the exclusion of three (8%) patients who did not fulfill the relative monocytosis criterion and eight (21%) patients with an MPN-associated mutation. These 11 patients formed the 2016 WHO others group; the remaining 27 formed the 2016 WHO CMML group. The significant difference in the platelet count and monocyte percentage between the two groups indicated that the 2016 WHO criteria lead to a more homogenous and improved definition of CMML compared with the 2008 WHO criteria, which may have led to over-diagnosis of CMML. More widespread use of molecular tests and more sophisticated clinical and morphological evaluations are necessary to diagnose CMML accurately.

An Automated Draft Report Generator for Peripheral Blood Smear Examinations Based on Complete Blood Count Parameters

Background Complete blood count (CBC) results play an important role in peripheral blood smear (PBS) examinations. Many descriptions in PBS reports may simply be translated from CBC parameters. We developed a computer program that automatically generates a PBS draft report based on CBC parameters and age- and sex-matched reference ranges. Methods The Java programming language was used to develop a computer program that supports a graphical user interface. Four hematology analyzers from three different laboratories were tested: Sysmex XE-5000 (Sysmex, Kobe, Japan), Sysmex XN-9000 (Sysmex), DxH800 (Beckman Coulter, Brea, CA, USA), and ADVIA 2120i (Siemens Healthcare Diagnostics, Eschborn, Germany). Input data files containing 862 CBC results were generated from hematology analyzers, middlewares, or laboratory information systems. The draft reports were compared with the content of input data files. Results We developed a computer program that reads CBC results from a data file and automatically writes a draft PBS report. Age- and sex-matched reference ranges can be automatically applied. After examining PBS, users can modify the draft report based on microscopic findings. Recommendations such as suggestions for further evaluations are also provided based on morphological findings, and they can be modified by users. The program was compatible with all four hematology analyzers tested. Conclusions Our program is expected to reduce the time required to manually incorporate CBC results into PBS reports. Systematic inclusion of CBC results could help improve the reliability and sensitivity of PBS examinations.

A Novel Translocation Involving RUNX1 and HOXA Gene Clusters in a Case of Acute Myeloid Leukemia with t(7;21)(p15;q22)

Translocations involving chromosome 21q22 are frequently observed in hematologic malignancies including acute myeloid leukemia (AML), most of which have been known to be involved in malignant transformation through transcriptional dysregulation of Runt-related transcription factor 1 (RUNX1) target genes. Nineteen RUNX1 translocational partner genes, at least, have been identified, but not Homeobox A (HOXA) genes so far. We report a novel translocation of RUNX1 into the HOXA gene cluster in a 57-year-old female AML patient who had been diagnosed with myelofibrosis 39 months ahead. G-banding showed 46,XX,t(7;21)(p15;q22). The involvement of RUNX1 and HOXA genes was confirmed by fluorescence in situ hybridization.