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.
Inter-observer and intra-observer variation in histologic tumor grading are well documented. To determine whether histologic disorderliness in the arrangement of tumor cells may serve as an objective criterion for grading, we tested the hypothesis the degree of disorderliness is related to the degree of tumor differentiation on which tumor grading is primarily based.
Borrowing from the statistical thermodynamic definition of entropy, we defined a novel mathematical formula to compute the relative degree of histologic disorderliness of tumor cells. We then analyzed a total of 51 photomicrographs of normal colorectal mucosa and colorectal adenocarcinoma with varying degrees of differentiation using our formula.
A one-way analysis of variance followed by post hoc pairwise comparisons using Bonferroni correction indicated that the mean disorderliness score was the lowest for the normal colorectal mucosa and increased with decreasing tumor differentiation.
Disorderliness, a pathologic feature of malignant tumors that originate from highly organized structures is useful as an objective tumor grading proxy in the field of digital pathology.
Neoplasm grading; Colonic neoplasms; Entropy
Extensive evidence has accumulated regarding the role of mesenchymal stromal cells (MSCs) in tumor progression, but the exact effects and mechanisms underlying this role remain unclear. We investigated the effects of MSC-associated tumor progression in MSC-sarcoma models and a gastric cancer metastatic model.
We conducted an in vitro growth kinetics assay and an in vivo tumor progression assay for sarcoma cells and gastric cancer cells in the presence or absence of MSCs.
MSC-cocultured human fibrosarcoma cells (HT1080) showed accelerated growth compared with HT1080 alone (79- vs 37-fold change, p<.050). For HT1080, human MSC-coinjected tumors showed significantly greater and highly infiltrative growth compared to those of HT1080 alone (p=.035). For mouse fibrosarcoma cells (WEHI164), mouse MSC-coinjected tumors had greater volume than those of WEHI164 alone (p=.141). For rat sarcoma cells (RR1022), rat MSC-coinjected tumors exhibited greater volume and infiltrative growth than those of RR1022 alone (p=.050). For human gastric cancer cells (5FU), tumors of 5FU alone were compact, nodular in shape, and expansile with good demarcation and no definite lung metastatic nodules, whereas tumors grown in the presence of human MSCs showed highly desmoplastic and infiltrative growth and multiple lung metastasis.
We observed morphological evidence for MSC-associated tumor progression of fibrosarcomas and gastric cancer cells.
Mesenchymal stromal cells; Tumor progression; Fibrosarcoma; Gastric cancer cells
Regulation of tumor microenvironment is closely involved in the prognosis of Hodgkin lymphoma (HL). Indoleamine 2,3-dioxygenase (IDO) is an enzyme acting as immune modulator through suppression of T-cell immunity. This study aims to investigate role of IDO in the microenvironment of HL.
A total of 121 cases of HL were enrolled to do immunohistochemistry for IDO, CD163, CD68, CD4, CD8, and FoxP3. Positivity was evaluated from area fractions or numbers of positive cells using automated image analyzer. Correlations between IDO expression and various cellular infiltrates and clinicopathologic parameters were examined and survival analyses were performed.
IDO was expressed in histiocytes, dendritic cells and some endothelial cells with variable degrees, but not in tumor cells. IDO positive cells were more frequently found in mixed cellularity type than other histologic types, and in cases with EBV+, high Ann Arbor stages, B symptoms, and high IPS (all p < 0.05). High IDO expression was associated with inferior survival (p < 0.001) and reflects an independent prognostic factor in nodular sclerosis HL.
This is the first study suggesting that IDO is the principle immunomodulator and is involved to adverse clinical outcomes of HL.
Hodgkin disease; Indoleamine-pyrrole 2,3-dioxygenase; Macrophages; Stromal cells; Tumor microenvironment; Epstein-barr virus infections; Pathology
Pathways defining susceptibility of normal cells to oncogenic transformation may be valuable therapeutic targets. We characterized the cell of origin and its critical pathways in MN1-induced leukemias. Common myeloid (CMP), but not granulocyte-macrophage progenitors (GMP) could be transformed by MN1. Complementation studies of CMP-signature genes in GMPs demonstrated that MN1-leukemogenicity required the MEIS1/AbdB-like HOX-protein complex. ChIP-sequencing identified common target genes of MN1 and MEIS1, and demonstrated identical binding sites for a large proportion of their chromatin targets. Transcriptional repression of MEIS1 targets in established MN1 leukemias demonstrated antileukemic activity. As MN1 relies on but cannot activate expression of MEIS1/AbdB-like HOX proteins, transcriptional activity of these genes determines cellular susceptibility to MN1-induced transformation, and may represent a promising therapeutic target.
PMID: 21741595 CAMSID: cams3759
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.
AML; Translocation; t(7;21); RUNX1; HOXA
Graft-versus-host disease (GVHD) is a common complication of allogeneic stem cell transplantation (allo-SCT). However, a similar syndrome has been reported in autologous stem cell transplantation (ASCT) as well. The target organs of GVHD in ASCT are the skin, liver and gastrointestinal (GI) tract, which are consistent with those in allo-SCT. Histologic findings from the skin and the mucosa of the GI tract also show similar features. Here we describe a case of autologous GVHD involving the skin of a patient who underwent ASCT for multiple myeloma. In this patient, the response to a total prednisone dose of 0.5 mg/kg/day was unsatisfactory, and the patient required more intensive and prolonged immunosuppressive therapy with slow tapering.
Multiple myeloma; Autologous stem cell transplantation; Autologous graft-versus-host disease
Gastric Hodgkin's lymphoma is extremely rare. We present a case of primary Hodgkin's lymphoma arising in the stomach of a 65-year-old woman. The patient complained of epigastric discomfort and reflux for one month. Endoscopic examination revealed a protruding lesion characterized by a smooth surface at the antrum. An abdominal computed tomography uncovered a 2.5 × 2.0 cm, exophytic submucosal mass. After the tentative preoperative diagnosis of a gastrointestinal stromal tumor, a gastric wedge resection was performed. Microscopic examination of the mass demonstrated a diffuse proliferation of large atypical lymphoid cells with mono- and binucleated pleomorphic nuclei and prominent nucleoli. Immunohistochemically, the tumor cells were positive for CD30, CD20, and CD79a, whereas they were negative for cytokeratin, carcinoembryonic antigen, CD3, CD15, epithelial membrane antigen, and anaplastic lymphoma kinase-1. Based on the morphological features and immunohistochemical results, in addition to the clinical findings, a diagnosis of primary gastric Hodgkin's lymphoma was established.
Stomach; Hodgkin's lymphoma; CD30 antigens
We report on a case of severe hepatotoxicity in a 52-year-old male with multiple myeloma (MM) who had received bortezomib therapy. At patient presentation, liver enzymes were normal, but started to markedly increase 3 days after the patient's second dose of bortezomib was administered, when free kappa light chains were noticeably reduced in the serum. After discontinuation of bortezomib, liver enzymes recovered gradually to baseline. Then, the patient was started on a thalidomide-containing regimen, which he was able to tolerate well. The patient achieved complete remission prior to autologous stem cell transplantation (ASCT). The patient underwent ASCT without occurrence of further liver toxicity.
Bortezomib; Hepatotoxicity; Multiple myeloma
Recent clinical observation reported that there was a significant correlation between change in circulating vascular endothelial growth factor (VEGF) levels and the occurrence of severe acute graft-versus-host disease (GVHD) following allogeneic hematopoietic stem cell transplantation (allo-HSCT), but the action mechanisms of VEGF in GVHD have not been demonstrated.
This study investigated whether or not blockade of VEGF has an effect on acute GVHD in a lethally irradiated murine allo-HSCT model of B6 (H-2b)→B6D2F1 (H-2b/d). Syngeneic or allogeneic recipient mice were injected subcutaneously with anti-VEGF peptides, dRK6 (50 µg/dose) or control diluent every other day for 2 weeks (total 7 doses).
Administration of the dRK6 peptide after allo-HSCT significantly reduced survival with greaterclinical GVHD scores and body weight loss. Allogeneic recipients injected with the dRK6 peptide exhibited significantly increased circulating levels of VEGF and expansion of donor CD3+ T cells on day +7 compared to control treated animals. The donor CD4+ and CD8+ T-cell subsets have differential expansion caused by the dRK6 injection. The circulating VEGF levels were reduced on day +14 regardless of blockade of VEGF.
Together these findings demonstrate that the allo-reactive responses after allo-HSCT are exaggerated by the blockade of VEGF. VEGF seems to be consumed during the progression of acute GVHD in this murine allo-HSCT model.
Vascular endothelial growth factors (VEGF); Allogeneic hematopoietic stem cell transplantation; Acute graft-versus-host disease; VEGF blockade; dRK6
Bone marrow mesenchymal stromal cells (MSCs) have been implicated in the microenvironmental support of hematopoietic stem cells (HSCs) and often co-transplanted with HSCs to facilitate recovery of ablated bone marrows. However, the precise effect of transplanted MSCs on HSC regeneration remains unclear because the kinetics of HSC self-renewal in vivo after co-transplantation has not been monitored. In this study, we examined the effects of intrafemoral injection of MSCs on HSC self-renewal in rigorous competitive repopulating unit (CRU) assays using congenic transplantation models in which stromal progenitors (CFU-F) were ablated by irradiation. Interestingly, naïve MSCs injected into femur contributed to the reconstitution of a stromal niche in the ablated bone marrows, but did not exert a stimulatory effect on the in-vivo self-renewal of co-transplanted HSCs regardless of the transplantation methods. In contrast, HSC self-renewal was four-fold higher in bone marrows intrafemorally injected with β-catenin-activated MSCs. These results reveal that naïve MSCs lack a stimulatory effect on HSC self-renewal in-vivo and that stroma must be activated during recoveries of bone marrows. Stromal targeting of wnt/β-catenin signals may be a strategy to activate such a stem cell niche for efficient regeneration of bone marrow HSCs.
bone marrow; bone marrow transplantation; hematopoietic stem cells; stem cell niche; stromal cells
Aquaporins (AQPs) have previously been associated with increased expression in solid tumors. However, its expression in hematologic malignancies including CML has not been described yet. Here, we report the expression of AQP5 in CML cells by RT-PCR and immunohistochemistry. While normal bone marrow biopsy samples (n = 5) showed no expression of AQP5, 32% of CML patient samples (n = 41) demonstrated AQP5 expression. In addition, AQP5 expression level increased with the emergence of imatinib mesylate resistance in paired samples (p = 0.047). We have found that the overexpression of AQP5 in K562 cells resulted in increased cell proliferation. In addition, small interfering RNA (siRNA) targeting AQP5 reduced the cell proliferation rate in both K562 and LAMA84 CML cells. Moreover, by immunoblotting and flow cytometry, we show that phosphorylation of BCR-ABL1 is increased in AQP5-overexpressing CML cells and decreased in AQP5 siRNA-treated CML cells. Interestingly, caspase9 activity increased in AQP5 siRNA-treated cells. Finally, FISH showed no evidence of AQP5 gene amplification in CML from bone marrow. In summary, we report for the first time that AQP5 is overexpressed in CML cells and plays a role in promoting cell proliferation and inhibiting apoptosis. Furthermore, our findings may provide the basis for a novel CML therapy targeting AQP5.