Despite the constant development of innovative therapeutic options for hematological malignancies, the gold-standard therapy regimen for curative treatment often includes allogeneic hematopoietic ...stem cell transplantation (HSCT). The graft-vs.-leukemia effect (GVL) is one of the main therapeutic goals that arises from HSCT. On the other hand, graft-vs.-host disease (GVHD) is still one of the main and most serious complications following allogeneic HSCT. In acute myeloid leukemia (AML), HSCT together with high-dose chemotherapy is used as a treatment option. An aggressive progression of the disease, a decreased response to treatment, and a poor prognosis are connected to internal tandem duplication (ITD) mutations in the Fms like tyrosine kinase 3 (FLT3) gene, which affects around 30% of AML patients. In this study, C3H/HeN mice received an allogeneic graft together with 32D-FLT3
AML cells to induce acute GVHD and GVL. It was examined if pre-incubation of the graft with the anti-human cluster of differentiation (CD) 4 antibody MAX.16H5 IgG
prevented the development of GVHD and whether the graft function was impaired. Animals receiving grafts pre-incubated with the antibody together with FLT3
AML cells survived significantly longer than mice receiving untreated grafts. The observed prolonged survival due to MAX.16H5 incubation of immune cell grafts prior to transplantation may allow an extended application of additional targeted strategies in the treatment of AML.
The process through which multipotential hematopoietic cells commit to distinct lineages involves the induction of specific transcription factors. PU.1 (also known as Spi-1) and GATA-1 are ...transcription factors essential for the development of myeloid and erythroid lineages, respectively. Overexpression of PU.1 and GATA-1 can block differentiation in lineages in which they normally are down-regulated, indicating that not only positive but negative regulation of these factors plays a role in normal hematopoietic lineage development. Here we demonstrate that a region of the PU.1 Ets domain (the winged helix-turn-helix wing) interacts with the conserved carboxyl-terminal zinc finger of GATA-1 and GATA-2 and that GATA proteins inhibit PU.1 transactivation of critical myeloid target genes. We demonstrate further that GATA inhibits binding of PU.1 to c-Jun, a critical coactivator of PU.1 transactivation of myeloid promoters. Finally, PU.1 protein can inhibit both GATA-1 and GATA-2 transactivation function. Our results suggest that interactions between PU.1 and GATA proteins play a critical role in the decision of stem cells to commit to erythroid vs. myeloid lineages.
The G protein-coupled oestrogen receptor 1 (GPER-1) is a potential prognostic marker in breast cancer. However, its role in male breast cancer (MBC) is still unknown. This study evaluates the ...expression of GPER-1 in MBC samples and correlates these data with clinical and pathological parameters including patients' survival.
For this retrospective analysis of a prospectively maintained cohort of patients with MBC, we examined 161 specimens for GPER-1 expression using immunohistochemistry. An immunoreactive score (IRS) was calculated based on staining intensity and the percentage of positive tumour cells. Then, we correlated GPER-1 IRS with clinical and pathological parameters, and overall and relapse-free survival.
About 40% of MBC samples were positive for GPER-1 expression (IRS ≥ 4). There was no significant correlation with clinicopathological parameters, such as hormone receptor status or grading. However, a statistical trend was observed for tumour size (≥ 2 cm,
= 0.093). Kaplan-Meier survival analysis revealed no significant correlation with relapse-free survival. However, there was a significant correlation with overall survival, but when we adjusted the log-rank
-value to compensate for the cut-off point optimization method, it rose above 0.1. Additionally, GPER-1-positive patients were older at diagnosis. When adjusted for age by multivariable Cox regression analysis, the significance of GPER-1 status for survival was further reduced.
We found no significant prognostic value of GPER-1 in this MBC cohort as anticipated from studies on female BC. Future studies with higher sample size are needed to further verify a potential sex-specific role of GPER-1.
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High expression of the leukemia‐associated gene meningioma‐1 (MN1) is frequently found at diagnosis of acute myeloid leukemia (AML) and ...associates with adverse outcomes. The presence of measurable residual disease (MRD) in complete remission (CR) indicates high risk of relapse and worse outcome in AML patients. However, the prognostic impact of MN1 expression levels as MRD marker has not been evaluated. Digital droplet polymerase chain reaction (ddPCR) is a novel technique allowing sensitive and specific absolute gene expression quantification. We retrospectively analyzed 124 AML patients who received allogeneic hematopoietic stem cell transplantation (HSCT) in CR or CR with incomplete peripheral recovery. Absolute MN1 copy numbers in peripheral blood were assessed prior to HSCT (median 7; range 0–29 days) using ddPCR. High pre‐HSCT MN1/Abelson murine leukemia viral oncogene homolog 1 gene (ABL1) copy numbers associated with a higher cumulative incidence of relapse after HSCT and—in relapsing patients—shorter time to relapse. In multivariable analysis, high pre‐HSCT MN1/ABL1 copy numbers remained an independent prognosticator for relapse after HSCT. Patients with the highest pre‐HSCT MN1/ABL1 copy numbers also had the highest risk of relapse. MN1 copy number assessment also added prognostic information to nucleophosmin 1 gene (NPM1) mutation‐ and brain and acute leukemia, cytoplasmic (BAALC) and Wilm's tumor gene 1 (WT1) expression‐based MRD evaluation. Our study demonstrates the feasibility of the novel ddPCR technique for MN1/ABL1 copy number assessment as a marker for MRD. Evaluation of MN1/ABL1 copy numbers allows the identification of patients at high risk of relapse, independently of other diagnostic risk factors and MRD markers.
Nuclear receptor coregulators play an important role in the transcriptional regulation of nuclear receptors. In the present study, we aimed to identify estrogen receptor α (ERα) interacting proteins ...in Tamoxifen treated MCF7 cells. Using in vitro GST‐pull down assay with ERα ligand‐binding domain (ERα‐LBD) and MS‐based proteomics approach we identified Profilin1 as a novel ERα interacting protein. Profilin1 contains I/LXX/L/H/I amino acid signature motif required for corepressor interaction with ERα. We show that these two proteins physically interact with each other both in vitro as well as in vivo by GST‐pull down and coimmunoprecipitation, respectively. We further show that these two proteins also colocalize together in the nucleus. Previous studies have reported reduced expression of Profilin1 in breast cancer; and here we found that Tamoxifen increases Profilin1 expression in MCF7 cells. Our data demonstrate that over expression of Profilin1 inhibits ERα‐mediated transcriptional activation as well as its downstream target genes in ERα positive breast cancer cells MCF7. In addition, Profilin1 overexpression in MCF7 cells leads to inhibition of cell proliferation that apparently is due to enhanced apoptosis. In nutshell, these data indicate that MS‐based proteomics approach identifies a novel ERα interacting protein Profilin1 that serves as a putative corepressor of ERα functions.
Transcriptional mechanisms responsible for low DAPK2 levels in particular AML subtypes.
DAPK2 is a proapoptotic protein that is mostly expressed in the hematopoietic tissue. A detailed DAPK2 ...expression analysis in two large AML patient cohorts revealed particularly low DAPK2 mRNA levels in APL. DAPK2 levels were restored in APL patients undergoing ATRA therapy. PML‐RARA is the predominant lesion in APL causing transcriptional repression of genes important for neutrophil differentiation. We found binding of PML‐RARA and PU.1, a myeloid master regulator, to RARA and PU.1 binding sites in the DAPK2 promoter. Ectopic expression of PML‐RARA in non‐APL, as well as knocking down PU.1 in APL cells, resulted in a significant reduction of DAPK2 expression. Restoring DAPK2 expression in PU.1 knockdown APL cells partially rescued neutrophil differentiation, thereby identifying DAPK2 as a relevant PU.1 downstream effector. Moreover, low DAPK2 expression is also associated with C/EBPα‐mutated AML patients, and we found C/EBPα‐dependent regulation of DAPK2 during APL differentiation. In conclusion, we identified first inhibitory mechanisms responsible for the low DAPK2 expression in particular AML subtypes, and the regulation of DAPK2 by two myeloid transcription factors underlines its importance in neutrophil development.
Infections and adverse drug reactions both contribute substantially to mortality after allogeneic stem cell transplantation. It is therefore crucial to the transplant physician to develop an optimal ...anti-infective strategy, i.e. one which is highly effective and shows few side effects. Caspofungin acetate, the founding member of the echinocandins, is widely used against invasive fungal infections. We retrospectively assessed the hepatotoxicity of caspofungin acetate when administered with cyclosporine A. We reviewed the medical charts of 20 recipients of an allogeneic transplant. In detail, the median value of alanine amino transferase before, during and after administration of caspofungin acetate was 0.39 standard error of the mean (SEM) 0.65, 0.77 (17) and 0.56 (0.77) μmol l⁻¹. The maximal value was 4-, 104- and 3.3-fold the upper normal level. The median value of aspartate amino transferase was 0.28 (SEM 0.45), 0.71 (26.26) and 0.60 (0.84) μmol l⁻¹. The maximal value before, during and after the administration of caspofungin acetate was 3.6-, 203- and 5.3-fold the upper normal level. The median value of gamma glutamyl transferase before, during and after administration of caspofungin acetate was 1.27 (SEM 1.78), 2.33 (3.41) and 1.77 (4.32) μmol l⁻¹. The maximal value was 1.38-, 2.53- and 1.93-fold the upper normal level. The median value of alkaline phosphatase before, during and after administration of caspofungin acetate was 1.11 (SEM 0.4), 1.97 (2.30) and 1.66 (5.48) μmol l⁻¹. The maximal value was 0.88-, 4.2- and 8.42-fold the upper normal level, respectively. The median value of total bilirubin before, during and after administration of caspofungin acetate was 23 (SEM 19.69), 38 (55.41) and 20 (67.23) μmol l⁻¹. The maximal value was 4.18-, 14.18- and 17.88-fold the upper normal level. Taken together, the elevations observed fell after the discontinuation of caspofungin acetate. This report is in accordance with published data. As expected, we did not find any evidence pointing to an increase in nephrotoxicity by caspofungin acetate.
The ETS domain transcription factor PU.1 is necessary for the development of monocytes and regulates, in particular, the expression
of the monocyte-specific macrophage colony-stimulating factor ...(M-CSF) receptor, which is critical for monocytic cell survival,
proliferation, and differentiation. The bZIP transcription factor c-Jun, which is part of the AP-1 transcription factor complex,
is also important for monocytic differentiation, but the monocyte-specific M-CSF receptor promoter has no AP-1 consensus binding
sites. We asked the question of whether c-Jun could promote the induction of the M-CSF receptor by collaborating with PU.1.
We demonstrate that c-Jun enhances the ability of PU.1 to transactivate the M-CSF receptor promoter as well as a minimal thymidine
kinase promoter containing only PU.1 DNA binding sites. c-Jun does not directly bind to the M-CSF receptor promoter but associates
via its basic domain with the ETS domain of PU.1. Consistent with our observation that AP-1 binding does not contribute to
c-Jun coactivation is the observation that the activation of PU.1 by c-Jun is blocked by overexpression of c-Fos. Phosphorylation
of c-Jun by c-Jun NH 2 -terminal kinase on Ser-63 and -73 does not alter the ability of c-Jun to enhance PU.1 transactivation. Activated Ras enhances
the transcriptional activity of PU.1 by up-regulating c-Jun expression without changing the phosphorylation pattern of PU.1.
The activation of PU.1 by Ras is blocked by a mutant c-Jun protein lacking the basic domain. The expression of this mutant
form of c-Jun also completely blocks 12- O -tetradecanoylphorbol-13-acetate-induced M-CSF receptor promoter activity during monocytic differentiation. We propose therefore
that c-Jun acts as a c-Jun NH 2 -terminal kinase-independent coactivator of PU.1, resulting in M-CSF receptor expression and development of the monocytic
lineage.
In the present study, we investigated the mechanism of CD44 ligation with the anti-CD44 monoclonal antibody A3D8 to inhibit the proliferation of human acute myeloid leukemia (AML) cells. The effects ...of A3D8 on myeloid cells were associated with specific disruption of cell cycle events and induction of G0/G1 arrest. Induction of G0/G1 arrest was accompanied by an increase in the expression of p21, attenuation of pRb phosphorylation and associated with decreased Cdk2 and Cdk4 kinase activities. Since c-Jun is an important regulator of proliferation and cell cycle progression, we analysed its role in A3D8-mediated growth arrest. We observed that A3D8 treatment of AML patient blasts and HL60/U937 cells led to the downregulation of c-Jun expression at mRNA and protein level. Transient transfection studies showed the inhibition of c-jun promoter activity by A3D8, involving both AP-1 sites. Furthermore, A3D8 treatment caused a decrease in JNK protein expression and a decrease in the level of phosphorylated c-Jun. Ectopic overexpression of c-Jun in HL60 cells was able to induce proliferation and prevent the antiproliferative effects of A3D8. In summary, these data identify an important functional role of c-Jun in the induction of cell cycle arrest and proliferation arrest of myeloid leukemia cells because of the ligation of the cell surface adhesion receptor CD44 by anti-CD44 antibody. Moreover, targeting of G1 regulatory proteins and the resulting induction of G1 arrest by A3D8 may provide new insights into antiproliferative and differentiation therapy of AML.
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