Calothrixin B derivatives induce apoptosis and cell cycle arrest on HEL cells through the ERK/Ras/Raf/MEK pathway

BACKGROUND

Acute erythroleukemia (AEL) is acute myeloid leukemia characterized by malignant erythroid proliferation. AEL has a low survival rate, which has seriously threatened the health of older adults. Calothrixin B is a carbazole alkaloid isolated from the cyanobacteria Calothrix and exhibits anti-cancer activity. To discover more potential anti-erythroleukemia compounds, we used calothrixin B as the structural skeleton to synthesize a series of new compounds.

METHODS

In the cell culture model, we evaluated apoptosis and cell cycle arrest using MTT assay, flow cytometry analysis, JC-1 staining, Hoechst 33258 staining, and Western blot. Additionally, assessing the curative effect in the animal model included observation of the spleen, HE staining, flow cytometry analysis, and detection of serum biochemical indexes.

RESULTS

Among the Calothrixin B derivatives, H-107 had the best activity against leukemic cell lines. H-107 significantly inhibited the proliferation of HEL cells with an IC50 value of 3.63 ± 0.33 μM. H-107 induced apoptosis of HEL cells by damaging mitochondria and activating the caspase cascade and arrested HEL cells in the G0/G1 phase. Furthermore, H-107 downregulated the protein levels Ras, p-Raf, p-MEK, p-ERK and c-Myc. Pretreatment with ERK inhibitor (U0126) increased H-107-induced apoptosis. Thus, H-107 inhibited the proliferation of HEL cells by the ERK /Ras/Raf/MEK signal pathways. Interestingly, H-107 promoted erythroid differentiation into the maturation of erythrocytes and effectively activated the immune cells in erythroleukemia mice.

CONCLUSION

Overall, our findings suggest that H-107 can potentially be a novel chemotherapy for erythroleukemia.

A detailed analysis of F-MuLV- and SFFV-infected cells in Friend virus-infected mice reveals the contribution of both F-MuLV- and SFFV-infected cells to the interleukin-10 host response

BACKGROUND

Friend virus (FV) is a complex of the Friend murine leukemia virus (F-MuLV) and the replication-defective, pathogenic spleen focus forming virus (SFFV). In the past, we used a fluorescently labeled F-MuLV to analyze FV target cells. To build on these findings, we have now created a double-labeled FV that contains a Katushka-labeled F-MuLV and an mTagBFP-labeled SFFV, which we have used to study the infection by the two individual viruses in the FV infection of highly susceptible BALB/c mice.

RESULTS

Our data show that the target cells of SFFV largely mirror those of F-MuLV, with the highest virus loads in erythroblasts, B cells and myeloid cells. The early phase of infection was dominated by cells infected by either SFFV or F-MuLV, whereas double-infected cells became dominant later in the course of infection with increasing viral loads. In the late phase of infection, the frequency of double-infected cells was similarly high as the frequencies of SFFV or F-MuLV single-infected cells, and single- and double-infected cells outnumbered the uninfected cells in the most highly infected cell populations such as erythroblasts. FV and retroviruses in general have been shown to induce interleukin 10 (IL-10) as a means of suppressing immune responses. Interestingly, we found in infected IL-10-eGFP reporter mice that SFFV-infected cells contributed to the IL-10-producing cell pool much more significantly than F-MuLV-infected cells, suggesting that the truncated SFFV envelope protein gp55 might play a role in IL-10 induction. Even though BALB/c mice mount notoriously weak immune responses against FV, infection of mice with an ablation of IL-10 expression in T cells showed transiently lower viral loads and stronger T cell activation, suggesting that IL-10 induction by FV and by SFFV in particular may contribute to a suppressed immune response in BALB/c mice.

CONCLUSION

Our data provide detailed information about both F-MuLV- and SFFV-infected cells during the course of FV infection in highly susceptible mice and imply that the pathogenic SFFV contributes to immune suppression.

Erythroleukemia treated effects of rat plasma profile and erythrocyte membranes

Erythroleukemia disease is caused by over production of malignant blood and immature large number of blood cells enters into peripheral compartment. Biophysical and biochemical changes in plasma and erythrocyte membrane in erythroleukemia treated rats were identified. Our study, leukemia is experimentally exposed in rats were injecting erythroleukemia cells (FLC) (H-2d) intravenously in adult rats and normal control rats were maintained. Significant increase in the activity of blood glucose, proteins levels, aspartate transaminase (AST) and alanine transaminase (ALT) values and significant decrease in haemoglobin (Hb), albumin levels in erythroleukemia treated rats were observed when compared with control rats. Cholesterol and low density liproprotein (LDL) levels increased significantly in erythroleukemia treated rats but triglycerides, high density lipoprotein (HDL) and very low density lipoprotein (VLDL) levels decreased significantly. Levels of red cell membrane cholesterol decreased in erythroleukemia treated rats in comparison with control while levels of phospholipids and proteins increased in erythrocytes of erythroleukemia treated rats. Red blood cell (RBC) and white blood cell (WBC) counts increased significantly and platelet count decreased. C/P (cholesterol/phospholipid) ratio decreased significantly in erythroleukemia treated rats. This study has been undertaken for the first time to investigate the effect of (FLC) (H-2d) erythroleukemia cells (treated) in intravenously in adult rats and normal control rats. Results indicate biophysical and biochemical alterations at molecular level in plasma and erythrocyte membrane.

Antiproliferative effect of upregulation of hsa-let-7c-5p in human acute erythroleukemia cells

New achievements in the field of cancer treatment are results of recent advances in molecular medicine and gene therapy. Usage of microRNAs (miRNAs) which are small noncoding RNAs is one of the molecular research lines for the diagnosis and treatment of cancers. miRNAs have an important role in post-transcriptional regulation of the gene expression and are involved in cellular activities such as growth, differentiation, cell death and cancer development. One of the miRNAs that showed downregulation in human acute erythroleukemia is hsa-let-7c-5p. Down-regulation of hsa-let-7c-5p has been reported in in vitro studies of different cancers. In the present study, upregulation of hsa-let-7c-5p is performed in human acute erythroleukemia cell line (KG-1) using miRNA mimic. qRT-PCR, MTT assay, Annexin-V, and propidium iodide staining at different time points after miRNA mimic transfection were accomplished to assess the expression level of hsa-let-7c-5p, cell viability, apoptosis and late apoptosis. In addition, the expression level of PBX2 oncogene, a validated target gene of hsa-let-7c-5p, is evaluated by RT-qPCR to show the effectivity of this approach on erythroleukemia cancer cells. Our results can be used in translational medicine for future investigation in acute erythroleukemia and to approach treatment based on miRNA mimic therapy.

Genetically Engineered In Vitro Erythropoiesis

Background

Engineered blood has the greatest potential to combat a predicted future shortfall in the US blood supply for transfusion treatments. Engineered blood produced from hematopoietic stem cell (HSC) derived red blood cells in a laboratory is possible, but critical barriers exist to the production of clinically relevant quantities of red blood cells required to create a unit of blood. Erythroblasts have a finite expansion capacity and there are many negative regulatory mechanisms that inhibit in vitro erythropoiesis. In order to overcome these barriers and enable mass production, the expansion capacity of erythroblasts in culture will need to be exponentially improved over the current state of art. This work focused on the hypothesis that genetic engineering of HSC derived erythroblasts can overcome these obstacles.

Objectives

The objective of this research effort was to improve in vitro erythropoiesis efficiency from human adult stem cell derived erythroblasts utilizing genetic engineering. The ultimate goal is to enable the mass production of engineered blood.

Methods

HSCs were isolated from blood samples and cultured in a liquid media containing growth factors. Cells were transfected using a Piggybac plasmid transposon.

Results

Cells transfected with SPI-1 continued to proliferate in a liquid culture media. Fluorescence-activated cell sorting (FACS) analysis on culture day 45 revealed a single population of CD71⁺CD117⁺ proerythroblast cells. The results of this study suggest that genetically modified erythroblasts could be immortalized in vitro by way of a system modeling murine erythroleukemia.

Conclusion

Genetic modification can increase erythroblast expansion capacity and potentially enable mass production of red blood cells.

E-cadherin is a specific marker for erythroid differentiation and has utility, in combination with CD117 and CD34, for enumerating myeloblasts in hematopoietic neoplasms

OBJECTIVES

E-cadherin, epithelial calcium-dependent cell adhesion protein, has been identified as a marker of immature erythroid precursors in recent years. However, the specificity of E-cadherin in bone marrow specimens for erythroblasts vs myeloblasts or other early hematopoietic precursors in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) has not been fully elucidated.

METHODS

We analyzed 105 cases of AML and MDS to evaluate the specificity of E-cadherin.

RESULTS

Of 84 cases of AML, including cases with megakaryocytic, erythroid, monocytic, and granulocytic differentiation, all five acute erythroleukemia cases were positive, as well as one case of megakaryoblastic leukemia that showed coexpression of glycophorin A. In addition, we demonstrate that a panel of three markers, E-cadherin, CD117, and CD34, is effective in identifying lineage-specific myeloblasts in cases of MDS where left-shifted erythroid hyperplasia may complicate morphologic assessment of myeloblasts.

CONCLUSIONS

In marrow specimens, E-cadherin is a useful marker for erythroid differentation.

Erythroleukemia and Its Differential Diagnosis

Acute erythroid leukemias encompass 2 main subtypes: acute erythroleukemia (erythroid/myeloid subtype) and pure erythroid leukemia. This article reviews the main clinicopathologic features of the acute erythroid leukemias and the criteria used to diagnose them. In this article, the differential diagnosis between acute erythroid leukemias and their mimics is discussed and helpful morphologic clues and diagnostic tests that help arrive at the correct diagnosis are provided. The appropriate application of diagnostic criteria, including ancillary testing, such as immunophenotyping, cytogenetics, and molecular genetic testing, is essential to categorize bone marrow erythroid proliferations.

Combined inhibition of PI3K and activation of MAPK p38 signaling pathways trigger erythroid alternative splicing switch of 4.1R pre-mRNA in DMSO-induced erythroleukemia cells

There is increasing evidence showing that many extracellular cues modulate pre-mRNA alternative splicing, through different signaling pathways. We here show that 4.1R exon 16 splicing is altered in response to specific signals. The switch from erythroblastic isoform lacking exon 16 to mature erythrocytic isoform containing this exon is tightly regulated during late erythroid differentiation, and blocage of this splicing switch in erythroleukemia cells is seen as a consequence of the deregulation of important regulatory pathways. We support that combined inhibition of PI3K and activation of p38 signaling pathways impinge on erythroid 4.1R pre-mRNA alternative splicing switch, and on cell differentiation as witnessed by hemoglobin production. By contrast, MEK/ERK signaling appeared not to affect neither cell hemoglobin production nor erythroid 4.1R pre-mRNA splicing. We also found that the signal-induced alternative splicing is not typically distinctive of EPO-non-responsive cells, but operates in EPO-responsive cells as well. Pre-mRNA splicing is a major regulatory mechanism at the crossroad between transcription and translation. We here provide evidence that inhibition of PI3K activates the splicing switch in a promoter-dependent manner, whereas p38 activation induces this event in a promoter-independent fashion. Our data further support that constitutive activation of EPO-R by the viral protein gp55 and the short form of the tyrosine kinase receptor Stk, transduces PI3K proliferation signal, but not MAPK p38 differentiation signal. Concurrently, this work lend credence to the concept that DMSO triggers transient activation of p38 signaling and irreversible inhibition of PI3K/AKT signaling pathway, hence uncovering an old conundrum regarding the mechanism by which DMSO induces erythroleukemia cell differentiation.

Treatment of acute erythroleukemia with Azacitidine: A case series

Acute erythroleukemia (AEL) is a rare form of acute myeloid leukemia (AML) often associated with a poor prognosis. It is more frequent in elderly patients, limiting the use aggressive therapies. Azacitidine is a hypomethylating agent with recognized efficacy in high risk myelodysplasia and AML in the elderly. Here we report 5 cases of AEL treated with Azacitidine. The cohort included 4 men and 1 woman, median age 70. One patient had been refractory to intensive chemotherapy, the others received Azacitidine as first line. Treatment was well tolerated. Four patients achieved transfusion independence. Two patients achieved complete remission and 1 achieved partial remission. After a median follow up time of 20 months, the median survival of the cohort was 20 months. Three patients died of disease progression. These results confirm the therapeutic value of Azacitidine in AEL.