VEGF targeted therapy in acute myeloid leukemia

A pyridinesulfonamide derivative FD268 suppresses cell proliferation and induces apoptosis via inhibiting PI3K pathway in acute myeloid leukemia

Aberration of PI3K signaling pathway has been confirmed to be associated with several hematological malignancies including acute myeloid leukemia (AML). FD268, a pyridinesulfonamide derivative characterized by the conjugation of 7-azaindole group, is a newly identified PI3K inhibitor showing high potent enzyme activity at nanomole concentration. In this study, we demonstrated that FD268 dose-dependently inhibits survival of AML cells with the efficacy superior to that of PI-103 (pan-PI3K inhibitor) and CAL-101 (selective PI3Kδ inhibitor) in the tested HL-60, MOLM-16, Mv-4-11, EOL-1 and KG-1 cell lines. Further mechanistic studies focused on HL-60 revealed that FD268 significantly inhibits the PI3K/Akt/mTOR signaling pathway, promotes the activation of pro-apoptotic protein Bad and downregulates the expression of anti-apoptotic protein Mcl-1, thus suppressing the cell proliferation and inducing caspase-3-dependent apoptosis. The bioinformatics analysis of the transcriptome sequencing data also indicated a potential involvement of the PI3K/Akt/mTOR pathway. These studies indicated that FD268 possesses high potent activity toward AML cells via inhibition of PI3K/Akt/mTOR signaling pathway, which sheds some light on the pyridinesulfonamide scaffold for further optimization and investigation.

Histone Deacetylase Inhibitor I3 Induces the Differentiation of Acute Myeloid Leukemia Cells with t (8; 21) or MLL Gene Translocation and Leukemic Stem-Like Cells

Acute myeloid leukemia (AML) is a heterogeneous disorder characterized by the clonal expansion and differentiation arrest of leukemic cells in peripheral blood and bone marrow. Though the treatment using cytarabine-based protocol for AML patients with t (8; 21) translocation has improved the 5-year overall survival rate, drug resistance continues to be the principal limiting factor for the cure of the disease. In addition, very few AML patients with mixed lineage leukemia gene rearrangements (MLLr) have a desirable outcome. This study evaluated the cell differentiation effect of a potent HDAC (histone deacetylase) inhibitor, I3, and its possible mechanism on the AML cells with t (8; 21) translocation or MLLr and leukemic stem-like cells (Kasumi-1, KG-1, MOLM-13, and THP-1). I3 exhibited efficient anti-proliferative activity on these cells via promoting cell differentiation, accompanied by the cell cycle exit at G0/G1. Importantly, I3 showed the properties of HDAC inhibition, as assessed by the acetylation of histones H3 and H4, which resulted in blocking the activation of the VEGF (vascular endothelial growth factor)-MAPK (mitogen-activated protein kinase) signaling pathway in the Kasumi-1 cell line. These data demonstrate that I3 could be a potent chromatin-remodeling agent to surmount the differentiation block in AML patients, including those with t (8; 21) translocation or MLLr, and could be a potent and selective agent for AML treatment.

Identify Multiple Gene-Drug Common Modules Via Constrained Graph Matching

Identifying gene-drug interactions is vital to understanding biological mechanisms and achieving precise drug repurposing. High-throughput technologies produce a large amount of pharmacological and genomic data, providing an opportunity to explore the associations between oncogenic genes and therapeutic drugs. However, most studies only focus on "one-to-one" or "one-to-many" interactions, ignoring the multivariate patterns between genes and drugs. In this article, a high-order graph matching model with hypergraph constraints is proposed to discover the gene-drug common regulatory modules. Moreover, the prior knowledge is formulated into hypergraph constraints to reveal their multiple correspondences, penalizing the tensor matching process. The experimental results on the synthetic data demonstrate the proposed model is robust to noise contamination and outlier corruption, achieving a better performance than four state-of-the-art methods. We then evaluate the statistical power of our proposed method on the pharmacogenomics data. Our identified gene-drug common modules not only show significantly enriched pathways associated with cancer but also manifest the highly close gene-drug interactions.

Long non-coding RNA LOC644135 is a potential prognostic indicator in cytogenetically normal acute myeloid leukemia

OBJECTIVES

Acute myeloid leukemia (AML) is a hematological malignancy with highly clinical heterogeneity resulting in poor outcomes. We aim to identify novel prognostic lncRNA in AML expecting to provide new clues for therapy in AML.

METHODS

Three cohorts were enrolled in this study. Differentially expressed lncRNAs between TCGA-AML cohort and GTEx cohort was identified by DESeq2. The relationship between expression level of LOC644135 and prognosis in AML was analyzed by multiple methods.

RESULTS

Pan-cancer analysis indicated that LOC644135 was most highly expressed in AML across 33 types of cancer. Patients with high expression of LOC644135 had poor overall prognosis in both TCGA-AML cohort and the TARGET-AML cohort. Especially, high expression of LOC644135 indicated inferior overall survival and event-free survival in CN-AML patients in the TCGA-AML cohort. Besides, CN-AML patients had higher expression of LOC644135 than normal samples. Multivariable analysis suggested that LOC644135 was an independent prognostic factor in AML. GSEA analysis showed that LOC644135 was associated with some immune-related pathways. Besides, high expression of LOC644135 was associated with less infiltration of CD8⁺ T cell.

CONCLUSION

Our findings indicated that LOC644135 was an independent prognostic factor in AML and provided a new idea in the development of therapy in AML.

The effect of novel synthetic semicarbazone- and thiosemicarbazone-linked 1,2,3-triazoles on the apoptotic markers, VEGFR-2, and cell cycle of myeloid leukemia

Vascular Endothelial Growth Factor II (VEGFR-2) has been proved as a rational target in cancer therapy. Although currently prescribed VEGFR-2 inhibitors are showing potent antitumor activity, they are often causing serious unwanted effects, restricting their extensive use as chemotherapeutics. Herein, after analyzing the structures of the effective VEGFR-2 inhibitor molecules, we report the synthesis of a new set of semicarbazone- and thiosemicarbazone-linked 1,2,3-triazoles with expected potency of inhibiting the VEGFR-2 signaling. The design of new compounds considered maintaining the essential pharmacophoric features of sorafenib for effective binding with the receptor target. All compounds have been evaluated for their growth inhibition effect against a panel of sixty cancer cells at the National Cancer Institute. Leukemia cancer cells, especially HL-60 and SR, were shown to be the most sensitive to the cytotoxic effect of new compounds. Thiosemicarbazones 21, 26, and 30 exhibited the best activity against almost all tested cancer cells. Therefore, a set of subsequent in vitro biological evaluations has been performed to understand the mechanistic effect of these compounds further. They inhibited the VEGFR-2 with IC₅₀ values of 0.128, 0.413, and 0.067 µM respectively compared with 0.048 µM of Sorafenib. The probable mechanistic effect of 30 has been further evaluated on a number of apoptotic and antiapoptotic markers including BAX, BCL2, caspase-3, and caspase-9. Results revealed the potential of the thiosemicarbazone-linked triazole 30 to induce both the early and the late apoptosis, elevate BAX/BCL2 ratio, induce caspase-3 & caspase-9, and arrest the HL-60 cell cycle at the G2/M and G0-G1 phases. Molecular docking of new semicarbazones and thiosemicarbazones into the proposed biological target receptor has also been performed. Results of docking studies proved the potential of new semicarbazone- and thiosemicarbazone-linked 1,2,3-triazoles to effectively bind with crucial residues of the VEGFR-2 binding pocket.

Anti-angiogenic activity of ShengMaBieJia decoction in vitro and in acute myeloid leukaemia tumour-bearing mouse models

Context: ShengMaBieJia decoction (SMBJD) is used to treat solid and hematological tumours; however, its anti-angiogenesis activity remains unclear.Objective: This study verified the anti-angiogenic effects of SMBJD in vitro and in tumour-bearing acute myeloid leukaemia (AML) mouse models.Materials and methods: In vivo, the chicken chorioallantoic membrane (CAM) and BALB/c null mouse xenograft models were treated with SMBJD (0, 2, 4, and 8 mg/mL) for 48 h and for 2 weeks, respectively. Anti-angiogenic activity was assessed according to microvessel density (MVD) and immunohistochemistry (IHC) targeting CD31 and VEGFR2. In vitro, proliferation viability, migratory activity and tube formation were measured. Western blots and polymerase chain reaction (PCR) assays were used to examine the levels of PI3K, Akt, and VEGF.Results: HPLC analyses revealed the active constituents of SMBJD such as liquiritin, cimifugin, ferulic, isoferulic, and glycyrrhizic acids. In vitro, SMBJD treatment decreased cellular migration, chemotaxis, and tube formation at non-cytotoxic concentrations (2, 4, and 8 mg/mL) in a time- and dose-dependent manner. The dosage of less than IC₂₀ is considered safe. In vivo, CAM models exhibited a decrease in MVD, and the tissues of xenografted mice possessed reduced CD31 and VEGFR2 expression. Conditioned media (CM) from AML cells (HL60 and NB4 cells) treated with non-cytotoxic doses of SMBJD inhibited chemotactic migration and tube formation in vitro. Both CM (HL60) and CM (NB4) exhibited downregulated expression of PI3K, Akt, and VEGF.Discussion and conclusions: SMBJD inhibited angiogenesis in AML through the PI3K/AKT pathway, which might be combined with targeted therapy to provide more effective treatment.

LINC00649 underexpression is an adverse prognostic marker in acute myeloid leukemia

BACKGROUND

Long noncoding RNAs (lncRNA) play a role in leukemogenesis, maintenance, development, and therapeutic resistance of AML. While few studies have focused on the prognostic significance of LINC00649 in AML, which we aim to investigate in this present study.

METHODS

We compared the expression level of LINC00649 between AML patients and healthy controls. The Kaplan-Meier curves of AML patients expressing high versus low level of LINC00649 was performed. The LINC00649 correlated genes/miRNAs/lncRNAs and methylation CpG sites were screened by Pearson correlation analysis with R (version 3.6.0), using TCGA-LAML database. The LINC00649 associated ceRNA network was established using lncBase 2.0 and miRWalk 2.0 online tools, combining results from correlation analysis. Finally, a prediction model was constructed using LASSO-Cox regression.

RESULTS

LINC00649 was underexpressed in bone marrow of AML group than that in healthy control group. The patients of LINC00649-low group have significantly inferior PFS and OS. A total of 154 mRNAs, 31 miRNAs, 28 lncRNAs and 1590 methylated CpG sites were identified to be significantly correlated with LINC00649. Furthermore, the network of ceRNA was established with 6 miRNAs and 122 mRNAs. The Lasso-Cox model fitted OS/PFS to novel prediction models, which integrated clinical factors, ELN risk stratification, mRNA/miRNA expression and methylation profiles. The analysis of time-dependent ROC for our model showed a superior AUC (AUC = 0.916 at 1 year, AUC = 0.916 at 3 years, and AUC = 0.891 at 5 years).

CONCLUSIONS

Low expression of LINC00649 is a potential unfavorable prognostic marker for AML patients, which requires the further validation. The analysis by LASSO-COX regression identified a novel comprehensive model with a superior diagnostic utility, which integrated clinical and genetic variables.

Theoretical Investigations on Interactions of Arylsulphonyl Indazole Derivatives as Potential Ligands of VEGFR2 Kinase

Vascular endothelial growth factor receptor 2 (VEGFR2) is a key receptor in the angiogenesis process. The VEGFR2 expression is upregulated in many cancers so this receptor is an important target for anticancer agents. In the present paper, we analyse interactions of several dimeric indazoles, previously investigated for anticancer activity, with the amino acids present in the VEGFR2 binding pocket. Using the docking method and MD simulations as well as theoretical computations (SAPT0, PIEDA, semi-empirical PM7), we confirmed that these azoles can efficiently bind into the kinase pocket and their poses can be stabilised by the formation of hydrogen bonds, π–π stacking, π–cation, and hybrid interactions with some amino acids of the kinase cavity like Ala866, Lys868, Glu885, Thr916, Glu917, and Phe918.

7‑Difluoromethyl‑5,4'‑dimethoxygenistein exerts anti‑angiogenic effects on acute promyelocytic leukemia HL‑60 cells by inhibiting the TLR4/NF‑κB signaling pathway

Angiogenesis plays an important role in the development and metastasis of tumors, and anti-angiogenesis agents are used to treat tumors. For example, the acute promyelocytic leukemia (APL) may be treated with arsenic trioxide. Angiogenesis in APL is a multi-step dynamic equilibrium process coordinated by various angiogenic stimulators and inhibitors, which play key roles in the occurrence, progression and chemosensitivity of this disease. Our research group previously synthesized 7-difluoromethyl-5,4′-dimethoxygenistein (DFMG), and found that it inhibits angiogenesis during atherosclerotic plaque formation. In the present study, the effect and mechanism of DFMG in angiogenesis induced by APL HL-60 cells was investigated using a chick embryo chorioallantoic membrane model and Matrigel tubule formation assays. The results obtained revealed an anti-angiogenesis effect of DFMG towards HL-60 cells. When the Toll-like receptor 4/nuclear factor-κB (TLR4/NF-κB) signaling pathway was inhibited, the anti-angiogenic effect of DFMG was further enhanced. However, when the TLR4/NF-κB signaling pathway was activated, the anti-angiogenic effect of DFMG was attenuated. These results demonstrated that DFMG inhibits angiogenesis induced by APL HL-60 cells, and provides insights into the mechanism by which DFMG inhibits the TLR4/NF-κB signaling pathway. In conclusion, in the present study, the anti-angiogenesis effect of DFMG on APL has been reported, and the mechanism by which DFMG induced the anti-angiogenesis effect was explored. These findings have provided a potential new drug candidate for the treatment of patients with APL.

Apatinib exhibits cytotoxicity toward leukemia cells by targeting VEGFR2-mediated prosurvival signaling and angiogenesis

OBJECTIVE

Vascular permeability contributes to disease progression and drug resistance in hematological malignancies, including AML. Thus, targeting angiogenic signaling is a promising treatment strategy, especially for relapsed and resistant AML. The aim of this study was to evaluate the efficacy of apatinib, a novel receptor tyrosine kinase inhibitor that selectively targets VEGFR2.

METHODS

Several AML cell lines were exposed to various concentrations of apatinib, and then CCK8 and Annexin V/PI assays were performed to determine IC50 values and apoptosis, respectively. The effect of apatinib against primary AML cells from 57 adult patients and 11 normal controls was also analyzed utilizing an apoptosis assay. Next, we tested the underlying mechanism of apatinib in AML using western blotting and mass cytometry (CyTOF). Finally, the activity of apatinib against tumor growth and angiogenesis was further evaluated in vivo in xenograft models.

RESULTS

We found apatinib significantly inhibited growth and promoted apoptosis in AML cell lines in vitro. Similarly, apatinib showed cytotoxicity against primary AML cells but didn't affect normal BMMCs. Its effect was highly correlated with several clinical features, such as NPM1 mutation, extramedullary infiltration, relapsed/refractory disease, and M2 and M5 FAB subtypes. In addition, apatinib suppressed AML growth and attenuated angiogenesis in xenograft models. Mechanistically, apatinib-induced cytotoxicity was closely associated with inhibition of the VEGFR2-mediated Src/STAT3 and AKT/mTOR pathways and induction of mitochondria-mediated apoptosis.

CONCLUSION

Apatinib exerts antileukemia effects by targeting VEGFR2-induced prosurvival signaling and angiogenesis, thus providing a rationale for the application of apatinib in AML.

Arsenic Trioxide and Thalidomide Combination Induces Autophagy Along with Apoptosis in Acute Myeloid Cell Lines

Objective

Autophagy and apoptosis play key roles in cancer survival and pathogenesis and are governed by specific genes which have a dual role in both cell death and survival. Arsenic trioxide (ATO) and thalidomide (THAL) are used for treatment of many types of hematologic malignancies. ATO prevents the proliferation of cells and induces apoptosis in some cancer cells. Moreover, THAL has immunomodulatory and antiangiogenic effects in malignant cells. The aim of present study was to examine the effects of ATO and THAL on U937 and KG-1 cells, and evaluation of mRNA expression level of VEGFs genes, PI3K genes and some of autophagy genes.

Materials and Methods

In this in vitro experimental study, U937 and KG-1 cells were treated by ATO (0.4-5 μM) and THAL (5-100 μM) for 24, 48 and 72 hours. Cell viability was measured by MTT assay. The apoptosis rate and cell cycle arrest were evaluated by flow cytometry (Annexin/PI) and cell cycle flow cytometry analysis, respectively. The effect of ATO/THAL on mRNAs expression was evaluated by real-time polymerase chain reaction (PCR).

Results

ATO/THAL combination enhanced cell apoptosis in a dose-dependent manner. Also, ATO/THAL induced SubG1/ G1 phase arrest. mRNA expression levels of VEGFC (contrary to other VEGFs isoform), PI3K, AKT, mTOR, MEK1, PTEN, IL6, LC3 and P62 genes were upregulated in acute myeloid leukemia (AML) cells following treatment with ATO/THAL.

Conclusion

Combined treatment with ATO and THAL can inhibit proliferation and invasion of AML cells by down-regulating ULK1 and BECLIN1 and up-regulating PTEN and IL6, and this effect was more marked than the effects of ATO and THAL alone.

Immunogenicity moderation effect of interleukin-24 on myelogenous leukemia cells

Previous studies have shown that interleukin-24 (IL-24) has tumor-suppressing activity by multiple pathways. However, the immunogenicity moderation effect of IL-24 on malignant cells has not been explored extensively. In this study, we investigated the role of IL-24 in immunogenicity modulation of the myelogenous leukemia cells. Data show that myelogenous leukemia cells express low levels of immunogenicity molecules. Treatment with IL-24 could enhance leukemia cell immunogenicity, predominantly regulate leukemia cells to produce immune-associated cytokines, and improve the cytotoxic sensitivity of these cells to immune effector cells. IL-24 expression could retard transplanted leukemia cell tumor growth in vivo in athymic nude mice. Moreover, IL-24 had marked effects on downregulating the expression of angiogenesis-related proteins vascular endothelial growth factor, cluster of differentiation (CD) 31, CD34, collagen IV and metastasis-related factors CD147, membrane type-1 matrix metalloproteinase (MMP), and MMP-2 and MMP-9 in transplanted tumors. These findings indicated novel functions of this antitumor gene and characterized IL-24 as a promising agent for further clinical trial for hematologic malignancy immunotherapy.

Elucidation of Novel Therapeutic Targets for Acute Myeloid Leukemias with RUNX1-RUNX1T1 Fusion

The RUNX1-RUNX1T1 fusion is a frequent chromosomal alteration in acute myeloid leukemias (AMLs). Although RUNX1-RUNX1T1 fusion protein has pivotal roles in the development of AMLs with the fusion, RUNX1-RUNX1T1, fusion protein is difficult to target, as it lacks kinase activities. Here, we used bioinformatic tools to elucidate targetable signaling pathways in AMLs with RUNX1-RUNX1T1 fusion. After analysis of 93 AML cases from The Cancer Genome Atlas (TCGA) database, we found expression of 293 genes that correlated to the expression of the RUNX1-RUNX1T1 fusion gene. Based on these 293 genes, the cyclooxygenase (COX), vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), and fibroblast growth factor receptor (FGFR) pathways were predicted to be specifically activated in AMLs with RUNX1-RUNX1T1 fusion. Moreover, the in vitro proliferation of AML cells with RUNX1-RUNX1T1 fusion decreased significantly more than that of AML cells without the fusion, when the pathways were inhibited pharmacologically. The results indicate that novel targetable signaling pathways could be identified by the analysis of the gene expression features of AMLs with non-targetable genetic alterations. The elucidation of specific molecular targets for AMLs that have a specific genetic alteration would promote personalized treatment of AMLs and improve clinical outcomes.

Wogonoside impedes the progression of acute myeloid leukemia through inhibiting bone marrow angiogenesis

Decreasing bone marrow (BM) microvessel density and circulating angiogenic cytokine levels are promising strategies for the treatment of relapsed and resistant acute myeloid leukemia (AML). Previous studies have reported that wogonoside could inhibit the progression of AML and suppress angiogenesis in a solid tumor, but the correlation of these two effects was ignored. In this research, we determined whether wogonoside could inhibit angiogenesis in this hematologic malignancy. We found that wogonoside could inhibit tumor growth and progression, and prolong the survival of nude mice inoculated with U937/MDR. Besides, reducing BM angiogenesis might cause therapeutic effect against resistant AML. Therefore, coculture between AML cells and BM stromal cells was established to imitate their crosstalk. Then, the effect of wogonoside on BM angiogenesis was tested in vitro and in vivo. We found that wogonoside could suppress microvessel formation in the chicken chorioallantoic membrane assay model and matrigel plug assay. The mechanism research revealed that wogonoside could block the JAK2-STAT3 pathway in AML cells and stromal cells to break their positive feedback. We detected several cytokines related to AML or angiogenesis and found that secreted interleukin-8 was a significant angiogenic cytokine to induce BM angiogenesis. These findings supported that new diagnostics and promising treatment strategies could be developed in relapsed and resistant AML patients.

Inhibitory Effects of Arsenic Trioxide and Thalidomide on Angiogenesis and Vascular Endothelial Growth Factor Expression in Leukemia Cells

Acute myeloid leukemia (AML) is a blood disorder characterized by uncontrolled proliferation of myeloid progenitors and decrease in the apoptosis rate. The vascular endothelial growth factor (VEGF) promotes blood vessel regeneration which might play important roles in development and progression of neoplasia. Our previous studies focused on cytotoxicity and anticancer effects of arsenic trioxide (ATO) and thalidomide (THAL) as an anti-VEGF compound in the AML cell model. ATO also affects regulatory genes involved in cell proliferation and apoptosis. The aim of present study was to examine the effects of ATO and THAL alone and in combination on U937 and KG-1 cells, with attention to mRNA expression for VEGF isoforms. Growth inhibitory effects was assessed by MTT assay and apoptosis induction was determined by Annexin/PI staining. mRNA expression levels were evaluated by real-time PCR. Our data indicated that ATO (1.618μM and 1μM in KG-1 and U937 cell lines respectively), THAL (80μM and 60μM) and their combination inhibited proliferation and induced apoptosis in our cell lines. mRNA expression of VEGF (A, B) decreased while C and D isoforms did not show any significant changes. Taken together, according to the obtained results, the VEGF autocrine loop could be a target as a therapeutic strategy for cases of AML.

Anti-Vascular Endothelial Growth Factor Effects of Sorafenib and Arsenic Trioxide in Acute Myeloid Leukemia Cell Lines

Acute myeloid leukemia (AML), is a clonal disorder caused by acquired somatic mutations and chromosomal rearrangements. According to some evidence, progression of hematolymphoid malignancies depends on the induction of new blood vessel formation under the influence of acute leukemia. Various factors are produced by cancer cells under hypoxic conditions to increase vascular formation. Among these, vascular endothelial growth factor (VEGF) plays a crucial role. Cytotoxicity and anticancer effects of arsenic trioxide (ATO) have been reported in many cancers. Sorafenib, known as an angiogenic inhibitor, decreases leukemic cell survival. The aim of this study was to indicate combination effects of ATO and sorafenib in two AML cell lines, KG-1 and U937. Effective doses was determined by MTT assay for both single and combination treatments. Percentages of apoptotic cells were evaluated by Annexin V FITC staining and mRNA levels of VEGF isoforms and receptor expression were investigated by Real-Time PCR. Our data show that sorafenib (5μM and 7μM in KG-1 and U937 cell lines respectively), ATO (1.618μM and 1μM in KG-1 and U937 cell lines respectively), and also their combination significantly increased the percentage of apoptotic cells. In addition the mRNA level of VEGF isoforms was downregulated in the U937 cell line while upregulated in KG-1 cells. Taken together, our results suggest that the VEGF autocrine loop may have an influence on AML development and progression and could be consider as a therapeutic target. The combination of sorafenib as a VEGF inhibitor with ATO synergistically inhibits cell proliferation and promotes apoptosis.

miR-125b promotes MLL-AF9-driven murine acute myeloid leukemia involving a VEGFA-mediated non-cell-intrinsic mechanism

The hematopoietic stem cell-enriched miR-125 family microRNAs (miRNAs) are critical regulators of hematopoiesis. Overexpression of miR-125a or miR-125b is frequent in human acute myeloid leukemia (AML), and the overexpression of these miRNAs in mice leads to expansion of hematopoietic stem cells accompanied by perturbed hematopoiesis with mostly myeloproliferative phenotypes. However, whether and how miR-125 family miRNAs cooperate with known AML oncogenes in vivo, and how the resultant leukemia is dependent on miR-125 overexpression, are not well understood. We modeled the frequent co-occurrence of miR-125b overexpression and MLL translocations by examining functional cooperation between miR-125b and MLL-AF9 By generating a knock-in mouse model in which miR-125b overexpression is controlled by doxycycline induction, we demonstrated that miR-125b significantly enhances MLL-AF9-driven AML in vivo, and the resultant leukemia is partially dependent on continued overexpression of miR-125b Surprisingly, miR-125b promotes AML cell expansion and suppresses apoptosis involving a non-cell-intrinsic mechanism. MiR-125b expression enhances VEGFA expression and production from leukemia cells, in part by suppressing TET2 Recombinant VEGFA recapitulates the leukemia-promoting effects of miR-125b, whereas knockdown of VEGFA or inhibition of VEGF receptor 2 abolishes the effects of miR-125b In addition, significant correlation between miR-125b and VEGFA expression is observed in human AMLs. Our data reveal cooperative and dependent relationships between miR-125b and the MLL oncogene in AML leukemogenesis, and demonstrate a miR-125b-TET2-VEGFA pathway in mediating non-cell-intrinsic leukemia-promoting effects by an oncogenic miRNA.

Levels of bone marrow microvessel density are crucial for evaluating the status of acute myeloid leukemia

The aim of the present study was to determine the efficacy of bone marrow microvessel density (BM-MVD) in the evaluation of the status of acute myeloid leukemia (AML). The levels of serum and bone marrow vascular endothelial growth factor (VEGF), and BM-MVD in 28 patients with AML, 10 patients with non-Hodgkin's lymphoma, 10 patients with anemia and 14 patients with AML that achieved complete remission for six months (AML-DFS) subsequent to chemotherapy were determined by ELISA and immunohistochemistry. The levels of serum VEGF in patients with hematological disorders were significantly increased compared with the levels in the healthy controls. The levels of BM VEGF and BM-MVD in AML patients were significantly higher compared with the levels in the patients with non-Hodgkin's lymphoma or anemia. Following chemotherapy, the levels of serum VEGF significantly increased and the levels of BM VEGF decreased in the AML patients, regardless of their therapeutic responses, compared with the levels prior to treatment. By contrast, the levels of BM-MVD in the AML patients were significantly reduced in the patients that completely recovered from AML (AML-DFS group), compared with those in other groups. The present data indicate that the levels of BM-MVD are valuable for evaluating the status of AML.

STAT3-dependent VEGF production from keratinocytes abrogates dendritic cell activation and migration by arsenic: a plausible regional mechanism of immunosuppression in arsenical cancers

Arsenic remains an important environmental hazard that causes several human cancers. Arsenic-induced Bowen's disease (As-BD), a skin carcinoma in situ, is the most common arsenical cancer. While great strides have been made in our understanding of arsenic carcinogenesis, how host immunity contributes to this process remains unknown. Patients with As-BD have an impaired contact hypersensitivity response. Although impaired T cell activation has been well-documented in arsenical cancers, how dendritic cell (DC), the key cell regulating innate immunity, regulates the immune response in arsenical cancers remains unclear. Using myeloid derived DC (MDDC) from patients with As-BD and normal controls as well as bone marrow derived DC (BMDC) from mice fed with or without arsenic, we measured the migration of DC. As-BD patients showed an impaired CCL21-mediated MDDC migration in vitro. Arsenic-fed mice had defective DC migration toward popliteal lymph nodes when injected with allogenic BMDCs via foot pad. Using skin from As-BD and normal controls, we found an increased expression of STAT3, a transcriptional factor contributing to impaired DC activation. Arsenic induced STAT3 activation and the production of VEGF in keratinocytes. The increase in VEGF was blocked by inhibiting STAT3 with RNA interference or pharmaceutically with JSI-124. While VEGF by itself minimally induced the expression of CD86 and MHC-II in MDDC, arsenic induced-MDDC activation was abolished by VEGF pretreatment. We concluded that the STAT3-VEGF axis in keratinocytes inhibits DC migration in the microenvironment of As-BD, indicating that cellular interactions play an important role in regulating the disease course of arsenical cancers.

Angiogenesis and proliferation index in patients with acute leukemia: a prospective study

Angiogenesis and proliferation as measured by microvessel density (MVD) and proliferation index (PI) are essential correlates of malignancy. The aim of our study was to evaluate difference between these values in AML and ALL and also to study the modulation in these parameters following achievement of remission in acute lymphoblastic leukemia. Differences between adult and adolescent cases of acute leukemia in relation to these values were also studied. We also tried to assess the relationship between angiogenesis and proliferation. Fifty-five patients with acute leukemia were included in the study. Trephine biopsies were immunostained with CD34 and factor VIIIrAg to demonstrate angiogenesis measured as MVD. Immunostaining with PCNA and Ki-67 was done to study proliferation. We found a significant increase in MVD and PI in cases when compared with controls (P < 0.0001). In addition cases with ALL had a significantly higher MVD compared to those with AML (P < 0.01). The patients with ALL who went into remission showed a significant reduction in MVD; PI remained high. The cases which did not achieve remission showed no significant reduction in either MVD or PI. All adolescent cases of ALL were similar to adults with respect to MVD and PI.