Emerging roles of epithelial-mesenchymal transition in hematological malignancies

The ETV6-MECOM fusion protein promotes EMT-related properties by repressing the transactivation activity of E-cadherin promoter in K562 leukemia cells

The ETV6-MECOM fusion gene, produced by the rare and recurrent chromosomal translocation t(3; 12) (q26; p13), is associated with high mortality and short survival in myeloid leukemia. However, its function and underlying mechanisms in leukemia progression remain unknown. In this study, leukemia-stable K562 cells expressing the ETV6-MECOM fusion protein were used to investigate the effects of the ETV6-MECOM oncoprotein. K562-ETV6-MECOM cells were undifferentiated and had reduced colony formation, increased cell migration and invasion, and increased sphere number and diameter in a spheroid formation assay, presenting epithelial-to-mesenchymal transition (EMT) traits. The expression of E-cadherin, a hallmark of EMT, was significantly downregulated at the transcriptional and translational level in K562-ETV6-MECOM cells to explore the mechanistic basis of EMT. Stepwise truncation, DNA sequence deletion, mutation analysis for E-cadherin promoter transactivation, and a dual luciferase assay indicated that the regulatory region of ETV6-MECOM is located in the DNA motif -1116 TTAAAA-1111 of E-cadherin promoter. Moreover, a chromatin immunoprecipitation assay showed that this oncoprotein binds to the DNA motif -1116 TTAAAA-1111 with the anti-EVI1 antibody. Although ETV6-MECOM upregulated the expressions of EMT master regulators, including SNAIL, SLUG, ZEB2, and TWIST2, their knockdown had no effect on EMT-related properties. However, overexpression of E-cadherin eliminated EMT traits in the presence of the ETV6-MECOM oncoprotein. These data confirmed that the ETV6-MECOM oncoprotein, not SNAIL, SLUG, ZEB2, or TWIST2, plays a critical role in inducing EMT traits in leukemia K562 cells. ETV6-MECOM induces EMT-related properties by downregulating the transcriptional expression of E-cadherin and repressing its transactivation activity by binding to its core motif -1116TTAAAA-1111 in leukemia K562 cells. These findings could contribute to the development of a therapeutic target for patients with myeloid leukemia characterized by ETV6-MECOM.

Epithelial-Mesenchymal Transition in Acute Leukemias

Epithelial-mesenchymal transition (EMT) is a metabolic process that confers phenotypic flexibility to cells and the ability to adapt to new functions. This transition is critical during embryogenesis and is required for the differentiation of many tissues and organs. EMT can also be induced in advanced-stage cancers, leading to further malignant behavior and chemotherapy resistance, resulting in an unfavorable prognosis for patients. Although EMT was long considered and studied only in solid tumors, it has been shown to be involved in the pathogenesis of hematological malignancies, including acute leukemias. Indeed, there is increasing evidence that EMT promotes the progression of acute leukemias, leading to the emergence of a more aggressive phenotype of the disease, and also causes chemotherapy resistance. The current literature suggests that the levels and activities of EMT inducers and markers can be used to predict prognosis, and that targeting EMT in addition to conventional therapies may increase treatment success in acute leukemias.

Multi-Enzyme Co-Expressed Nanomedicine for Anti-Metastasis Tumor Therapy by Up-Regulating Cellular Oxidative Stress and Depleting Cholesterol

Tumor cells movement and migration are inseparable from the integrity of lipid rafts and the formation of lamellipodia, and lipid rafts are also a prerequisite for the formation of lamellipodia. Therefore, destroying the lipid rafts is an effective strategy to inhibit tumor metastasis. Herein, a multi-enzyme co-expressed nanomedicine: cholesterol oxidase (CHO) loaded Co─PN3 single-atom nanozyme (Co─PN3 SA/CHO) that can up-regulate cellular oxidative stress, disrupt the integrity of lipid rafts, and inhibit lamellipodia formation to induce anti-metastasis tumor therapy, is developed. In this process, Co─PN3 SA can catalyze oxygen (O2 ) and hydrogen peroxide (H2 O2 ) to generate reactive oxygen species (ROS) via oxidase-like and Fenton-like properties. The doping of P atoms optimizes the adsorption process of the intermediate at the active site and enhances the ROS generation properties of nanomedicine. Meantime, O2 produced by catalase-like catalysis can combine with excess cholesterol to generate more H2 O2 under CHO catalysis, achieving enhanced oxidative damage to tumor cells. Most importantly, cholesterol depletion in tumor cells also disrupts the integrity of lipid rafts and inhibits the formation of lamellipodia, greatly inhibiting the proliferation and metastasis of tumor cells. This strategy by up-regulating cellular oxidative stress and depleting cellular cholesterol constructs a new idea for anti-metastasis-oriented cancer therapy strategies.

Expression profiling of extramedullary acute myeloid leukemia suggests involvement of epithelial-mesenchymal transition pathways

Extramedullary (EM) colonization is a rare complication of acute myeloid leukemia (AML), occurring in about 10% of patients, but the processes underlying tissue invasion are not entirely characterized. Through the application of RNAseq technology, we examined the transcriptome profile of 13 AMLs, 9 of whom presented an EM localization. Our analysis revealed significant deregulation within the extracellular matrix (ECM)-receptor interaction and focal-adhesion pathways, specifically in the EM sites. The transcription factor TWIST1, which is known to impact on cancer invasion by dysregulating epithelial-mesenchymal-transition (EMT) processes, was significantly upregulated in EM-AML. To test the functional impact of TWIST1 overexpression, we treated OCI-AML3s with TWIST1-siRNA or metformin, a drug known to inhibit tumor progression in cancer models. After 48 h, we showed downregulation of TWIST1, and of the EMT-related genes FN1 and SNAI2. This was associated with significant impairment of migration and invasion processes by Boyden chamber assays. Our study shed light on the molecular mechanisms associated with EM tissue invasion in AML, and on the ability of metformin to interfere with key players of this process. TWIST1 may configure as candidate marker of EM-AML progression, and inhibition of EMT-pathways may represent an innovative therapeutic intervention to prevent or treat this complication.

Fabrication of a three-dimensional bone marrow niche-like acute myeloid Leukemia disease model by an automated and controlled process using a robotic multicellular bioprinting system

BACKGROUND

Acute myeloid leukemia (AML) is a hematological malignancy that remains a therapeutic challenge due to the high incidence of disease relapse. To better understand resistance mechanisms and identify novel therapies, robust preclinical models mimicking the bone marrow (BM) microenvironment are needed. This study aimed to achieve an automated fabrication process of a three-dimensional (3D) AML disease model that recapitulates the 3D spatial structure of the BM microenvironment and applies to drug screening and investigational studies.

METHODS

To build this model, we investigated a unique class of tetramer peptides with an innate ability to self-assemble into stable hydrogel. An automated robotic bioprinting process was established to fabricate a 3D BM (niche-like) multicellular AML disease model comprised of leukemia cells and the BM's stromal and endothelial cellular fractions. In addition, monoculture and dual-culture models were also fabricated. Leukemia cell compatibility, functionalities (in vitro and in vivo), and drug assessment studies using our model were performed. In addition, RNAseq and gene expression analysis using TaqMan arrays were also performed on 3D cultured stromal cells and primary leukemia cells.

RESULTS

The selected peptide hydrogel formed a highly porous network of nanofibers with mechanical properties similar to the BM extracellular matrix. The robotic bioprinter and the novel quadruple coaxial nozzle enabled the automated fabrication of a 3D BM niche-like AML disease model with controlled deposition of multiple cell types into the model. This model supported the viability and growth of primary leukemic, endothelial, and stromal cells and recapitulated cell-cell and cell-ECM interactions. In addition, AML cells in our model possessed quiescent characteristics with improved chemoresistance attributes, resembling more the native conditions as indicated by our in vivo results. Moreover, the whole transcriptome data demonstrated the effect of 3D culture on enhancing BM niche cell characteristics. We identified molecular pathways upregulated in AML cells in our 3D model that might contribute to AML drug resistance and disease relapse.

CONCLUSIONS

Our results demonstrate the importance of developing 3D biomimicry models that closely recapitulate the in vivo conditions to gain deeper insights into drug resistance mechanisms and novel therapy development. These models can also improve personalized medicine by testing patient-specific treatments.

FOXN Transcription Factors: Regulation and Significant Role in Cancer

A growing number of studies have demonstrated that cancer development is closely linked to abnormal gene expression, including alterations in the transcriptional activity of transcription factors. The Forkhead box class N (FOXN) proteins FOXN1-6 form a highly conserved class of transcription factors, which have been shown in recent years to be involved in the regulation of malignant progression in a variety of cancers. FOXNs mediate cell proliferation, cell-cycle progression, cell differentiation, metabolic homeostasis, embryonic development, DNA damage repair, tumor angiogenesis, and other critical biological processes. Therefore, transcriptional dysregulation of FOXNs can directly affect cellular physiology and promote cancer development. Numerous studies have demonstrated that the transcriptional activity of FOXNs is regulated by protein-protein interactions, microRNAs (miRNA), and posttranslational modifications (PTM). However, the mechanisms underlying the molecular regulation of FOXNs in cancer development are unclear. Here, we reviewed the molecular regulatory mechanisms of FOXNs expression and activity, their role in the malignant progression of tumors, and their value for clinical applications in cancer therapy. This review may help design experimental studies involving FOXN transcription factors, and enhance their therapeutic potential as antitumor targets.

Phenotypic and functional characterization of subpopulation of Imatinib resistant chronic myeloid leukemia cell line

PURPOSE

Chronic myeloid leukemia (CML) is a hematological malignancy characterized by the presence of BCR-ABL protein. Imatinib (IMA) is considered as the first line therapy in management of CML which particularly targets the BCR-ABL tyrosine kinase protein. However, emergence of resistance to IMA hinders its clinical efficiency. Hence, identifying novel targets for therapeutic approaches in CML treatment is of great importance. Here, we characterize a new subpopulation of highly adherent IMA-resistant CML cells that express stemness and adhesion markers compared to naive counterparts.

MATERIALS AND METHODS

We performed several experimental assays including FISH, flow cytometry, and gene expression assays. Additionally, bioinformatics analysis was performed by normalized web-available microarray data (GSE120932) to revalidate and introduce probable biomarkers. Protein-protein interactions (PPI) network was analyzed by the STRING database employing Cytoscape v3.8.2.

RESULTS

Our findings demonstrated that constant exposure to 5 ​μM IMA led to development of the adherent phenotype (K562R-adh). FISH and BCR-ABL expression analysis indicated that K562R-adh cells were derived from the original cells (K562R). In order to determine the role of various genes involved in epithelial-mesenchymal transition (EMT) and stem cell characterization, up/down-regulation of various genes including cancer stem cell (CSC), adhesion and cell surface markers and integrins were observed which was similar to the findings of the GSE120932 dataset.

CONCLUSION

Treating CML patients with tyrosine kinase inhibitors (TKIs) as well as targeting adhesion molecules deemed to be effective approaches in prevention of IMA resistance emergence which in turn may provide promising effects in the clinical management of CML patients.

Induction of Reactive Bone Stromal Fibroblasts in 3D Models of Prostate Cancer Bone Metastases

A dynamic interplay between prostate cancer (PCa) cells and reactive bone stroma modulates the growth of metastases within the bone microenvironment. Of the stromal cells, metastasis-associated fibroblasts (MAFs) are known to contribute but are the least studied cell type in PCa tumour progression. It is the aim of the current study to establish a biologically relevant 3D in vitro model that mimics the cellular and molecular profiles of MAFs found in vivo. Using 3D in vitro cell culture models, the bone-derived fibroblast cell line, HS-5, was treated with conditioned media from metastatic-derived PCa cell lines, PC3 and MDA-PCa 2b, or mouse-derived fibroblasts 3T3. Two corresponding reactive cell lines were propagated: HS5-PC3 and HS5-MDA, and evaluated for alterations in morphology, phenotype, cellular behaviour, plus protein and genomic profiles. HS5-PC3 and HS5-MDA displayed distinct alterations in expression levels of N-Cadherin, non-functional E-Cadherin, alpha-smooth muscle actin (α-SMA), Tenascin C, and vimentin, along with transforming growth factor receptor expression (TGF β R1 and R2), consistent with subpopulations of MAFs reported in vivo. Transcriptomic analysis revealed a reversion of HS5-PC3 towards a metastatic phenotype with an upregulation in pathways known to regulate cancer invasion, proliferation, and angiogenesis. The exploitation of these engineered 3D models could help further unravel the novel biology regulating metastatic growth and the role fibroblasts play in the colonisation process.

MicroRNA-143 acts as a tumor suppressor through Musashi-2/DLL1/Notch1 and Musashi-2/Snail1/MMPs axes in acute myeloid leukemia

BACKGROUND

The previous studies have revealed that abnormal RNA-binding protein Musashi-2 (MSI2) expression is associated with cancer progression through post-transcriptional mechanisms, however mechanistic details of this regulation in acute myeloid leukemia (AML) still remain unclear. Our study aimed to explore the relationship between microRNA-143 (miR-143) and MSI2 and to clarify their clinical significance, biological function and mechanism.

METHODS

Abnormal expression of miR-143 and MSI2 were evaluated in bone marrow samples from AML patients by quantitative real time-PCR. Effects of miR-143 on regulating MSI2 expression were investigated using luciferase reporter assay. Functional roles of MSI2 and miR-143 on AML cell proliferation and migration were determined by CCK-8 assay, colony formation, and transwell assays in vitro and in mouse subcutaneous xenograft and orthotopic transplantation models in vivo. RNA immunoprecipitation, RNA stability measurement and Western blotting were performed to assess the effects of MSI2 on AML.

RESULTS

We found that MSI2 was significantly overexpressed in AML and exerted its role of promoting AML cell growth by targeting DLL1 and thereby activating Notch signaling pathway. Moreover, we found that MSI2 bound to Snail1 transcript and inhibited its degradation, which in turn upregulated the expression of matrix metalloproteinases. We also found that MSI2 targeting miR-143 is downregulated in AML. In the AML xenograft mouse model, overexpression of MSI2 recapitulated its leukemia-promoting effects, and overexpression of miR-143 partially attenuated tumor growth and prevented metastasis. Notably, low expression of miR-143, and high expression of MSI2 were associated with poor prognosis in AML patients.

CONCLUSIONS

Our data demonstrate that MSI2 exerts its malignant properties via DLL1/Notch1 cascade and the Snail1/MMPs axes in AML, and upregulation of miR-143 may be a potential therapeutic approach for AML.

Plasma protein biomarker profiling reveals major differences between acute leukaemia, lymphoma patients and controls

Aiming to accommodate the unmet need for easily accessible biomarkers with a focus on biological differences between haematological diseases, the diagnostic value of plasma proteins in acute leukaemias and lymphomas was investigated. A multiplex proximity extension assay (PEA) was used to analyze 183 proteins in diagnostic plasma samples from 251 acute leukaemia and lymphoma patients and compared with samples from 60 healthy controls. Multivariate modelling using partial least square discriminant analysis revealed highly significant differences between distinct disease subgroups and controls. The model allowed explicit distinction between leukaemia and lymphoma, with few patients misclassified. Acute leukaemia samples had higher levels of proteins associated with haemostasis, inflammation, cell differentiation and cell-matrix integration, whereas lymphoma samples demonstrated higher levels of proteins known to be associated with tumour microenvironment and lymphoma dissemination. PEA technology can be used to screen for large number of plasma protein biomarkers in low µL sample volumes, enabling the distinction between controls, acute leukaemias and lymphomas. Plasma protein profiling could help gain insights into the pathophysiology of acute leukaemia and lymphoma and the technique may be a valuable tool in the diagnosis of these diseases.

Estrogen Receptor β (ESR2) Transcriptome and Chromatin Binding in a Mantle Cell Lymphoma Tumor Model Reveal the Tumor-Suppressing Mechanisms of Estrogens

Simple Summary

Mantle cell lymphoma (MCL) is much more common in males than in females. The reason for this is not clear, but research has indicated that the female sex hormones, estrogens, have a protective effect on MCL development. To study this further, mice were transplanted with MCL cells and treated with an estrogen that selectively activates ESR2, the main nuclear estrogen receptor in lymphoma cells. The activation of ESR2 resulted in reduced MCL tumor growth of MCL tumors that were both sensitive and resistant to a newly developed drug (ibrutinib). The mechanism for this effect was investigated by analyzing gene expression and ESR2 binding to target genes. The results show that the affected genes were enriched in several malignancy-related biological processes, including MCL. Furthermore, the results suggested an interplay between the lymphoma cells and the tumor microenvironment in response to ESR2 activation. Altogether, the results clarify the mechanisms of ESR2-mediated MCL growth impairment by estrogens and provide a possible explanation for the sex difference in incidence. Furthermore, targeting ESR2 may be an option when considering the treatment of MCL.

Abstract

Mantle cell lymphoma (MCL) is a non-Hodgkin lymphoma with one of the highest male-to-female incidence ratios. The reason for this is not clear, but epidemiological as well as experimental data have suggested a role for estrogens, particularly acting through estrogen receptor β (ESR2). To study the ESR2 effects on MCL progression, MCL cells sensitive and resistant to the Bruton tyrosine kinase inhibitor ibrutinib were grafted to mice and treated with the ESR2-selective agonist diarylpropionitrile (DPN). The results showed that the DPN treatment of mice grafted with both ibrutinib-sensitive and -resistant MCL tumors resulted in impaired tumor progression. To identify the signaling pathways involved in the impaired tumor progression following ESR2 agonist treatment, the transcriptome and ESR2 binding to target genes were investigated by genome-wide chromatin immunoprecipitation in Granta-519 MCL tumors. DPN-regulated genes were enriched in several biological processes that included cell–cell adhesion, endothelial–mesenchymal transition, nuclear factor-kappaB signaling, vasculogenesis, lymphocyte proliferation, and apoptosis. In addition, downregulation of individual genes, such as SOX11 and MALAT1, that play a role in MCL progression was also observed. Furthermore, the data suggested an interplay between the lymphoma cells and the tumor microenvironment in response to the ESR2 agonist. In conclusion, the results clarify the mechanisms by which estrogens, via ESR2, impair MCL tumor progression and provide a possible explanation for the sex-dependent difference in incidence. Furthermore, targeting ESR2 with a selective agonist may be an additional option when considering the treatment of both ibrutinib-sensitive and -resistant MCL tumors.

Leukemic Stem Cell: A Mini-Review on Clinical Perspectives

Hematopoietic stem cells (HSCs) are known for their ability to proliferate and self-renew, thus being responsible for sustaining the hematopoietic system and residing in the bone marrow (BM). Leukemic stem cells (LSCs) are recognized by their stemness features such as drug resistance, self-renewal, and undifferentiated state. LSCs are also present in BM, being found in only 0.1%, approximately. This makes their identification and even their differentiation difficult since, despite the mutations, they are cells that still have many similarities with HSCs. Although the common characteristics, LSCs are heterogeneous cells and have different phenotypic characteristics, genetic mutations, and metabolic alterations. This whole set of alterations enables the cell to initiate the process of carcinogenesis, in addition to conferring drug resistance and providing relapses. The study of LSCs has been evolving and its application can help patients, where through its count as a biomarker, it can indicate a prognostic factor and reveal treatment results. The selection of a target to LSC therapy is fundamental. Ideally, the target chosen should be highly expressed by LSCs, highly selective, absence of expression on other cells, in particular HSC, and preferentially expressed by high numbers of patients. In view of the large number of similarities between LSCs and HSCs, it is not surprising that current treatment approaches are limited. In this mini review we seek to describe the immunophenotypic characteristics and mechanisms of resistance presented by LSCs, also approaching possible alternatives for the treatment of patients.

Cancer-associated fibroblast-derived exosomal miR-18b promotes breast cancer invasion and metastasis by regulating TCEAL7

Studies have shown that cancer-associated fibroblasts (CAFs) play an irreplaceable role in the occurrence and development of tumors. Therefore, exploring the action and mechanism of CAFs on tumor cells is particularly important. In this study, we compared the effects of CAFs-derived exosomes and normal fibroblasts (NFs)-derived exosomes on breast cancer cells migration and invasion. The results showed that exosomes from both CAFs and NFs could enter into breast cancer cells and CAFs-derived exosomes had a more enhancing effect on breast cancer cells migration and invasion than NFs-derived exosomes. Furthermore, microRNA (miR)-18b was upregulated in CAFs-derived exosomes, and CAFs-derived exosomes miR-18b can promote breast cancer cell migration and metastasis by specifically binding to the 3'UTR of Transcription Elongation Factor A Like 7 (TCEAL7). The miR-18b-TCEAL7 pathway promotes nuclear Snail ectopic activation by activating nuclear factor-kappa B (NF-κB), thereby inducing epithelial-mesenchymal transition (EMT) and promoting cell invasion and metastasis. Moreover, CAFs-derived exosomes miR-18b could promote mouse xenograft model tumor metastasis. Overall, our findings suggest that CAFs-derived exosomes miR-18b promote nuclear Snail ectopic by targeting TCEAL7 to activate the NF-κB pathway, thereby inducing EMT, invasion, and metastasis of breast cancer. Targeting CAFs-derived exosome miR-18b may be a potential treatment option to overcome breast cancer progression.

Mechanisms Involved in the Promoting Activity of Fibroblasts in HTLV-1-Mediated Lymphomagenesis: Insights into the Plasticity of Lymphomatous Cells

Among the mechanisms leading to progression to Adult T-cell Leukaemia/Lymphoma in Human T-cell Leukaemia Virus type 1 (HTLV-1)-infected subjects, the contribution of stromal components remains poorly understood. To dissect the role of fibroblasts in HTLV-1-mediated lymphomagenesis, transcriptome studies, cytofluorimetric and qRT-PCR analyses of surface and intracellular markers linked to plasticity and stemness in coculture, and in vivo experiments were performed. A transcriptomic comparison between a more lymphomagenic (C91/III) and the parental (C91/PL) cell line evidenced hyperactivation of the PI3K/Akt pathway, confirmed by phospho-ELISA and 2-DE and WB analyses. C91/III cells also showed higher expression of mesenchymal and stemness genes. Short-term coculture with human foreskin fibroblasts (HFF) induced these features in C91/PL cells, and significantly increased not only the cancer stem cells (CSCs)-supporting CD10+GPR77+ HFF subpopulation, but also the percentage of ALDH1bright C91/PL cells. A non-cytotoxic acetylsalicylic acid treatment decreased HFF-induced ALDH1bright C91/PL cells, downregulated mesenchymal and stemness genes in cocultured cells, and delayed lymphoma growth in immunosuppressed mice, thus hindering the supportive activity of HFF on CSCs. These data suggest that crosstalk with HFF significantly intensifies the aggressiveness and plasticity of C91/PL cells, leading to the enrichment in lymphoma-initiating cells. Additional research is needed to better characterize these preliminary findings.

Src family kinases, adaptor proteins and the actin cytoskeleton in epithelial-to-mesenchymal transition

Over a century of scientific inquiry since the discovery of v-SRC but still no final judgement on SRC function. However, a significant body of work has defined Src family kinases as key players in tumor progression, invasion and metastasis in human cancer. With the ever-growing evidence supporting the role of epithelial-mesenchymal transition (EMT) in invasion and metastasis, so does our understanding of the role SFKs play in mediating these processes. Here we describe some key mechanisms through which Src family kinases play critical role in epithelial homeostasis and how their function is essential for the propagation of invasive signals. Video abstract.

ZEB2 Knock-down Induces Apoptosis in Human Myeloid Leukemia HL-60 Cells

INTRODUCTION

Acute myeloid leukemia (AML) is the most prevalent type of cancer in the adult hematopoietic system. Conventional therapies are associated with unfavorable side effects in individuals diagnosed with AML. These after-effects with partial remission reflect the urgent need for novel therapeutic approaches for inducing apoptosis, specifically in malignant cells, without affecting other cells. As a transcription factor (TF), ZEB2 (Zinc Finger E-Box Binding Homeobox 2) regulates the expression of specific genes in normal conditions. However, increased expression of ZEB2 is reported in various cancers, especially in AML, which is related to a higher degree of apoptosis inhibition of malignant cells. In this work, the role of ZEB2 in apoptosis inhibition is surveyed through ZEB2 specific knocking-down in human myeloid leukemia HL-60 cells.

MATERIALS AND METHODS

Transfection of HL-60 cells was conducted using ZEB2-siRNA at concentrations of 20, 40, 60, and 80 pmol within 24, 48, and 72 h. After determining the optimum dose and time, flow cytometry was used to measure the apoptosis rate. The MTT assay was also utilized to evaluate the cytotoxic impact of transfection on the cells. The expression of candidate genes was measured before and after transfection using qRT-PCR.

RESULTS

According to obtained results, suppression of ZEB2 expression through siRNA was associated with the induction of apoptosis, increased pro-apoptotic, and decreased anti-apoptotic gene expression. Transfection of ZEB2-siRNA was also associated with reduced cell proliferation and viability.

CONCLUSION

Our study results suggest that ZEB2 suppression in myeloid leukemia cells through apoptosis induction could be a proper therapeutic method.

The Aurora kinase/β-catenin axis contributes to dexamethasone resistance in leukemia

Glucocorticoids, such as dexamethasone and prednisolone, are widely used in cancer treatment. Different hematological malignancies respond differently to this treatment which, as could be expected, correlates with treatment outcome. In this study, we have used a glucocorticoid-induced gene signature to develop a deep learning model that can predict dexamethasone sensitivity. By combining gene expression data from cell lines and patients with acute lymphoblastic leukemia, we observed that the model is useful for the classification of patients. Predicted samples have been used to detect deregulated pathways that lead to dexamethasone resistance. Gene set enrichment analysis, peptide substrate-based kinase profiling assay, and western blot analysis identified Aurora kinase, S6K, p38, and β-catenin as key signaling proteins involved in dexamethasone resistance. Deep learning-enabled drug synergy prediction followed by in vitro drug synergy analysis identified kinase inhibitors against Aurora kinase, JAK, S6K, and mTOR that displayed synergy with dexamethasone. Combining pathway enrichment, kinase regulation, and kinase inhibition data, we propose that Aurora kinase or its several direct or indirect downstream kinase effectors such as mTOR, S6K, p38, and JAK may be involved in β-catenin stabilization through phosphorylation-dependent inactivation of GSK-3β. Collectively, our data suggest that activation of the Aurora kinase/β-catenin axis during dexamethasone treatment may contribute to cell survival signaling which is possibly maintained in patients who are resistant to dexamethasone.

A Novel Platform to Test In Vivo Single Gene Dependencies in t(8,21) and t(15,17) AML Confirms Zeb2 as Leukemia Target

Simple Summary

Mouse models are extensively used to study human diseases, including cancer. They are particularly useful to evaluate the role of specific genes in the tumorigenic process. The platform we present allows to effectively induce in vivo silencing of any potential candidate gene in two acute myeloid leukemia mouse models, with the scope of furthering the understanding of this gene’s role in the biology of leukemia.

Abstract

The increased usage of high-throughput technologies in cancer research, including genetic and drug screens, generates large sets of candidate targets that need to be functionally validated for their roles in tumor development. Thus, reliable and robust in vivo model systems are needed to perform reverse genetic experiments. Ideally, these models should allow for a conditional silencing of the target and an unambiguous identification of engineered cancer cells. Here, we present a platform consisting of: (i) t(8;21) and t(15;17) driven acute myeloid leukemia (AML) transgenic mice with constitutive expression of green fluorescent protein (GFP) and inducible expression of Cre recombinase, and (ii) REX, a modified pSico lentiviral vector for inducible shRNA expression and red fluorescent protein (RFP) as a selection marker. In this system, leukemic cells from transgenic mice are transduced with REX, flow sorted, and transplanted into syngeneic hosts. Gene interference is induced in established tumors by tamoxifen treatment. Dual-color cell fluorescence guides the in vivo identification of shRNA interfered AML cells, monitoring engraftment and disease progression. We tested the platform by inducing knockdown of Zeb2, a gene upregulated by AML1-ETO and PML-RARα oncogenes in pre-leukemic hematopoietic stem cell compartment, and observed a significant delay in leukemia onset. This proves the power and utility of the platform and confirms Zeb2 contribution to the pathogenesis of AML.

Cyano Enone-Bearing Triterpenoid Soloxolone Methyl Inhibits Epithelial-Mesenchymal Transition of Human Lung Adenocarcinoma Cells In Vitro and Metastasis of Murine Melanoma In Vivo

Introduction of α-cyano α,β-unsaturated carbonyl moiety into natural cyclic compounds markedly improves their bioactivities, including inhibitory potential against tumor growth and metastasis. Previously, we showed that cyano enone-bearing derivatives of 18βH-glycyrrhetinic (GA) and deoxycholic acids displayed marked cytotoxicity in different tumor cell lines. Moreover, GA derivative soloxolone methyl (SM) was found to induce ER stress and apoptosis in tumor cells in vitro and inhibit growth of carcinoma Krebs-2 in vivo. In this work, we studied the effects of these compounds used in non-toxic dosage on the processes associated with metastatic potential of tumor cells. Performed screening revealed SM as a hit compound, which inhibits motility of murine melanoma B16 and human lung adenocarcinoma A549 cells and significantly suppresses colony formation of A549 cells. Further study showed that SM effectively blocked transforming growth factor β (TGF-β)-induced epithelial-mesenchymal transition (EMT) of A549 cells: namely, inhibited TGF-β-stimulated motility and invasion of tumor cells as well as loss of their epithelial characteristics, such as, an acquisition of spindle-like phenotype, up- and down-regulation of mesenchymal (vimentin, fibronectin) and epithelial (E-cadherin, zona occludens-1 (ZO-1)) markers, respectively. Network pharmacology analysis with subsequent verification by molecular modeling revealed that matrix metalloproteinases MMP-2/-9 and c-Jun N-terminal protein kinase 1 (JNK1) can be considered as hypothetical primary targets of SM, mediating its marked anti-EMT activity. The inhibitory effect of SM on EMT revealed in vitro was further confirmed in a metastatic model of murine B16 melanoma: SM was found to effectively block metastatic dissemination of melanoma B16 cells in vivo, increase expression of E-cadherin and suppress expression of MMP-9 in lung metastatic foci. Altogether, our data provided valuable information for a better understanding of the antitumor activity of cyano enone-bearing semisynthetic compounds and revealed SM as a promising anti-metastatic drug candidate.

Prognostic significance of Twist, ZEB1 and Slug in peripheral T-cell lymphomas

ABSTRACT Objectives: To investigate the protein expression of the epithelial-mesenchymal transition-inducing transcription factors (TFs) Twist, ZEB1 and Slug in peripheral T-cell lymphomas (PTCL) and their correlation with clinical parameters. Methods: The expression of these TFs was studied in 53 diagnostic biopsy specimens of several different PTCL subtypes with immunohistochemistry. Patient data were retrospectively collected from patient records and a statistical analysis was performed. Results: All three TFs were widely expressed. ZEB1 and Slug had correlations with clinical outcome. In all PTCL cases, high nuclear ZEB1 percentage correlated with a favorable progression-free survival (PFS) (3-year PFS: 70% vs. 34%; P = 0.010) and strong nuclear Slug intensity correlated with an unfavorable PFS (3-year PFS: 17% vs. 62%; P = 0.036). Discussion: The correlations between PFS and ZEB1 or Slug protein expression have not previously been established in PTCLs. The impact of ZEB1 and Slug expression on prognosis differed from our findings in DLBCL and the impact of ZEB1 expression was in line with current studies on mycosis fungoides and sézary syndrome. The findings may be explained by the roles these TFs play in hematopoiesis. Conclusion: ZEB1 and Slug may have potential clinical value for evaluating prognosis in PTCLs. The study size was small and heterogenous, and larger studies are warranted.

Curcumin inhibited the growth and invasion of human monocytic leukaemia SHI-1 cells in vivo by altering MAPK and MMP signalling

Context: Curcumin, a polyphenolic compound extracted from the rhizome of the tropical plant Curcuma longa L. (Zingiberaceae), has been considered as a cancer chemopreventive drug by American National Cancer Institute.Objective: To examine the effect of curcumin on acute monocytic leukaemia SHI-1 cells in vivo.Materials and methods: The SHI-1 cells (1 × 10⁶ cells in 0.1 mL PBS) were injected subcutaneously into the right flanks of the female SCID mice. Curcumin dissolved in olive oil (15 and 30 mg/kg) was administered (i.p.) to mice once a day for 15 days while the control group received olive oil injection. Tumour proliferation and apoptosis were examined by PCNA, TUNEL and cleaved caspase-3 staining. The expression of MAPK, NF-κB, MMP9, MMP2 and vimentin were confirmed by RT-PCR, immunohistochemistry or western blotting.Results: Administration of curcumin significantly inhibited tumour growth, as the tumour weight decreased from 0.67 g (control) to 0.47 g (15 mg/kg) and 0.35 g (30 mg/kg). Curcumin inhibited the expression of PCNA and increased the degree of TUNEL and cleaved caspase-3 staining in tumour tissue. The results of western blotting showed that curcumin treatment inhibited NF-κB and ERK signalling while activating p38 and JNK. Moreover, curcumin attenuated the mRNA transcription and protein expression of MMP2 and MMP9. Curcumin also suppressed the level of vimentin.Discussion and conclusions: Our study demonstrates that curcumin can inhibit the growth and invasion of human monocytic leukaemia in vivo, suggesting the possible use of curcumin for anti-metastasis in leukaemia and the value of determining its unique target.

Truncation of MYH8 tail in AML: a novel prognostic marker with increase cell migration and epithelial-mesenchymal transition utilizing RAF/MAPK pathway

MYH8 is an actin-based motor protin involved in integrin-mediated cell adhesion and migration. Heretofore, the association of MYH8 mutation and cancer is unclear. In this study, we investigated the biologic significance of novel MYH8 tail truncation mutation, R1292X, in acute myeloid leukemia (AML) which was discovered by whole-exome sequencing and targeted re-sequencing of 209 AML patients. The patients harboring the mutation all relapsed within 3.8-20.9 months. To explore the functional consequence of the mutation in AML progress, we established knock-in cell lines using CRISPR-Cas9 genome editing. Using the established mutant model, we assessed traits of cancer progress. The mutant cells had improved motility, which was confirmed by immunofluorescence staining, wound healing, transwell migration and adhesion assay. The cell morphology and cell cycle were altered to be accessible to migration and epithelial-to-mesenchymal transition (EMT) transcription factors were also increased. The Raf and p44/42 MAPK pathway was a major regulator of these characteristics proved by a screening of signal transduction and inhibitor assay. Further, a public cancer genome database (cBioPortal) shows that MYH8 tail truncation mutations occurring near the R1292 position of the genome may have a significant function in cancer. In conclusion, truncation of MYH8 could be a novel prognostic marker related to poor prognosis by inducing cell migration and EMT features, and inhibition of the Raf/MAPK pathway would be a therapeutic strategy for AML patients with MYH8 tail truncation.

Selective dysregulation of ABC transporters in methotrexate-resistant leukemia T-cells can confer cross-resistance to cytarabine, vincristine and dexamethasone, but not doxorubicin

Pediatric acute lymphoblastic leukemia (pALL) includes 75 % of childhood leukemias, and methotrexate (MTX) is one of the most effective chemotherapy agents prescribed for pALL treatment. The aim of this study was to establish and characterize an MTX-resistant tumor cell model in order to study the mechanism contributing to drug sensitivity loss in pALL. Parental CCRF-CEM cells were treated with a gradual increasing concentration of MTX from 5 nM to 1.28 μM. The resistant subline was then characterized according to the cellular morphology, cellular growth curves and specific mRNA expression changes associated with drug resistance in ALL. Moreover, in vitro cytotoxicity assays were used to analyze cells relative responsiveness to a set of clinically used anti-ALL chemotherapy drugs. The morphological changes observed in the new R-CCRF-CEM/MVCD subline were associated with dysregulation of the EMT-related genes, Twist1 and CDH1. Cells demonstrated downregulation of ABCC1 and the overexpression of ABCA2, ABCA3, and ABCB1 membrane transporters. However, short treatment of the sensitive and parental cell line with MTX did not affect the expression profiles of the former ABC pumps. Moreover, R-CCRF-CEM/MVCD cells demonstrated cross-resistance to cytarabine (cytosine arabinoside, ara-C), vincristine, and dexamethasone, but not doxorubicin. The induced cross-resistance to specific chemotherapy drugs may possibly be attributed to selective dysregulation of the ABC transporters and EMT-related genes. These data may pave the way for the development of new cancer therapeutic strategies.

Biphasic Regulation of Mesenchymal Genes Controls Fate Switches During Hematopoietic Differentiation of Human Pluripotent Stem Cells

Epithelial-mesenchymal transition (EMT) or its reverse process mesenchymal-epithelial transition (MET) occurs in multiple physiological and pathological processes. However, whether an entire EMT-MET process exists and the potential function during human hematopoiesis remain largely elusive. Utilizing human pluripotent stem cell (hPSC)-based systems, it is discovered that while EMT occurs at the onset of human hematopoietic differentiation, MET is not detected subsequently during differentiation. Instead, a biphasic activation of mesenchymal genes during hematopoietic differentiation of hPSCs is observed. The expression of mesenchymal genes is upregulated during the fate switch from pluripotency to the mesoderm, sustained at the hemogenic endothelium (HE) stage, and attenuated during hemogenic endothelial cell (HEP) differentiation to hematopoietic progenitor cells (HPCs). A similar expression pattern of mesenchymal genes is also observed during human and murine hematopoietic development in vivo. Wnt signaling and its downstream gene SNAI1 mediate the up-regulation of mesenchymal genes and initiation of mesoderm induction from pluripotency. Inhibition of transforming growth factor-β (TGF-β) signaling and downregulation of HAND1, a downstream gene of TGF-β, are required for the downregulation of mesenchymal genes and the capacity of HEPs to generate HPCs. These results suggest that the biphasic regulation of mesenchymal genes is an essential mechanism during human hematopoiesis.

Inhibition of PIM1 kinase attenuates bleomycin-induced pulmonary fibrosis in mice by modulating the ZEB1/E-cadherin pathway in alveolar epithelial cells

PIM1 is serine/threonine protein kinase that is involved in numerous biological processes. Pulmonary fibrosis (PF) is a chronic pathological result of the dysfunctional repair of lung injury without effective therapeutic treatments. In the current study, we investigated whether PIM1 inhibition would improve bleomycin (BLM)-induced pulmonary fibrosis. In a BLM-induced pulmonary fibrosis model, PIM1 was persistently upregulated in fibrotic lung tissues. Furthermore, PIM1 inhibition by the PIM1-specific inhibitor SMI-4a showed protective effects against BLM-induced mortality. Furthermore, SMI-4a suppressed hydroxyproline deposition and reversed epithelial-mesenchymal transition (EMT) formation, which was characterized by E-cadherin and α-SMA expression in vivo. More importantly, the ZEB1/E-cadherin pathway was found to be closely associated with BLM-induced pulmonary fibrosis. After the in vitro treatment of A549 cells, PIM1 regulated E-cadherin expression by dependently modulating the activity of the transcription factor ZEB1. These findings were verified in vivo after SMI-4a administration. Finally, an shPIM1-expressing adeno-associated virus was delivered via intratracheal injection to induce a long-term PIM1 deficiency in the alveolar epithelium. AAV-mediated PIM1 knockdown in the lung tissues alleviated BLM-induced pulmonary fibrosis, as indicated by collagen accumulation reduction, pulmonary histopathological mitigation and EMT reversion. These findings enhance our understanding of the roles of PIM1 in BLM-induced pulmonary fibrosis and suggest PIM1 inhibition as a potential therapeutic strategy in chronic pulmonary injuries.

FtH-Mediated ROS Dysregulation Promotes CXCL12/CXCR4 Axis Activation and EMT-Like Trans-Differentiation in Erythroleukemia K562 Cells

The cell-microenvironment communication is essential for homing of hematopoietic stem cells in stromal niches. Recent evidences support the involvement of epithelial-to-mesenchymal (EMT) process in hematopoietic stem cell homeostasis as well as in leukemia cells invasiveness and migration capability. Here, we demonstrate that the alteration of iron homeostasis and the consequent increase of redox metabolism, mediated by the stable knock down of ferritin heavy chain (FtH), enhances the expression of CXCR4 in K562 erythroleukemia cells, thus promoting CXCL12-mediated motility. Indeed, addition of the CXCR4 receptor antagonist AMD3100 reverts this effect. Upon FtH knock down K562 cells also acquire an “EMT-like” phenotype, characterized by the increase of Snail, Slug and Vimentin with the parallel loss of E-cadherin. By using fibronectin as substrate, the cell adhesion assay further shows a reduction of cell adhesion capability in FtH-silenced K562 cells. Accordingly, confocal microscopy shows that adherent K562 control cells display a variety of protrusions while FtH-silenced K562 cells remain roundish. These phenomena are largely due to the reactive oxygen species (ROS)-mediated up-regulation of HIF-1α/CXCR4 axis which, in turn, promotes the activation of NF-κB and the enhancement of EMT features. These data are confirmed by treatments with either N-acetylcysteine (NAC) or AMD3100 or NF-κB inhibitor IκB-alpha which revert the FtH-silenced K562 invasive phenotype. Overall, our findings demonstrate the existence of a direct relationship among iron metabolism, redox homeostasis and EMT in the hematological malignancies. The effects of FtH dysregulation on CXCR4/CXCL12-mediated K562 cell motility extend the meaning of iron homeostasis in the leukemia cell microenvironment.

Emerging Role of Podocalyxin in the Progression of Mature B-Cell Non-Hodgkin Lymphoma

Mature B-cell non-Hodgkin lymphoma (B-NHL) constitutes a group of heterogeneous malignant lymphoproliferative diseases ranging from indolent to highly aggressive forms. Although the survival after chemo-immunotherapy treatment of mature B-NHL has increased over the last years, many patients relapse or remain refractory due to drug resistance, presenting an unfavorable prognosis. Hence, there is an urgent need to identify new prognostic markers and therapeutic targets. Podocalyxin (PODXL), a sialomucin overexpressed in a variety of tumor cell types and associated with their aggressiveness, has been implicated in multiple aspects of cancer progression, although its participation in hematological malignancies remains unexplored. New evidence points to a role for PODXL in mature B-NHL cell proliferation, survival, migration, drug resistance, and metabolic reprogramming, as well as enhanced levels of PODXL in mature B-NHL. Here, we review the current knowledge on the contribution of PODXL to tumorigenesis, highlighting and discussing its role in mature B-NHL progression.

Cellular and molecular alterations induced by low‑dose fisetin in human chronic myeloid leukemia cells

The present study aimed to evaluate the cellular and molecular effects of low concentrations of the flavonoid, fisetin, on K562 human chronic myeloid leukemia cells, in the context of both potential anti-proliferative and anti-metastatic effects. Thiazolyl blue tetrazolium bromide assay, Trypan blue exclusion assay, Annexin V/propidium iodide test, cell cycle analysis, Transwell migration and invasion assays, the fluorescence staining of β-catenin and F-actin as well as reverse transcription-quantitative polymerase chain reaction were performed to achieve the research goal. Furthermore, the nature of the interaction between fisetin and arsenic trioxide in the K562 cells was analyzed according to the Chou-Talalay median-effect method. We found that low concentrations of fisetin had not only a negligible effect on the viability and apoptosis of the K562 cells, but also modulated the mRNA levels of selected metastatic-related markers, accompanied by an increase in the migratory and invasive properties of these cancer cells. Although some markers of cell death were significantly elevated in response to fisetin treatment, these were counterbalanced through anti-apoptotic and pro-survival signals. With decreasing concentrations of fisetin and arsenic trioxide, the antagonistic interactions between the 2 agents increased. On the whole, the findings of this study suggest that careful consideration should be taken when advising cancer patients to take fisetin as a dietary supplement and when considering fisetin as a potential candidate for the treatment of chronic myeloid leukemia. Further more detailed studies are required to confirm our findings.

Up-regulation of EMT-related gene VCAN by NPM1 mutant-driven TGF-β/cPML signalling promotes leukemia cell invasion

Acute myeloid leukemia (AML) with mutated nucleophosmin (NPM1) is acknowledged as a distinct leukemia entity in the 2016 updated World Health Organization (WHO) classification. NPM1-mutated AML patients are correlated with higher extramedullary involvement. Epithelial-mesenchymal transition (EMT) is one of the key steps which cause distant metastasis in tumor. However, whether EMT-related programs contribute to cell invasion in NPM1-mutated AML remains unclear. In this study, we identified the EMT-related gene versican (VCAN) in NPM1-mutated AML across three patient datasets. Further experiments validated the elevated VCAN expression in NPM1-mutated AML primary blasts and OCI-AML3 cells with NPM1 mutation. Mechanistic studies revealed that increased VCAN expression was at least partially regulated by NPM1 mutant via TGF-β/cPML/Smad signalling. Functional evaluations showed that silencing VCAN by shRNA significantly suppressed cell migration and invasion capacity, whereas increased VCAN by overexpressing NPM1-mA enhanced migration and invasion ability of leukemia cells. Finally, we found that high expression of VCAN was associated with poor prognosis in AML patients. These findings provide insights into the involvement of EMT-related gene VCAN in the pathogenesis of NPM1-mutated leukemia, which suggests that VCAN is an attractive target for novel diagnostic and therapeutic strategies in NPM1-mutated AML.

Transcriptome analysis of Sézary syndrome and lymphocytic-variant hypereosinophilic syndrome T cells reveals common and divergent genes

Sézary syndrome (SS) is an aggressive cutaneous T cell lymphoma with pruritic skin inflammation and immune dysfunction, driven by neoplastic, clonal memory T cells in both peripheral blood and skin. To gain insight into abnormal gene expression promoting T cell dysfunction, lymphoproliferation and transformation in SS, we first compared functional transcriptomic profiles of both resting and activated CD4⁺CD45RO⁺ T cells from SS patients and normal donors to identified differential expressed genes. Next, a meta-analysis was performed to compare our SS data to public microarray data from a novel benign disease control, lymphocytic-variant hypereosinophilic syndrome (L-HES). L-HES is a rare, clonal lymphoproliferation of abnormal memory T cells that produces similar clinical symptoms as SS, including severe pruritus and eosinophilia. Comparison revealed gene sets specific for either SS (370 genes) or L-HES (519 genes), and a subset of 163 genes that were dysregulated in both SS and L-HES T cells compared to normal donor T cells. Genes confirmed by RT-qPCR included elevated expression of PLS3, TWIST1 and TOX only in SS, while IL17RB mRNA was increased only in L-HES. CDCA7 was increased in both diseases. In an L-HES patient who progressed to peripheral T cell lymphoma, the malignant transformation identified increases in the expression of CDCA7, TIGIT, and TOX, which are highly expressed in SS, suggesting that these genes contribute to neoplastic transformation. In summary, we have identified gene expression biomarkers that implicate a common transformative mechanism and others that are unique to differentiate SS from L-HES.

Single-Cell Lymphocyte Heterogeneity in Advanced Cutaneous T-cell Lymphoma Skin Tumors

PURPOSE

The heterogeneity of tumor cells presents a major challenge to cancer diagnosis and therapy. Cutaneous T-cell lymphomas (CTCL) are a group of T lymphocyte malignancies that primarily affect skin. Lack of highly specific markers for malignant lymphocytes prevents early diagnosis, while only limited treatment options are available for patients with advanced stage CTCL. Droplet-based single-cell transcriptome analysis of CTCL skin biopsies opens avenues for dissecting patient-specific T lymphocyte heterogeneity, providing a basis for identifying specific markers for diagnosis and cure of CTCL.

EXPERIMENTAL DESIGN

Single-cell RNA-sequencing was performed by Droplet-based sequencing (10X Genomics), focusing on 14,056 CD3⁺ lymphocytes (448 cells from normal and 13,608 cells from CTCL skin samples) from skin biopsies of 5 patients with advanced-stage CTCL and 4 healthy donors. Protein expression of identified genes was validated in advanced stage CTCL skin tumors by immunohistochemistry and confocal immunofluorescence microscopy.

RESULTS

Our analysis revealed a large inter- and intratumor gene expression heterogeneity in the T lymphocyte subset, as well as a common gene expression signature in highly proliferating lymphocytes that was validated in multiple advanced-stage skin tumors. In addition, we established the immunologic state of reactive lymphocytes and found heterogeneity in effector and exhaustion programs across patient samples.

CONCLUSIONS

Single-cell analysis of CTCL skin tumor samples reveals patient-specific landscapes of malignant and reactive lymphocytes within the local microenvironment of each tumor, giving an unprecedented view of lymphocyte heterogeneity and identifying tumor-specific molecular signatures, with important implications for diagnosis and personalized disease treatment.