Pharmacological Activation of Potassium Channel Kv11.1 with NS1643 Attenuates Triple Negative Breast Cancer Cell Migration by Promoting the Dephosphorylation of Caveolin-1.

The prevention of metastasis is a central goal of cancer therapy. Caveolin-1 (Cav-1) is a structural membrane and scaffolding protein shown to be a key regulator of late-stage breast cancer metastasis. However, therapeutic strategies targeting Cav-1 are still lacking.

Molecular Activation of the Kv11.1 Channel Reprograms EMT in Colon Cancer by Inhibiting TGFβ Signaling via Activation of Calcineurin.

Control of ionic gradients is critical to maintain cellular homeostasis in both physiological and pathological conditions, but the role of ion channels in cancer cells has not been studied thoroughly. In this work we demonstrated that activity of the Kv11.1 potassium channel plays a vital role in controlling the migration of colon cancer cells by reversing the epithelial-to-mesenchymal transition (EMT) into the mesenchymal-to-epithelial transition (MET).

Compensatory expression of NRF2-dependent antioxidant genes is required to overcome the lethal effects of Kv11.1 activation in breast cancer cells and PDOs.

Potassium channels are important regulators of cellular homeostasis and targeting these proteins pharmacologically is unveiling important mechanisms in cancer cell biology. Here we demonstrate that pharmacological stimulation of the Kv11.1 potassium channel activity results in mitochondrial reactive oxygen species (ROS) production and fragmentation in breast cancer cell lines and patient-derived organoids independent of breast cancer subtype.

Repurposing Kir6/SUR2 Channel Activator Minoxidil to Arrests Growth of Gynecologic Cancers.

Gynecologic cancers are among the most lethal cancers found in women, and, advanced stage cancers are still a treatment challenge. Ion channels are known to contribute to cellular homeostasis in all cells and mounting evidence indicates that ion channels could be considered potential therapeutic targets against cancer. Nevertheless, the pharmacologic effect of targeting ion channels in cancer is still understudied.

PARP Inhibition Synergizes with Melphalan but Does not Reverse Resistance Completely.

High-dose melphalan (MEL) and autologous stem cell transplantation (ASCT) is the standard of care in the treatment of multiple myeloma (MM). Resistance to MEL has been linked to increased DNA repair. Here we sought to identify whether inhibition of poly(ADP-ribose) polymerase (PARP) synergizes with MEL and can overcome resistance.

Chromatin-Modifying Agent-Expanded Human Cord Blood Cells Display Reduced Allostimulatory Capacity.

The limited number of hematopoietic stem cells (HSC) within a single unit of human cord blood currently limits its use as an alternate graft source. However, we have developed a strategy using 5-aza-2'-deoxycytidine (5azaD) and trichostatin A (TSA), which expands transplantable HSC 7- to 10-fold. In our current studies, we have assessed the allostimulatory capacity of the 5azaD/TSA-expanded grafts.

Blockade of TNFα to Improve Human CD34+ Cell Repopulating Activity in Allogeneic Stem Cell Transplantation.

Early release of TNFα after hematopoietic stem cell transplantation (HSCT) correlates with development of acute graft-vs.-host disease (GVHD). Here we tested the effect of TNFα and alloreactive T cells on early hematopoietic HSC genotype and function.

Synergistic Cytotoxic Effect of Busulfan and the PARP Inhibitor Veliparib in Myeloproliferative Neoplasms.

Patients with high-risk myeloproliferative neoplasms (MPNs), and in particular myelofibrosis (MF), can be cured only with allogeneic hematopoietic stem cell transplantation (HSCT). Because MPNs and JAK2-mutated cells show genomic instability, stalled replication forks, and baseline DNA double-strand breaks, DNA repair inhibition with poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors represents a potential novel therapy. Because the alkylating agent busulfan is integral in conditioning regimens for HSCT and leads to stalled replication forks through DNA strand cross-linking, we hypothesized that PARP inhibition with veliparib in combination with busulfan may lead to synergistic cytotoxicity in MPN cells.

miR-9 upregulation leads to inhibition of erythropoiesis by repressing FoxO3.

MicroRNAs (miRNAs) are emerging as critical regulators of normal and malignant hematopoiesis. In previous studies of acute myeloid leukemia miR-9 overexpression was commonly observed. Here, we show that ectopic expression of miR-9 in vitro and in vivo significantly blocks differentiation of erythroid progenitor cells with an increase in reactive oxygen species (ROS) production.

T Cell-Mediated Rejection of Human CD34 Cells Is Prevented by Costimulatory Blockade in a Xenograft Model.

A xenograft model of stem cell rejection was developed by co-transplantating human CD34 and allogeneic CD3 T cells into NOD-scid ɣ-chain mice. T cells caused graft failure when transplanted at any CD34/CD3 ratio between 1:50 and 1:.1.

Critical role of miR-9 in myelopoiesis and EVI1-induced leukemogenesis.

MicroRNA-9 (miR-9) is emerging as a critical regulator of organ development and neurogenesis. It is also deregulated in several types of solid tumors; however, its role in hematopoiesis and leukemogenesis is not yet known. Here we show that miR-9 is detected in hematopoietic stem cells and hematopoietic progenitor cells, and that its expression increases during hematopoietic differentiation.

Activation of Wnt/β-catenin protein signaling induces mitochondria-mediated apoptosis in hematopoietic progenitor cells.

The canonical Wnt/β-catenin signaling is activated during development, tumorigenesis, and in adult homeostasis, yet its role in maintenance of hematopoietic stem/progenitor cells is not firmly established. Here, we demonstrate that conditional expression of an active form of β-catenin in vivo induces a marked increase in the frequency of apoptosis in hematopoietic stem/progenitor cells (HSCs/HPCs). Activation of Wnt/β-catenin signaling in HPCs in vitro elevates the activity of caspases 3 and 9 and leads to a loss of mitochondrial membrane potential (ΔΨ(m)), indicating that it induces the intrinsic mitochondrial apoptotic pathway.

The oncoprotein EVI1 and the DNA methyltransferase Dnmt3 co-operate in binding and de novo methylation of target DNA.

EVI1 has pleiotropic functions during murine embryogenesis and its targeted disruption leads to prenatal death by severely affecting the development of virtually all embryonic organs. However, its functions in adult tissues are still unclear. When inappropriately expressed, EVI1 becomes one of the most aggressive oncogenes associated with human hematopoietic and solid cancers.

Preferential nuclear accumulation of JAK2V617F in CD34+ but not in granulocytic, megakaryocytic, or erythroid cells of patients with Philadelphia-negative myeloproliferative neoplasia.

Recently, Dawson et al identified a previously unrecognized nuclear role of JAK2 in the phosphorylation of histone H3 in hematopoietic cell lines. We searched nuclear JAK2 in total bone marrow (BM) cells and in 4 sorted BM cell populations (CD34(+), CD15(+), CD41(+), and CD71(+)) of 10 myeloproliferative neoplasia (MPN) patients with JAK2V617F mutation and 5 patients with wild-type JAK2 MPN. Confocal immunofluorescent images and Western blot analyses of nuclear and cytoplasmic fractions found nuclear JAK2 in CD34(+) cells of 10 of 10 JAK2-mutated patients but not in patients with wild-type JAK2.

Methylation and silencing of miRNA-124 by EVI1 and self-renewal exhaustion of hematopoietic stem cells in murine myelodysplastic syndrome.

By expressing EVI1 in murine bone marrow (BM), we previously described a myelodysplastic syndrome (MDS) model characterized by pancytopenia, dysmegakaryopoiesis, dyserythropoiesis, and BM failure. The mice invariably died 11-14 months after BM transplantation (BMT). Here, we show that a double point mutant EVI1-(1+6Mut), unable to bind Gata1, abrogates the onset of MDS in the mouse and re-establishes normal megakaryopoiesis, erythropoiesis, BM function, and peripheral blood profiles.

Consistent up-regulation of Stat3 Independently of Jak2 mutations in a new murine model of essential thrombocythemia.

Janus-activated kinase 2 (JAK2) mutations are common in myeloproliferative disorders; however, although they are detected in virtually all polycythemia vera patients, they are found in approximately 50% of essential thrombocythemia (ET) patients, suggesting that converging pathways/abnormalities underlie the onset of ET. Recently, the chromosomal translocation 3;21, leading to the fusion gene AML1/MDS1/EVI1 (AME), was observed in an ET patient. After we forced the expression of AME in the bone marrow (BM) of C57BL/6J mice, all the reconstituted mice died of a disease with symptoms similar to ET with a latency of 8 to 16 months.

Repression of RUNX1 activity by EVI1: a new role of EVI1 in leukemogenesis.

Recurring chromosomal translocations observed in human leukemia often result in the expression of fusion proteins that are DNA-binding transcription factors. These altered proteins acquire new dimerization properties that result in the assembly of inappropriate multimeric transcription complexes that deregulate hematopoietic programs and induce leukemogenesis. Recently, we reported that the fusion protein AML1/MDS1/EVI1 (AME), a product of a t(3;21)(q26;q22) associated with chronic myelogenous leukemia and acute myelogenous leukemia, displays a complex pattern of self-interaction.

EVI1 and hematopoietic disorders: history and perspectives.

The ecotropic viral integration site 1 (EVI1) gene was identified almost 20 years ago as the integration site of an ecotropic retrovirus leading to murine myeloid leukemia. Since its identification, EVI1 has slowly been recognized as one of the most aggressive oncogenes associated with human leukemia. Despite the effort of many investigators, still very little is known about this gene.

The distal zinc finger domain of AML1/MDS1/EVI1 is an oligomerization domain involved in induction of hematopoietic differentiation defects in primary cells in vitro.

AML1/MDS1/EVI1 (AME) is a chimeric transcription factor produced by the (3;21)(q26;q22) translocation. This chromosomal translocation is associated with de novo and therapy-related acute myeloid leukemia and with the blast crisis of chronic myelogenous leukemia. AME is obtained by in-frame fusion of the AML1 and MDS1/EVI1 (ME) genes.

Corepressor CtBP1 interacts with and specifically inhibits CBP activity.

Transcription repression in eukaryotes is mediated by a wide variety of transcription factors that usually recruit corepressors and form corepressor complexes at the specific promoter sites. One of these corepressors is the C-terminal-binding protein (CtBP) which was first identified as a protein that binds to the C-terminal region of the adenovirus E1A protein. CtBP has a strong role in both development and oncogenesis.

EVI1 promotes cell proliferation by interacting with BRG1 and blocking the repression of BRG1 on E2F1 activity.

EVI1 is a complex protein required for embryogenesis and inappropriately expressed in many types of human myeloid leukemia. Earlier we showed that the forced expression of EVI1 in murine hematopoietic precursor cells leads to their abnormal differentiation and increased proliferation. In this report, we show that EVI1 physically interacts with BRG1 and its functional homolog BRM in mammalian cells.

The role of EVI1 in normal and leukemic cells.

One of the genes associated with both murine and human myeloid leukemia is EVI1 (ecotropic viral integration 1 site). EVI1 was first identified as a common locus of retroviral integration in myeloid tumors found in AKXD mice. The exact mechanism by which EVI1 induces leukemogenesis is not clear.

SUV39H1 interacts with AML1 and abrogates AML1 transactivity. AML1 is methylated in vivo.

Acute myeloid leukemia 1 (AML1) belongs to a family of DNA-binding proteins highly conserved through evolution. AML1 regulates the expression of several hematopoietic genes and is essential for murine fetal liver hematopoiesis. We report here that the histone methyltransferase SUV39H1, a mammalian ortholog of the Drosophila melanogaster SU(VAR) 3-9, forms complex with AML1.

P/CAF and GCN5 acetylate the AML1/MDS1/EVI1 fusion oncoprotein.

Lysine acetyltransferases modulate the activity of many genes by modifying the lysine residues of both core histones and transcription-related factors. These modifications are tightly controlled in the cell because they are involved in vital processes such as cell cycle progression, differentiation, and apoptosis. Therefore, any deregulation of acetylation/deacetylation equilibrium or inappropriate modifications could lead to different diseases.

The leukemia-associated transcription repressor AML1/MDS1/EVI1 requires CtBP to induce abnormal growth and differentiation of murine hematopoietic cells.

The leukemia-associated fusion gene AML1/MDS1/EVI1 (AME) encodes a chimeric transcription factor that results from the (3;21)(q26;q22) translocation. This translocation is observed in patients with therapy-related myelodysplastic syndrome (MDS), with chronic myelogenous leukemia during the blast crisis (CML-BC), and with de novo or therapy-related acute myeloid leukemia (AML). AME is obtained by in-frame fusion of the AML1 and MDS1/EVI1 genes.