Integration of single-cell transcriptomes and biological function reveals distinct behavioral patterns in bone marrow endothelium.

Heterogeneity of endothelial cell (EC) populations reflects their diverse functions in maintaining tissue's homeostasis. However, their phenotypic, molecular, and functional properties are not entirely mapped. We use the Tie2-CreERT2;Rosa26-tdTomato reporter mouse to trace, profile, and cultivate primary ECs from different organs.

COVID-19 vaccination elicits an evolving, cross-reactive antibody response to epitopes conserved with endemic coronavirus spike proteins.

The COVID-19 pandemic has triggered the first widespread vaccination campaign against a coronavirus. Many vaccinated subjects are previously naive to SARS-CoV-2; however, almost all have previously encountered other coronaviruses (CoVs), and the role of this immunity in shaping the vaccine response remains uncharacterized. Here, we use longitudinal samples and highly multiplexed serology to identify mRNA-1273 vaccine-induced antibody responses against a range of CoV Spike epitopes, in both phylogenetically conserved and non-conserved regions.

Pre-clinical data supporting immunotherapy for HIV using CMV-HIV-specific CAR T cells with CMV vaccine.

T cells engineered to express HIV-specific chimeric antigen receptors (CARs) represent a promising strategy to clear HIV-infected cells, but to date have not achieved clinical benefits. A likely hurdle is the limited T cell activation and persistence when HIV antigenemia is low, particularly during antiretroviral therapy (ART). To overcome this issue, we propose to use a cytomegalovirus (CMV) vaccine to stimulate CMV-specific T cells that express CARs directed against the HIV-1 envelope protein gp120.

Engineered extracellular vesicles directed to the spike protein inhibit SARS-CoV-2.

SARS-CoV-2 (CoV-2) viral infection results in COVID-19 disease, which has caused significant morbidity and mortality worldwide. A vaccine is crucial to curtail the spread of SARS-CoV-2, while therapeutics will be required to treat ongoing and reemerging infections of SARS-CoV-2 and COVID-19 disease. There are currently no commercially available effective anti-viral therapies for COVID-19, urging the development of novel modalities.

COVID-19 vaccination recruits and matures cross-reactive antibodies to conserved epitopes in endemic coronavirus Spike proteins.

The COVID-19 pandemic has triggered the first widespread vaccination campaign against a coronavirus. Most vaccinated subjects are naïve to SARS-CoV-2, however almost all have previously encountered other coronaviruses (CoVs) and the role of this immunity in shaping the vaccine response remains uncharacterized. Here we use longitudinal samples and highly-multiplexed serology to identify mRNA-1273 vaccine-induced antibody responses against a range of CoV Spike epitopes and in both phylogenetically conserved and non-conserved regions.

The Earliest T-Precursors in the Mouse Embryo Are Susceptible to Leukemic Transformation.

Acute lymphoblastic leukemia (ALL) is the most common malignancy in pediatric patients. About 10-15% of pediatric ALL belong to T-cell ALL (T-ALL), which is characterized by aggressive expansion of immature T-lymphoblasts and is categorized as high-risk leukemia. Leukemia initiating cells represent a reservoir that is responsible for the initiation and propagation of leukemia.

Therapeutic targeting of the E3 ubiquitin ligase SKP2 in T-ALL.

Timed degradation of the cyclin-dependent kinase inhibitor p27 by the E3 ubiquitin ligase F-box protein SKP2 is critical for T-cell progression into cell cycle, coordinating proliferation and differentiation processes. SKP2 expression is regulated by mitogenic stimuli and by Notch signaling, a key pathway in T-cell development and in T-cell acute lymphoblastic leukemia (T-ALL); however, it is not known whether SKP2 plays a role in the development of T-ALL. Here, we determined that SKP2 function is relevant for T-ALL leukemogenesis, whereas is dispensable for T-cell development.

Functional analysis of HOXA10 and HOXB4 in human medulloblastoma cell lines.

Medulloblastoma (MB) is a malignant childhood brain tumor which at molecular level is classified into at least four major subtypes: WNT, SHH, group C and group D differing in response to treatment. Previous studies have associated changes in expression levels and activation of certain HOX genes with MB development. In the present study, we investigate the role of HOX genes in two attributes acquired by tumor cells: migration and proliferation potential, as well as, in vivo tumorigenic potential.

Ref-1/APE1 as a Transcriptional Regulator and Novel Therapeutic Target in Pediatric T-cell Leukemia.

The increasing characterization of childhood acute lymphoblastic leukemia (ALL) has led to the identification of multiple molecular targets but has yet to translate into more effective targeted therapies, particularly for high-risk, relapsed T-cell ALL. Searching for master regulators controlling multiple signaling pathways in T-ALL, we investigated the multifunctional protein redox factor-1 (Ref-1/APE1), which acts as a signaling "node" by exerting redox regulatory control of transcription factors important in leukemia. Leukemia patients' transcriptome databases showed increased expression in T-ALL of Ref-1 and other genes of the Ref-1/SET interactome.

Cell Adhesion Molecule CD166 Drives Malignant Progression and Osteolytic Disease in Multiple Myeloma.

Multiple myeloma is incurable once osteolytic lesions have seeded at skeletal sites, but factors mediating this deadly pathogenic advance remain poorly understood. Here, we report evidence of a major role for the cell adhesion molecule CD166, which we discovered to be highly expressed in multiple myeloma cell lines and primary bone marrow cells from patients. CD166 multiple myeloma cells homed more efficiently than CD166 cells to the bone marrow of engrafted immunodeficient NSG mice.

Sepsis Induces Hematopoietic Stem Cell Exhaustion and Myelosuppression through Distinct Contributions of TRIF and MYD88.

Toll-like receptor 4 (TLR4) plays a central role in host responses to bacterial infection, but the precise mechanism(s) by which its downstream signaling components coordinate the bone marrow response to sepsis is poorly understood. Using mice deficient in TLR4 downstream adapters MYD88 or TRIF, we demonstrate that both cell-autonomous and non-cell-autonomous MYD88 activation are major causes of myelosuppression during sepsis, while having a modest impact on hematopoietic stem cell (HSC) functions. In contrast, cell-intrinsic TRIF activation severely compromises HSC self-renewal without directly affecting myeloid cells.

Notch-dependent repression of miR-155 in the bone marrow niche regulates hematopoiesis in an NF-κB-dependent manner.

The microRNA miR-155 has been implicated in regulating inflammatory responses and tumorigenesis, but its precise role in linking inflammation and cancer has remained elusive. Here, we identify a connection between miR-155 and Notch signaling in this context. Loss of Notch signaling in the bone marrow (BM) niche alters hematopoietic homeostasis and leads to lethal myeloproliferative-like disease.

CD166 regulates human and murine hematopoietic stem cells and the hematopoietic niche.

We previously showed that immature CD166(+) osteoblasts (OB) promote hematopoietic stem cell (HSC) function. Here, we demonstrate that CD166 is a functional HSC marker that identifies both murine and human long-term repopulating cells. Both murine LSKCD48(-)CD166(+)CD150(+) and LSKCD48(-)CD166(+)CD150(+)CD9(+) cells, as well as human Lin(-)CD34(+)CD38(-)CD49f(+)CD166(+) cells sustained significantly higher levels of chimerism in primary and secondary recipients than CD166(-) cells.

APE1/Ref-1 regulates STAT3 transcriptional activity and APE1/Ref-1-STAT3 dual-targeting effectively inhibits pancreatic cancer cell survival.

Pancreatic cancer is a largely incurable disease, and increasing evidence supports strategies targeting multiple molecular mediators of critical functions of pancreatic ductal adenocarcinoma cells. Intracellular redox state modulates the activity of various signal transduction pathways and biological processes, including cell survival, drug resistance and responsiveness to microenvironmental factors. Recently, it has been shown that the transcription factor STAT3 is under redox control, but the mechanisms involved in its regulation are unknown.

Establishment and characterization of a novel cell line derived from human thymoma AB tumor.

Thymomas are low-grade epithelial tumors of the anterior mediastinum. The complexity of the disease and the lack of in vitro and in vivo models hamper the development of better therapeutics. In this study, we report a novel cell line, designated as IU-TAB-1, which was established from a patient with stage II thymoma (World Health Organization-type AB).

Autonomous murine T-cell progenitor production in the extra-embryonic yolk sac before HSC emergence.

The extra-embryonic yolk sac (YS) is the first hematopoietic site in the mouse embryo and is thought to generate only primitive erythroid and myeloerythroid progenitor cells before definitive HSC emergence within the embryo on E10.5. Here, we have shown the existence of T cell-restricted progenitors in the E9.

A noncanonical Flt3ITD/NF-κB signaling pathway represses DAPK1 in acute myeloid leukemia.

Purpose: Death-associated protein kinase 1 (DAPK1), a tumor suppressor, is a rate-limiting effector in an endoplasmic reticulum (ER) stress-dependent apoptotic pathway. Its expression is epigenetically suppressed in several tumors. A mechanistic basis for epigenetic/transcriptional repression of DAPK1 was investigated in certain forms of acute myeloid leukemia (AML) with poor prognosis, which lacked ER stress-induced apoptosis.

Aberrant expression of functional BAFF-system receptors by malignant B-cell precursors impacts leukemia cell survival.

Despite exhibiting oncogenic events, patient's leukemia cells are responsive and dependent on signals from their malignant bone marrow (BM) microenvironment, which modulate their survival, cell cycle progression, trafficking and resistance to chemotherapy. Identification of the signaling pathways mediating this leukemia/microenvironment interplay is critical for the development of novel molecular targeted therapies.We observed that primary leukemia B-cell precursors aberrantly express receptors of the BAFF-system, BAFF-R, BCMA, and TACI.

Increased CCL2 and IL-8 in the bone marrow microenvironment in acute lymphoblastic leukemia.

Background: The interactions of acute lymphoblastic leukemia (ALL) blasts with bone marrow (BM) stromal cells have a positive impact on leukemia cell survival. In the present study, we proposed to identify and investigate the role of molecules critically involved in leukemia--microenvironment crosstalk.

Procedure: Gene expression profiling analyses of BM mesenchymal stem cells (BMMSC) were performed following stimulation by ALL cells.

Targeting of active mTOR inhibits primary leukemia T cells and synergizes with cytotoxic drugs and signaling inhibitors.

Objective: Rationally designed therapies aim at the specific disruption of critical signaling pathways activated by malignant transformation or signals from the tumor microenvironment. Because mammalian target of rapamycin (mTOR) is an important signal integrator and a key translational regulator, we evaluated its potential involvement in T-cell acute lymphoblastic leukemia (T-ALL) and whether mTOR blockade synergizes with chemotherapeutic agents or other signaling antagonists to inhibit primary leukemia T cells.

Materials And Methods: mTOR signaling status was assessed using biochemical, immunostaining, and molecular regulation studies and functional assays performed to assess the impact of mTOR blockade on T-ALL proliferation, survival, and cell cycle.

Stem cell regulatory niches and their role in normal and malignant hematopoiesis.

Purpose Of Review: In the postnatal life, hematopoietic stem cell (HSC) niches are specialized microenvironments in the bone marrow that are essential for the maintenance and function of HSCs. The purpose of this review is to discuss the concept of HSC niche in light of recent studies that broaden its complexity and better define its molecular regulation. Also, we will discuss recent studies addressing the impact of leukemia development on HSC regulation and normal hematopoiesis, while discussing the potential regulation of leukemia-initiating cells by bone marrow niches.

Smooth muscle cells orchestrate the endothelial cell response to flow and injury.

Background: Local modulation of vascular mammalian target of rapamycin (mTOR) signaling reduces smooth muscle cell (SMC) proliferation after endovascular interventions but may be associated with endothelial cell (EC) toxicity. The trilaminate vascular architecture juxtaposes ECs and SMCs to enable complex paracrine coregulation but shields SMCs from flow. We hypothesized that flow differentially affects mTOR signaling in ECs and SMCs and that SMCs regulate mTOR in ECs.

Antiproliferative effects of a series of cyclic imides on primary endothelial cells and a leukemia cell line.

The present study describes the cytotoxic properties of a series of 15 cyclic imides observed against different endothelial cells and K562 leukemic cells. Initially, eight structurally unrelated compounds were evaluated against cultured bone marrow endothelial cells (BMEC) and human umbilical vein endothelial cells (HUVEC). Only two imides showed cytotoxic activity at 10 microM.

PTEN posttranslational inactivation and hyperactivation of the PI3K/Akt pathway sustain primary T cell leukemia viability.

Mutations in the phosphatase and tensin homolog (PTEN) gene leading to PTEN protein deletion and subsequent activation of the PI3K/Akt signaling pathway are common in cancer. Here we show that PTEN inactivation in human T cell acute lymphoblastic leukemia (T-ALL) cells is not always synonymous with PTEN gene lesions and diminished protein expression. Samples taken from patients with T-ALL at the time of diagnosis very frequently showed constitutive hyperactivation of the PI3K/Akt pathway.