Src, Akt, NF-κB, BCL-2 and c-IAP1 may be involved in an anti-apoptotic effect in patients with BCR-ABL positive and BCR-ABL negative acute lymphoblastic leukemia

Central gene transcriptional regulatory networks shaping monocyte development in bone marrow

The development of monocytes in bone marrow is a complex process with multiple steps. We used RNA-seq data to analyze the transcriptome profiles in developing stages of monocytes, including hematopoietic stem cells (HSCs), common myeloid progenitors (CMPs), granulocyte-monocyte progenitors (GMPs), and monocytes. We found that genes related to potassium and other cation transmembrane activities and ion binding were upregulated during the differentiation of HSCs into CMPs. Protein transport and membrane surface functional molecules were significantly upregulated in the GMP stage. The CD42RAC and proteasome pathways are significantly upregulated during the development of HSCs into monocytes. Transcription factors Ank1, Runx2, Hmga2, Klf1, Nfia, and Bmyc were upregulated during the differentiation of HSCs into CMPs; Gfi1 and Hmgn2 were highly expressed during the differentiation of CMPs into GMPs; Seventeen transcription factors including Foxo1, Cdkn2d, Foxo3, Ep300, Pias1, Nfkb1, Creb1, Bcl6, Ppp3cb, Stat5b, Nfatc4, Mef2a, Stat6, Ifnar2, Irf7, Irf5, and Cebpb were identified as potentially involved in the development of GMPs into monocytes in mice and humans. In metabolism pathway regulation, HSCs have high glucose, lipid, and nucleic acid metabolism activities; CMPs mainly up regulate the TCA cycle related genes; and GMPs have extremely active metabolisms, with significantly elevated pentose phosphate pathway, TCA cycle, histidine metabolism, and purine metabolism. In the monocyte phase, the tricarboxylic acid (TCA) cycle is reduced, and the anaerobic glycolysis process becomes dominated. Overall, our studies offer the kinetics and maps of gene transcriptional expressions and cell metabolisms during monocyte development in bone marrow.

Hemopoietic Cell Kinase amplification with Protein Tyrosine Phosphatase Receptor T depletion leads to polycythemia, aberrant marrow erythoid maturation, and splenomegaly

Deletion of long arm of chromosome 20 [del(20q)] is the second most frequent recurrent chromosomal abnormality in hematological malignancies. It is detected in 10% of myeloproliferative neoplasms, 4-5% of myelodysplastic syndromes, and 1-2% of acute myeloid leukaemia. Recurrent, non-random occurrence of del(20q) indicates that it is a pathogenic driver in myeloid malignancies. Genetic mapping of patient samples has identified two regions of interest on 20q - the "Common Deleted Region" (CDR) and "Common Retained Region" (CRR), which was often amplified. We proposed that the CDR contained tumor suppressor gene(s) (TSG) and the CRR harbored oncogene(s); loss of a TSG together with over-expression of an oncogene favored development of myeloid malignancies. Protein Tyrosine Phosphatase Receptor T (PTPRT) and Hemopoietic cell kinase (HCK) were identified to be the likely candidate TSG and oncogene respectively. Retroviral transduction of HCK into PTPRT-null murine LKS+ stem and progenitor cells resulted in hyperproliferation in colony forming assays and hyperphosphorylation of intracellular STAT3. Furthermore, over half of the murine recipients of these transduced cells developed erythroid hyperplasia, polycythemia and splenomegaly at 12 months, although no leukemic phenotype was observed. The findings suggested that HCK amplification coupled with PTPRT loss in del(20q) leads to development of a myeloproliferative phenotype.

A novel orally available Syk/Src/Jak2 inhibitor, SKLB-850, showed potent anti-tumor activities in B cell lymphoma (BCL) models

B cell lymphoma (BCL) is the most frequently diagnosed type of non-Hodgkin lymphoma (NHL), and accounts for about 4% of all cancers in the USA. Kinases spleen tyrosine kinase (Syk), Src, and Janus kinase 2 (JAK2) have been thought as potential targets for the treatment of BCL. We have recently developed a multikinase inhibitor, SKLB-850, which potently inhibits Syk, Src, and JAK2. The aim of this study is to investigate the anti-BCL activities and mechanisms of action of SKLB-850 both in vitro and in vivo. Our results showed that SKLB-850 significantly inhibited BCL cell proliferation, and induced apoptosis of BCL cells. It could considerably decrease the secretion of chemokines CCL3, CCL4, and CXCL12. Oral administration of SKLB-850 considerably suppressed the tumor growth in BCL xenograft models (Ramos and HBL-1) in a dose-dependent manner. Immunohistochemistry of tumor tissues showed that SKLB-850 efficiently inhibited the activation of Syk/ERK, Src/FAK and JAK2/Stat3 pathways. Collectively, SKLB-850 could be a promising agent for the treatment of BCL, hence deserving further study.

ADAM28 overexpression regulated via the PI3K/Akt pathway is associated with relapse in de novo adult B-cell acute lymphoblastic leukemia

B-cell acute lymphoblastic leukemia (B-ALL) in adults is a very challenging disease. Relapse following remission after induction chemotherapy remains the major barrier to patient survival. ADAM28 is overexpressed in several human tumors and is related to cell proliferation and lymph node metastasis. To date, no information has been available on the prognostic role of ADAM28 in B-ALL. Fifty consecutive patients with de novo B-ALL and 22 healthy donors were enrolled in this study and were followed for 2.8 years. Our data suggested that ADAM28 expression in B-ALL patients was significantly increased (P<0.0001). Patients experiencing disease relapse exhibited significantly increased ADAM28 expression, compared with those with favorable outcomes (P=0.0094). Notably, ADAM28 overexpression was associated with lower probabilities of relapse-free survival (RFS) and event-free survival (EFS) (P<0.001) and was a significant prognostic factor (P<0.001). In vitro, the PI3K/Akt pathway inhibitor, as well as arsenic trioxide (ATO), down-regulated ADAM28 expression. Our results were the first to indicate that ADAM28 overexpression in B-ALL patients is correlated with relapse. ADAM28 overexpression is potentially regulated by the PI3K/Akt pathway. These data demonstrate that ADAM28 might serve as a novel biomarker for evaluating relapse in B-ALL and as a potential therapeutic target in B-ALL patients.

The casein kinase 2 inhibitor, CX-4945, as an anti-cancer drug in treatment of human hematological malignancies

The casein kinase 2 (CK2) protein kinase is a pro-survival kinase and therapeutic target in treatment of various human cancers. CK2 overexpression has been demonstrated in hematological malignancies, including chronic lymphocytic leukemia, chronic myeloid leukemia, acute lymphoblastic leukemia, acute myeloid leukemia, and multiple myeloma. CX-4945, also known as Silmitasertib, is an orally administered, highly specific, ATP-competitive inhibitor of CK2. CX-4945 induces cytotoxicity and apoptosis and is currently being evaluated in clinical trials for treatment of many cancer types. In the past 2 years, the focus on the therapeutic potential of CX-4945 has shifted from solid tumors to hematological malignancies. CX-4945 exerts anti-proliferative effects in hematological tumors by downregulating CK2 expression and suppressing activation of CK2-mediated PI3K/Akt/mTOR signaling pathways. Furthermore, combination of CX-4945 with other inhibitors yielded synergistic effects in cell death induction. These new findings demonstrate that CK2 overexpression contributes to blood cancer cell survival and resistance to chemotherapy. Combinatorial use of CX-4945 is a promising therapeutic tool for treatment of hematological malignancies.

Src family kinases and their role in hematological malignancies

The Src family protein tyrosine kinases (SFKs) are non-receptor intracellular kinases that have important roles in both hematopoiesis and leukemogenesis. The derangement of their expression or activation has been demonstrated to contribute to hematological malignancies. This review first examines the mechanisms of SFK overexpression and hyperactivation, emphasizing the dysregulation of the upstream modulators. Subsequently, the role of SFK up-regulation in the initiation, progression and therapy resistance of many hematological malignancies is also analyzed. The presented evidence endeavors to highlight the influence of SFK up-regulation on an extensive number of hematological malignancies and the need to consider them as candidates in targeted anticancer therapy.

Adult B-cell acute lymphoblastic leukemia cells display decreased PTEN activity and constitutive hyperactivation of PI3K/Akt pathway despite high PTEN protein levels

Adult B-cell acute lymphoblastic leukemia remains a major therapeutic challenge, requiring a better characterization of the molecular determinants underlying disease progression and resistance to treatment. Here, using a phospho-flow cytometry approach we show that adult diagnostic B-cell acute lymphoblastic leukemia specimens display PI3K/Akt pathway hyperactivation, irrespective of their BCR-ABL status and despite paradoxically high basal expression of PTEN, the major negative regulator of the pathway. Protein kinase CK2 is known to phosphorylate PTEN thereby driving PTEN protein stabilization and concomitant PTEN functional inactivation. In agreement, we found that adult B-cell acute lymphoblastic leukemia samples show significantly higher CK2 kinase activity and lower PTEN lipid phosphatase activity than healthy controls. Moreover, the clinical-grade CK2 inhibitor CX-4945 (Silmitasertib) reversed PTEN levels in leukemia cells to those observed in healthy controls, and promoted leukemia cell death without significantly affecting normal bone marrow cells. Our studies indicate that CK2-mediated PTEN posttranslational inactivation, associated with PI3K/Akt pathway hyperactivation, are a common event in adult B-cell acute lymphoblastic leukemia and suggest that CK2 inhibition may constitute a valid, novel therapeutic tool in this malignancy.