cx-4945 and Precursor-T-Cell-Lymphoblastic-Leukemia-Lymphoma

Topics: Casein Kinase II; Cell Line, Tumor; Chromatin Assembly and Disassembly; Class I Phosphatidylinositol 3-Kinases; Gene Expression Regulation, Leukemic; HEK293 Cells; Humans; Ikaros Transcription Factor; Naphthyridines; Phenazines; Phosphatidylinositol 3-Kinases; Phosphorylation; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Promoter Regions, Genetic; Protein Binding; Signal Transduction

Human acute T-lymphocytic leukemia (T-ALL) is one of the most commonly diagnosed hematological disorders, and is characterized by poor prognosis and survival rate. Despite the development of new therapeutic approaches, leukemia treatment options remain limited. In this study, we investigated the immunosuppressive and anti-proliferative effects of the synthetic estrogen diethylstilbestrol (DES), both alone and combined with the casein kinase 2 (CK2) inhibitor CX-4945. Our results indicated that DES induced caspase-dependent apoptosis in a human T-ALL cell line (Jurkat cells), while exerting no significant cytotoxicity in normal peripheral blood mononuclear cells (PBMCs). Phytohaemagglutinin and phorbol 12-myristate 13-acetate induced interleukin (IL)-2 production and activation of NF-κB signaling pathways, which were both inhibited by DES. Moreover, DES exerted synergistic effects with CX-4945 on proliferation and IL-2 production in Jurkat cells. Our results demonstrated that DES exerts anti-proliferative and immunosuppressive effects through inhibition of CK2 and the NF-κB signaling pathway in human T-ALL Jurkat cells.

Topics: Antineoplastic Agents; Apoptosis; Casein Kinase II; Cell Line, Tumor; Cell Proliferation; Cell Survival; Diethylstilbestrol; Drug Synergism; Humans; Immunosuppressive Agents; Interleukin-2; Jurkat Cells; Leukocytes, Mononuclear; Naphthyridines; NF-kappa B; Phenazines; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Signal Transduction

Since 1970, the isolated and identified components of Brucea javanica (L.) Merr. have been known to contain anticancer effects, particularly antileukemic effect. In this study, the inhibitory effect of Brucea javanica (BJ) on cell growth and inflammation was confirmed in human T-cell acute lymphocytic leukemia (T-ALL) cells, and its efficacy as an antileukemic agent was verified. Our results showed that BJ extract induced caspase-dependent apoptosis of T-ALL Jurkat cells through inhibition of the CK2-mediated signaling pathway, while exerting no significant cytotoxicity in normal peripheral blood mononuclear cells. Moreover, BJ extract suppressed the NF-κB signaling pathway, thus, inhibiting the interleukin (IL)-2 expression induced by phorbol 12-myristate 13-acetate (PMA) and phytohemagglutinin (PHA). Notably, combined treatment with BJ extract plus CX-4945 or imatinib exerted enhanced inhibitory effects on T-ALL cell growth and IL-2 production. Overall, these results suggest that BJ extract can be a potent therapeutic herbal agent for T-ALL treatment and prevention of IL-2 mediated inflammatory immune responses.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Brucea; Casein Kinase II; Caspase 3; Caspase 8; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Humans; Imatinib Mesylate; Immunosuppressive Agents; Interleukin-2; Jurkat Cells; Naphthyridines; NF-kappa B; Phenazines; Phosphorylation; Phytotherapy; Plant Extracts; Plants, Medicinal; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-akt; Signal Transduction; Time Factors

Topics: Azepines; Casein Kinase II; Cell Line, Tumor; Drug Synergism; Female; Humans; Male; Naphthyridines; Neoplasm Proteins; Phenazines; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Protein Stability; Receptor, Notch1; Triazoles

The proteasome inhibitor bortezomib is a new targeted treatment option for refractory or relapsed acute lymphoblastic leukemia (ALL) patients. However, a limited efficacy of bortezomib alone has been reported. A terminal pro-apoptotic endoplasmic reticulum (ER) stress/unfolded protein response (UPR) is one of the several mechanisms of bortezomib-induced apoptosis. Recently, it has been documented that UPR disruption could be considered a selective anti-leukemia therapy. CX-4945, a potent casein kinase (CK) 2 inhibitor, has been found to induce apoptotic cell death in T-ALL preclinical models, via perturbation of ER/UPR pathway. In this study, we analyzed in T- and B-ALL preclinical settings, the molecular mechanisms of synergistic apoptotic effects observed after bortezomib/CX-4945 combined treatment. We demonstrated that, adding CX-4945 after bortezomib treatment, prevented leukemic cells from engaging a functional UPR in order to buffer the bortezomib-mediated proteotoxic stress in ER lumen. We documented that the combined treatment decreased pro-survival ER chaperon BIP/Grp78 expression, via reduction of chaperoning activity of Hsp90. Bortezomib/CX-4945 treatment inhibited NF-κB signaling in T-ALL cell lines and primary cells from T-ALL patients, but, intriguingly, in B-ALL cells the drug combination activated NF-κB p65 pro-apoptotic functions. In fact in B-cells, the combined treatment induced p65-HDAC1 association with consequent repression of the anti-apoptotic target genes, Bcl-xL and XIAP. Exposure to NEMO (IKKγ)-binding domain inhibitor peptide reduced the cytotoxic effects of bortezomib/CX-4945 treatment. Overall, our findings demonstrated that CK2 inhibition could be useful in combination with bortezomib as a novel therapeutic strategy in both T- and B-ALL.

Topics: Antineoplastic Agents; Apoptosis; Blotting, Western; Bortezomib; Casein Kinase II; Cell Line, Tumor; Cell Survival; Drug Synergism; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Heat-Shock Proteins; Humans; Jurkat Cells; Microscopy, Fluorescence; Naphthyridines; Neoplastic Stem Cells; Phenazines; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Transcription Factor RelA; Unfolded Protein Response

Constitutively active casein kinase 2 (CK2) signaling is a common feature of T-cell acute lymphoblastic leukemia (T-ALL). CK2 phosphorylates PTEN (phosphatase and tensin homolog) tumor suppressor, resulting in PTEN stabilization and functional inactivation. Downregulation of PTEN activity has an impact on PI3K/Akt/mTOR signaling, which is of fundamental importance for T-ALL cell survival. These observations lend compelling weight to the application of CK2 inhibitors in the therapy of T-ALL. Here, we have analyzed the therapeutic potential of CX-4945-a novel, highly specific, orally available, ATP-competitive inhibitor of CK2α. We show that CX-4945 treatment induced apoptosis in T-ALL cell lines and patient T lymphoblasts. CX-4945 downregulated PI3K/Akt/mTOR signaling in leukemic cells. Notably, CX-4945 affected the unfolded protein response (UPR), as demonstrated by a significant decrease in the levels of the main UPR regulator GRP78/BIP, and led to apoptosis via upregulation of the ER stress/UPR cell death mediators IRE1α and CHOP. In vivo administration of CX-4945 to a subcutaneous xenotransplant model of human T-ALL significantly delayed tumor growth. Our findings indicate that modulation of the ER stress/UPR signaling through CK2 inhibition could be exploited for inducing apoptosis in T-ALL cells and that CX-4945 may be an efficient treatment for those T-ALLs displaying upregulation of CK2α/PI3K/Akt/mTOR signaling.

Topics: Animals; Antineoplastic Agents; Casein Kinase II; Cell Division; Endoplasmic Reticulum Chaperone BiP; Humans; Mice; Mice, Inbred NOD; Mice, SCID; Naphthyridines; Neoplasm Proteins; Phenazines; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Signal Transduction; Unfolded Protein Response