nitrophenols and Precursor-T-Cell-Lymphoblastic-Leukemia-Lymphoma

Topics: Apoptosis; Biphenyl Compounds; Caspase 8; Caspase Inhibitors; Cell Line; Cell Line, Tumor; Ceramides; Drug Resistance, Neoplasm; fas Receptor; HEK293 Cells; Humans; Membrane Proteins; Nitrophenols; Oligopeptides; Piperazines; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Protein Binding; Proto-Oncogene Proteins c-bcl-2; RNA Interference; RNA, Small Interfering; Sphingolipids; Sphingosine N-Acyltransferase; Sulfonamides

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Biphenyl Compounds; Drug Liberation; Drug Synergism; Female; Humans; Interleukin-1 Receptor-Associated Kinases; Jurkat Cells; Lactic Acid; Mice; Nanoparticles; Nitrophenols; Piperazines; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Sulfonamides; Xenograft Model Antitumor Assays

Signaling via the MyD88/IRAK pathway in T cells is indispensable for cell survival; however, it is not known whether this pathway functions in the progression of T acute lymphoblastic leukemia (T-ALL). Here, we determined that compared with thymic and peripheral T cells, T-ALL cells from patients have elevated levels of IRAK1 and IRAK4 mRNA as well as increased total and phosphorylated protein. Targeted inhibition of IRAK1 and IRAK4, either with shRNA or with a pharmacological IRAK1/4 inhibitor, dramatically impeded proliferation of T-ALL cells isolated from patients and T-ALL cells in a murine leukemia model; however, IRAK1/4 inhibition had little effect on cell death. We screened several hundred FDA-approved compounds and identified a set of drugs that had enhanced cytotoxic activity when combined with IRAK inhibition. Administration of an IRAK1/4 inhibitor or IRAK knockdown in combination with either ABT-737 or vincristine markedly reduced leukemia burden in mice and prolonged survival. IRAK1/4 signaling activated the E3 ubiquitin ligase TRAF6, increasing K63-linked ubiquitination and enhancing stability of the antiapoptotic protein MCL1; therefore, IRAK inhibition reduced MCL1 stability and sensitized T-ALL to combination therapy. These studies demonstrate that IRAK1/4 signaling promotes T-ALL progression through stabilization of MCL1 and suggest that impeding this pathway has potential as a therapeutic strategy to enhance chemotherapeutic efficacy.

Topics: Animals; Antineoplastic Agents; Benzimidazoles; Biphenyl Compounds; Cell Proliferation; Cell Survival; Drug Synergism; Female; HEK293 Cells; Humans; Interleukin-1 Receptor-Associated Kinases; Jurkat Cells; MCF-7 Cells; Mice, Inbred C57BL; Mice, Inbred NOD; Mice, SCID; Myeloid Cell Leukemia Sequence 1 Protein; Nitrophenols; Piperazines; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Protein Stability; Sulfonamides; TNF Receptor-Associated Factor 6; Vincristine; Xenograft Model Antitumor Assays

Early T-cell precursor-acute lymphoblastic leukemia (ETP-ALL) has been identified as a high-risk subtype of pediatric T-cell acute lymphoblastic leukemia (T-ALL). Conventional chemotherapy is not fully effective for this subtype of leukemia; therefore, potential therapeutic targets need to be explored. Analysis of the gene expression patterns of the transcription factors in pediatric T-ALL revealed that MEF2C and FLT3 were expressed at higher levels in ETP-ALL than typical T-ALL. Using human T-ALL and BaF3 cell lines with high expression levels of MEF2C, the present study tested whether the BCL2 inhibitor (ABT-737) restores the sensitivity to prednisolone (PSL), because MEF2C causes PSL resistance, possibly by augmenting the anti-apoptotic activity of BCL2. Treatment with PSL and ABT-737 caused a significant reduction in the IC50 of PSL in the MEF2C-expressing LOUCY cells, in addition to the MEF2C-transduced BaF3 cells, but not in the non-MEF2C-expressing Jurkat cells. The combination treatment significantly accelerated the killing of primary leukemic blast cells of ETP-ALL with high expression levels of MEF2C, which were co-cultured with murine stromal cells. These findings suggest that BCL2 inhibitors may be a therapeutic candidate in vivo for patients with ETP-ALL with high expression levels of MEF2C.

Topics: Animals; Apoptosis; Biphenyl Compounds; Cell Line, Tumor; Coculture Techniques; fms-Like Tyrosine Kinase 3; Gene Expression Regulation, Leukemic; Humans; Jurkat Cells; MEF2 Transcription Factors; Mice; Nitrophenols; Piperazines; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Prednisolone; Proto-Oncogene Proteins c-bcl-2; Sulfonamides

To design rational therapies for JAK2-driven hematological malignancies, we functionally dissected the key survival pathways downstream of hyperactive JAK2. In tumors driven by mutant JAK2, Stat1, Stat3, Stat5, and the Pi3k and Mek/Erk pathways were constitutively active, and gene expression profiling of TEL-JAK2 T-ALL cells revealed the upregulation of prosurvival Bcl-2 family genes. Combining the Bcl-2/Bcl-xL inhibitor ABT-737 with JAK2 inhibitors mediated prolonged disease regressions and cures in mice bearing primary human and mouse JAK2 mutant tumors. Moreover, combined targeting of JAK2 and Bcl-2/Bcl-xL was able to circumvent and overcome acquired resistance to single-agent JAK2 inhibitor treatment. Thus, inhibiting the oncogenic JAK2 signaling network at two nodal points, at the initiating stage (JAK2) and the effector stage (Bcl-2/Bcl-xL), is highly effective and provides a clearly superior therapeutic benefit than targeting just one node. Therefore, we have defined a potentially curative treatment for hematological malignancies expressing constitutively active JAK2.

Topics: Animals; Apoptosis; Apoptosis Regulatory Proteins; Bcl-2-Like Protein 11; bcl-X Protein; Biphenyl Compounds; Cell Line, Tumor; Cell Survival; Drug Resistance, Neoplasm; Gene Expression Profiling; Humans; Janus Kinase 2; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Inbred NOD; Mice, SCID; Neoplasm Transplantation; Nitriles; Nitrophenols; Piperazines; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins; Pyrazoles; Pyrimidines; Signal Transduction; Sulfonamides; Transplantation, Heterologous

The effective use of targeted therapy is highly dependent on the identification of responder patient populations. Loss of FBW7, which encodes a tumour-suppressor protein, is frequently found in various types of human cancer, including breast cancer, colon cancer and T-cell acute lymphoblastic leukaemia (T-ALL). In line with these genomic data, engineered deletion of Fbw7 in mouse T cells results in T-ALL, validating FBW7 as a T-ALL tumour suppressor. Determining the precise molecular mechanisms by which FBW7 exerts antitumour activity is an area of intensive investigation. These mechanisms are thought to relate in part to FBW7-mediated destruction of key proteins relevant to cancer, including Jun, Myc, cyclin E and notch 1 (ref. 9), all of which have oncoprotein activity and are overexpressed in various human cancers, including leukaemia. In addition to accelerating cell growth, overexpression of Jun, Myc or notch 1 can also induce programmed cell death. Thus, considerable uncertainty surrounds how FBW7-deficient cells evade cell death in the setting of upregulated Jun, Myc and/or notch 1. Here we show that the E3 ubiquitin ligase SCF(FBW7) (a SKP1-cullin-1-F-box complex that contains FBW7 as the F-box protein) governs cellular apoptosis by targeting MCL1, a pro-survival BCL2 family member, for ubiquitylation and destruction in a manner that depends on phosphorylation by glycogen synthase kinase 3. Human T-ALL cell lines showed a close relationship between FBW7 loss and MCL1 overexpression. Correspondingly, T-ALL cell lines with defective FBW7 are particularly sensitive to the multi-kinase inhibitor sorafenib but resistant to the BCL2 antagonist ABT-737. On the genetic level, FBW7 reconstitution or MCL1 depletion restores sensitivity to ABT-737, establishing MCL1 as a therapeutically relevant bypass survival mechanism that enables FBW7-deficient cells to evade apoptosis. Therefore, our work provides insight into the molecular mechanism of direct tumour suppression by FBW7 and has implications for the targeted treatment of patients with FBW7-deficient T-ALL.

Topics: Amino Acid Sequence; Animals; Apoptosis; Benzenesulfonates; Biphenyl Compounds; Cell Cycle Proteins; Cell Line, Tumor; F-Box Proteins; F-Box-WD Repeat-Containing Protein 7; Glycogen Synthase Kinase 3; Humans; Mice; Molecular Sequence Data; Myeloid Cell Leukemia Sequence 1 Protein; Niacinamide; Nitrophenols; Phenylurea Compounds; Phosphorylation; Piperazines; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Protein Binding; Proto-Oncogene Proteins c-bcl-2; Pyridines; SKP Cullin F-Box Protein Ligases; Sorafenib; Sulfonamides; Tumor Suppressor Proteins; Ubiquitin-Protein Ligases; Ubiquitination