A small molecule inhibitor of Pim protein kinases blocks the growth of precursor T-cell lymphoblastic leukemia/lymphoma

Abstract

The serine/threonine Pim kinases are upregulated in specific hematologic neoplasms, and play an important role in key signal transduction pathways, including those regulated by MYC, MYCN, FLT3-ITD, BCR-ABL, HOXA9, and EWS fusions. We demonstrate that SMI-4a, a novel benzylidene-thiazolidine-2, 4-dione small molecule inhibitor of the Pim kinases, kills a wide range of both myeloid and lymphoid cell lines with precursor T-cell lymphoblastic leukemia/lymphoma (pre-T-LBL/T-ALL) being highly sensitive. Incubation of pre-T-LBL cells with SMI-4a induced G1 phase cell-cycle arrest secondary to a dose-dependent induction of p27 Kip1 , apoptosis through the mitochondrial pathway, and inhibition of the mammalian target of rapamycin C1 (mTORC1) pathway based on decreases in phosphop70 S6K and phospho-4E-BP1, 2 substrates of this enzyme. In addition, treatment of these cells with SMI-4a was found to induce phosphorylation of extracellular signal-related kinase1/2 (ERK1/2), and the combination of SMI-4a and a mitogenactivated protein kinase kinase 1/2 (MEK1/2) inhibitor was highly synergistic in killing pre-T-LBL cells. In immunodeficient mice carrying subcutaneous pre-T-LBL tumors, treatment twice daily with SMI-4a caused a significant delay in the tumor growth without any change in the weight, blood counts, or chemistries. Our data suggest that inhibition of the Pim protein kinases may be developed as a therapeutic strategy for the treatment of pre-T-LBL. (Blood. 2010;115:824-833) IntroductionThe serine/threonine Pim protein kinase is overexpressed in multiple hematopoietic tumors, with an approximately 3-fold increase in chronic lymphocytic leukemia, non-Hodgkin lymphoma, 1,2 and many primary human myeloid leukemic samples. 3 The level of Pim mRNA correlated with the doubling time of the chronic lymphocytic leukemia. Likewise, in mantle cell lymphoma the level of Pim protein kinase expression predicted poor patient outcome. 4 Pim protein kinase is targeted by aberrant hypermutation in 50% of the cases 5 of diffuse large B-cell lymphomas and mutations are detected in primary central nervous system lymphomas 6 and AIDS-associated non-Hodgkin lymphoma. 6 Murine models point to a role for Pim protein kinases in enhancing the transforming activity of several transcription factors known to be drivers of hematopoietic malignancies. For example, the Pim1 and Pim2 genes were originally cloned as a proviral insertion in murine lymphomas 7 that markedly enhanced both the incidence and speed of Myc-driven lymphomagenesis. 8 When the E-Pim1 transgene alone is overexpressed in mice, they exhibit a low-level (10%) occurrence of T-cell lymphoblastic lymphoma/ leukemia. 9 Conversely, E-N-myc or E-L-myc transgenic mice develop T-cell or B-cell lymphomas, respectively, and the rate of development of these tumors is greatly enhanced by breeding with E-Pim1 transgenic mice. 10 Using a retroviral tagging model in mice transgenic for the E2A-PBX1 fusion oncogenes, the Pim1 locus was targeted in 48% of the T-cell lymphomas and the occurrence of ...

Inhibition of autophagy enhances SMI-4a-induced growth inhibition and apoptosis of melanoma cells

“…An inhibitory effect of PIM-1 silencing on the proliferation of melanoma cells has been previously suggested [3]. SMI-4a is a small molecular highly selective PIM-1 inhibitor that has been found to block PIM-1 kinase activity in vitro and in vivo [14]. In this study, we demonstrated that blockade of PIM-1 with SMI4a results in a remarkable decrease in cell viability, and data from the colony formation assay was consistent with this observation.…”

Targeted inhibition of mTORC1 and mTORC2 by active-site mTOR inhibitors has cytotoxic effects in T-cell acute lymphoblastic leukemia

“…An important protein having a role in hypoxia-induced drug-resistance could be PIM-1 kinase, which is known to be induced by HIF-1a, 34 as demonstrated by the use of a selective PIM-1 kinase inhibitor. 44 Nevertheless, the efficacy of the combined treatment (active site mTOR inhibitors plus VCR) in the presence of stromal cells was inferior to that detected in suspension cultures. This probably reflects activation of additional survival pathways by stromal cells.…”

3,5-Bis(aminopyrimidinyl)indole Derivatives: Synthesis and Evaluation of Pim Kinase Inhibitory Activities

“…MV4-11 cells, which have an ITD mutation in the Flt3 receptor, were reported to be more sensitive to pim inhibitors than K562 cells that overexpress the antiapoptotic Bcr-Abl. [21][22][23][24] Correspondingly, compound 6c showed growth inhibition in a dose dependent manner and about 34% inhibition of MV4-11cells at 20 μM concentration, but did not inhibit the proliferation of K562 cells. These results suggested that our modified 3,5-bis(aminopyrimidinyl)-indole is a promising leading structure as a pan-pim kinase inhibitor.…”