The PIM Family of Serine/Threonine Kinases in Cancer

Min

et al. 2015

J Virol

The life cycle of hepatitis C virus (HCV) is highly dependent on host cellular proteins for virus propagation. In order to identify the cellular factors involved in HCV propagation, we performed protein microarray assay using the HCV nonstructural 5A (NS5A) protein as a probe. Of ϳ9,000 human cellular proteins immobilized in a microarray, approximately 90 cellular proteins were identified as NS5A interactors. Of these candidates, Pim1, a member of serine/threonine kinase family composed of three different isoforms (Pim1, Pim2, and Pim3), was selected for further study. Pim kinases share a consensus sequence which overlaps with kinase activity. Pim kinase activity has been implicated in tumorigenesis. In the present study, we verified the physical interaction between NS5A and Pim1 by both in vitro pulldown and coimmunoprecipitation assays. Pim1 interacted with NS5A through amino acid residues 141 to 180 of Pim1. We demonstrated that protein stability of Pim1 was increased by NS5A protein and this increase was mediated by protein interplay. Small interfering RNA (siRNA)-mediated knockdown or pharmacological inhibition of Pim kinase abrogated HCV propagation. By employing HCV pseudoparticle entry and single-cycle HCV infection assays, we further demonstrated that Pim kinase was involved in HCV entry at a postbinding step. These data suggest that Pim kinase may represent a new host factor for HCV entry. IMPORTANCEPim1 is an oncogenic serine/threonine kinase. HCV NS5A protein physically interacts with Pim1 and contributes to Pim1 protein stability. Since Pim1 protein expression level is upregulated in many cancers, NS5A-mediated protein stability may be associated with HCV pathogenesis. Either gene silencing or chemical inhibition of Pim kinase abrogated HCV propagation in HCVinfected cells. We further showed that Pim kinase was specifically required at an early entry step of the HCV life cycle. Thus, we have identified Pim kinase not only as an HCV cell entry factor but also as a new anti-HCV therapeutic target.

Section: Discussionmentioning

confidence: 99%

Section: Identification Of Pim1 As An Ns5a Interactor In Protein Arraymentioning

confidence: 96%

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Pim Kinase Interacts with Nonstructural 5A Protein and Regulates Hepatitis C Virus Entry

Min

et al. 2015

J Virol

Clinical Cancer Research

“…LGB321 is unique relative to previously described PIM inhibitors (10)(11)(12)(13), in that it is active in PIM2-dependent cell lines (14), a kinase that has proven difficult to inhibit in the cellular context. Consistent with its activity on all three PIM kinases, LGB321 inhibits proliferation of a number of cell lines derived from diverse hematologic malignancies, including multiple myeloma, AML, CML, and B-cell NHL.…”

Section: Introductionmentioning

confidence: 99%

Pan-PIM Kinase Inhibition Provides a Novel Therapy for Treating Hematologic Cancers

García

Langowski

Wang

et al. 2014

107

112

Purpose: PIM kinases have been shown to act as oncogenes in mice, with each family member being able to drive progression of hematologic cancers. Consistent with this, we found that PIMs are highly expressed in human hematologic cancers and show that each isoform has a distinct expression pattern among disease subtypes. This suggests that inhibitors of all three PIMs would be effective in treating multiple hematologic malignancies.Experimental Design: Pan-PIM inhibitors have proven difficult to develop because PIM2 has a low K m for ATP and, thus, requires a very potent inhibitor to effectively block the kinase activity at the ATP levels in cells. We developed a potent and specific pan-PIM inhibitor, LGB321, which is active on PIM2 in the cellular context.Results:LGB321 is active on PIM2-dependent multiple myeloma cell lines, where it inhibits proliferation, mTOR-C1 signaling and phosphorylation of BAD. Broad cancer cell line profiling of LGB321 demonstrates limited activity in cell lines derived from solid tumors. In contrast, significant activity in cell lines derived from diverse hematological lineages was observed, including acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), multiple myeloma and non-Hodgkin lymphoma (NHL). Furthermore, we demonstrate LGB321 activity in the KG-1 AML xenograft model, in which modulation of pharmacodynamics markers is predictive of efficacy. Finally, we demonstrate that LGB321 synergizes with cytarabine in this model. Conclusions:We have developed a potent and selective pan-PIM inhibitor with single-agent antiproliferative activity and show that it synergizes with cytarabine in an AML xenograft model. Our results strongly support the development of Pan-PIM inhibitors to treat hematologic malignancies.

“…and Akt are regarded to be parallel and redundant apoptotic inhibiting pathway. [16] It has been proved that Pim-2 has the feature of mitogen and can promote the malignant transformation of hematopoietic cells and liver cell line. And Pim-2 can cooperate with C-myc in the tumorigenesis of lymphoma.…”

Section: The Variation Of the Apoptotic Protein Expression Level Befomentioning

confidence: 99%

The role of Pim-2 in apoptotic signal transduction pathway of hepatocellular carcinoma

Chen

Yang

2017

Int Surg J

Background: Hepatocellular carcinoma (HCC) is one of the most frequent malignant tumors. The objective was to investigate the role of serine/threonine kinase Pim-2 in apoptosis signal transduction pathway, because there is little study about its contribution to apoptosis in hepatocellular carcinoma.Methods: The Pim-2 gene and protein expression were examined by qRT-PCR, Western blot and immunohistochemical stain in HCC tissues and normal liver tissues. The plasmid pCI-neo-Pim2 was transfected into human hepatoma cell line SMMC7721 by lipofectamine. Total RNAs were extracted from SMMC7721 cell in logarithm growth phase. The mRNA expression of Pim-2, Akt-1 (protein kinase B), 4E-BP1 (translation repressor of mammalian target of rapamycln), SOCS-1 (repressor of cytokine), Bad（Bcl-xL/Bcl-2 associated death promoter, Bim（Bc1-2 interacting mediator of cell death）and Puma (p53 upregulated modulator of apoptosis) were identified by qRT-PCR. The cell cycle of post-transfected SMMC7721 cells was assessed by flow cytometry.Results: Pim-2 expression was enhanced in HCC. In post-transfected SMMC7721 cells, Pim-2 mRNA expression was up-regulated, level of Bad mRNA was attenuated, furthermore, the transcription level of Akt-1, SOCS-1, 4E-BP1, Bim and Puma gene wasn’t variety. Up-graulated Pim-2 can’t cause distinct change of cell cycle or apoptosis in hepatoma cell.Conclusions: The serine/threonine kinase Pim-2 plays an import role in the development of HCC, Pim-2 dependent maintenance of cell size and survival correlated with its ability to maintain down-regulated expression of the BH3 protein Bad. Pim-2 is not a trigger in cell-autonomous survival or inhibiting apoptosis in hepatocellular carcinoma. Pim-2 is a redundancy pathway of survival signaling.