Melanoma can be stratified into unique subtypes based on distinct pathologies. The acral/mucosal melanoma subtype is characterized by aberrant and constitutive activation of the proto-oncogene ...receptor tyrosine kinase C-KIT, which drives tumorigenesis. Treatment of these melanoma patients with C-KIT inhibitors has proven challenging, prompting us to investigate the downstream effectors of the C-KIT receptor. We determined that C-KIT stimulates MAP kinase-interacting serine/threonine kinases 1 and 2 (MNK1/2), which phosphorylate eukaryotic translation initiation factor 4E (eIF4E) and render it oncogenic. Depletion of MNK1/2 in melanoma cells with oncogenic C-KIT inhibited cell migration and mRNA translation of the transcriptional repressor SNAI1 and the cell cycle gene CCNE1. This suggested that blocking MNK1/2 activity may inhibit tumor progression, at least in part, by blocking translation initiation of mRNAs encoding cell migration proteins. Moreover, we developed an MNK1/2 inhibitor (SEL201), and found that SEL201-treated KIT-mutant melanoma cells had lower oncogenicity and reduced metastatic ability. Clinically, tumors from melanoma patients harboring KIT mutations displayed a marked increase in MNK1 and phospho-eIF4E. Thus, our studies indicate that blocking MNK1/2 exerts potent antimelanoma effects and support blocking MNK1/2 as a potential strategy to treat patients positive for KIT mutations.
The organization of the symbiotic system (i.e., distribution and ultrastructure of symbionts) and the mode of inheritance of symbionts in two species, Nysius ericae and Nithecus jacobaeae belonging ...to Heteroptera: Lygaeidae, are described. Like most hemipterans, Nysius ericae and Nithecus jacobaeae harbor obligate prokaryotic symbionts. The symbiotic bacteria are harbored in large, specialized cells termed bacteriocytes which are localized in the close vicinity of the ovaries as well as inside the ovaries. The ovaries are composed of seven ovarioles of the telotrophic type. Bacteriocytes occur in each ovariole in the basal part of tropharium termed the infection zone. The bacteriocytes form a ring surrounding the early previtellogenic oocytes. The cytoplasm of the bacteriocytes is tightly packed with large elongated bacteria. In the bacteriocytes of Nysius ericae, small, rod-shaped bacteria also occur. Both types of bacteria are transovarially transmitted from one generation to the next.
The family of PIM serine/threonine kinases includes three highly conserved oncogenes,
and
, which regulate multiple prosurvival pathways and cooperate with other oncogenes such as
. Recent genomic ...CRISPR-Cas9 screens further highlighted oncogenic functions of PIMs in diffuse large B-cell lymphoma (DLBCL) cells, justifying the development of small-molecule PIM inhibitors and therapeutic targeting of PIM kinases in lymphomas. However, detailed consequences of PIM inhibition in DLBCL remain undefined. Using chemical and genetic PIM blockade, we comprehensively characterized PIM kinase-associated prosurvival functions in DLBCL and the mechanisms of PIM inhibition-induced toxicity. Treatment of DLBCL cells with SEL24/MEN1703, a pan-PIM inhibitor in clinical development, decreased BAD phosphorylation and cap-dependent protein translation, reduced MCL1 expression, and induced apoptosis. PIM kinases were tightly coexpressed with MYC in diagnostic DLBCL biopsies, and PIM inhibition in cell lines and patient-derived primary lymphoma cells decreased MYC levels as well as expression of multiple MYC-dependent genes, including
. Chemical and genetic PIM inhibition upregulated surface CD20 levels in an MYC-dependent fashion. Consistently, MEN1703 and other clinically available pan-PIM inhibitors synergized with the anti-CD20 monoclonal antibody rituximab
, increasing complement-dependent cytotoxicity and antibody-mediated phagocytosis. Combined treatment with PIM inhibitor and rituximab suppressed tumor growth in lymphoma xenografts more efficiently than either drug alone. Taken together, these results show that targeting PIM in DLBCL exhibits pleiotropic effects that combine direct cytotoxicity with potentiated susceptibility to anti-CD20 antibodies, justifying further clinical development of such combinatorial strategies. SIGNIFICANCE: These findings demonstrate that inhibition of PIM induces DLBCL cell death via MYC-dependent and -independent mechanisms and enhances the therapeutic response to anti-CD20 antibodies by increasing CD20 expression.
The green leafhopper, Cicadella viridis lives in symbiotic association with microorganisms. The ultrastructural and molecular analyses have shown that in the body of the C. viridis two types of ...bacteriocyte endosymbionts are present. An amplification and sequencing of 16S rRNA genes revealed that large, pleomorphic bacteria display a high similarity (94–100%) to the endosymbiont ‘Candidatus Sulcia muelleri’ (phylum Bacteroidetes), whereas long, rod-shaped microorganisms are closely related to the γ-proteobacterial symbiont Sodalis (97–99% similarity). Both endosymbionts may be harbored in their own bacteriocytes as well as may co-reside in the same bacteriocytes. The ultrastructural observations have revealed that the Sodalis-like bacteria harboring the same bacteriocytes as bacterium Sulcia may invade the cells of the latter. Bacteria Sulcia and Sodalis-like endosymbionts are transovarially transmitted from one generation to the next. However, Sodalis-like endosymbionts do not invade the ovaries individually, but only inside Sulcia cells. Apart from bacteriocyte endosymbionts, in the body of C. viridis small, rod-shaped bacteria have been detected, and have been identified as being closely related to γ-proteobacterial microorganism Pectobacterium (98–99% similarity). The latter are present in the sheath cells of the bacteriomes containing bacterium Sulcia as well as in fat body cells.
•In the body of Cicadella viridis two types of bacteriocyte endosymbionts occur.•Pleomorphic bacteria are related to ‘Candidatus Sulcia muelleri’.•Rod-shaped bacteria are related to the Sodalis-like bacteria.•Endosymbionts are transovarially transmitted from one generation to the next.
Inhibition of oncogenic transcriptional programs is a promising therapeutic strategy. A substituted tricyclic benzimidazole, SEL120-34A, is a novel inhibitor of Cyclin-dependent kinase 8 (CDK8), ...which regulates transcription by associating with the Mediator complex. X-ray crystallography has shown SEL120-34A to be a type I inhibitor forming halogen bonds with the protein's hinge region and hydrophobic complementarities within its front pocket. SEL120-34A inhibits phosphorylation of STAT1 S727 and STAT5 S726 in cancer cells in vitro. Consistently, regulation of STATs- and NUP98-HOXA9- dependent transcription has been observed as a dominant mechanism of action in vivo. Treatment with the compound resulted in a differential efficacy on AML cells with elevated STAT5 S726 levels and stem cell characteristics. In contrast, resistant cells were negative for activated STAT5 and revealed lineage commitment. In vivo efficacy in xenotransplanted AML models correlated with significant repression of STAT5 S726. Favorable pharmacokinetics, confirmed safety and in vivo efficacy provide a rationale for the further clinical development of SEL120-34A as a personalized therapeutic approach in AML.
The mitogen-activated protein kinase (MAPK)-interacting kinases 1 and 2 (MNKs 1/2) and their downstream target eIF4E, play a role in oncogenic transformation, progression and metastasis. These ...results provided rationale for development of first MNKs inhibitors, currently in clinical trials for cancer treatment. Inhibitors of the MNKs/eIF4E pathway are also proposed as treatment strategy for inflammatory conditions. Here we present results of optimization of indazole-pyridinone derived MNK1/2 inhibitors among which compounds 24 and 26, selective and metabolically stable derivatives. Both compounds decreased levels of eIF4E Ser206 phosphorylation (pSer209-eIF4E) in MOLM16 cell line. When administered in mice compounds 24 and 26 significantly improved survival rates of animals in the endotoxin lethal dose challenge model, with concomitant reduction of proinflammatory cytokine levels – TNFα and IL-6 in serum. Identified MNK1/2 inhibitors represent a novel class of immunomodulatory compounds with a potential for the treatment of inflammatory diseases including sepsis.
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•A series of indazole-pyridinone derivatives as MNK1/2 inhibitors were designed.•Compounds 24 and 26 have been identified as potent, selective, and metabolically stable derivatives.•Both compounds decreased levels of pSer209-eIF4E in MOLM16 cell line.•Treatment with both compounds protected against LPS-induced septic shock in mouse model of sepsis.
Gene duplications restricted to single lineage combined with an asymmetric evolution of the resulting genes may play particularly important roles in this lineage's biology. We searched and identified ...asymmetrical evolution in nine gene families that duplicated exclusively in rodents and are present as single-copies in human, dog, cow, elephant, opossum, chicken, lizard, and Western clawed frog. Among those nine gene families are Fas apoptosis inhibitory molecule (Faim), implicated in apoptosis, and Sperm antigen 6 (Spag6), implicated in sperm mobility. Both genes were duplicated in or before the Muroidea ancestor. Due to the highly asymmetric evolution of the resulting paralogs, the existence of these duplications had been previously overlooked. Interestingly, Spag6, previously regarded and characterized as a single-copy ortholog of human Spag6, turns out to be a Muroidea-specific paralog. Conversely, the newly identified, highly divergent Spag6-BC061194 is in fact the parental gene. In consequence, this gene represents a rare exception from the general rule of rapid evolution of derived rather than parental genes following gene duplication. Unusual genes such as murine Spag6 may help to understand which mechanisms are responsible for this rule.
Growing evidence links stress hormones with development and progression of various cancer types. The aim of this study was to assess susceptibility of cutaneous and uveal melanoma cells to adrenaline ...(AD).
The expression of β-2-adrenergic receptor in primary cutaneous (FM-55-P), primary uveal (92-1, Mel202) and metastatic cutaneous (A375) melanoma cells was estimated at mRNA, protein and cell surface levels. The impact of AD on cell proliferation and migration was also studied.
The expression of β-2-adrenergic receptor was cell line-dependent. Adrenaline treatment caused a slight stimulation of melanoma cell proliferation and activation of matrix metalloproteinases. Adrenaline-treated uveal melanoma cells showed an increased migration rate, whereas, in cutaneous melanoma cells, no changes or even lower migration speed were observed.
Melanoma cell susceptibility to AD varies depending on origin and progression stage. Metastatic cutaneous melanoma cells were found to be less responsive to AD than primary cutaneous and uveal melanoma cells.
Background: T cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematopoietic malignancy characterized by an aberrant proliferation of immature thymocytes affecting preferentially children ...and adolescents. Approximately 70% of T-ALL cases have activating mutations of the NOTCH1 followed by oncogenic pathways PI3K/Akt, the anti-apoptotic BCL-2 family, and CDKN2A/2B cell cycle regulators 1, 2. Unlike other leukemias such as chronic myeloid leukemia (CML) and Philadelphia-positive ALL, which are kinase-driven malignancies 3, 4, the initiating events in T-ALL cause the ectopic expression of transcription factors that drive leukemogenesis, hence targeted therapies needed to focused on this field. Cyclin Dependent Kinase 8 (CDK8) and its paralog CDK19, restrain activation of super-enhancer-associated tumor suppressors and lineage commitment genes in leukemia. Moreover CDK8 phosphorylates intracellular domain (ICD) and regulates activation and turnover of NOTCH1 5, 6, indicating that targeting CDK8 with specific inhibitors may be considered as a novel therapeutic strategy for T-ALL. RVU120 is a first-in-class, specific and selective inhibitor of CDK8/CDK19, currently in phase Ib dose-escalation trial in patients with relapsed or refractory (R/R) AML and HR-MDS (NCT04021368).
Objectives: The goals of these studies were to investigated the effectiveness of RVU120 and other non-related CDK8/19 inhibitors against T-ALL cell lines/PDXs, including GSI-resistant lines. Comprehensive analysis of target inhibition and apoptotic signatures were evaluated. The clinical relevance of RVU120 in LICs was confirmed in Patient derived xenografts (PDXs).
Results:
T-ALL cell lines and PDXs were treated with RVU120 and other chemically non-related CDK8/19 inhibitors in different concentration for 12-18 days, and the changes in cell number and apoptosis using flow cytometry analysis were determined. High differential efficacy in double-digit nM range has been observed for NOTCH1 PEST domain mutant cell lines including GSI-sensitive HPB-ALL cells and GSI-resistant cells PF-382, KOPT-K1, and MOLT4, where both inhibition of cell proliferation and induction of apoptosis were observed. GI-resistant cell lines SUP-T1, SUP-T11, MOLT16 and JURKAT were considered as moderately sensitive and LOUCY (early T-cell phenotype ALL), and CCRF-CEM devoid those phenotype, were considered as resistant to RVU120. Results form etsblished cell lines were further corroborated in patient-derived xenograft cells (PDX) treated with RVU120. In T-ALL PDX 6522288 (Notch1 HD /PEST mut, TET2 mut, U2AF1 mut, WT1 mut and CUL76- CDKN2A/B mut, PTEN-/-) treatment with RVU120 was followed by a reduction in cell number and induction of apoptosis in phenotypically defined leukemia initiating cells (LICs) CD34+CD7+CD19-, with calculated IC50s value for bulk and LICs as 92.8 nM and 141.8 nM, respectively. The clinical relevance of these findings and impact on LICs are under the evaluation in PDX mice model. Mechanistically, treatment with RVU120 reduced the phosphorylation of STAT5 and STAT1 as well as the level of MYC and anti-apoptotic proteins MCL1, but induced expression of BAX in sensitive cells. Hence, inhibition of CDK8 is a novel approach to target the LICs in T-ALL.
Conclusion:
Inhibition of CDK8 by RVU120 triggers inhibition of cell proliferation and apoptosis in cell lines and LICs in T-ALL. Further clinical study is warranted to study the efficacy of RVU120 and CDK8 inhibition in T-ALL.
Keywords: CDK8, RVU120, apoptosis, T-ALL, LICs in PDX model
Reference
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Golas: Ryvu Therapeutics: Current Employment. Windak: Ryvu Therapeutics: Current Employment. Rzymski: Ryvu Therapeutics: Current Employment, Current equity holder in publicly-traded company. Andreeff: ONO Pharmaceuticals: Research Funding; AstraZeneca: Research Funding; Glycomimetics: Consultancy; Daiichi-Sankyo: Consultancy, Research Funding; Breast Cancer Research Foundation: Research Funding; Karyopharm: Research Funding; Reata, Aptose, Eutropics, SentiBio; Chimerix, Oncolyze: Current holder of individual stocks in a privately-held company; Amgen: Research Funding; Aptose: Consultancy; Medicxi: Consultancy; Oxford Biomedica UK: Research Funding; Novartis, Cancer UK; Leukemia & Lymphoma Society (LLS), German Research Council; NCI-RDCRN (Rare Disease Clin Network), CLL Foundation; Novartis: Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy; Senti-Bio: Consultancy. Borthakur: GSK: Consultancy; Astex: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Ryvu: Research Funding; University of Texas MD Anderson Cancer Center: Current Employment; Protagonist: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; ArgenX: Membership on an entity's Board of Directors or advisory committees.
Abstract
Background Acute myeloid leukemia (AML) is a heterogeneous disease characterized by rapid proliferation of leukemic blasts and high rate of acquired resistance to drugs. Differentiating ...agent ATRA has been established as a backbone of APL treatment, however its activity in other leukemias is limited. Knowing that Cyclin Dependent Kinase 8 (CDK8) can maintain tumor dedifferentiation and embryonic stem cell pluripotency, we investigated whether CDK8 inhibitor SEL120 could effectively target leukemia by induction of lineage commitment. SEL120 is a specific, selective inhibitor of CDK8 and its paralog CDK19. A first-in-human phase Ib clinical trial with SEL120 in AML or HR-MDS patients is currently ongoing. To better understand the mechanism of action of SEL120 in AML, we studied effects of SEL120 on differentiation as one of the important anti-leukemic activities of the compound.
Methods Global transcriptional changes were analyzed by RNAseq at different time points to capture early and long-term effects of SEL120. Genome-wide profiling of DNA-binding was performed by CHIPseq. Cell cycle, proliferation and lineage specific markers were studied by flow cytometry. Differentiation potential of AML cells was studied in semi-solid methylcellulose-based media to asses colony formation of SEL120 treated blasts.
Results SEL120 treatment leads to decreased CDK8 occupancy and increased RNA Pol II occupancy as well as changes in the peak distribution among promoter and enhancer regions. SEL120 could repress many “stemness” genes and induce the expression of genes involved in lineage commitment, including regulators of erythroid/megakaryocytic fate, such as RGS18, KLF1, FLI1 and GATA1/2. Moreover, for the first time, we showed that prolonged exposure of AML CD34+ cells to SEL120 could lead to colony formation in semi-solid media. Detailed analysis by flow cytometry at early and late time points reflected sequential changes in the expression of lineage-specific surface markers, characterizing differentiation and the presence of cells of myeloid or erythroid/megakaryocytic origin.
Conclusion In addition to established role of CDK8 in regulation of tumor suppressor genes we present evidence for an essential role of CDK8 in lineage controlling-functions. Previously we reported specific cytotoxicity of SEL120 on cells positive for stemness markers such as CD34+. We further expanded on these studies, showing profound morphological changes in AML blasts during prolonged exposure to SEL120, correlating with increased expression of myeloid and erythroid/megakaryocytic markers. Based on these findings further studies are warranted to investigate the efficacy of SEL120 in anemia associated with bone marrow failures in AML and MDS. Combination of direct effects of SEL120 on viability of cells, with a strong differentiation potential, represents a promising profile for a drug in successful leukemia treatment.
Citation Format: Urszula Pakulska, Elzbieta Adamczyk, Katarzyna Dziedzic, Katarzyna Wiklik, Michal Combik, Michal Mikula, Aniela Golas, Marta Obacz, Magdalena Masiejczyk, Przemyslaw Juszczynski, Magdalena Cybulska, Milena Mazan, Krzysztof Brzozka, Tomasz Rzymski. SEL120, a CDK8/CDK19 inhibitor, possesses strong multilineage differentiation potential in AML abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1018.
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