The small molecule SI113 synergizes with mitotic spindle poisons in arresting the growth of human glioblastoma multiforme

Glioblastoma multiforme (GBM) is the deadliest brain tumor. State-of-art GBM therapy often fails to ensure control of a disease characterized by high frequency of recurrences and progression. In search for novel therapeutic approaches, we assayed the effect of compounds from a cancer drug library on the ADF GBM cell line, establishing their elevated sensitivity to mitotic spindle poisons. Our previous work showed that the effectiveness of the spindle poison paclitaxel in inhibiting cancer cell growth was dependent on the expression of RANBP1, a regulatory target of the serine/threonine kinase SGK1. Recently, we developed the small molecule SI113 to inhibit SGK1 activity. Therefore, we explored the outcome of the association between SI113 and selected spindle poisons, finding that these drugs generated a synergistic cytotoxic effect in GBM cells, drastically reducing their viability and clonogenic capabilities in vitro, as well as inhibiting tumor growth in vivo. We also defined the molecular bases of such a synergistic effect. Because SI113 displays low systemic toxicity, yet strong activity in potentiating the effect of radiotherapy in GBM cells, we believe that this drug could be a strong candidate for clinical trials, with the aim to add it to the current GBM therapeutic approaches

SI113, a Specific Inhibitor of the Sgk1 Kinase Activity that Counteracts Cancer Cell Proliferation

Background/Aims: Published observations on serum and glucocorticoid regulated kinase 1 (Sgk1) knockout murine models and Sgk1-specific RNA silencing in the RKO human colon carcinoma cell line point to this kinase as a central player in colon carcinogenesis and in resistance to taxanes. Methods: By in vitro kinase activity inhibition assays, cell cycle and viability analysis in human cancer model systems, we describe the biologic effects of a recently identified kinase inhibitor, SI113, characterized by a substituted pyrazolo[3,4-d]pyrimidine scaffold, that shows specificity for Sgk1. Results: SI113 was able to inhibit in vitro cell growth in cancer cells derived from tumors with different origins. In RKO cells, this kinase inhibitor blocked insulin-dependent phosphorylation of the Sgk1 substrate Mdm2, the main regulator of p53 protein stability, and induced necrosis and apoptosis when used as a single agent. Finally, SI113 potentiated the effects of paclitaxel on cell viability. Conclusion: Since SI113 appears to be effective in inducing cell death in RKO cells, potentiating paclitaxel sensitivity, we believe that this new molecule could be efficiently employed, alone or in combination with paclitaxel, in colon cancer chemotherapy

Lyn sustains oncogenic signaling in chronic lymphocytic leukemia by strengthening SET-mediated inhibition of PP2A.

Aberrant protein kinase activities, and the consequent dramatic increase of Ser/Thr and -Tyr phosphorylation, promote the deregulation of the survival pathways in chronic lymphocytic leukemia (CLL), which is crucial to the pathogenesis and progression of the disease. In this study, we show that the tumor suppressor Protein Phosphatase 2A (PP2A), one of the major Ser/Thr phosphatase, is in an inhibited form due to the synergistic contribution of two events, the interaction with its physiological inhibitor SET and the phosphorylation of Y307 of the catalytic subunit of PP2A. The latter event is mediated by Lyn, a Src family kinase previously found to be overexpressed, delocalized and constitutively active in CLL cells. This Lyn/PP2A axis accounts for the persistent high level of phosphorylation of the phosphatase's targets and represents a key connection linking phosphotyrosine- and phosphoserine/threonine-mediated oncogenic signals. The data herein presented show that the disruption of the SET/PP2A complex by a novel FTY720-analogue (MP07-66) devoid of immunosuppressive effects leads to the reactivation of PP2A, which in turn triggers apoptosis of CLL cells. When used in combination with SFK inhibitors, the action of MP07-66 is synergistically amplified, providing a new option in the therapeutic strategy for CLL patients

Iron and Ferritin Modulate MHC Class I Expression and NK Cell Recognition

The ability of pathogens to sequester iron from their host cells and proteins affects their virulence. Moreover, iron is required for various innate host defense mechanisms as well as for acquired immune responses. Therefore, intracellular iron concentration may influence the interplay between pathogens and immune system. Here, we investigated whether changes in iron concentrations and intracellular ferritin heavy chain (FTH) abundance may modulate the expression of Major Histocompatibility Complex molecules (MHC), and susceptibility to Natural Killer (NK) cell cytotoxicity. FTH downregulation, either by shRNA transfection or iron chelation, led to MHC surface reduction in primary cancer cells and macrophages. On the contrary, mouse embryonic fibroblasts (MEFs) from NCOA4 null mice accumulated FTH for ferritinophagy impairment and displayed MHC class I cell surface overexpression. Low iron concentration, but not FTH, interfered with IFN-γ receptor signaling, preventing the increase of MHC-class I molecules on the membrane by obstructing STAT1 phosphorylation and nuclear translocation. Finally, iron depletion and FTH downregulation increased the target susceptibility of both primary cancer cells and macrophages to NK cell recognition. In conclusion, the reduction of iron and FTH may influence the expression of MHC class I molecules leading to NK cells activation

Bone marrow niche trafficking of miR-126 controls the self-renewal of leukemia stem cells in chronic myelogenous leukemia

Leukemia stem cells (LSCs) in individuals with chronic myelogenous leukemia (CML) (hereafter referred to as CML LSCs) are responsible for initiating and maintaining clonal hematopoiesis. These cells persist in the bone marrow (BM) despite effective inhibition of BCR–ABL kinase activity by tyrosine kinase inhibitors (TKIs). Here we show that although the microRNA (miRNA) miR-126 supported the quiescence, self-renewal and engraftment capacity of CML LSCs, miR-126 levels were lower in CML LSCs than in long-term hematopoietic stem cells (LT-HSCs) from healthy individuals. Downregulation of miR-126 levels in CML LSCs was due to phosphorylation of Sprouty-related EVH1-domain-containing 1 (SPRED1) by BCR–ABL, which led to inhibition of the RAN–exportin-5–RCC1 complex that mediates miRNA maturation. Endothelial cells (ECs) in the BM supply miR-126 to CML LSCs to support quiescence and leukemia growth, as shown using mouse models of CML in which Mir126a (encoding miR-126) was conditionally knocked out in ECs and/or LSCs. Inhibition of BCR–ABL by TKI treatment caused an undesired increase in endogenous miR-126 levels, which enhanced LSC quiescence and persistence. Mir126a knockout in LSCs and/or ECs, or treatment with a miR-126 inhibitor that targets miR-126 expression in both LSCs and ECs, enhanced the in vivo anti-leukemic effects of TKI treatment and strongly diminished LSC leukemia-initiating capacity, providing a new strategy for the elimination of LSCs in individuals with CML

Analisi tridimensionale agli elementi finiti di una frana in argille innescata da scavo al piede e verifica della strategia di mitigazione del rischio

Le frane di prima attivazione di versanti in argille consistenti sature, innescate da scavo al piede nel lungo periodo come conseguenza dei processi di consolidazione negativa delle pressioni interstiziali, sono state nel tempo oggetto di numerosi studi. Una frana di questa tipologia ha interessato tra il 1980 ed il 1998 un versante in argille pleistoceniche a nord della città di Lucera (Foggia). Lollino e coautori (2011) hanno presentato una interpretazione dettagliata dell’evoluzione tenso-deformativa del versante nel tempo fino al raggiungimento delle condizioni di collasso con l’ausilio di analisi bidimensionali. Nel presente lavoro è stato sviluppato un modello tridimensionale agli elementi finiti del versante nell’ipotesi di comportamento elasto-plastico drenato del terreno al fine di indagare l’evoluzione 3-D del processo di frana; ulteriori analisi numeriche sono state quindi condotte per verificare l’efficacia degli interventi di mitigazione del rischio messi in opera in anni recenti. I risultati del modello sono in accordo con le osservazioni di sito e confermano che la strategia di intervento adottata sia da considerarsi efficace rispetto all’obiettivo di stabilizzazione del versant

The transcription activation function of C/EBPalpha is required for induction of granulocytic differentiation

The CCAAT/enhancer binding protein-a. (C/EBPalpha) is a transcription factor required for differentiation of myeloid progenitors. In addition to specific DNA binding, C/EBPa is also involved in protein-protein interactions, some of which (p21, Cdk2/Cdk4, E2F) appear to be required for inhibition of proliferation and possibly differentiation. To investigate the mechanisms of C/EBPalpha-induced granulocytic differentiation, we generated C/EBPalpha mutants reportedly defective in DNA binding, transactivation, and Cdk2/Cdk4 and E2F interaction and assessed their effects in a myeloid precursor cell line, primary bone marrow and C/EBPalpha knockout fetal liver precursor cells. We show here that the DNA binding-deficient Lys298Glu mutant, the E2F binding-deficient basic region mutant 2 (BRM-2) carrying the IIe294AIa and Arg 47AIa substitutions, and the transactivation-deficient N-terminus truncated p30 mutant all fall to promote differentiation on ectopic expression in myeloid precursor cells. By contrast, ectopic expression of the Cdk2/ Cdk4 interaction-deficient Delta177-191 mutant promotes differentiation and induces gene expression as effectively as wildtype C/EBPa. Thus, the integrity of the transactivation and DNA binding domains, but not of the Cdk2/Cdk4 interaction region, is necessary for C/EBPalpha-induced differentiation. Since the E2F binding-deficient BRM-2 mutant interacted with E2F-1 but failed to activate gene expression, our results lend support to the hypothesis that activation of gene transcription is the determining factor in C/EBPalpha-dependent differentiation

Microbiological and Physical Changes Produced by Different Air–Powders on Contaminated Titanium Implant Surfaces: An In Vitro Pilot Study

Air–powder abrasive treatment has shown interesting results for dental implant treatments; however, which powder is most effective is still an open question. This in vitro pilot study aims to compare the ability of six different powders (sodium bicarbonate powder—65 µm and 40 µm; glycine powder; erythritol powder—with and without cetylpyridinium chloride and calcium carbonate) to remove biofilm from contaminated titanium discs and to evaluate the physical effects of such treatments on surface topography. Seventy-four titanium discs with two different surface roughness were treated after S. sanguinis contamination. Cleaning ability and surface changes were assessed by scanning electron and confocal laser scanning microscopy as well as profilometry. All treated surfaces showed minimal bacterial residues compared to untreated ones, regardless of the treatment provided (remaining biofilm range 11.4% to 28.4% on machined discs—range 10.7% to 18.3% on moderately rough surface discs). No relevant changes on the microscopic ultrastructure of the disc surfaces were noted. The different treatments reduced biofilm up to 89.3 and 88.6% on moderately rough and machined discs, respectively, and they all showed statistically significant superiority over calcium carbonate powder. None of the tested treatments rendered the disc surfaces biofilm-free. Therefore, combined mechanical and chemical decontamination methods are still recommended to achieve maximum biofilm removal for peri-implantitis treatment.</jats:p