Activation of an endothelial Notch1-Jagged1 circuit induces VCAM1 expression, an effect amplified by interleukin-1β

The Notch1 and Notch4 signaling pathways regulate endothelial cell homeostasis. Inflammatory cytokines induce the expression of endothelial adhesion molecules, including VCAM1, partly by downregulating Notch4 signaling. We investigated the role of endothelial Notch1 in this IL-1β-mediated process. Brief treatment with IL-1β upregulated endothelial VCAM1 and Notch ligand Jagged1. IL-1β decreased Notch1 mRNA levels, but levels of the active Notch1ICD protein remained constant. IL-1β-mediated VCAM1 induction was downregulated in endothelial cells subjected to pretreatment with a pharmacological inhibitor of the γ-secretase, which activates Notch receptors, producing NotchICD. It was also downregulated in cells in which Notch1 and/or Jagged1 were silenced.Conversely, the forced expression of Notch1ICD in naïve endothelial cells upregulated VCAM1 per se and amplified IL-1β-mediated VCAM1 induction. Jagged1 levels increased and Notch4 signaling was downregulated in parallel. Finally, Notch1ICD and Jagged1 expression was upregulated in the endothelium of the liver in a model of chronic liver inflammation.In conclusion, we describe here a cell-autonomous, pro-inflammatory endothelial Notch1-Jagged1 circuit (i) triggering the expression of VCAM1 even in the absence of inflammatory cytokines and (ii) enhancing the effects of IL-1β. Thus, IL-1β regulates Notch1 and Notch4 activity in opposite directions, consistent with a selective targeting of Notch1 in inflamed endothelium

Surgical site infection after caesarean section. Space for post-discharge surveillance improvements and reliable comparisons

Surgical site infections (SSI) after caesarean section (CS) represent a substantial health system concern. Surveying SSI has been associated with a reduction in SSI incidence. We report the findings of three (2008, 2011 and 2013) regional active SSI surveillances after CS in community hospital of the Latium region determining the incidence of SSI. Each CS was surveyed for SSI occurrence by trained staff up to 30 post-operative days, and association of SSI with relevant characteristics was assessed using binomial logistic regression. A total of 3,685 CS were included in the study. A complete 30 day post-operation follow-up was achieved in over 94% of procedures. Overall 145 SSI were observed (3.9% cumulative incidence) of which 131 (90.3%) were superficial and 14 (9.7%) complex (deep or organ/space) SSI; overall 129 SSI (of which 89.9% superficial) were diagnosed post-discharge. Only higher NNIS score was significantly associated with SSI occurrence in the regression analysis. Our work provides the first regional data on CS-associated SSI incidence, highlighting the need for a post-discharge surveillance which should assure 30 days post-operation to not miss data on complex SSI, as well as being less labour intensive

Notch signaling involvement in endothelial responses to inflammation: Jagged1 and Notch1 mediate IL-1b iInduced up-regulation of adhesion molecules

Obiettivo--Il signaling di Notch, attraverso l’attivazione dei recettori Notch1 e Notch4, gioca un ruolo chiave nella determinazione e nell’omeostasi dell’endotelio. Il TNFa determina la down-regolazione di Notch4 e del target gene Hes1, e questa modulazione causa la perdita della quiescenza e l’induzione della molecola di adesione vasale (VCAM-1) nelle cellule endoteliali (ECs). Questo studio mira ad investigare la regolazione dei componenti del signaling di Notch indotta dall’IL-1b ed il loro coinvolgimento nell’up-regolazione delle molecole di adesione. Metodi e Risultati--Abbiamo dimostrato che l’IL-1b induce una forte up-regolazione di Jagged1, e mentre l’attivazione di Notch4 diminuisce, la forma attiva di Notch1 (Notch1ICD) rimane costante. La complessiva inibizione del signaling di Notch, attraverso un inibitore della g-secretasi, determina una riduzione nell’up-regolazione di VCAM-1 indotta dall’IL-1b. Inoltre, il silenziamento di Jagged1 ha un effetto negativo sull’up-regolazione delle molecole di adesione indotta dall’IL-1b e il doppio silenziamento di Jagged1 e Notch1 determina un effetto ancora maggiore. In aggiunta, la forzata over-espressione di Notch1ICD induce l’espressione di VCAM-1, e questo effetto aumenta dopo il trattamento con l’IL-1b. Nelle cellule over-esprimenti Notch1ICD, inibendo chimicamente la traslocazione nucleare di NF-kB indotta dall’IL-1b, non si riduce significativamente l’up-regolazione di VCAM-1. In fine, l’over-espressione di Hes1, durante il trattamento con l’IL-1b, inibisce l’up-regolazione delle molecole di adesione e reprime la trascrizione di Jagged1, indicando un loop regolativo negativo tra i componenti del signaling di Notch. Conclusioni—Complessivamente i risultati indicano che Jagged1 segnala attraverso Notch1, e Notch1 e’ il recettore piu’ importante nella risposta infiammatoria delle ECs. Inoltre, in presenza di Notch1 l’induzione delle molecole di adesione risulta solo parzialmente dipendente da NF-kB.Objective--Notch signaling plays a key role in endothelial determination and homeostasis through Notch 1 and Notch 4 receptors. In endothelial cells (ECs) the TNFa determines the down-regulation of Notch4 and Hes1 and this modulation are associated with the loss of quiescence and the up-regulation of vascular cell adhesion molecules-1 (VCAM-1), This study investigated the regulation of Notch signaling components upon IL-1β induction and their implication in the up-regulation of adhesion molecules. Methods and Results-- We showed that IL-1β induced a strong up-regulation of the Notch ligand Jagged1. Strikingly, while Notch4 activation decreased, Notch1 active form (Notch1ICD) remained constant. The global inhibition of Notch activation through a g-secretase inhibitor resulted in reduction of IL-1β-induced VCAM-1 up-regulation. Moreover, the silencing of Jagged1 partially affected the up-regulation of adhesion molecules induced by IL-1b, and the double silencing of Jagged1 and Notch1 led to a higher reduction of the adhesion molecules expression after IL-1β treatment. Interestingly, Notch1ICD forced expression induced VCAM-1 expression in ECs and increased the up-regulation induced by IL-1β treatment. Chemical inhibition of the NF-kB nuclear translocation induced by IL-1β treatment did not significantly reduce VCAM-1 expression in Notch1ICD expressing cells. Finally, Hes1 over-expression during IL-1β treatment inhibited the up-regulation of adhesion molecules and, concomitantly, repressed Jagged1 trascription, suggesting a negative regulative loop between Notch signaling component. Conclusions--All together our results indicate that, Jagged1 sustains Notch1 activation that specifies the effects of IL-1β. Thus, Notch1 is the most important receptor involved in inflammatory responses of ECs, and its function is, at least in part, NF-kB-dependent

Characterization of a FOXG1:TLE1 transcriptional network in glioblastoma‐initiating cells

Glioblastoma (GBM) is the most common and deadly malignant brain cancer of glial cell origin, with a median patient survival of less than 20 months. Transcription factors FOXG1 and TLE1 promote GBM propagation by supporting maintenance of brain tumour‐initiating cells (BTICs) with stem‐like properties. Here, we characterize FOXG1 and TLE1 target genes in GBM patient‐derived BTICs using ChIP‐Seq and RNA‐Seq approaches. These studies identify 150 direct FOXG1 targets, several of which are also TLE1 targets, involved in cell proliferation, differentiation, survival, chemotaxis and angiogenesis. Negative regulators of NOTCH signalling, including CHAC1, are among the transcriptional repression targets of FOXG1:TLE1 complexes, suggesting a crosstalk between FOXG1:TLE1 and NOTCH‐mediated pathways in GBM. These results provide previously unavailable insight into the transcriptional programs underlying the tumour‐promoting functions of FOXG1:TLE1 in GBM

Transcription factors FOXG1 and Groucho/TLE promote glioblastoma growth

Glioblastoma (GBM) is the most common and deadly malignant brain cancer, with a median survival of <2 years. GBM displays a cellular complexity that includes brain tumour-initiating cells (BTICs), which are considered as potential key targets for GBM therapies. Here we show that the transcription factors FOXG1 and Groucho/TLE are expressed in poorly differentiated astroglial cells in human GBM specimens and in primary cultures of GBM-derived BTICs, where they form a complex. FOXG1 knockdown in BTICs causes downregulation of neural stem/progenitor and proliferation markers, increased replicative senescence, upregulation of astroglial differentiation genes and decreased BTIC-initiated tumour growth after intracranial transplantation into host mice. These effects are phenocopied by Groucho/TLE knockdown or dominant inhibition of the FOXG1:Groucho/TLE complex. These results provide evidence that transcriptional programmes regulated by FOXG1 and Groucho/TLE are important for BTIC-initiated brain tumour growth, implicating FOXG1 and Groucho/TLE in GBM tumourigenesi

MicroRNA 483‐3p overexpression unleashes invasive growth of metastatic colorectal cancer via NDRG1 downregulation and ensuing activation of the ERBB3/AKT axis

In colorectal cancer, the mechanisms underlying tumor aggressiveness require further elucidation. Taking advantage of a large panel of human metastatic colorectal cancer xenografts and matched stem‐like cell cultures (m‐colospheres), here we show that the overexpression of microRNA 483‐3p (miRNA‐483‐3p; also known as MIR‐483‐3p), encoded by a frequently amplified gene locus, confers an aggressive phenotype. In m‐colospheres, endogenous or ectopic miRNA‐483‐3p overexpression increased proliferative response, invasiveness, stem cell frequency, and resistance to differentiation. Transcriptomic analyses and functional validation found that miRNA‐483‐3p directly targets NDRG1, known as a metastasis suppressor involved in EGFR family downregulation. Mechanistically, miRNA‐483‐3p overexpression induced the signaling pathway triggered by ERBB3, including AKT and GSK3β, and led to the activation of transcription factors regulating epithelial–mesenchymal transition (EMT). Consistently, treatment with selective anti‐ERBB3 antibodies counteracted the invasive growth of miRNA‐483‐3p‐overexpressing m‐colospheres. In human colorectal tumors, miRNA‐483‐3p expression inversely correlated with NDRG1 and directly correlated with EMT transcription factor expression and poor prognosis. These results unveil a previously unrecognized link between miRNA‐483‐3p, NDRG1, and ERBB3‐AKT signaling that can directly support colorectal cancer invasion and is amenable to therapeutic targeting

MET inhibition overcomes radiation resistance of glioblastoma stem-like cells

Glioblastoma (GBM) contains stem‐like cells (GSCs) known to be resistant to ionizing radiation and thus responsible for therapeutic failure and rapidly lethal tumor recurrence. It is known that GSC radioresistance relies on efficient activation of the DNA damage response, but the mechanisms linking this response with the stem status are still unclear. Here, we show that the MET receptor kinase, a functional marker of GSCs, is specifically expressed in a subset of radioresistant GSCs and overexpressed in human GBM recurring after radiotherapy. We elucidate that MET promotes GSC radioresistance through a novel mechanism, relying on AKT activity and leading to (i) sustained activation of Aurora kinase A, ATM kinase, and the downstream effectors of DNA repair, and (ii) phosphorylation and cytoplasmic retention of p21, which is associated with anti‐apoptotic functions. We show that MET pharmacological inhibition causes DNA damage accumulation in irradiated GSCs and their depletion in vitro and in GBMs generated by GSC xenotransplantation. Preclinical evidence is thus provided that MET inhibitors can radiosensitize tumors and convert GSC‐positive selection, induced by radiotherapy, into GSC eradication

Mutated axon guidance gene PLXNB2 sustains growth and invasiveness of stem cells isolated from cancers of unknown primary

The genetic changes sustaining the development of cancers of unknown primary (CUP) remain elusive. The whole-exome genomic profiling of 14 rigorously selected CUP samples did not reveal specific recurring mutation in known driver genes. However, by comparing the mutational landscape of CUPs with that of most other human tumor types, it emerged a consistent enrichment of changes in genes belonging to the axon guidance KEGG pathway. In particular, G842C mutation of PlexinB2 (PlxnB2) was predicted to be activating. Indeed, knocking down the mutated, but not the wild-type, PlxnB2 in CUP stem cells resulted in the impairment of self-renewal and proliferation in culture, as well as tumorigenic capacity in mice. Conversely, the genetic transfer of G842C-PlxnB2 was sufficient to promote CUP stem cell proliferation and tumorigenesis in mice. Notably, G842C-PlxnB2 expression in CUP cells was associated with basal EGFR phosphorylation, and EGFR blockade impaired the viability of CUP cells reliant on the mutated receptor. Moreover, the mutated PlxnB2 elicited CUP cell invasiveness, blocked by EGFR inhibitor treatment. In sum, we found that a novel activating mutation of the axon guidance gene PLXNB2 sustains proliferative autonomy and confers invasive properties to stem cells isolated from cancers of unknown primary, in EGFR-dependent manner