Rebound growth of BRAF mutant pediatric glioma cells after MAPKi withdrawal is associated with MAPK reactivation and secretion of microglia-recruiting cytokines

INTRODUCTION: Patients with pediatric low-grade gliomas (pLGGs), the most common primary brain tumors in children, can often benefit from MAPK inhibitor (MAPKi) treatment. However, rapid tumor regrowth, also referred to as rebound growth, may occur once treatment is stopped, constituting a significant clinical challenge. METHODS: Four patient-derived pediatric glioma models were investigated to model rebound growth in vitro based on viable cell counts in response to MAPKi treatment and withdrawal. A multi-omics dataset (RNA sequencing and LC-MS/MS based phospho-/proteomics) was generated to investigate possible rebound-driving mechanisms. Following in vitro validation, putative rebound-driving mechanisms were validated in vivo using the BT-40 orthotopic xenograft model. RESULTS: Of the tested models, only a BRAFV600E-driven model (BT-40, with additional CDKN2A/Bdel) showed rebound growth upon MAPKi withdrawal. Using this model, we identified a rapid reactivation of the MAPK pathway upon MAPKi withdrawal in vitro, also confirmed in vivo. Furthermore, transient overactivation of key MAPK molecules at transcriptional (e.g. FOS) and phosphorylation (e.g. pMEK) levels, was observed in vitro. Additionally, we detected increased expression and secretion of cytokines (CCL2, CX3CL1, CXCL10 and CCL7) upon MAPKi treatment, maintained during early withdrawal. While increased cytokine expression did not have tumor cell intrinsic effects, presence of these cytokines in conditioned media led to increased attraction of microglia cells in vitro. CONCLUSION: Taken together, these data indicate rapid MAPK reactivation upon MAPKi withdrawal as a tumor cell intrinsic rebound-driving mechanism. Furthermore, increased secretion of microglia-recruiting cytokines may play a role in treatment response and rebound growth upon withdrawal, warranting further evaluation

Association between self-rated depressive symptoms and mucosal expression of NF-κ B in patients with upper gastrointestinal symptoms

Abstract Background Previous clinical studies have reported elevated levels of depressive symptoms in selected samples of patients with gastritis. The objective of this study was to examine the associations of specific biomarkers of inflammation expressed in mucosal tissue from the stomach with mood and anxiety symptoms in adult patients with upper gastrointestinal symptoms. Methods In this monocentric, observational study, a total of 32 study participants were included who were referred for a routine diagnostic upper endoscopic assessment based on the suspected clinical diagnosis of gastritis. All participants completed the Hospital Anxiety and Depression Scale (HADS) before undergoing gastroscopy. Immunohistochemical stainings from biopsy sections were performed to evaluate the expression level of nuclear factor kappa B (NF-κ B), myeloperoxidase (MPO) and inducible nitric oxide synthase (iNOS). Results Our findings confirmed that nearly half of the study cohort (n = 13; 41%) displayed positive HADS depression scores above the clinically relevant cut-off level of ≥ 8. Regression models demonstrated that depressive symptoms were significantly and positively associated with the expression level of NF-κ B in biopsies from the upper gastrointestinal tract. Conclusions In summary, our study showed a significant association between NF-κ B expression and clinically relevant depressive symptoms in patients with gastritis, as assessed by a self-rated psychometric questionnaire. Further investigations are needed to confirm this relationship and to identify the pathophysiological mechanisms involved.Open-Access-Publikationsfonds 202

Rewritable polymer brush micropatterns grafted by triazolinedione click chemistry

Triazolinedione (TAD) click reactions were combined with microcontact chemistry to print, erase, and reprint polymer brushes on surfaces. By patterning substrates with a TAD-tagged atom-transfer radical polymerization initiator (ATRP-TAD) and subsequent surface initiated ATRP, it was possible to graft micropatterned polymer brushes from both alkene- and indole-functionalized substrates. As a result of the dynamic nature of the Alder-ene adduct of TAD and indole at elevated temperatures, the polymer pattern could be erased while the regenerated indole substrate could be reused to print new patterns. To demonstrate the robustness of the methodology, the write-erase cycle was repeated four times

Design of a thermally controlled sequence of triazolinedione-based click and transclick reactions

The reaction of triazolinediones (TADs) and indoles is of particular interest for polymer chemistry applications, as it is a very fast and irreversible additive-free process at room temperature, but can be turned into a dynamic covalent bond forming process at elevated temperatures, giving a reliable bond exchange or 'transclick' reaction. In this paper, we report an in-depth study aimed at controlling the TAD-indole reversible click reactions through rational design of modified indole reaction partners. This has resulted in the identification of a novel class of easily accessible indole derivatives that give dynamic TAD-adduct formation at significantly lower temperatures. We further demonstrate that these new substrates can be used to design a directed cascade of click reactions of a functionalized TAD moiety from an initial indole reaction partner to a second indole, and finally to an irreversible reaction partner. This controlled sequence of click and transclick reactions of a single TAD reagent between three different substrates has been demonstrated both on small molecule and macromolecular level, and the factors that control the reversibility profiles have been rationalized and guided by mechanistic considerations supported by theoretical calculations