Gemcitabine therapeutically disrupts essential SIRT1-mediated p53 repression in atypical teratoid/rhabdoid tumors.

Atypical teratoid/rhabdoid tumors (ATRTs) are highly malignant embryonal tumors of the central nervous system with a dismal prognosis. Using a newly developed and validated patient-derived ATRT culture and xenograft model, alongside a panel of primary ATRT models, we found that ATRTs are selectively sensitive to the nucleoside analog gemcitabine. Gene expression and protein analyses indicate that gemcitabine treatment causes the degradation of sirtuin 1 (SIRT1), resulting in cell death through activation of nuclear factor κB (NF-κB) and p53.

Atypical teratoid/rhabdoid tumoroids reveal subgroup-specific drug vulnerabilities.

Atypical teratoid/rhabdoid tumors (ATRTs) represent a rare, but aggressive pediatric brain tumor entity. They are genetically defined by alterations in the SWI/SNF chromatin remodeling complex members SMARCB1 or SMARCA4. ATRTs can be further classified in different molecular subgroups based on their epigenetic profiles.

Ophthalmological Findings in Youths With a Newly Diagnosed Brain Tumor.

Importance: Visual impairment is an irreversible adverse effect in individuals who experienced a childhood brain tumor. Ophthalmological evaluation at diagnosis enables early detection of vision loss, decision-making about treatment, and when applicable, the timely use of visual interventions. However, awareness of visual impairment in clinical practice is suboptimal, and adherence to ophthalmological evaluation needs to be improved.

Transient Hepatotoxicity Induced by Vinblastine in a Young Girl with Chiasmatic Low Grade Glioma.

Background: Vinblastine (VBL) is a cytostatic drug frequently applied in children with lymphoma and progressive low-grade glioma (LGG), with hematotoxicity as the main side effect.

Case Report: Here, the case of a 7-month-old girl with tumor progression of an LGG during standard chemotherapy with carboplatin and vincristine, is presented. Switching to VBL led to a 20-30- fold increase of transaminases (grade IV CTCAE 5.

(Immuno)proteasomes as therapeutic target in acute leukemia.

The clinical efficacy of proteasome inhibitors in the treatment of multiple myeloma has encouraged application of proteasome inhibitor containing therapeutic interventions in (pediatric) acute leukemia. Here, we summarize the positioning of bortezomib, as first-generation proteasome inhibitor, and second-generation proteasome inhibitors in leukemia treatment from a preclinical and clinical perspective. Potential markers for proteasome inhibitor sensitivity and/or resistance emerging from leukemia cell line models and clinical sample studies will be discussed focusing on the role of immunoproteasome and constitutive proteasome (subunit) expression, PSMB5 mutations, and alternative mechanisms of overcoming proteolytic stress.

Higher ratio immune versus constitutive proteasome level as novel indicator of sensitivity of pediatric acute leukemia cells to proteasome inhibitors.

The ex vivo sensitivity of pediatric leukemia cells to the proteasome inhibitor bortezomib was compared to 3 next generation proteasome inhibitors: the epoxyketone-based irreversible proteasome inhibitors carfilzomib, its orally bio-available analog ONX 0912, and the immunoproteasome inhibitor ONX 0914. LC50 values were determined by MTT cytotoxicity assays for 29 childhood acute lymphoblastic leukemia and 12 acute myeloid leukemia patient samples and correlated with protein expression levels of the constitutive proteasome subunits (β5, β1, β2) and their immunoproteasome counterparts (β5i, β1i, β2i). Acute lymphoblastic leukemia cells were up to 5.

Effect of noncompetitive proteasome inhibition on bortezomib resistance.

Background: Bortezomib and the other proteasome inhibitors that are currently under clinical investigation bind to the catalytic sites of proteasomes and are competitive inhibitors. We hypothesized that proteasome inhibitors that act through a noncompetitive mechanism might overcome some forms of bortezomib resistance.

Methods: 5-amino-8-hydroxyquinoline (5AHQ) was identified through a screen of a 27-compound chemical library based on the quinoline pharmacophore to identify proteasome inhibitors.

A new link between steroid resistance, glucocorticoid receptor and nuclear factor kappa B p65 in idiopathic nephrotic syndrome.

Objectives: The aim of our study was to investigate levels of glucocorticoid receptor (GRalpha), nuclear factor kappa B (NFkappaB) p65/p50 and inhibitor of NFkappaB alpha (IkappaBalpha) in the peripheral mononuclear blood cells (PMBC) of children with idiopathic nephrotic syndrome (INS).

Methods: The expression of GRalpha, NFkappaBp65/p50 and IkappaBalpha was determined in 59 patients (age 10.2+/-5.

Molecular basis of bortezomib resistance: proteasome subunit beta5 (PSMB5) gene mutation and overexpression of PSMB5 protein.

The proteasome inhibitor bortezomib is a novel anticancer drug that has shown promise in the treatment of refractory multiple myeloma. However, its clinical efficacy has been hampered by the emergence of drug-resistance phenomena, the molecular basis of which remains elusive. Toward this end, we here developed high levels (45- to 129-fold) of acquired resistance to bortezomib in human myelomonocytic THP1 cells by exposure to stepwise increasing (2.

Trabectedin (ET-743, Yondelis) is a substrate for P-glycoprotein, but only high expression of P-glycoprotein confers the multidrug resistance phenotype.

Trabectedin (ET-743, Yondelis) is a novel anticancer drug currently undergoing phase II and III investigations. There are various and conflicting reports whether trabectedin is a substrate for P-glycoprotein (P-gp), an important factor in drug disposition and multi-drug resistance (MDR). We have now unambiguously shown that trabectedin is a P-gp substrate by investigating vectorial transport over monolayers of LLC-PK1 pig kidney and Madine-Darby Canine kidney (MDCK) cells and the mdr1a and/or MDR1 transfected subclones.

LacdiNAc-glycans constitute a parasite pattern for galectin-3-mediated immune recognition.

Although Gal beta 1-4GlcNAc (LacNAc) moieties are the most common constituents of N-linked glycans on vertebrate proteins, GalNAc beta 1-4GlcNAc (LacdiNAc, LDN)-containing glycans are widespread in invertebrates, such as helminths. We postulated that LDN might be a molecular pattern for recognition of helminth parasites by the immune system. Using LDN-based affinity chromatography and mass spectrometry, we have identified galectin-3 as the major LDN-binding protein in macrophages.