3 research outputs found
Investigating the mechanisms of methotrexate neurotoxicity in patients with childhood leukaemia and long-term survivors.
Background/Objectives
Adverse neurological events are common (4-20%) during treatment for pediatric acute lymphoblastic leukaemia (ALL) and include seizures, stroke like syndrome and leukoencephalopathy. In addition, chronic neurotoxicity is emerging as a worrying late effect of treatment with long-term survivors experiencing decreased executive function, processing speed and memory function. Survivors are also at increased risk of experiencing learning difficulties, social withdrawal issues and inattention hyperactivity disorders. Methotrexate, an anti-folate chemotherapy agent, is a mainstay of pediatric leukemia treatment regimens globally and is widely implicated as a cause of these neurological side effects. We hypothesise that methotrexate disrupts DNA methylation via effects on S-adenosyl methionine, a key metabolic component that has previously been described to regulate genes involved in myelination.
Design/Methods
Using both the oligodendrocytic-like cell line MO3.13 and glial cells derived from induced pluripotent stem cells (iPSC) treated with methotrexate, we assayed for changes in DNA methylation and effects on gene expression using whole-genome methylation arrays and RNAseq, respectively. Genes with corresponding methylation and expression changes were selected for further studies of expression by real-time qPCR and assessment of protein levels.
Results
We identified DNA methylation and corresponding expression changes in genes involved in neurodevelopmental pathways and neurological disorders. Of particular interest was dose-dependent demethylation and increased gene expression of IRS1, a vital component of insulin signalling pathways that is highly expressed in neural tissue and implicated in regulating cognitive performance. We also detected altered DNA methylation within the PLP1 gene, which encodes the most prevalent protein component of myelin. We found that methotrexate treatment in iPSC-derived oligodendrocytes resulted in increased PLP1 methylation associated with a reduction in PLP1 transcript levels as well as PLP1 protein levels.
Conclusions
Our work provides insight as to the biological mechanisms behind methotrexate-induced neurological side effects for the first time and implicates altered insulin signalling and myelination pathways as a potential causative factor in neurotoxicity. Further work including the use of animal models is warranted for advancing these results towards informing clinical practice
Qualified predictions for microarray and proteomics pattern diagnostics with confidence machines
Targeting apoptosis pathways in glioblastoma
The treatment of glioblastoma remains a major challenge for clinicians since these highly aggressive brain tumors are relatively resistant towards radio- and chemotherapy. The pathways that control apoptosis are altered in glioblastoma cells leading to resistance towards apoptotic stimuli in general. In this review we describe the alterations affecting the p53 pathway, the BCL-2 protein family, the inhibitor of apoptosis proteins and several growth factor pathways involved in the regulation of programmed cell death and define possible targets for new therapies within these apoptotic pathways in glioblastomas. Moreover, we review strategies to target death receptor pathways, most notably to render the glioblastoma cells more susceptible towards this approach without enhancing toxicity in general. Most of the strategies targeting apoptosis in glioblastomas presented here are in a pre-clinical stage of development, however, they all share the ultimative goal to improve the outcome for glioblastoma patients