ABSTRACT
Hepatoblastoma (HB) is a rare childhood tumour with an evolving molecular landscape. We present the first comprehensive metabolomic analysis using untargeted and targeted liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-MS/MS) of paired tumour and non-tumour surgical samples in HB patients (n = 8 pairs). This study demonstrates that the metabolomic landscape of HB is distinct from that of non-tumour (NT) liver tissue, with 35 differentially abundant metabolites mapping onto pathways such as fatty acid transport, glycolysis, the tricarboxylic acid (TCA) cycle, branched-chain amino acid degradation and glutathione synthesis. Targeted metabolomics demonstrated reduced short-chain acylcarnitines and a relative accumulation of branched-chain amino acids. Medium- and long-chain acylcarnitines in HB were similar to those in NT. The metabolomic changes reported are consistent with previously reported transcriptomic data from tumour and non-tumour samples (49 out of 54 targets) as well as metabolomic data obtained using other techniques. Gene set enrichment analysis (GSEA) from RNAseq data (n = 32 paired HB and NT samples) demonstrated a downregulation of the carnitine metabolome and immunohistochemistry showed a reduction in CPT1a (n = 15 pairs), which transports fatty acids into the mitochondria, suggesting a lack of utilisation of long-chain fatty acids in HB. Thus, our findings suggest a reduced metabolic flux in HB which is corroborated at the gene expression and protein levels. Further work could yield novel insights and new therapeutic targets.
ABSTRACT
Proliferative retinopathies are associated with formation of fibrous epiretinal membranes. At present, there is no pharmacological intervention for the treatment of retinopathies. Cytokines such as TGFß are elevated in the vitreous humor of the patients with proliferative vitro-retinopathy, diabetic retinopathy and age-related macular degeneration. TGFß isoforms lead to epithelial-mesenchymal transition (EMT) or trans-differentiation of the retinal pigment epithelial (RPE) cells. PI3K/Akt and MAPK/Erk pathways play important roles in the EMT of RPE cells. Therefore, inhibition of EMT by pharmacological agents is an important therapeutic strategy in retinopathy. Dichloroacetate (DCA) is shown to prevent proliferation and EMT of cancer cell lines but its effects are not explored on the prevention of EMT of RPE cells. In the present study, we have investigated the role of DCA in preventing TGFß2 induced EMT of RPE cell line, ARPE-19. A wound-healing assay was utilized to detect the anti-EMT effect of DCA. The expressions of EMT and cell adhesion markers were carried out by immunofluorescence, western blotting, and quantitative real-time PCR. The expression of MAPK/Erk and PI3K/Akt pathway members was carried out using western blotting. We found that TGFß2 exposure leads to an increase in the wound healing response, expression of EMT markers (Fibronectin, Collagen I, N-cadherin, MMP9, S100A4, α-SMA, Snai1, Slug) and a decrease in the expression of cell adhesion/epithelial markers (ZO-1, Connexin 43, E-cadherin). These changes were accompanied by the activation of PI3K/Akt and MAPK/Erk pathways. Simultaneous exposure of DCA along with TGFß2 significantly inhibited wound healing response, expression of EMT markers and cell adhesion/epithelial markers. Furthermore, DCA and TGFß2 effectively attenuated the activation of MAPK/Erk/JNK and PI3K/Akt/GSK3ß pathways. Our results demonstrate that DCA has a strong anti-EMT effect on the ARPE-19 cells and hence can be utilized as a therapeutic agent in the prevention of proliferative retinopathies.
