Low-grade, pilocytic astrocytomas are treated by resection, but additional therapy is necessary for those tumors with anaplastic features. Arsenic trioxide (As2O3) is emerging as an effective chemotherapeutic agent for treatment of leukemia and malignant glioma, where we propose that cathepsin L silencing enables lower, less harmful As2O3 concentrations to achieve the desired cytotoxic effect. Here, we evaluated the effects of As2O3 combined with stable cathepsin L shRNA silencing on cell viability/metabolic activity, and apoptosis in primary cultures of recurrent malignantly transformed pilocytic astrocytoma (MPA). These cells expressed high cathepsin L levels, and when grown as monolayers and spheroids. However, after silencing of cathepsin L expression, As2O3 treatment was cytotoxic to MPA spheroids and there was an increase in As2O3-mediated apoptosis in MPA-si spheroids, as indicated by elevated caspases 3/7 activity. Therefore, cathepsin L silencing by gene manipulation can be applied when a more aggressive approach is needed in treatment astrocytomas with anaplastic features and possibly GBM.
COBISS.SI-ID: 4369743
Glioblastoma stem cells (GSC) are a faction of therapy-resistant cancer cells in a glioblastoma (GBM). GSC home into protective niches by the interaction between GSC receptors CXCR4/CXCR7 and the chemoattractant SDF-1α. The cysteine protease CatK, with SDF-1α degrading ability, is also expressed in GSC niches. In this study, we demonstrated by mass spectrometric analysis that CatK cleaves the N-terminal domain of SDF-1α, which is the region of SDF-1α that binds to its receptors. We localized SDF-1α, CXCR4 and CatK in niches in GBM tissue sections. Moreover, 2D and 3D invasion experiments using CXCR4/7-expressing GSC and GBM cells showed that SDF-1α had chemotactic activity, whereas CatK cleavage products of SDF-1α did not. We propose that CatK activity may be a promising strategy to prevent homing of GSC in niches and render them more sensitive to therapy.
COBISS.SI-ID: 4162895
Glioblastoma multiforme are an aggressive form of brain tumors that are characterized by distinct invasion of single glioblastoma cells, which infiltrate the brain parenchyma. This appears to be stimulated by the communication between cancer and stromal cells. Mesenchymal stem cells (MSCs) are part of the glioblastoma microenvironment, and their ‘cross-talk’ with glioblastoma cells is still poorly understood. This is the first demonstration of glioblastoma cell-type-specific responses to MSCs in direct glioblastoma co-cultures, where MSCs inhibited the invasion of U87 cells and enhanced the invasion of U373. MSC-enhanced invasion of U373 cells was assisted by overexpression of selected roteases. In contrast, these proteases had no effect on U87 cell invasion under MSC co-culturing. Finally, we identified differentially expressed genes, in U87 and U373 cells that could explain different response of these cell lines to MSCs. In conclusion, we demonstrated that MSC/glioblastoma cross-talk is different in the two glioblastoma cell phenotypes, which contributes to tumor heterogeneity
COBISS.SI-ID: 4238415
Increased eutrophication of water bodies promotes cyanobacterial blooming that is hazardous due to the production of various bioactive compounds. In the present study the combined genotoxic effects of two ubiquitously present cyanotoxins, namely microcystin-LR (MCLR) and cylindrospermopsin (CYN) were studied. Comet and Cytokinesis block micronucleus assays were used to detect induction of DNA strand breaks (sb) and genomic instability, respectively, along with the transcriptional analyses of the expression of selected genes involved in xenobiotic metabolism, immediate/early cell response and DNA-damage response. The results showed that genotoxic potential of the MCLR/CYN mixture is comparable to that of CYN alone, which indicated that CYN exerts higher genotoxic potential than MCLR.
COBISS.SI-ID: 4420431
Cell lines which are currently used in genotoxicity tests lack enzymes which activate/detoxify mutagens. Therefore, rodent derived liver preparations are used which reflect their metabolism in humans only partly; as a consequence misleading results are often obtained. Previous findings suggest that certain liver cell lines express phase I/II enzymes and detect promutagens without activation; however, their use is hampered by different shortcomings. The aim of this study was the identification of a suitable cell line. The sensitivity of twelve hepatic cell lines was investigated in single cell gel electrophoresis assays. Furthermore, characteristics of these lines were studied which are relevant for their use in genotoxicity assays (mitotic activity, p53 status, chromosome number, and stability). Three lines (HuH6, HCC1.2, and HepG2) detected representatives of five classes of promutagens, namely, IQ and PhIP (HAAs), B(a)P (PAH), NDMA (nitrosamine), and AFB1 (aflatoxin), and were sensitive towards reactive oxygen species (ROS).
COBISS.SI-ID: 4521807