Abstract
Resistance to cancer drugs is a complex phenomenon which could be influenced by in vitro conditions. However, tumour-derived cell cultures are routinely used for studies related to mechanisms of drug responsiveness or the search for new therapeutic approaches. The purpose of our work was to identify the potential differences in drug resistance and response to treatment of glioblastoma with the use of three in vitro models: traditional adherent culture, serum-free spheroid culture and novel adherent serum-free culture.The experimental models were evaluated according to ‘stemness state‘ and epithelial-to-mesenchymal transition (EMT) status, invasion capability and their expression pattern of genes related to the phenomenon of tumour drug resistance. Additionally, the response to drug treatments of three different culture models was compared with regard to the type of cell death.Multi-gene expression profiling revealed differences between examined culture types with regard to the expression pattern of the selected genes. Functionally, the examined genes were related to drug resistance and metabolism, DNA damage and repair and cell cycle control, and included potential therapeutic targets.Cytotoxicity analyses confirmed that environmental factors can influence not only the molecular background of glioblastoma drug-resistance and efficiency of treatment, but also the mechanisms/pathways of cell death, which was reflected by a distinct intensification of apoptosis and autophagy observed in particular culture models. Our results suggest that parallel exploitation of different in vitro experimental models can be used to reveal the spectrum of cancer cell resistance capability, especially regarding intra-heterogeneous glioblastomas.
Highlights
Tumour-derived cell cultures are a common model used in studies of drug resistance mechanisms or the search for new therapeutic approaches
The resistance of cells to anticancer drugs may result from a variety of factors including the ‘stemness state’, epithelial-to-mesenchymal transition (EMT) status and invasion potential, or the expression pattern of genes related to drug metabolism/efflux and cell death defence mechanisms, e.g. the interplay between apoptosis, autophagy and necrosis, mechanisms of DNA damage repair or cell cycle control [5,6,7,8]
After an initial period of cell culture establishment and expansion, the cells were subjected to three different culture conditions: an adherent culture in traditional serum-supplemented medium (DMEM/F12 medium with 10% fetal bovine serum (FBS)), a spheroid culture (NBM medium with N2, B27, epidermal growth factor (EGF), basic fibroblast growth factor (bFGF) and heparin) and a novel method of adherent culture on a synthetic vitronectin-mimicking surface in serum-free medium (NBM medium with NSC and G5 supplements)
Summary
Tumour-derived cell cultures are a common model used in studies of drug resistance mechanisms or the search for new therapeutic approaches. The aim of the present study was to analyse the most likely mechanisms underlying the phenomenon of glioblastoma resistance by comparing three experimental in vitro models of glioblastoma (traditional adherent culture supplemented with serum, serum-free spheroid culture and novel adherent serum-free culture alternative to spheroid system), and to compare the response of these models to treatment with temozolomide (TMZ) or tamoxifen, with regard to cell death type. Our analysis of the multifactorial background of glioblastoma drug resistance and chemosensitivity acts as a counterpoint to existing reports which typically recommend individual experimental models for studies of tumour drug response The resistance of cells to anticancer drugs may result from a variety of factors including the ‘stemness state’, epithelial-to-mesenchymal transition (EMT) status and invasion potential, or the expression pattern of genes related to drug metabolism/efflux and cell death defence mechanisms, e.g. the interplay between apoptosis, autophagy and necrosis, mechanisms of DNA damage repair or cell cycle control [5,6,7,8].
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