In vitro investigation of epigenetic regulators related to chemo-resistance and stemness of CD133+VE cells sorted from U87MG cell line

Glioblastoma (GBM) is the most common and malignant adult primary brain tumor with frequent relapse and resistance to therapies. Glioma stem cells, a rare population, is thought to be the reason behind the treatment’s failure. It is imperative to investigate the disease mechanisms and identify the biomarkers by which glioma stem cells would contribute to treatment relapse and resistance to already available chemotherapeutic agents. The CD133+VE cells were isolated from U87MG cell line and characterized by morphological features, cell viability, self-renewal efficiency, migration potential and karyotyping. Doxorubicin Cisplatin, Irinotecan, Etoposide and Temozolomide were used to determine the anti-proliferative effect on CD133+VE cells. Confocal microcopy was used to localize the chemotherapeutic agents in the CD133+VE cells. In quest of epigenetic biomarkers, RNA sequencing was performed to find the role of lncRNAs in stemness and resistance to therapies. U87cell line and CD133-VE cells were kept as controls for all the experiments. It was found that CD133+VEcells were highly proliferative with increased migration potential, elevated IC50 values against chemotherapeutic agents and showed distinct karyotyping related to pluripotency. Chemotherapeutic agent such as Doxorubicin was localized outside the nucleus revealing the drug resistance as evident by confocal microscopy. RNA sequencing revealed 126 differentially expressed lncRNAs (DELs) in CD133+VEcells among which lncRNA LOXL1-AS1 was highly upregulated and lncRNA PAX8-AS1 was significantly downregulated. These lncRNAs has been reported to be related to drug resistance, migration and epithelial- to- mesenchymal transmission (EMT), self-renewal and stemness properties contributing to poor prognosis and disease relapse.