Status of INSR, LRP1 and VCL transcripts on CD133+ Glioblastoma Multiforme Stem Cells

OBJECTIVE Objective of this research is to explore new therapeutic targets within cell adhesion molecules to diminish specifically Glioblastoma Multiforme (GBM) stem cells (GSC). One of the most frequently encountered glioma tumours is GBM. CD133 is a cell surface protein that is well‐known GSC marker. Temozolomide (TMZ) is an alkylated drug that is used to eliminate cancer cells. Even if it is used in GBM, since it is not enough to diminish glioblastoma stem cells, tumour recurrence is observed. Via identifying molecular mechanisms of GBM stem cells novel therapeutic targets in the treatment process and drug resistance are going to set and underlined. Cell adhesion proteins mediate crosstalk of cells which results invasion or migration. Cell adhesion process is also crucial to maintain multicellular structure. Those molecules might have a contribution in cell signalling. Therefore, cell adhesion molecules are thought to be essential elements for cancer development and metastasis. Taking it in consideration, it is important to investigate and determine micro array profile of CD133+ GSCs in cell adhesion molecules point of view. Aim of this study is to scan 88 cell adhesion process related genes in GSCs where CD133 is a crucial stem cell marker. METHODS To perform this aim, we have isolated CD133+ cells from others by MACS method via AC133 CD133 antibody by using primary culture cells extracted from tissues of 10 GBM patients. Then, following RNA isolation from those positive and negative cells, cDNA synthesis was performed. Finally according to micro array protocol, cell adhesion array was applied. Proper results were collected and analysed statistically by using SPSS software RESULTS As a result, INSR (insulin receptor), LRP1 (low density lipoprotein receptor) and VCL (vinculin) genes seems to be upregulated in CD133+ GCSs compared CD133− cells 6,08, 4,94, 2,21 folds respectively. DISCUSSION GBM is using glucose uptake mechanisms to maintain cancer cells and evade apoptosis. Therefore we observed elevated transcripts of INSR gene, one of the main regulators of glucose uptake. We determined that GSCs are expressing INSR 6,08 fold higher than non‐GSCs. Thereby, it can be deducted that INSR can be responsible from the maintenance of the GSCs, hence GBM drug resistance. Furthermore, increased LRP1 transcript levels were observed in CD133+ GSCs compared to CD133− GBM cells (4,94 fold). LRP1 is involved in several cellular signalling pathways. For instance, LRP1 has a role in the induction together with EphA2 of AKT pathway, promoting cell invasion and motility. Therefore, LRP1 might be an important marker for GBM invasion and motility. We also detected increased transcript levels of Vinculin that is crucial for cell‐cell interaction playing a role to connect integrin molecules to actin cytoskeleton. VCL gene expression level was found 2,21 fold higher in CD133+ GSCs compared to non‐GSCs. As VCL protein influences cell motility by binding talin, it might be significant for GBM stem cell movement and migration. In summary, we found increased transcript levels of INSR, LRP1 and VCL genes in CD133+ GSCs. It is important to use specific markers to target cancer stem cells. In addition to CD133, targeting INSR, LRP1 and VCL might be essential to eliminate GSCs and improve stem cell based GBM therapies. Further studies are required to confirm the impact of these promising GSCs markers. This research has been supported by The Scientific and Technological Research Council of Turkey (No:114S189).