Forsøksdyr: The role of GPX7 in Glioblastoma cell invasion

Godkjenningsdato 27.08.2020

Godkjenningsperiode 01.09.2020-01.09.2022

1) Purpose of the Experiment : Glioblastoma (GBM) is the most aggressive primary brain tumor and characterized by its highly invasive nature. These invasive tumor cells escape current treatment strategies and lead to tumor recurrence. In a shRNA interference screen we have identified the glutathione peroxidase 7 (GPX7) as potential invasion-essential gene in GBM, which is higher expressed in invasive patient-derived GBM cell lines compared to non-invasive ones. We have observed in in vitro and ex vivo experiments, that the knockdown of GPX7 is able to reduce the invasion potential of an invasive GBM cell line (BG7), while its overexpression resulted in an increased invasion potential in a non-invasive GBM cell line (NCH644). We further generated a CRISPR/Cas9-based knockout of GPX7 in the invasive GBM cell line BG7, which did not show a significant effect in in vitro invasion assays. This project should help us to verify our in vitro and ex vivo findings and investigate the effect of the GPX7 knockout in an in vivo setting. We will use BG7 control cells and BG7 single clones with the GPX7 knockout for implantation into the brain of nude rats. We will determine the invasion potential of these cells and see if they are less invasive compared to control cells after orthotopic implantation into the brains of nude rats. The animals will be followed up by MRI imaging. The experiment will provide insight into the role of GPX7 in modulating the invasive behaviour of GBM cells.

2) Expected Distress for animals : We will implant brain tumor cells into the brains of nude rats. Tumors will develop and imaged regularly by MRI. From extensive prior experience, these surgical procedures are well tolerated by the animals. When tumors reach a size of 125mm3 as verified by MRI, the animals will be euthanized, and the tumors will be removed for further analysis. Based also on prior experience, and due to the fact that the animals will be euthanised before symptoms related to tumor burden appear, there should be a minor animal distress.

3) Expected Scientific or societal benefit : GBM is a very aggressive and also highly invasive tumor of the brain with dismal prognosis. Basic understanding of the invasive behaviour and development of new treatment strategies are needed to improve the survival of these patients.

4) Number of animals : 18 and Type : Nude Rats

5) Replacement, reduction and improvement : We have already performed extensive experiments in the cell culture using ex-vivo brain slice cultures. In order to validate our results in vitro and to evaluate a future therapeutic potential, we need to perform an in vivo experiment. In addition tumor cell invasion is a very complex process that is highly dependent on the tumor microenvironment and cannot be fully mimicked in vitro.