Preclinical gene therapy in glioblastoma multiforme: Using olfactory ensheathing cells containing a suicide gene

Abstract

Aims: Glioblastoma multiforme (GBM) is the most malignant type of brain tumor resistant to current treatments. Recently, suicide gene therapy with the Herpex Simplex Virus thymidine kinase (HSV-tk) gene has been developed with high therapeutic potency, even in clinical trials. The primary challenge to establishing a gene therapy strategy is how to transfer the desired gene into the tumor site. The olfactory ensheathing cells (OECs) secreting neurotropic and anti-inflammatory factors have a high migration capacity, making them applicable for gene therapy. We examined our new construct OECs containing the HSV-tk gene for their migration and tumoricidal ability in animal models of GBM.

Main methods: Isolated OECs were transduced by the HSV-tk gene (OEC-tks). OEC-tks or PBS were injected ipsilaterally or contralaterally into the tumor-bearing rats, followed by gancyclovir (GCV) or PBS administration. At the end of the treatment, tumor size, apoptosis, and animal survival were assessed.

Key findings: Our findings demonstrated that tumor size was significantly decreased in OEC-tks ipsilateral and contralateral groups, followed by GCV injections. Furthermore, both groups' pro-apoptotic protein and gene expressions were up-regulated, whereas Bcl-2 protein expression was down-regulated. Besides, apoptosis in the OEC-tks ipsilateral/GCV group was higher in the intratumoral region, and this percentage was higher in the OEC-tks contralateral/GCV group in the peritumoral region. Interestingly, our new construct increased animal survival rate and reduced body weight loss.

Significance: OECs could serve as a novel carrier for gene therapy, have a high migration capability to the GBM and eventually suppress tumor progression.

Keywords: Cancer; GCV: gancyclovir; Glioblastoma multiforme; Olfactory ensheathing cells; Suicide gene therapy; Thymidine kinase gene.