gms | German Medical Science

Objective: Axitinib is a small-molecule protein-tyrosine kinase receptor inhibitor specifically targeting the family of vascular endothelial growth factor receptors, in addition to platelet-derived growth factor receptors and proto-oncogene c-Kit. It's the aim of this study to investigate the effects of axitinib on glioma cell growth in a model of ex vivo organotypic brain slice cultures of human gliomas and primary glioma cell cultures in combination with permanent glioma cell lines.

Method: We used a panel of multiple resected human malignant glioma samples, which were treated with axitinib for prolonged periods in an ex vivo organotypic brain slice model that allowed quantification of invasion, proliferation, and angiogenesis by staining the treated samples for CD31, GFAP, EMA, Iba-1, Ki-67, and cleaved caspase 3, as well as PAS and HE. Furthermore, MTT and BrdU assays of primary human glioma cell cultures and the permanent glioblastoma cell lines A172, and LN229 were used to investigate the viability and proliferation inhibitory effects of axitinib. Apoptosis analysis proceeded by detecting the cleavage of caspase-3 and PARP, whereas autophagy was analyzed by detection of cleaved LC3B-II. The levels of proteins were probed by Western blotting.

Results: Multi tyrosin kinase inhibition by axitinib led to a decrease in number of proliferative cells, and an increase of apoptotic cells as well as necrotic areas in organotypic brain slice cultures of human gliomas. In glioma cell cultures, axitinib treatment led to a significant reduction of viability as well as inhibition of proliferation of human glioma cells in a time and concentration dependent manner. There was no relevant difference of efficacy of tyrosin kinase inhibition concerning primary cell cultures and permanent cell lines. Furthermore, multi tyrosin kinase inhibition induced apoptosis in a caspase-dependent manner in glioma cells. Apoptosis was accompanied by defective autophagy, demonstrated by the detection of cleaved LC3B-II.

Conclusions: Axitinib effectively inhibits tumor progression in an organotypic ex vivo model of human gliomas. Furthermore multi tyrosin kinase inhibition by axitinib leads to proliferation and viability inhibition in gliomas, as well as to an induction of apoptosis in those tumors. These results suggest that axitinib could constitute a therapeutic alternative for the treatment of human gliomas.