Axitinib induces senescence-associated cell death and necrosis in glioma cell lines: The proteasome inhibitor, bortezomib, potentiates axitinib-induced cytotoxicity in a p21(Waf/Cip1) dependent manner.

Maria Beatrice Morelli,Angela Santoni,Claudio Cardinali,Giovanni Bernardini,Matteo Santoni,Giorgio Santoni,Massimo Nabissi,Consuelo Amantini

doi:10.18632/oncotarget.13769

Abstract

Glioblastoma is associated with a poor overall survival despite new treatment advances. Antiangiogenic strategies targeting VEGF based on tyrosine kinase inhibitors (TKIs) are currently undergoing extensive research for the treatment of glioma.Herein we demonstrated that the TKI axitinib induces DNA damage response (DDR) characterized by γ-H2AX phosphorylation and Chk1 kinase activation leading to G2/M cell cycle arrest and mitotic catastrophe in U87, T98 and U251 glioma cell lines. Moreover, we found that p21(Waf1/Cip1) increased levels correlates with induction of ROS and senescence-associated cell death in U87 and T98 cell lines, which are reverted by N-acetyl cysteine pretreatment. Conversely, U251 cell line showed a resistant phenotype in response to axitinib treatment, as evidenced by cell cycle arrest but no sign of cell death.The combinatorial use of axitinib with other therapies, with the aim of inhibiting multiple signaling pathways involved in tumor growth, can increase the efficiency of this TKI. Thus, we addressed the combined effects of axitinib with no toxic doses of the proteasome inhibitor bortezomib on the growth of U87 and T98 axitinib-sensitive and axitinib-resistant U251 cell lines. Compared to single treatments, combined exposure was more effective in inhibiting cell viability of all glioma cell lines, although with different cell death modalities. The regulation of key DDR and cell cycle proteins, including Chk1, γ-H2AX and p21(Waf1/Cip1) was also studied in glioma cell lines.Collectively, these findings provide new perspectives for the use of axitinib in combination with Bortezomib to overcome the therapy resistance in gliomas.

Highlights

Glioblastoma (GBM) is a high angiogenic malignancy
We have recently reported that axitinib induces activation of DNA damage response (DDR), senescence and mitotic catastrophe in RCC cell lines [7]; at present, very few data using this tyrosine kinase inhibitors (TKIs) have been provided in GBM
To evaluate whether axitinib treatment could trigger the DDR in glioma cells, we initially investigated the presence of γ-H2AX (H2AX), Ser139 phosphorylated variant of histone 2A associated with DNA double-strand breaks [23]

Summary

Introduction

Glioblastoma (GBM) is a high angiogenic malignancy. GBM secretes high levels of vascular endothelial growth factor (VEGF) that promotes endothelial cell proliferation, blood brain barrier permeability and angiogenesis [1, 2]. They are aggressive tumors that generally respond poorly to therapy consisting of surgery, radiation, and conventional chemotherapy. Targeted agents hold significant promise as novel therapeutic adjuncts; these new therapies are still in clinical trial phase. A new current focuses on www.impactjournals.com/oncotarget the angiogenic tyrosine kinase receptors (TRKs) and their signaling pathway inactivation. The anti-VEGF antibody bevacizumab was the first TKI approved in 2009 by the Food and Drug Administration (FDA) as a second-line treatment of recurrent GBM [4]

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