Journal of Spine & NeurosurgeryISSN: 2325-9701

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Research Article, J Spine Neurosurg Vol: 5 Issue: 6

Differential Cell Death Effects in Glioblastoma after Drug- Induced DNA Damage Laboratory Investigation

Chen MY1,2,3*, Fuji T1, Cheung B1, Graf MR2, Holt SE4, Clark AJ2,3, Chidambaram A3, Lin J1, Jandial R1 and Broaddus WC2,3
1Division of Neurosurgery, City of Hope National Medical Center, Duarte, California, USA
2Department of Neurosurgery, Virginia Commonwealth University, Medical College of Virginia Hospitals, Virginia Commonwealth University Health System, Richmond, Virginia, USA
3Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, Virginia, USA
4Department of Biology, Department of Chemistry, Virginia State University, Petersburg, Virginia, USA
Corresponding author : Dr. Mike Y. Chen
City of Hope National Medical Center,Division of Neurosurgery, MOB 2001, 1500 East Duarte Road, Duarte, CA 91010,USA
Tel: (626) 471-7100
Fax:
(626) 471-7344
E-mail: [email protected]
Received: June 09, 2016 Accepted: July 12, 2016 Published: July 22, 2016
Citation: Chen MY, Fuji T, Cheung B, Graf MR, Holt SE, et al. (2016) Differential Cell Death Effects in Glioblastoma after Drug-Induced DNA Damage Laboratory Investigation. J Spine Neurosurg 5:6. doi:10.4172/2325-9701.1000248

Abstract

Object: Glioblastomas are difficult tumors to eradicate because of resistance to apoptosis and other mechanisms of programmed cell death such as autophagy. We hypothesized that DNA damage, regardless of etiology, would cause autophagy. To test our hypothesis, we examined the ability of two DNA damaging agents, 1, 3-Bis (2-chloroethyl)-1-nitrosourea (BCNU) and cisplatin, to induce autophagy. Materials and methods: DNA damage was assessed by western blot for ?-H2AX and immunofluorescence for phospho-53BP1. Autophagy was measured by microtubule-associated protein 1 light chain (LC3) and beclin 1 western blots, acridine orange staining, response to the 3-MA inhibitor, and autophagosome detection using electron microscopy. To study apoptosis, we examined levels of BAX and BAK, TUNEL staining, inhibition with ZVAD.fmk and caspase 3/7 activation. Results: The levels of the DNA damage indicators ?-H2AX and 53BP1 increased with both BCNU and cisplatin. While LC3-II autophagy proteins were highly expressed in BCNU samples, LC3-II levels were below the limits of detection in cells treated with cisplatin. Caspase 3/7 activation only slightly increased with BCNU, but markedly increased with cisplatin. Surprisingly, BAX and BAK levels did not change in response to either chemotherapeutic compound. Significant TUNEL staining was evident in cisplatin, but not BCNU-treated cells, and the pancaspase inhibitor, ZVAD.fmk, did not diminish cell death after BCNU treatment. Conclusion: Although both drugs caused DNA damage, we concluded not all DNA damage results in a specific type of cell death, as BCNU-related cell death in glioblastomas occurs through autophagy and cisplatin predominantly induces apoptosis. The specific molecular mechanisms underlying the activation of autophagy remain obscure.

Keywords: Apoptosis; Autophagy; BCNU; Cisplatin; Glioblastoma; DNA damage

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