Phosphatidylinositol 3-Kinase/AKT Pathway Inhibition by Doxazosin Promotes Glioblastoma Cells Death, Upregulation of p53 and Triggers Low Neurotoxicity

PLoS One. 2016 Apr 28;11(4):e0154612. doi: 10.1371/journal.pone.0154612. eCollection 2016.

Abstract

Glioblastoma is the most frequent and malignant brain tumor. Treatment includes chemotherapy with temozolomide concomitant with surgical resection and/or irradiation. However, a number of cases are resistant to temozolomide, as well as the human glioblastoma cell line U138-MG. We investigated doxazosin's (an antihypertensive drug) activity against glioblastoma cells (C6 and U138-MG) and its neurotoxicity on primary astrocytes and organoptypic hippocampal cultures. For this study, the following methods were used: citotoxicity assays, flow cytometry, western-blotting and confocal microscopy. We showed that doxazosin induces cell death on C6 and U138-MG cells. We observed that doxazosin's effects on the PI3K/Akt pathway were similar as LY294002 (PI3K specific inhibitor). In glioblastoma cells treated with doxasozin, Akt levels were greatly reduced. Upon examination of activities of proteins downstream of Akt we observed upregulation of GSK-3β and p53. This led to cell proliferation inhibition, cell death induction via caspase-3 activation and cell cycle arrest at G0/G1 phase in glioblastoma cells. We used in this study Lapatinib, a tyrosine kinase inhibitor, as a comparison with doxazosin because they present similar chemical structure. We also tested the neurocitotoxicity of doxazosin in primary astrocytes and organotypic cultures and observed that doxazosin induced cell death on a small percentage of non-tumor cells. Aggressiveness of glioblastoma tumors and dismal prognosis require development of new treatment agents. This includes less toxic drugs, more selective towards tumor cells, causing less damage to the patient. Therefore, our results confirm the potential of doxazosin as an attractive therapeutic antiglioma agent.

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects*
  • Astrocytes / drug effects
  • Brain Neoplasms / drug therapy*
  • Caspase 3 / metabolism
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Chromones / pharmacology
  • Doxazosin / pharmacology*
  • Doxazosin / toxicity
  • Enzyme Activation / drug effects
  • G1 Phase Cell Cycle Checkpoints / drug effects
  • Glioblastoma / drug therapy*
  • Glycogen Synthase Kinase 3 beta / biosynthesis
  • Hippocampus / drug effects
  • Humans
  • Lapatinib
  • Morpholines / pharmacology
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoinositide-3 Kinase Inhibitors*
  • Proto-Oncogene Proteins c-akt / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-akt / metabolism
  • Quinazolines / pharmacology
  • Rats
  • Rats, Wistar
  • Tumor Suppressor Protein p53 / biosynthesis*

Substances

  • Antineoplastic Agents
  • Chromones
  • Morpholines
  • Phosphoinositide-3 Kinase Inhibitors
  • Quinazolines
  • Tumor Suppressor Protein p53
  • Lapatinib
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • Glycogen Synthase Kinase 3 beta
  • Proto-Oncogene Proteins c-akt
  • Caspase 3
  • Doxazosin

Grant support

The authors have no support or funding to report.