Biomol Ther.  2019 Nov;27(6):530-539. 10.4062/biomolther.2019.151.

Etoposide Induces Mitochondrial Dysfunction and Cellular Senescence in Primary Cultured Rat Astrocytes

• Bang M
• Kim DG
• Gonzales E
• Kwon KJ
• Shin CY

• KMID: 2462880
• DOI: http://doi.org/10.4062/biomolther.2019.151

Abstract

Brain aging is an inevitable process characterized by structural and functional changes and is a major risk factor for neurodegenerative diseases. Most brain aging studies are focused on neurons and less on astrocytes which are the most abundant cells in the brain known to be in charge of various functions including the maintenance of brain physical formation, ion homeostasis, and secretion of various extracellular matrix proteins. Altered mitochondrial dynamics, defective mitophagy or mitochondrial damages are causative factors of mitochondrial dysfunction, which is linked to age-related disorders. Etoposide is an anti-cancer reagent which can induce DNA stress and cellular senescence of cancer cell lines. In this study, we investigated whether etoposide induces senescence and functional alterations in cultured rat astrocytes. Senescence-associated β-galactosidase (SA-β-gal) activity was used as a cellular senescence marker. The results indicated that etoposide-treated astrocytes showed cellular senescence phenotypes including increased SA-β-gal-positive cells number, increased nuclear size and increased senescence-associated secretory phenotypes (SASP) such as IL-6. We also observed a decreased expression of cell cycle markers, including Phospho-Histone H3/Histone H3 and CDK2, and dysregulation of cellular functions based on wound-healing, neuronal protection, and phagocytosis assays. Finally, mitochondrial dysfunction was noted through the determination of mitochondrial membrane potential using tetramethylrhodamine methyl ester (TMRM) and the measurement of mitochondrial oxygen consumption rate (OCR). These data suggest that etoposide can induce cellular senescence and mitochondrial dysfunction in astrocytes which may have implications in brain aging and neurodegenerative conditions.

Keyword

Astrocytes; Energy homeostasis; Mitochondria; Cellular Senescence; Phagocytosis; Wound Healing

MeSH Terms

Aging
Animals
Astrocytes*
Brain
Cell Aging*
Cell Cycle
Cell Line
DNA
Etoposide*
Extracellular Matrix Proteins
Homeostasis
Interleukin-6
Membrane Potential, Mitochondrial
Mitochondria
Mitochondrial Degradation
Mitochondrial Dynamics
Neurodegenerative Diseases
Neurons
Neuroprotection
Oxygen Consumption
Phagocytosis
Phenotype
Rats*
Risk Factors
Wound Healing
DNA
Etoposide
Extracellular Matrix Proteins
Interleukin-6