Generating senescent airway epithelial cell populations using low-concentration doxorubicin or etoposide

Abstract

Introduction: Chronic obstructive pulmonary disease (COPD) is associated with accelerated lung aging. In the COPD lung, there is an accumulation of senescent cells that may, in part, be due to a lack of clearance. To investigate this, a robust source of well-characterised senescent cells is required. Doxorubicin (DOXO) and etoposide (Etop) at sub-cytotoxic concentrations activate the DNA-damage response (DDR) pathway, leading to the induction of cellular senescence and could be used to generate a senescent cell population for study.

Aim: To induce senescence in BEAS-2B cells using DOXO and Etop.

Methods: Senescent BEAS-2B cells were generated by repeated exposure to 50nM DOXO or 1mM Etop for a total of 6 days. Cell cycle checkpoint inhibitors, anti-aging molecule sirtuin-1 and senescence associated secretory phenotype (SASP) marker expression were measured using western blotting and ELISA. Senescent cells were identified by senescence-associated-b-galactosidase (SA-β-gal) expression.

Results: In BEAS-2B cells, 50nM DOXO treatment induced senescence in ~60% of cells (n=7, p<0.01), p21 protein expression (4-fold, p<0.01), reduced sirtuin-1 protein expression (~50%, p<0.05) and induced secretion of IL-6 (10-fold, p<0.05), CXCL-8 (6-fold, p<0.05) and PAI-1 (3-fold, p<0.01). 1mM etoposide treatment induced ~60% SA-b-gal (n=5, p<0.001), p21 protein expression (8-fold, p=0.1), secretion of IL-6 (19-fold, p=0.09), CXCL-8 (11-fold, p<0.05) and PAI-1 (3-fold, p<0.01).

Conclusion: Sub-cytotoxic double-hit DOXO and Etop treatments are required to induce senescence in BEAS-2B cells via p21 induction of cell cycle arrest and may provide a model that can be used in future experiments.