Paclitaxel Impedes EGFR-mutated PC9 Cell Growth Reactive Oxygen Species-mediated DNA Damage and EGFR/PI3K/AKT/mTOR Signaling Pathway Suppression.

BACKGROUND/AIM: Paclitaxel is used as a first-line and subsequent therapy for the treatment of various cancers. However, the function and mechanisms of action of paclitaxel in non-small-cell lung cancer (NSCLC) remain unknown. In this study, the molecular mechanism underlying the anticancer activity of paclitaxel was investigated in vitro in a human NSCLC cell line carrying the EGFR exon 19 deletion (PC9).

MATERIALS AND METHODS

PC9 cells were treated with paclitaxel and then evaluated with a cell viability assay, DAPI staining, Giemsa staining, apoptosis assay, reactive oxygen species (ROS) assay, terminal deoxynucleotidyl transferase dUTP nick-end labeling assay and Western blotting.

RESULTS

Paclitaxel markedly decreased the viability of PC9 cells and induced morphological signs of apoptosis. The apoptotic effects of paclitaxel were observed through caspase cascade activation, along with ROS generation and loss of mitochondrial membrane potential (MMP). Furthermore, paclitaxel induced ROS-mediated DNA damage that triggered the activation of the extrinsic pathway of apoptosis via the up-regulation of death receptor (DR5) and caspase-8 activation. In addition, we found that paclitaxel effectively suppressed the EGFR/PI3K/AKT/mTOR signaling pathway to impede PC9 cell growth. Paclitaxel induced cell cycle arrest at the G1 phase in response to DNA damage, in association with the suppression of CDC25A, Cdk2 and Cyclin E1 protein expression.

CONCLUSION

Paclitaxel showed anticancer effects against NSCLC by activating extrinsic and intrinsic apoptotic pathways through enhancing ROS generation, inducing cell cycle arrest, and suppressing EGFR/PI3K/AKT/mTOR signaling pathway.