14-Deoxycoleon U-induced endoplasmic reticulum stress-mediated apoptosis, autophagy, and cell cycle arrest in lung adenocarcinoma

Objective: 14-Deoxycoleon U is a natural abietane-type diterpene and exerts an inhibitory effect on tumor cells proliferation, which suggests that 14-Deoxycoleon U may be a potent anti-cancerous lead compound for lung cancer treatment. This study was to evaluate potential of 14-Deoxycoleon U to treat lung adenocarcinoma in vitro and in vivo.

Methods: In the present study, the cell viability and apoptosis morphology of 14-Deoxycoleon U-treated A549 and LLC cells were explored using cell counting kit-8 assay and Hoechst 33258 staining. Then, the protein expressions about apoptosis, endoplasmic reticulum (ER) stress, autophagy and cell cycle were measured using Western blot. The autophagosome formation of 14-Deoxycoleon U-treated A549 cells was visualized using a confocal microscopy. LLC lung adenocarcinoma model was established.

Results: The results indicated that 14-Deoxycoleon U significantly inhibited A549 and LLC cell proliferation in a dose-dependent manner via caspase-dependent apoptosis. Furthermore, apoptosis of both cells was mediated by 14-Deoxycoleon U-induced ER stress. In addition, 14-Deoxycoleon U-induced A549 and LLC cell autophagy, thus promoting their death. Moreover, 14-Deoxycoleon U-induced cell cycle arrest in both cells via inhibition of cyclin D3, cyclin-dependent kinase 6, CDC2 and up-regulation of p21. In vivo results showed that administration of 14-Deoxycoleon U significantly suppressed LLC growth and adverse effects of 14-Deoxycoleon U on organs might be lower than of adriamycin.

Conclusion: Overall, our results demonstrated that 14-Deoxycoleon U represses in vitro and in vivo growth of lung adenocarcinoma through ER stress-mediated apoptosis accompanied by autophagy and cell cycle arrest.