Dihydroisotanshinone I regulates ferroptosis via PI3K/AKT pathway to enhance cisplatin sensitivity in lung adenocarcinoma.

Abstract

Objectives: Dihydroisotanshinone I (DT) is a kind of diterpenoid compound extracted from the dried roots of Salvia miltiorrhiza Bunge, and exhibits multiple biological activities including anti-tumor activity. Cisplatin is one of the first-line drugs for the treatment of lung adenocarcinoma (LAUD), but the drug resistance and toxicity limit its efficacy. DT is known to induce apoptosis and ferroptosis, but it is unclear whether DT can inhibit the cisplatin-resistant LAUD cells and reverse the drug resistance in LAUD. Therefore, our study intends to establish the cisplatin-resistant human LAUD cells (A549/DDP), and figure out the influence and related mechanisms of DT reversing cisplatin resistance in A549/DDP cells, so as to provide a theoretical basis for the DT as a new natural candidate for the treatment of LAUD.

Methods: The establishment of A549/DDP was the continuous stimulation by exposing A549 to gradient concentrations of Cisplatin. The cell viability of A549 and A549/DDP was detected by CCK-8 kit, and the IC50 value was calculated. The morphological changes of A549 and A549/DDP cells were observed by an inverted microscope. The contents of malondialdehyde (MDA) and glutathione (GSH) in A549/DDP cells after drug treatment were detected by related kits. The levels of Fe2+, cytosolic reactive oxygen species (ROS), and lipid reactive oxygen species (lipid ROS) were detected by a fluorescence microplate reader or fluorescence cell imager according to the related fluorescent probe kit instructions. Western blot was used to detect the expressions of PI3K, phospho-PI3K, AKT, phospho-AKT, MDM2, p53, GPX4, and SLC7A11 in A549/DDP after different drug treatments.

Key findings: Our study demonstrated that the inhibitory effect of DT on A549 and A549/DDP cells was time-dependent and concentration-dependent, and DT and DDP had a synergistic effect on inhibiting the proliferation of A549/DDP cells. Furthermore, DT mainly induced ferroptosis in A549/DDP cells and synergized with cisplatin to promote ferroptosis in A549/DDP cells. The result of KEGG pathway analysis, molecular docking and western blot showed that DT could enhance the cisplatin sensitivity of A549/DDP by inhibiting PI3K/MDM2/P53 signaling pathway.

Conclusions: Consequently, we concluded that DT promotes ferroptosis in cisplatin-resistant LAUD A549/DDP cells. Additionally, DT reverses cisplatin resistance by promoting ferroptosis via PI3K/MDM2/P53 pathway in A549/DDP cells.