HSP70-mediated regulation of P-glycoprotein SUMOylation suppresses ferroptosis to drive thermoresistance in non-small cell lung cancer.

OBJECTIVE

Hyperthermia is a potential therapy for non-small cell lung cancer (NSCLC); however, cell resistance to hyperthermia remains challenging. This study investigated the role of heat shock protein 70 (HSP70) in regulating small ubiquitin-like modifier modification (SUMOylation) of P-glycoprotein (P-gp) in the resistance of NSCLC cells to hyperthermia.

METHODS

Human NSCLC cells (A549) were exposed to hyperthermia and subjected to HSP70 overexpression/knockdown, P-gp silencing, or Erastin/Ferrostatin-1 treatment. Nude mice received inoculation with A549 cells infected with adenoviral vectors overexpressing HSP70 (Ad-HSP70) before hyperthermia. Verapamil was selected as an inhibitor of P-gp in vivo. A series of experiments were performed to analyze cellular and molecular changes, including viability, migration, invasion, ferroptosis-related indices, and mitochondrial dysfunction. HSP70-P-gp interaction, SUMOylation, and protein stability were examined using co-immunoprecipitation and cycloheximide assays.

RESULTS

HSP70 overexpression accelerated the malignant properties of A549 cells while restricting ferroptosis, thus driving thermoresistance. Furthermore, activating ferroptosis partially annulled these effects of HSP70 overexpression, whereas inhibiting ferroptosis partially counteracted the suppressive effect of HSP70 knockdown on the thermoresistance of A549 cells. HSP70 interacted with P-gp to modulate its SUMOylation, thereby increasing the stability and levels of P-gp protein. P-gp knockdown partially blocked the effect of HSP70 and restored the sensitivity of A549 cells to hyperthermia. HSP70 suppressed oxidative stress and mitochondrial dysfunction by upregulating P-gp. In vivo, HSP70-mediated SUMOylation of P-gp inhibited ferroptosis, promoting tumor growth and thermoresistance.

CONCLUSIONS

HSP70 suppresses oxidative stress and mitochondrial dysfunction through SUMOylation of P-gp, thereby inhibiting ferroptosis and promoting thermoresistance in A549 NSCLC cells.