Stress‑induced catecholamines attenuate sorafenib efficacy by inhibiting ferroptosis in β2‑adrenergic receptor positive renal cell carcinoma.

Abstract

Ferroptosis, an iron‑dependent form of non‑apoptotic cell death, is a potential target for cancer therapy. Sorafenib, a molecular targeted agent for renal cell carcinoma (RCC), is involved in ferroptosis induction. Chronic stress, mediated by catecholamines via β2‑adrenergic receptors (ADRB2), promotes cancer progression, yet its influence on drug resistance and ferroptosis remains elusive. To investigate ADRB expression in RCC, immunohistochemistry of surgical specimens was performed and assessed ADRB mRNA and protein levels were assessed by RT‑qPCR and western blotting in RCC cell lines. To determine whether β‑adrenergic signaling modulates sorafenib sensitivity, we used ADRB2‑expresing ACHN cells and conducted MTS cell viability assays following β‑adrenergic agonist isoproterenol (ISO) stimulation, ADRB2 knockdown by siRNA, as well as a restraint‑stress mouse model in which catecholamine levels were elevated, bearing ACHN cells or ACHN cells with ADRB2 knockdown by shRNA. To evaluate the involvement of ferroptosis, we applied the ferroptosis inhibitor ferrostatin‑1 (Fer‑1) and inducers erastin and RSL3, and measured cell viability, malondialdehyde and reactive oxygen species. To elucidate the mechanism underlying the ISO effect on ferroptosis, MAPK pathway activity was assessed by western blotting and MTS assays performed under MAPK inhibition. The present study confirmed ADRB2 expression in RCC by immunohistochemistry of surgical specimens. Using the ADRB2‑expressing RCC cell line ACHN, the present study demonstrated that stimulation with the β‑adrenergic agonist isoproterenol (ISO) conferred resistance to sorafenib both in vitro and in a mouse stress model; this effect was abrogated by ADRB2 knockdown. Similarly to ISO, Fer‑1 diminished sorafenib sensitivity in ACHN cells. Erastin and RSL3 markedly decreased cell viability, however, ISO attenuated ferroptosis in ACHN cells. Mechanistically, ISO inhibited the phosphorylation of ERK1/2, p38 and JNK, all of which contribute to ferroptosis suppression. These findings provide evidence that chronic stress‑induced ADRB2 activation promotes sorafenib resistance by mitigating ferroptotic cell death.