Loperamide enhances the radiosensitivity of cervical cancer cells via ferroptosis induction.

Abstract

Cervical cancer is a malignant tumor that threatens women's health and radiotherapy represents a major therapeutic approach for its treatment; however, radioresistance frequently leads to treatment failure. The present study aimed to investigate whether loperamide (LOP), a µ‑opioid receptor agonist commonly used as an antidiarrheal agent, could enhance the radiosensitivity of cervical cancer cells by regulating ferroptosis. A Cell Counting Kit‑8 assay was used to evaluate the cytotoxicity of LOP in SiHa and HeLa cells, and EdU and colony formation assays were performed to assess cell proliferation. In addition, wound‑healing and Transwell assays were performed to detect cell migration. Flow cytometry was applied to measure cell apoptosis and intracellular reactive oxygen species (ROS) levels, and colorimetric assays were used to determine malondialdehyde (MDA) and glutathione (GSH) contents. The mRNA and protein expression levels of the ferroptosis‑related markers GSH peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11) were analyzed using reverse transcription‑quantitative PCR and western blotting. The results showed that LOP significantly inhibited the viability of SiHa and HeLa cells, and exerted a synergistic effect with radiotherapy (combination index <1) to suppress cell proliferation and migration. Combined treatment with LOP and radiotherapy markedly increased apoptosis and ROS accumulation, elevated MDA levels and reduced GSH levels. Moreover, the combination treatment significantly downregulated the expression of GPX4 and SLC7A11. These findings indicated that LOP enhances the radiosensitivity of cervical cancer cells, with ferroptosis induction via inhibition of the GPX4/SLC7A11 axis as a contributing mechanism. Both apoptosis and ferroptosis were induced by the combination treatment, suggesting that the radiosensitizing effect may involve multiple cell death pathways. These observations provide a basis for further investigation into LOP as a potential radiosensitizing agent in cervical cancer.