Therapeutic effects of Icariside II on radiation cystitis: revealing the mechanistic role of the FN1/Itgαvβ6-PI3K/AKT signaling pathway using single-cell RNA sequencing.

OBJECTIVES: Radiation cystitis (RC) is a common complication of pelvic radiotherapy and is characterized by persistent bladder inflammation that can ultimately progress to fibrosis. However, the specific cell types involved in RC and targeted molecular therapies remain poorly understood, hindering the development of effective treatment strategies. This study focused on the molecular complexity of RC, aiming to elucidate the effects of radiation on bladder cells via single-cell RNA sequencing (scRNA-seq) and to investigate the protective role and underlying mechanisms of Icariside II (ICA II) in RC treatment. MATERIALS AND METHODS: A rat model of RC was established, and single-cell RNA sequencing (scRNA-seq) was performed to analyze the molecular impact of radiation on different bladder cell types. Intercellular communication analysis was conducted to identify key signaling pathways involved in RC progression. The findings from scRNA-seq were validated through in vitro experiments. Additionally, coimmunoprecipitation and molecular dynamics (MD) simulations were used to assess the effect of ICA II on the binding affinity between fibronectin 1 (FN1) and Integrin alpha v beta 6 (Itgαvβ6). RESULTS: ScRNA-seq analysis revealed 16 distinct cell types within the bladder, including epithelial cells, fibroblasts, smooth muscle cells, endothelial cells, and immune cells, revealing substantial cellular heterogeneity in RC. Intercellular communication analysis revealed that FN1 expression was markedly upregulated following radiation exposure. FN1 binds to its receptor Itgαvβ6, activating the PI3K/AKT signaling pathway and promoting fibrosis. MD simulations and in vitro assays further confirmed that ICA II effectively disrupted the FN1-Itgαvβ6 interaction, inhibited the activation of the PI3K/AKT pathway, and downregulated markers associated with fibrosis and epithelial‒mesenchymal transition (EMT). CONCLUSIONS: This study identified the FN1-Itgαvβ6 interaction as a critical driver of fibrosis in RC. These findings suggest that ICA II may serve as a promising therapeutic agent for RC by targeting the FN1/Itgαvβ6-PI3K/AKT signaling axis to mitigate fibrosis progression.