1124 - Radiation-Induced Extracellular Vesicles from Cancer-Associated Fibroblasts Facilitate Esophageal Squamous Cell Carcinomametastasis through the miR-193a-3p/PTEN/Akt Pathway
Presenter(s)
Y. Pang1, Z. Zhu2, and X. Yang2; 1Fudan University Shanghai Cancer Center, shanghai, China, 2Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China
Purpose/Objective(s): Radiotherapy is a critical treatment for esophageal squamous cell carcinoma (OSCC); however, recurrence and metastasis following radiation therapy are the major factors that contribute to treatment failure. Understanding the mechanisms underlying tumor metastasis after radiotherapy is critical for improving patient prognosis.
Materials/Methods: KYSE150 OSCC cells were coimplanted with nonirradiated (0 Gy) or irradiated (8 Gy) CAFs in nude mice to determine the role of irradiated CAF in vivo. Exosomes were isolated from CAFs using differential centrifugation and analysed via electron microscopy and immunoblotting. Transwell assays were used to evaluate the impact of exosomes from irradiated CAFs on OSCC cell migration and invasion in vitro. RNA sequencing identified differentially expressed microRNAs (miRNAs), with functional experiments validating the role of miR-193a-3p. Luciferase assays identified miR-193a-3p targets, and further experiments confirmed the downstream pathway. Plasma samples from 32 patients and tissue samples from 76 patients OSCC were analyzed for miR-193a-3p and PTEN expression.
Results: Irradiated CAFs significantly promoted lung metastasis of OSCC cells in vivo, and exosomes derived from irradiated CAFs enhanced OSCC cell invasion, migration, and metastasis. Exosomes from irradiated CAFs exhibited increased miR-193a-3p levels, which in turn, elevated miR-193a-3p in OSCC cells; this process was inhibited by RNase, Triton X-100, or GW4869. Knockdown of miR-193a-3p weakened the proinvasive, migratory, and epithelial–mesenchymal transition (EMT) activities of CAF exosomes. Luciferase assays confirmed PTEN as a target of miR-193a-3p, with overexpression of miR-193a-3p leading to decreased PTEN expression and increased p-Akt expression. In vivo, coinjection of miR-193a-3p–knockdown CAFs with KYSE150 OSCC cells resulted in smaller tumors, fewer lung metastases, and increased PTEN and E-cadherin expression but decreased p-Akt and Snail expression. Clinically, in a prospective cohort of 32 patients with OSCC undergoing concurrent chemoradiotherapy, plasma exosomal miR-193a-3p levels were significantly elevated after radiation. In a retrospective cohort of 76 patients with OSCC, Kaplan-Meier analysis showed that high miR-193a-3p expression was associated with shorter disease-free survival, distant metastasis-free survival, and overall survival, while high PTEN expression correlated with longer survival. Cox regression analyses identified miR-193a-3p as an independent predictor of poor prognosis in patients with OSCC.
Conclusion: Our study discovered a novel mechanism by which EVs from irradiated CAFs promote OSCC metastasis through miR-193a-3p–mediated PTEN/Akt signaling. Targeting the exosomal miR-193a-3p–mediated interaction between CAFs and tumor cells is a promising strategy for improving the outcomes of OSCC patients with radiotherapy.