2295 - Esophageal Squamous Cell Carcinoma-Derived Extracellular Vesicles Enhance Natural Killer Cell Antitumor Activity after Radiotherapy via the Mir-4516/TNFAIP3 Axis

03:00pm - 04:00pm ET

Poster Hall - Exhibit Hall A

Screen: 27

POSTER

Presenter(s)

Yue Zhou, MD - Fudan University, Shanghai, Shanghai

Y. Zhou¹, Y. Gan², X. Yang¹, and Z. Zhu³; ¹Fudan University Shanghai Cancer Center, Shanghai, China, ²State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China, ³Department of Radiation Oncology, Fudan University Shanghai Cancer Center, Shanghai, China

Purpose/Objective(s): Esophageal squamous cell carcinoma (ESCC) remains highly aggressive with poor clinical outcomes despite advances in radiotherapy (RT). Beyond inducing direct tumor cell death, RT can reshape antitumor immunity, yet how RT potentiates natural killer (NK) cell responses in ESCC is not well defined.

Materials/Methods:

Extracellular vesicles (EVs) were isolated from irradiated and non-irradiated ESCC cells and characterized by transmission electron microscopy, nanoparticle tracking analysis, and Western blotting. NK cell activation and function were assessed by flow cytometry, cytotoxicity assays, and ELISA. EV miRNA cargo was profiled by sequencing, and candidate mechanisms were validated using luciferase reporter assays and gain- or loss-of-function approaches. Antitumor efficacy was evaluated in murine syngeneic and human xenograft models. Clinical relevance was examined by quantifying plasma EV–miR-4516 levels and NK cell activity in ESCC patients before and after RT.

Results: Reanalysis of a publicly available single-cell RNA-seq dataset (GSE221561) indicated increased NK cell infiltration and cytotoxicity in ESCC patients receiving neoadjuvant chemoradiotherapy compared with neoadjuvant chemotherapy. In subcutaneous ESCC-bearing mice, NK cell depletion (anti-NK1.1) attenuated the tumor control achieved by irradiation, supporting a causal contribution of NK cells to RT efficacy. EVs from irradiated tumor cells (EV-IR) markedly enhanced NK cell degranulation and cytokine secretion. miRNA sequencing identified miR-4516 as a dominant functional cargo enriched in EV-IR; EV-IR transferred miR-4516 into NK cells, suppressed TNFAIP3 (NF-?B signaling inhibitor) and then activated NF-?B signaling. Pharmacologic blockade of EV release or inhibition of miR-4516 abrogated NK cell activation. Clinically, increased post-RT plasma EV–miR-4516 levels were associated with lower TNFAIP3 expression, enhanced NK cytotoxicity, and prolonged progression-free survival in ESCC patients.

Conclusion:

RT augments NK cell–mediated antitumor immunity in ESCC through EV-mediated delivery of miR-4516, which targets TNFAIP3 to activate NF-?B signaling. Plasma EV–miR-4516 may serve as a positive biomarker of immune activation after RT and a potential therapeutic target to enhance anti-tumor immunity of NK cells.