2484 - Roles of Mitochondrial Inner Membrane Protein SLC25A5 in Radiation-Induced Cell Death of Esophageal Squamous Cell Carcinoma

Purpose/Objective(s):

This study aimed to investigate the role of SLC25A5 in modulating radiotherapy sensitivity in Esophageal squamous cell carcinoma (ESCC) and to delineate the molecular mechanism linking mitochondrial signaling, transcriptional regulation, and ferroptosis.

Materials/Methods:

Clinical ESCC specimens were analyzed to assess SLC25A5 expression and its association with therapeutic response and prognosis. Functional assays including clonogenic survival, apoptosis and ferroptosis detection, lipid peroxidation measurement, ROS quantification, and xenograft models were employed to evaluate radiosensitivity. Proteomic and phosphoproteomic profiling were conducted to identify downstream signaling alterations following SLC25A5 knockdown. Subcellular fractionation, co-immunoprecipitation, chromatin immunoprecipitation, and luciferase reporter assays were performed to characterize the mechanistic axis governing STAT1 phosphorylation dynamics and ACSL4 transcriptional regulation.

Results:

SLC25A5 was significantly upregulated in ESCC tissues and was enriched in radiotherapy-resistant tumors, correlating with unfavorable clinical outcomes. Genetic silencing of SLC25A5 markedly enhanced radiation-induced cell death and suppressed tumor growth in vivo. Mechanistically, ionizing radiation triggers the translocation of SLC25A5 from mitochondria to the cytoplasm and its interaction with the dephosphorylase DUSP3. This interaction promotes the dephosphorylation of STAT1, thereby altering the transcriptional activity of STAT1 on the ferroptosis-related target gene ACSL4. SLC25A5 depletion reprogrammed STAT1 signaling and significantly upregulated ACSL4 expression, promoting lipid peroxidation and ferroptotic vulnerability. Notably, the mode of cell death differed according to differentiation status: poorly differentiated ESCC cells preferentially underwent ferroptosis upon SLC25A5 inhibition, whereas well-differentiated cells exhibited a tendency toward necroptosis signaling, indicating differentiation-dependent death pathway selection.

Conclusion:

Our findings identify SLC25A5 as a previously unrecognized regulator of radiation response in ESCC. By orchestrating a mitochondrial-cytosolic signaling cascade involving DUSP3-mediated STAT1 phosphorylation remodeling and ACSL4-driven ferroptosis, SLC25A5 establishes a molecular switch that governs ferroptosis and radiotherapy sensitivity. Targeting the SLC25A5-DUSP3-STAT1-ACSL4 axis may provide a rational strategy for overcoming radioresistance and optimizing precision radiotherapy in ESCC.