KEY POINTS
- Investigators integrated single-cell RNA sequencing from eight nasopharyngeal carcinoma samples—four treatment-naive and four radioresistant recurrent tumors—with transcriptomic data from radioresistant cell models. After quality control, 89,919 single cells were included.
- Clinical associations were examined in three public datasets: one containing eight radiosensitive and 12 radioresistant tumors, one with 42 tumors and four normal samples, and an outcome cohort of 88 treatment-naive patients. TFDP2 was enriched in radioresistant disease, and higher expression was associated with poorer survival.
- Functional experiments used parental and radioresistant C666-1 and HONE-1 cell lines exposed to 0, 2, 4, or 6 Gy. TFDP2 knockdown reduced clonogenic survival and proliferation after irradiation, whereas overexpression increased survival and reduced radiation-induced DNA-damage signaling.
- TFDP2 expression increased lactate production and extracellular acidification while suppressing oxygen consumption after 4 Gy, indicating a shift from oxidative phosphorylation toward glycolysis. Silencing TFDP2 reversed these metabolic changes.
- Transcriptomic screening identified PDK3 as the most consistent downstream metabolic target. TFDP2 increased PDK3 transcription, and chromatin immunoprecipitation and promoter-reporter experiments supported direct transcriptional regulation through the TFDP2–E2F1 complex.
- PDK3 knockdown reduced colony formation after 2–6 Gy, increased residual γ-H2AX damage, lowered lactate production and extracellular acidification, and restored oxygen consumption. It also reversed the radioresistant phenotype produced by TFDP2 overexpression.
- Xenograft experiments using local 6 Gy irradiation supported the cellular findings, but the work did not test a clinically available selective PDK3 inhibitor, establish a reproducible patient-level assay, or demonstrate that TFDP2 predicts benefit from radiotherapy rather than general prognosis.
CLINICAL TAKEAWAY
The TFDP2-PDK3 axis provides a plausible metabolic explanation for acquired radioresistance in nasopharyngeal carcinoma and identifies PDK3 as a potential radiosensitization target. The findings are hypothesis-generating and require validation in patient cohorts and pharmacological models before influencing treatment.