TCEA3 (transcription elongation factor A3) is a member of the TFIIS family that facilitates RNA polymerase II transcription elongation by helping polymerase bypass template-encoded arresting sites that normally trap elongating complexes 1. During myogenesis, TCEA3 is upregulated and directly recruited by myogenic regulatory factors (MyoD and myogenin) to promote muscle-specific gene expression, traveling with elongating polymerase II through gene coding regions 1. Beyond its canonical elongation function, TCEA3 exhibits tumor-suppressive properties across multiple cancer types. In gastric cancer, TCEA3 expression is significantly downregulated, and restoration inhibits proliferation and induces apoptosis 2. Similarly, TCEA3 is suppressed in ovarian cancer and rhabdomyosarcoma; ectopic expression triggers JNK-dependent apoptosis in ovarian cancer via TGFβ receptor I interaction 3 and activates both intrinsic and extrinsic apoptotic pathways in rhabdomyosarcoma 4. Conversely, in non-small cell lung cancer, elevated tRF-Leu-CAG suppresses TCEA3 expression, promoting proliferation, migration, and paclitaxel resistance through enhanced autophagy 5. In biliary atresia, TCEA3 is downregulated and shows potential causal association with disease pathogenesis 6. The linc01105/miR-650/TCEA3 axis regulates gastric cancer growth and metastasis, with TCEA3 downregulation associated with poor prognosis 7. These findings establish TCEA3 as both a transcriptional regulator and apoptosis inducer with significant clinical relevance in cancer and developmental disease.