Dysregulated inclusion of BOLA3 exon 3 promoted by HNRNPC accelerates the progression of esophageal squamous cell carcinoma.

Dysregulated RNA splicing events produce transcripts that facilitate esophageal squamous cell carcinoma (ESCC) progression, but how this splicing process is abnormally regulated remains elusive. Here, we unveiled a novel alternative splicing axis of BOLA3 transcripts and its regulator HNRNPC in ESCC. The long-form BOLA3 (BOLA3-L) containing exon 3 exhibited high expression levels in ESCC and was associated with poor prognosis. Functional assays demonstrated the protumorigenic function of BOLA3-L in ESCC cells. Additionally, HNRNPC bound to BOLA3 mRNA and promoted BOLA3 exon 3 inclusion forming BOLA3-L. High HNRNPC expression was positively correlated with the presence of BOLA3-L and associated with an unfavorable prognosis. HNRNPC knockdown effectively suppressed the malignant biological behavior of ESCC cells, which were significantly rescued by BOLA3-L overexpression. Moreover, BOLA3-L played a significant role in mitochondrial structural and functional stability. E2F7 acted as a key transcription factor that promoted the upregulation of HNRNPC and inclusion of BOLA3 exon 3. Our findings provided novel insights into how alternative splicing contributes to ESCC progression.