Spi-1 proto-oncogene regulates mRNA hypertranscription and malignant progression in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent and lethal cancers worldwide. Despite multimodal therapeutic advances, long-term survival remains poor, underscoring the need to identify novel molecular drivers of disease aggressiveness. Hypertranscription is a genome-wide increase in total RNA output that has emerged as a hallmark of oncogenic transformation. However, the role of mRNA-specific hypertranscription in HNSCC and its underlying molecular drivers remain undefined. In the present study, we investigated the association between mRNA hypertranscription and malignant phenotypes in HNSCC. Single-cell transcriptomics data revealed that elevated mRNA hypertranscription was significantly associated with the activation of oncogenic pathways and poor clinical outcomes. Through transcription factor activity analysis, we identified the transcription factor Spi-1 Proto-Oncogene (SPI1) as a potential regulator of mRNA hypertranscription in HNSCC malignant cells. Loss- and gain-of-function experiments in HNSCC cell lines and xenograft models established that SPI1 drives cell proliferation, invasion, migration, and tumor growth in vitro and in vivo. Mechanistically, inducible SPI1 overexpression elevated nascent RNA synthesis as measured by EU incorporation, and integrative ChIP-seq/RNA-seq profiling identified direct genomic targets of SPI1 enriched in oncogenic transcriptional programs. Collectively, our findings show that SPI1-driven mRNA hypertranscription is important in HNSCC progression and provide novel insights into the transcriptional dysregulation underlying aggressive malignancies.