Twist1-YY1-p300 complex promotes the malignant progression of HCC through activation of miR-9 by forming phase-separated condensates at super-enhancers and relieved by metformin.

Hepatocellular carcinoma (HCC) is one of the leading causes of death, which deserves further study to reveal the underlying molecular mechanisms. Studies have shown that miR-9 in associated with poor prognosis in HCC patients. However, the mechanisms of transcriptional activation regulation of miR-9 and its role in the malignant progression of HCC have been rarely investigated. Some transcriptional coactivators can form phase-separated condensates at super-enhancers that compartmentalize and concentrate the transcription apparatus to drive robust gene expression. Here, we demonstrate that Twist1 and YY1 could form a transcriptional complex with p300, creating local high-concentration phase-separated interaction hubs at the super-enhancers of miR-9 and activate its expression to promote the malignant progression of HCC by stimulating the migration and invasion of hepatocellular carcinoma cells. Twist1-YY1-p300 phase-separated condensates were disrupted by metformin (Met) and thus reduce miR-9 expression, thereby inhibiting the malignant progression of HCC. Our study demonstrates that the Twist1 transcriptional factor complex involved in the malignant progression of HCC can form phase separation condensates at super-enhancers of miR-9 to promote the expression of oncogenes in HCC cells. It provides a potential target for the therapy of HCC and offers insights into the mechanism of Met in HCC inhibition.

YY1 Promotes Endothelial Cell-Dependent Tumor Angiogenesis in Hepatocellular Carcinoma by Transcriptionally Activating VEGFA.

Hepatocellular carcinoma (HCC) is a typical hypervascular solid tumor that requires neoangiogenesis for growth. The vascular endothelial growth factor (VEGF) is the most potent proangiogenic factor in neovascularization. The multifunctional Yin-Yang 1 (YY1) is involved in the regulation of tumor malignancy of HCC. However, the relationship between YY1 and endothelial cell-dependent tumor angiogenesis in HCC remains unclear. In this study, we observed that YY1 is positively correlated with microvessel density (MVD) and poor prognosis in HCC tissues. We further found that YY1 promotes the transcriptional activity of VEGFA by binding its promoter in HCC. The secreted VEGFA from HCC cells activates phosphorylation of VEGFR2 to promotes tube formation, cell migration, and invasion of vascular endothelial cells in vitro, and promotes tumor growth and angiogenesis in vivo. In addition, upregulation of YY1 enhanced resistance of bevacizumab in HCC cells. These results indicate that YY1 plays essential roles in HCC angiogenesis and resistance of bevacizumab by inducing VEGFA transcription and that YY1 may represent a potential molecular target for antiangiogenic therapy during HCC progression.