Enhancer Hijacking in ccRCC Driven by Structural Variation and 3D Genome Disruption

Overview

This study reveals that structural variants (SVs) in clear cell renal cell carcinoma (ccRCC) disrupt 3D genome architecture, leading to enhancer hijacking and oncogene activation. Using long-read sequencing and 3D genomic analyses, a novel enhancer hijacking event activating SEMA5B was identified, alongside a prognostic model based on enhancer hijacking events.

Background

Clear cell renal cell carcinoma (ccRCC) is the most common and aggressive subtype of renal cell carcinoma, with high recurrence and metastasis rates and poor response to conventional therapies. While mutations in key genes like VHL and PBRM1 are well characterized, the role of large-scale structural variants (SVs) in ccRCC pathogenesis remains underexplored. SVs can alter gene expression by disrupting 3D chromatin organization and repositioning regulatory elements such as enhancers. Advances in long-read sequencing and 3D genome mapping enable detailed characterization of SVs and their functional consequences in cancer.

Data Highlights

Key Findings

• Long-read nanopore sequencing enabled high-quality detection of numerous high-confidence structural variants in ccRCC cell lines compared to normal renal epithelial cells.
• SVs disrupt 3D genome architecture, including compartment shifts, TAD boundary alterations, and chromatin loop reconfiguration, affecting gene regulation.
• A novel enhancer hijacking event was identified that constitutively activates the proto-oncogene SEMA5B in ccRCC.
• Integration of Hi-C, ChIP-seq, and RNA-seq data revealed the mechanistic link between SVs, 3D chromatin changes, and aberrant oncogenic transcriptional programs.
• A machine learning-based prognostic model leveraging cancer-specific enhancer hijacking events demonstrated robust predictive performance for ccRCC outcomes.

Clinical Implications

Understanding the role of SV-driven enhancer hijacking in ccRCC provides new molecular targets for therapeutic intervention and biomarker development. The prognostic model based on enhancer hijacking events may improve risk stratification and guide personalized treatment strategies. These insights highlight the importance of integrating 3D genome architecture analyses in cancer diagnostics and precision oncology.

Conclusion

This study elucidates how structural variants disrupt 3D genome organization to drive oncogene activation via enhancer hijacking in ccRCC, expanding the molecular understanding of this malignancy. The findings offer novel avenues for targeted therapies and prognostic assessment in renal cancer.

References

1. Zhao et al. 2024 -- Enhancer Hijacking in Clear Cell Renal Cell Carcinoma is Driven by Structural Variation and Disruption of 3D Genome Architecture