The Challenge
Colorectal cancer (CRC) involves complex genetic and epigenetic alterations. While TAD structures are generally stable, researchers hypothesized that fine-scale enhancer-promoter (E-P) loops might be "rewired" in cancer cells to drive oncogene expression, but standard Hi-C lacked the resolution to see these subtle changes.
The Solution
The research team integrated Promoter Capture Hi-C (PCHi-C) with standard Hi-C. This dual approach allowed them to map the global chromatin architecture (Hi-C) while simultaneously zooming in on thousands of promoter interactions (PCHi-C) with high sensitivity.
The Results
The study identified thousands of Differential Promoter Interactions (DPIs) between CRC samples and controls. PCHi-C revealed that specific risk variants (GWAS hits) in non-coding regions were physically looping to contact and activate known CRC oncogenes. These loops were absent in normal tissue. The data showed that chromatin topology is fine-tuned at the loop level during tumorigenesis.

The Conclusion
PCHi-C successfully linked non-coding genetic variance to transcriptional dysregulation in cancer, identifying novel therapeutic targets that were invisible to expression profiling alone.
Source: Wang, X., et al. "Integrated promoter-capture Hi-C and Hi-C analysis reveals fine-tuned regulation of the 3D chromatin architecture in colorectal cancer." Frontiers in Genetics (2025).



Figure 1: Pan-Promoter Interactome