Integrative Functional Genomics Implicates EPB41 Dysregulation in Hepatocellular Carcinoma Risk

Area of Science:

• Genetics
• Oncology
• Genomics

Background:

• Genome-wide association studies (GWASs) have identified numerous cancer susceptibility single nucleotide polymorphisms (SNPs), but their underlying molecular mechanisms remain largely unknown.
• Functional evaluation of these SNPs is crucial for understanding their role in cancer heritability and risk.
• Investigating regulatory variants offers a promising avenue for uncovering novel cancer pathogenesis pathways.

Purpose of the Study:

• To develop an integrative functional genomics approach to identify cancer susceptibility SNPs within transcription factor-binding sites.
• To pinpoint specific genetic variants that modulate transcription factor binding and influence cancer risk.
• To elucidate the molecular mechanisms by which identified SNPs contribute to hepatocellular carcinoma (HCC) development.

Main Methods:

• Integration of functional genomic data, including c-Myc cistromics, 1000 Genomes, and TRANSFAC matrix, to annotate SNPs.
• Genotyping of 12 candidate SNPs in 1,806 HBV-related HCC cases and 1,708 controls.
• Functional assays (cell proliferation, wound healing, transwell, mouse xenograft) to assess the impact of the identified SNP on gene expression and HCC progression.

Main Results:

• Twelve SNPs within the c-Myc cistrome were annotated for their potential to modulate c-Myc binding affinity in HCC.
• A significant HCC susceptibility SNP, rs157224G>T, was identified in Chinese populations (T allele: OR=1.64, P=5.2×10⁻⁶).
• The risk allele rs157224T was associated with decreased c-Myc-mediated transcriptional regulation of EPB41, identifying EPB41 as a HCC susceptibility gene.
• EPB41 expression was significantly reduced in HCC tissues, particularly in metastatic samples.

Conclusions:

• Regulatory genetic variants play a significant role in HCC pathogenesis.
• The identified SNP rs157224G>T contributes to HCC predisposition by altering c-Myc binding and EPB41 expression.
• This study provides novel pathogenic insights into HCC through a genome-wide functional genomics approach.