Gene expression analysis identifies global gene dosage sensitivity in cancer

Area of Science:

• Genomics
• Cancer Biology
• Molecular Biology

Background:

• Somatic copy number alterations (SCNAs) are common in cancer, but their direct impact on gene expression is not fully understood.
• Identifying downstream molecular effects of SCNAs is crucial for understanding cancer development and progression.

Purpose of the Study:

• To investigate the relationship between individual SCNAs and gene expression levels.
• To develop a method for correcting gene expression profiles for major biological variation.
• To assess gene dosage sensitivity across a large cohort of cancer samples.

Main Methods:

• Reanalyzed 77,840 expression profiles to identify 'transcriptional components' explaining gene expression variation.
• Developed 'functional genomic mRNA' profiling by correcting expression data for these components.
• Applied the method to 16,172 patient-derived tumor samples.

Main Results:

• A limited set of transcriptional components explained most gene expression variation and predicted gene function.
• Residual expression levels after correction strongly correlated with DNA copy number.
• 99% of abundantly expressed human genes demonstrated positive correlation between DNA copy number and expression, indicating global gene dosage sensitivity.
• Replicated known SCNA loci and identified recurrently disrupted genes in genomically unstable cancers.

Conclusions:

• Gene expression is globally sensitive to DNA copy number changes in cancer.
• The developed method enhances the ability to link SCNAs to their functional consequences.
• This approach aids in identifying key genes disrupted by copy number aberrations in cancer genomics.