Tumor transcriptome sequencing reveals allelic expression imbalances associated with copy number alterations

Area of Science:

• Genomics
• Cancer Research
• Transcriptomics

Background:

• Massively parallel sequencing, particularly RNA-Seq, is emerging as a powerful alternative to microarrays for studying gene expression and copy number alterations in tumors.
• RNA-Seq provides advantages over microarrays, including somatic mutation detection and precise measurement of allele-specific expression.

Purpose of the Study:

• To investigate the advantages of a novel, strand-specific RNA-Seq method for analyzing oral squamous cell carcinomas.
• To explore the genomic underpinnings of gene expression changes in tumors by integrating transcriptomic and genomic data.

Main Methods:

• Application of a novel, strand-specific RNA-Seq method to tumor and matched normal tissues from three oral squamous cell carcinoma patients.
• Whole-genome sequencing of tumor and normal tissue from one patient to correlate genomic alterations with transcriptomic changes.

Main Results:

• The RNA-Seq method accurately measures allelic imbalance, providing genome-wide insights into cancer etiology.
• Differentially expressed genes in tumors were enriched for cell adhesion and differentiation functions, as were allelically imbalanced genes.
• Allelic imbalance in tumors is associated with copy number mutations, which strongly correlate with changes in transcript abundance.

Conclusions:

• Allele-specific deletions and duplications are key drivers of allele-specific gene expression changes during tumor development.
• RNA-Seq is a valuable tool for uncovering complex genomic and transcriptomic interactions in cancer.