Transcriptome analysis implicates MYC as a driver of early onset colorectal cancer

Despite a global decrease in colorectal cancer (CRC) incidence, the prevalence of early onset colorectal cancer (EOCRC), or those occurring in individuals before the age of 50, has been steadily increasing over the past several decades. When compared to later onset colorectal cancers (LOCRCs) in individuals over 50, our understanding of the genetic and molecular underpinnings of EOCRCs is limited. Here, we conducted transcriptomic analysis of patient-matched normal colonic segments and tumors to identify gene expression programs involved in carcinogenesis. Amongst differentially expressed genes, we found increased expression of the c-MYC (MYC) proto-oncogene and its downstream targets in tumor samples. We identify tumors with high and low differential MYC expression, and patients with high-MYC tumors were older and overweight or obese. We also detect elevated expression of the PVT1 long-non-coding RNA (lncRNA) in most tumors and find gains in copy number for both MYC and PVT1 gene loci in 35% of tumors evaluated. Our transcriptome analysis indicates that EOCRC can be sub-classified into groups based on differential MYC expression and suggests that MYC is a critical driver of most CRCs that develop in younger patients. Overall design: Gene expression profiles of 21 surgically resected tumors and patient-matched adjacent colonic segments from early onset colorectal cancer patients were generated by deep sequencing.