# HERV Modulation in Colorectal Carcinoma Patients: A Snapshot of Endogenous Retroviral Transcriptome

## TL;DR

This study explores how human endogenous retroviruses (HERVs) are expressed differently in colorectal cancer tissues compared to normal tissues, identifying a specific HERV-H transcript that is highly expressed in cancer.

## Contribution

The study provides a detailed analysis of HERV transcriptional modulation in colorectal cancer and identifies a novel HERV-H transcript with potential relevance to tumor progression.

## Key findings

- 102 HERVs were significantly modulated in colorectal cancer, mostly downregulated.
- A HERV-H transcript on chromosome Xp22.3 was highly expressed in CRC samples and may encode a partial Pol protein.
- The study highlights interindividual variability in HERV expression in CRC patients.

## Abstract

Human endogenous retroviruses (HERVs) are proviral relics of infections that affected primates' germ line. Many HERV elements retain a residual capacity to encode transcripts and proteins that have been occasionally domesticated for the host physiology. In addition, HERV transcriptional modulation is of great interest to clarify the etiology of complex disorders such as cancer, even if a few studies assessed the specific HERV loci modulated in tumor tissues. In the present work, we used a transcriptomic approach to investigate the specific expression of ~3300 HERV loci in paired tumor and normal tissues of 7 colorectal cancer (CRC) patients. A total of 102 HERVs were significantly modulated in CRC, with a general tendency towards downregulation. Of note, among the 42 upregulated HERVs 23 belonged to the HERV‐H group, that is the most investigated in CRC. De novo transcriptome reconstruction and qPCR validation allowed to identify a transcript from a HERV‐H locus on chromosome Xp22.3 with high specific expression in CRC samples, potentially encoding for a partial Pol protein. These results provide a detailed description of HERV transcriptional variations in CRC and its interindividual variability, identifying a HERV‐H transcript that deserves further investigation for its possible impact on tumor progression.