349 Long non-coding RNAs and skin fibrosis consequent to radiotherapy

Abstract

In this study, we explore the role of long non-coding RNAs (lncRNAs) as biomarkers of radiation- induced skin fibrosis. Skin fibrosis, a common late complication of radiotherapy, is characterized by myofibroblast proliferation and pathological deposition of extracellular matrix, with TGFB1 pathway as a known master switch. However, epigenetic mechanisms of fibrosis development are still poorly described. Transcriptome sequencing (NGS RNA-seq) was performed for untransformed fibroblast strains isolated from non-irradiated skin samples of 85 patients presenting with severe complications of radiotherapy. Clustering analysis of gene expression data was used to define sub-populations of patients and differentially expressed genes between sub-populations were identified using EdgeR. Functional enrichment analysis was performed via Gene Ontology and Reactome. Co-expressed lncRNAs and fibrosis- and matrix modeling-related transcripts were identified by WGCNA R package. Two sub-populations of patients were found by clustering analysis of gene expression data: cluster 1 (45 patients) and cluster 2 (40 patients), which differed by 2 163 messenger RNAs (mRNAs) and 291 lncRNAs. Cluster 1 was characterized by the enrichment of a set of 272 mRNAs relative to extracellular matrix remodeling and fibrosis, when compared to cluster 2. A weighted co-expression network analysis identified 12 lncRNAs co-expressed in cluster 1 with 137 major fibrosis-related genes, including TGFB1, metalloproteinases and collagens. These candidate lncRNAs are currently investigated for their response to TGFB1 and radiation exposure, their involvement in myofibroblast activation, and their functional role in fibrosis gene regulation. From the exploration of this set of new molecular regulators, we anticipate the description of original skin fibrosis susceptibility biomarkers and effectors, and the discovery of potential anti-fibrosis therapeutic targets.