Oncofusion-driven de novo enhancer assembly promotes malignancy in Ewing sarcoma via aberrant expression of the stereociliary protein LOXHD1

Cell Rep. 2022 Jun 14;39(11):110971. doi: 10.1016/j.celrep.2022.110971.

Abstract

Ewing sarcoma (EwS) is a highly aggressive tumor of bone and soft tissues that mostly affects children and adolescents. The pathognomonic oncofusion EWSR1::FLI1 transcription factor drives EwS by orchestrating an oncogenic transcription program through de novo enhancers. By integrative analysis of thousands of transcriptomes representing pan-cancer cell lines, primary cancers, metastasis, and normal tissues, we identify a 32-gene signature (ESS32 [Ewing Sarcoma Specific 32]) that stratifies EwS from pan-cancer. Among the ESS32, LOXHD1, encoding a stereociliary protein, is the most highly expressed gene through an alternative transcription start site. Deletion or silencing of EWSR1::FLI1 bound upstream de novo enhancer results in loss of the LOXHD1 short isoform, altering EWSR1::FLI1 and HIF1α pathway genes and resulting in decreased proliferation/invasion of EwS cells. These observations implicate LOXHD1 as a biomarker and a determinant of EwS metastasis and suggest new avenues for developing LOXHD1-targeted drugs or cellular therapies for this deadly disease.

Keywords: CP: Cancer; CP: Molecular biology; EWSR1::FLI1; Ewing sarcoma; LOXHD1; biomarker; enhancer; hypoxia; integrative genomics; metastasis; transcription.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Carrier Proteins* / genetics
  • Cell Line, Tumor
  • Child
  • Enhancer Elements, Genetic*
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Oncogene Proteins, Fusion* / genetics
  • Oncogene Proteins, Fusion* / metabolism
  • Proteins / metabolism
  • Proto-Oncogene Protein c-fli-1 / genetics
  • Proto-Oncogene Protein c-fli-1 / metabolism
  • RNA-Binding Protein EWS / genetics
  • RNA-Binding Protein EWS / metabolism
  • Sarcoma, Ewing* / genetics
  • Sarcoma, Ewing* / pathology

Substances

  • Carrier Proteins
  • LOXHD1 protein, human
  • Oncogene Proteins, Fusion
  • Proteins
  • Proto-Oncogene Protein c-fli-1
  • RNA-Binding Protein EWS