PAX3-FOXO1 drives miR-486-5p and represses miR-221 contributing to pathogenesis of alveolar rhabdomyosarcoma

Oncogene. 2018 Apr;37(15):1991-2007. doi: 10.1038/s41388-017-0081-3. Epub 2018 Jan 25.

Abstract

Rhabdomyosarcoma is the most common soft-tissue sarcoma in childhood and histologically resembles developing skeletal muscle. Alveolar rhabdomyosarcoma (ARMS) is an aggressive subtype with a higher rate of metastasis and poorer prognosis. The majority of ARMS tumors (80%) harbor a PAX3-FOXO1 or less commonly a PAX7-FOXO1 fusion gene. The presence of either the PAX3-FOXO1 or PAX7-FOXO1 fusion gene foretells a poorer prognosis resulting in clinical re-classification as either fusion-positive (FP-RMS) or fusion-negative RMS (FN-RMS). The PAX3/7-FOXO1 fusion genes result in the production of a rogue transcription factors that drive FP-RMS pathogenesis and block myogenic differentiation. Despite knowing the molecular driver of FP-RMS, targeted therapies have yet to make an impact for patients, highlighting the need for a greater understanding of the molecular consequences of PAX3-FOXO1 and its target genes including microRNAs. Here we show FP-RMS patient-derived xenografts and cell lines display a distinct microRNA expression pattern. We utilized both loss- and gain-of function approaches in human cell lines with knockdown of PAX3-FOXO1 in FP-RMS cell lines and expression of PAX3-FOXO1 in human myoblasts and identified microRNAs both positively and negatively regulated by the PAX3-FOXO1 fusion protein. We demonstrate PAX3-FOXO1 represses miR-221/222 that functions as a tumor suppressing microRNA through the negative regulation of CCND2, CDK6, and ERBB3. In contrast, miR-486-5p is transcriptionally activated by PAX3-FOXO1 and promotes FP-RMS proliferation, invasion, and clonogenic growth. Inhibition of miR-486-5p in FP-RMS xenografts decreased tumor growth, illustrating a proof of principle for future therapeutic intervention. Therefore, PAX3-FOXO1 regulates key microRNAs that may represent novel therapeutic vulnerabilities in FP-RMS.

Publication types

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

MeSH terms

  • Animals
  • Cell Proliferation / genetics
  • Cell Transformation, Neoplastic / genetics
  • Cells, Cultured
  • Child
  • Female
  • Gene Expression Profiling
  • Gene Expression Regulation, Neoplastic
  • Gene Knockdown Techniques
  • HEK293 Cells
  • Humans
  • Mice
  • Mice, SCID
  • MicroRNAs / genetics*
  • Microarray Analysis
  • Muscle Neoplasms / genetics*
  • Muscle Neoplasms / pathology
  • Oncogene Proteins, Fusion / genetics
  • Oncogene Proteins, Fusion / physiology*
  • Paired Box Transcription Factors / genetics
  • Paired Box Transcription Factors / physiology*
  • Rhabdomyosarcoma, Alveolar / genetics*
  • Rhabdomyosarcoma, Alveolar / pathology

Substances

  • MIRN221 microRNA, human
  • MIRN486 microRNA, human
  • MicroRNAs
  • Oncogene Proteins, Fusion
  • PAX3-FOXO1A fusion protein, human
  • Paired Box Transcription Factors