DNMT3A and DNMT3B Targeting as an Effective Radiosensitizing Strategy in Embryonal Rhabdomyosarcoma

Cells. 2021 Oct 30;10(11):2956. doi: 10.3390/cells10112956.

Abstract

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood. Recently, we demonstrated the overexpression of both DNA methyltransferase 3A (DNMT3A) and 3B (DNMT3B) in RMS tumour biopsies and cell lines compared to normal skeletal muscle. Radiotherapy may often fail due to the abnormal expression of some molecules able to drive resistance mechanisms. The aim of this study was to analyse the involvement of DNMT3A and DNMT3B in radioresistance in RMS. RNA interference experiments against DNMT3A/3B were performed in embryonal RMS cells, upon ionizing radiation (IR) exposure and the effects of the combined treatment on RMS cells were analysed. DNMT3A and DNMT3B knocking down increased the sensitivity of RMS cells to IR, as indicated by the drastic decrease of colony formation ability. Interestingly, DNMT3A/3B act in two different ways: DNMT3A silencing triggers the cellular senescence program by up-regulating p16 and p21, whilst DNMT3B depletion induces significant DNA damage and impairs the DNA repair machinery (ATM, DNA-PKcs and Rad51 reduction). Our findings demonstrate for the first time that DNMT3A and DNMT3B overexpression may contribute to radiotherapy failure, and their inhibition might be a promising radiosensitizing strategy, mainly in the treatment of patients with metastatic or recurrent RMS tumours.

Keywords: DNA damage; DNMT3A; DNMT3B; RNA interference; differentiation therapies; radiotherapy; rhabdomyosarcoma; senescence; target therapies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle / radiation effects
  • Cell Differentiation / radiation effects
  • Cell Line, Tumor
  • Cell Proliferation / radiation effects
  • Cellular Senescence / radiation effects
  • Clone Cells
  • Cyclin-Dependent Kinase Inhibitor p21 / metabolism
  • DNA (Cytosine-5-)-Methyltransferases / genetics
  • DNA (Cytosine-5-)-Methyltransferases / metabolism*
  • DNA Damage
  • DNA Methyltransferase 3A / genetics
  • DNA Methyltransferase 3A / metabolism*
  • DNA Methyltransferase 3B
  • Enzyme Activation / radiation effects
  • Gene Expression Regulation, Neoplastic
  • Gene Silencing / radiation effects
  • Histones / metabolism
  • Humans
  • Muscle Development / radiation effects
  • Radiation Tolerance* / genetics
  • Radiation, Ionizing
  • Rhabdomyosarcoma, Embryonal / genetics
  • Rhabdomyosarcoma, Embryonal / radiotherapy*
  • Up-Regulation / genetics
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Cyclin-Dependent Kinase Inhibitor p21
  • H2AX protein, human
  • Histones
  • DNA (Cytosine-5-)-Methyltransferases
  • DNA Methyltransferase 3A
  • p38 Mitogen-Activated Protein Kinases