CDK4/6 Inhibitor LEE011 Is a Potential Radiation-sensitizer in Head and Neck Squamous Cell Carcinoma: An In Vitro Study

Anticancer Res. 2019 Feb;39(2):713-720. doi: 10.21873/anticanres.13167.

Abstract

Background: Radiotherapy (RT) combined with a radiosensitizer represents an important treatment for head and neck squamous cell carcinoma (HNSCC). Only few chemotherapy agents are currently approved as radiosensitizers for targeted therapy. In this study, the potent cyclin-dependent kinase 4/6 (CDK4/6) inhibitor LEE011 was tested for potential to act as a radiosensitizer during RT.

Materials and methods: RT enhancement by LEE011 was assessed by in vitro clonogenic assay, flow cytometry, and western blot in a variety of HNSCC cell lines. The HNSCC cell line OML1 and its radiation-resistant clone OML1-R were used.

Results: LEE011 induced cell-cycle arrest in SCC4/SCC25 cells during the G1/M phase through inhibition of retinoblastoma protein phosphorylation. LEE011 enhanced the effects of radiation in OML1 cells and overcame radiation resistance in OML1-R cells.

Conclusion: LEE011 is a potential radiosensitizer that can enhance the cytotoxic effects of RT. Clinical trials including LEE011 during RT for HNSCC should be considered.

Keywords: CDK4/6 inhibitor; LEE011; head and neck cancer; radioresistance; radiosensitization.

MeSH terms

  • Aminopyridines / pharmacology*
  • Apoptosis / drug effects
  • Cell Cycle
  • Cell Line, Tumor
  • Cell Proliferation
  • Cyclin-Dependent Kinase 4 / antagonists & inhibitors
  • Cyclin-Dependent Kinase 6 / antagonists & inhibitors
  • Head and Neck Neoplasms / drug therapy*
  • Head and Neck Neoplasms / radiotherapy*
  • Humans
  • Mouth Neoplasms / drug therapy
  • Mouth Neoplasms / radiotherapy
  • Phosphorylation
  • Purines / pharmacology*
  • Radiation-Sensitizing Agents / pharmacology*
  • Retinoblastoma Binding Proteins / metabolism
  • Squamous Cell Carcinoma of Head and Neck / drug therapy*
  • Squamous Cell Carcinoma of Head and Neck / radiotherapy*
  • Ubiquitin-Protein Ligases / metabolism

Substances

  • Aminopyridines
  • Purines
  • RB1 protein, human
  • Radiation-Sensitizing Agents
  • Retinoblastoma Binding Proteins
  • Ubiquitin-Protein Ligases
  • CDK4 protein, human
  • CDK6 protein, human
  • Cyclin-Dependent Kinase 4
  • Cyclin-Dependent Kinase 6
  • ribociclib