Lapatinib decreases the ACTH production and proliferation of corticotroph tumor cells

Endocr J. 2019 Jun 28;66(6):515-522. doi: 10.1507/endocrj.EJ18-0491. Epub 2019 Mar 15.


Cushing's disease is almost always caused by hypersecretion of adrenocorticotropic hormone (ACTH) from a pituitary adenoma. A mutation in the deubiquitinase gene USP8 has been found in human ACTH-producing pituitary adenoma cells. This mutational hotspot hyperactivates USP8, rescuing epidermal growth factor receptor (EGFR) from lysosomal degradation and ensuring its sustained signaling in Cushing's disease. An EGFR inhibitor would be an effective anti-tumor agent in EGFR-related tumors. We investigated the effect of a potent dual tyrosine kinase inhibitor, lapatinib, on ACTH production and cell proliferation in AtT-20 mouse corticotroph tumor cells. Lapatinib decreased proopiomelanocortin (Pomc) mRNA levels and ACTH levels in AtT-20 cells and also inhibited cell proliferation, induced apoptosis, and decreased pituitary tumor-transforming gene 1 (Pttg1), a hallmark of pituitary tumors, mRNA levels. KSN/Slc nude mice were subcutaneously inoculated with AtT-20 cells. After 1 week, the mice were randomized either to control or lapatinib groups. The inhibitor decreased the tumor weight of AtT-20 allografts in vivo versus control mice. Lapatinib also significantly decreased Pomc and Pttg1 mRNA levels in the tumor and plasma ACTH and corticosterone levels in vivo. Thus, lapatinib decreases the ACTH production and proliferation of corticotroph tumor cells. An EGFR-targeting therapy could be an important treatment for Cushing's disease.

Keywords: Adrenocorticotropic hormone; Cushing’s disease; Pituitary tumor; Proopiomelanocortin; Treatment.

MeSH terms

  • ACTH-Secreting Pituitary Adenoma / drug therapy
  • ACTH-Secreting Pituitary Adenoma / pathology
  • Adenoma / drug therapy
  • Adenoma / pathology
  • Adrenocorticotropic Hormone / blood
  • Adrenocorticotropic Hormone / metabolism*
  • Animals
  • Antineoplastic Agents / pharmacology*
  • Antineoplastic Agents / therapeutic use
  • Cell Line, Tumor
  • Cell Proliferation / drug effects*
  • Corticosterone / blood
  • Corticotrophs / drug effects*
  • Corticotrophs / metabolism
  • Corticotrophs / pathology
  • Lapatinib / pharmacology*
  • Lapatinib / therapeutic use
  • Mice
  • Mice, Nude
  • Neoplasm Transplantation
  • Protein Kinase Inhibitors / pharmacology*
  • Protein Kinase Inhibitors / therapeutic use


  • Antineoplastic Agents
  • Protein Kinase Inhibitors
  • Lapatinib
  • Adrenocorticotropic Hormone
  • Corticosterone