Regulation of the EGFR Pathway by HSP90 Is Involved in the Pathogenesis of Cushing's Disease

  • Front Endocrinol (Lausanne). 2021 Jan 18:11:601984. doi: 10.3389/fendo.2020.601984.
Yue Shen  1  2 ,  Chenxing Ji  1  2 ,  Xuemin Jian  3 ,  Juan Zhou  3 ,  Qilin Zhang  1  2 ,  Nidan Qiao  1  2 ,  Yichao Zhang  1  2 ,  Xuefei Shou  1  2 ,  Xiang Zhou  1  2 ,  Zengyi Ma  1  2
Affiliations
  • 1. Department of Neurosurgery, Huashan Hospital, Shanghai Medical College, Fudan University, Neurosurgical Institute of Fudan University, Shanghai Clinical Medical Center of Neurosurgery, Shanghai Key Laboratory of Brain Function Restoration and Neural Regeneration, Shanghai, China.
  • 2. Shanghai Pituitary Tumor Center, Shanghai, China.
  • 3. Shanghai Jiao Tong University School of Medicine, Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), and the Collaborative Innovation Center for Brain Science, Shanghai Jiao Tong University, Shanghai, China.
PMID: 33537004 DOI: 10.3389/fendo.2020.601984
Abstract

Purpose: To investigate the role of heat-shock protein HSP90 in adrenocorticotropic hormone (ACTH)-secreting cells, and to explore the potential clinical application of an inhibitor of HSP90, 17-N-allylamino-17-demethoxygeldanamycin(17-AAG) in corticotropinomas [also known as "Cushing's disease" (CD)].

Methods: Culture of mouse pituitary tumor [AtT-20/D16v-F2 (ATCC® CRL-1795™)] cells and human pituitary ACTH-secreting tumor cells were employed. Hepatocellular carcinoma cell line (HLE) was used to evaluate EGFR inhibition by 17-AAG. Cell viability was evaluated using a commercial kit. The ACTH level was measured by a radioimmunoassay. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to measure expression of proopiomelanocortin (POMC) mRNA. Western blotting was done to measure protein levels.

Results: 17-AAG suppressed the viability and proliferation, and promoted the Apoptosis, of AtT-20/D16v-F2 cells. 17-AAG suppressed the synthesis and secretion of ACTH in AtT-20/D16v-F2 cells and down-regulated POMC transcription. 17-AAG acted in a similar pattern upon treatment with human pituitary ACTH-secreting tumor cells. Inhibition by 17-AAG was stronger in human pituitary ACTH-secreting tumor cells carrying the ubiquitin-specific protease-8 (USP8) mutant in comparison with cells carrying wild-type USP8.

Conclusions: The HSP90 Inhibitor 17-AAG reduced the viability and secretory function of human pituitary ACTH-secreting tumor cells, and tumor cells carrying the USP8 mutant were more sensitive to 17-AAG than tumor cells carrying wild-type USP8. 17-AAG could be a potential treatment option for CD.

Keywords
17-N-allylamino-17-demethoxygeldanamycin/tanespimycin; Cushing’s disease; Hsp90; epidermal growth factor receptor; pathogenesis.
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