Everolimus induces G1 cell cycle arrest through autophagy-mediated protein degradation of cyclin D1 in breast cancer cells

Guang Chen, Xiao Fei Ding, Hakim Bouamar, Kyle Pressley, Lu Zhe Sun

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Everolimus inhibits mammalian target of rapamycin complex 1 (mTORC1) and is known to cause induction of autophagy and G1 cell cycle arrest. However, it remains unknown whether everolimus-induced autophagy plays a critical role in its regulation of the cell cycle. We, for the first time, suggested that everolimus could stimulate autophagy-mediated cyclin D1 degradation in breast cancer cells. Everolimus-induced cyclin D1 degradation through the autophagy pathway was investigated in MCF-10DCIS-.COM and MCF-7 cell lines upon autophagy inhibitor treatment using Western blot assay. Everolimus-stimulated autophagy and decrease in cyclin D1 were also tested in explant human breast tissue. Inhibiting mTORC1 with everolimus rapidly increased cyclin D1 degradation, whereas 3-methyladenine, chloroquine, and bafilomycin A1, the classic autophagy inhibitors, could attenuate everolimus-induced cyclin D1 degradation. Similarly, knockdown of autophagy-related 7 (Atg-7) also repressed everolimus-triggered cyclin D1 degradation. In addition, everolimus-induced autophagy occurred earlier than everolimus-induced G1 arrest, and blockade of autophagy attenuated everolimus-induced G1 arrest. We also found that everolimus stimulated autophagy and decreased cyclin D1 levels in explant human breast tissue. These data support the conclusion that the autophagy induced by everolimus in human mammary epithelial cells appears to cause cyclin D1 degradation resulting in G1 cell cycle arrest. Our findings contribute to our knowledge of the interplay between autophagy and cell cycle regulation mediated by mTORC1 signaling and cyclin D1 regulation.

Original languageEnglish (US)
Pages (from-to)C244-C252
JournalAmerican Journal of Physiology - Cell Physiology
Volume317
Issue number2
DOIs
StatePublished - Aug 2019

Keywords

  • Autophagy
  • Cell cycle
  • Cyclin D1
  • Everolimus
  • MTORC1 inhibitor

ASJC Scopus subject areas

  • Physiology
  • Cell Biology

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