HDAC6-dependent ciliophagy is involved in ciliary loss and cholangiocarcinoma growth in human cells and murine models

Estanislao Peixoto, Sujeong Jin, Kristen Thelen, Aalekhya Biswas, Seth Richard, Manuela Morleo, Adrian Mansini, Stephanie Holtorf, Fabrizia Carbone, Nunzia Pastore, Andrea Ballabio, Brunella Franco, Sergio A. Gradilone

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Reduced ciliary expression is reported in several tumors, including cholangiocarcinoma (CCA). We previously showed primary cilia have tumor suppressor characteristics, and HDAC6 is involved in ciliary loss. However, mechanisms of ciliary disassembly are unknown. Herein, we tested the hypothesis that HDAC6-dependent autophagy of primary cilia, i.e., ciliophagy, is the main mechanism driving ciliary disassembly in CCA. Using the cancer genome atlas database, human CCA cells, and a rat orthotopic CCA model, we assessed basal and HDAC6-regulated autophagy levels. The effects of RNA-silencing or pharmacological manipulations of ciliophagy on ciliary expression were assessed. Interactions of ciliary proteins with autophagy machinery was assessed by immunoprecipitations. Cell proliferation was assessed by MTS and IncuCyte. A CCA rat model was used to assess the effects of pharmacological inhibition of ciliophagy in vivo. Autophagy is increased in human CCA, as well as in a rat orthotopic CCA model and human CCA cell lines. Autophagic flux was decreased via inhibition of HDAC6, while it was increased by its overexpression. Inhibition of autophagy and HDAC6 restores cilia and decreases cell proliferation. LC3 interacts with HDAC6 and ciliary proteins, and the autophagy cargo receptor involved in targeting ciliary components to the autophagy machinery is primarily NBR1. Treatment with chloroquine, Ricolinostat (ACY-1215), or their combination decreased tumor growth in vivo. Mice that overexpress the autophagy transcription factor TFEB show a decrease of ciliary number. These results suggest that ciliary disassembly is mediated by HDAC6-regulated autophagy, i.e., ciliophagy. Inhibition of ciliophagy may decrease cholangiocarcinoma growth and warrant further investigations as a potential therapeutic approach. NEW & NOTEWORTHY This work identifies novel targets against primary ciliary disassembly that can lead to new cholangiocarcinoma therapeutic strategies. Furthermore, ciliary loss has been described in different tumors, increasing the significance of our research.

Original languageEnglish (US)
Pages (from-to)G1022-G1033
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume318
Issue number6
DOIs
StatePublished - Jun 2020

Bibliographical note

Funding Information:
We thank Telethon Institute of Genetics and Medicine Bioinformatics Core. This work was supported by National Institutes of Health Grant R01CA183764 (to S. A. Gradilone), the Randy Shaver Cancer Research and Community Fund Award (to S. A. Gradilone), the Chainbreaker GOpher a Cure award, provided by the Masonic Cancer Center University of Minnesota, The Hormel Foundation, and by Italian Association for Cancer Research (AIRC) Grant IG17711 (to B. Franco).

Funding Information:
This work was supported by National Institutes of Health Grant R01CA183764 (to S. A. Gradilone), the Randy Shaver Cancer Research and Community Fund Award (to S. A. Gradilone), the Chainbreaker GOpher a Cure award, provided by the Masonic Cancer Center University of Minnesota, The Hormel Foundation, and by Italian Association for Cancer Research (AIRC) Grant IG17711 (to B. Franco).

Publisher Copyright:
Copyright © 2020 the American Physiological Society

Keywords

  • Autophagy
  • Cargo receptors
  • Ciliophagy
  • LC3
  • NBR1
  • Primary cilia

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

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