Sushi domain-containing protein 4 binds to epithelial growth factor receptor and initiates autophagy in an EGFR phosphorylation independent manner

Research output: Contribution to journalArticlepeer-review

Abstract

BACKGROUND: Sushi domain-containing protein 4 (SUSD4) is a recently discovered protein with unknown cellular functions. We previously revealed that SUSD4 can act as complement inhibitor and as a potential tumor suppressor.

METHODS: In a syngeneic mouse model of breast cancer, tumors expressing SUSD4 had a smaller volume compared with the corresponding mock control tumors. Additionally, data from three different expression databases and online analysis tools confirm that for breast cancer patients, high mRNA expression of SUSD4 in the tumor tissue correlates with a better prognosis. In vitro experiments utilized triple-negative breast cancer cell lines (BT-20 and MDA-MB-468) stably expressing SUSD4. Moreover, we established a cell line based on BT-20 in which the gene for EGFR was knocked out with the CRISPR-Cas9 method.

RESULTS: We discovered that the Epithelial Growth Factor Receptor (EGFR) interacts with SUSD4. Furthermore, triple-negative breast cancer cell lines stably expressing SUSD4 had higher autophagic flux. The initiation of autophagy required the expression of EGFR but not phosphorylation of the receptor. Expression of SUSD4 in the breast cancer cells led to activation of the tumor suppressor LKB1 and consequently to the activation of AMPKα1. Finally, autophagy was initiated after stimulation of the ULK1, Atg14 and Beclin-1 axis in SUSD4 expressing cells.

CONCLUSIONS: In this study we provide novel insight into the molecular mechanism of action whereby SUSD4 acts as an EGFR inhibitor without affecting the phosphorylation of the receptor and may potentially influence the recycling of EGFR to the plasma membrane.

Original languageEnglish
Pages (from-to)363
JournalJournal of Experimental and Clinical Cancer Research
Volume41
Issue number1
DOIs
Publication statusPublished - 2022 Dec 29

Bibliographical note

© 2022. The Author(s).

Subject classification (UKÄ)

  • Medicinal Chemistry
  • Cancer and Oncology

Free keywords

  • Humans
  • Animals
  • Mice
  • Triple Negative Breast Neoplasms/metabolism
  • Phosphorylation
  • ErbB Receptors/genetics
  • Receptors, Growth Factor/metabolism
  • Autophagy
  • Cell Line, Tumor

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