Citation

  • Authors: Chadelle L. et al.
  • Year: 2022
  • Journal: Cancer Lett 526 112-130
  • Applications: in vitro / siRNA / INTERFERin
  • Cell types:
    1. Name: MDA-MB-231
      Description: Human breast adenocarcinoma cells
      Known as: MDAMB231
    2. Name: MDA-MB-436

Method

For siRNA transfections, duplexes (3.6 nM final) were introduced into the cells using reverse transfection using the Interferin transfection reagent according to the manufacturer's protocol. When two successive siRNA transfection rounds were performed, cells were re-plated 48 h after the first transfection.

Abstract

The cytoskeleton and cell-matrix adhesions constitute a dynamic network that controls cellular behavior during development and cancer. The Focal Adhesion Kinase (FAK) is a central actor of these cell dynamics, promoting cell-matrix adhesion turnover and active membrane fluctuations. However, the initial steps leading to FAK activation and subsequent promotion of cell dynamics remain elusive. Here, we report that the serine/threonine kinase PKCθ participates in the initial steps of FAK activation. PKCθ, which is strongly expressed in aggressive human breast cancers, controls the dynamics of cell-matrix adhesions and active protrusions through direct FAK activation, thereby promoting cell invasion and lung metastases. Using various tools for in vitro and live cell studies, we precisely decipher the molecular mechanisms of FAK activation. PKCθ directly interacts with the FAK FERM domain to open FAK conformation through PKCθ's specific V3 domain, while phosphorylating FAK at newly identified serine/threonine residues within nascent adhesions, inducing cell dynamics and aggressive behavior. This study thus places PKCθ-directed FAK opening and phosphorylations as an original mechanism controlling dynamic, migratory, and invasive abilities of aggressive breast cancer cells, further strengthening the emerging oncogenic function of PKCθ.

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