PEA-15 facilitates EGFR dephosphorylation via ERK sequestration at increased ER–PM contacts in TNBC cells

• PEA-15 sequestrates phosphorylated ERK1/2 in the cytoplasm and increases intracellular calcium concentration.
• Contact between the plasma membrane and endoplasmic reticulum is triggered by overexpression of PEA-15.
• PEA-15 influences dephosphorylation of EGFR by ER-localized PTP1B in MDA-MB-468 TNBC cells.

Phosphoprotein enriched in astrocytes of 15kDa (PEA-15) is known to sequester extracellular signal-regulated kinase (ERK) in the cytoplasm, inhibiting tumorigenesis of human breast cancer cells. Here, we describe how PEA-15 expression affects the dephosphorylation of epidermal growth factor receptor (EGFR) through endoplasmic reticulum (ER)–plasma membrane (PM) contacts in MDA-MB-468, triple-negative breast cancer (TNBC) cells. The increased intracellular calcium concentration resulting from increased cytoplasmic phosphorylated ERK facilitates movement of ER-anchored calcium sensors to the PM. The driving force of trans-localization of calcium-dependent proteins enhances the contact between the activated EGFR and ER-localized phosphatase, PTP1B. Consequently, our findings suggest a mechanism underneath the facilitation of EGFR dephosphorylation by cytoplasmic PEA-15 expression inside TNBC cells, which may be one of the dynamic mechanisms for down-regulation of activated EGFR in cancer cells.