ERK1/2-dependent activation of FCHSD2 drives cancer cell-selective regulation of clathrin-mediated endocytosis

Abstract

Clathrin-mediated endocytosis (CME) regulates the uptake of cell surface receptors, as well as their downstream signaling activities. We recently reported that signaling reciprocally regulates CME in cancer cells and that the crosstalk can contribute to cancer progression. To further explore the nature and extent of the crosstalk between signaling and CME in cancer cell biology, we analyzed a panel of oncogenic signaling kinase inhibitors for their effects on CME. Inhibition of several kinases selectively affected CME function in cancer cells. Among these, ERK1/2 inhibition selectively inhibited CME in cancer cells by decreasing the rate of CCP initiation. We identified an ERK1/2 substrate, the FCH/F-BAR and SH3 domain-containing protein, FCHSD2, as being essential for the ERK1/2-dependent effects on CME and CCP initiation. ERK1/2 phosphorylation activates FCHSD2 and regulates EGFR endocytic trafficking as well as downstream signaling activities. Loss of FCHSD2 activity in non-small-cell lung cancer cells leads to increased cell surface expression and altered signaling downstream of EGFR, resulting in enhanced cell proliferation and migration. The expression level of FCHSD2 is positively correlated with higher cancer patient survival rate, suggesting that FCHSD2 negatively affects cancer progression. These findings provide new insight into the mechanisms and consequences of the reciprocal regulation of signaling and CME in cancer cells.\n\nSignificanceClathrin-mediated endocytosis (CME) determines the internalization of receptors and their downstream signaling. We discovered that CME is differentially regulated by specific signaling kinases in cancer cells. In particular, ERK1/2-mediated phosphorylation of the FCH/F-BAR and double SH3 domains-containing protein 2 (FCHSD2) regulates CME, and the trafficking and signaling activities of EGF receptors. This reciprocal interaction negatively regulates cancer proliferation and migration. The expression level of FCHSD2 is positively correlated with higher cancer patient survival rates. This study identifies signaling pathways that impinge on the endocytic machinery and reveals a molecular nexus for crosstalk between intracellular signaling and CME. Cancer cells specifically adapt this crosstalk as a determinant for tumor progression, which has implications for novel therapeutics against cancers.