EGF-SNX3-EGFR axis drives tumor progression and metastasis in triple-negative breast cancers

Abstract

Epidermal growth factor receptor (EGFR) has critical roles in epithelial cell physiology. Over-expression and over-activation of EGFR have been implicated in diverse cancers, including triple-negative breast cancers (TNBCs), prompting anti-EGFR therapies. Therefore, developing potent therapies and addressing the inevitable drug resistance mechanisms necessitates deciphering of EGFR related networks. Here, we describe Sorting Nexin 3 (SNX3), a member of the recycling retromer complex, as a critical player in the epidermal growth factor (EGF) stimulated EGFR network in TNBCs. We show that SNX3 is an immediate and sustained target of EGF stimulation initially at the protein level and later at the transcriptional level, causing increased SNX3 abundance. Using a proximity labeling approach, we observed increased interaction of SNX3 and EGFR upon EGF stimulation. We also detected colocalization of SNX3 with early endosomes and endocytosed EGF. Moreover, we show that EGFR protein levels are sensitive to SNX3 loss. Transient RNAi models of SNX3 downregulation have a temporary reduction in EGFR levels. In contrast, long-term silencing forces cells to recover and overexpress EGFR mRNA and protein, resulting in increased proliferation, colony formation, migration, invasion in TNBC cells, and increased tumor growth and metastasis in syngeneic models. Consistent with these results, low SNX3 and high EGFR mRNA levels correlate with poor relapse-free survival in breast cancer patients. Overall, our results suggest that SNX3 is a critical player in the EGFR network in TNBCs with implications for other cancers dependent on EGFR activity.

Multifaceted Roles of Retromer in EGFR Trafficking and Signaling Activation

“…A peptide array screen also suggests SNX27′s FERM domain could interact with phosphorylated NPXY motif within EGFR and other receptor tyrosine kinases [ 35 ]. Recently, SNX3 was also shown to bind with EGFR using biotin proximal labelling approach, and SNX5 immunoprecipitated with EGFR in Huh7—a hepatocyte-derived carcinoma cell line [ 23 , 25 ]. Despite all these, solid evidence for direct interactions between EGFR and retromer/SNXs is still largely lacking.…”

“…Some experimental evidence indicates the links between SNXs and EGFR. For example, the interactions of SNX1, SNX3, or SNX5 with EGFR have been observed by various experimental approaches, such as yeast two hybrid study, coimmunoprecipitation and proximity biotinylation labeling [ 23 , 24 , 25 ]. Furthermore, these studies have utilized either overexpression or siRNA-based knock-down approaches to determine their roles in EGFR.…”

Construction of a prognostic model related to copper dependence in breast cancer by single-cell sequencing analysis

“…Goh et al (2015 ) found that DLAT was up-regulated in gastric cancer cells and may be one of the potential drug targets in mitochondria. SNX3 is involved in intracellular protein trafficking and acts as a key factor driving tumor progression and metastasis in triple-negative breast cancer ( Cicek et al, 2022 ). TTC3 is a ubiquitin E3 ligase that promotes the degradation of Akt ubiquitination and phosphorylation ( Suizu et al, 2009 ).…”

EGFR endocytosis: more than meets the eye

“…Our recent study contributes to understanding the role of deregulated endocytosis in cancer by describing the tumor suppressor role of SNX3 (Sorting Nexin 3) in TNBCs [ 30 ]. SNX3 is a member of the recycling retromer complex and is a critical player in the retromer complex.…”

“…In EGFR-positive non-tumorigenic mammary cells (MCF10A) and HEK293 cells, EGF treatment causes an immediate upregulation of SNX3 protein levels. The rapid upregulation is initially due to enhanced protein stability, but prolonged EGF stimulation leads to transcriptional upregulation and 3′UTR shortening of SNX3 [ 30 , 31 ]. After establishing EGF/EGFR-specific upregulation of SNX3, we investigated how SNX3 might, in turn, regulate EGFR.…”