Eps15 homology domain 1 promotes the evolution of papillary thyroid cancer by regulating endocytotic recycling of epidermal growth factor receptor

EHD1-dependent traffic of IGF-1 receptor to the cell surface is essential for Ewing sarcoma tumorigenesis and metastasis

Overexpression of the EPS15 Homology Domain containing 1 (EHD1) protein has been linked to tumorigenesis but whether its core function as a regulator of intracellular traffic of cell surface receptors plays a role in oncogenesis remains unknown. We establish that EHD1 is overexpressed in Ewing sarcoma (EWS), with high EHD1 mRNA expression specifying shorter patient survival. ShRNA-knockdown and CRISPR-knockout with mouse Ehd1 rescue established a requirement of EHD1 for tumorigenesis and metastasis. RTK antibody arrays identified IGF-1R as a target of EHD1 regulation in EWS. Mechanistically, we demonstrate a requirement of EHD1 for endocytic recycling and Golgi to plasma membrane traffic of IGF-1R to maintain its surface expression and downstream signaling. Conversely, EHD1 overexpression-dependent exaggerated oncogenic traits require IGF-1R expression and kinase activity. Our findings define the RTK traffic regulation as a proximal mechanism of EHD1 overexpression-dependent oncogenesis that impinges on IGF-1R in EWS, supporting the potential of IGF-1R and EHD1 co-targeting.

EHD1-dependent traffic of IGF-1 receptor to the cell surface is essential for Ewing sarcoma tumorigenesis and metastasis

Overexpression of EPS15 Homology Domain containing 1 (EHD1) has been linked to tumorigenesis but whether its core function as a regulator of intracellular traffic of cell surface receptors plays a role in oncogenesis remains unknown. We establish that EHD1 is overexpressed in Ewing sarcoma (EWS), with high EHD mRNA expression specifying shorter patient survival. ShRNA and CRISPR-knockout with mouse Ehd1 rescue established a requirement of EHD1 for tumorigenesis and metastasis. RTK antibody arrays identified the IGF-1R as a target of EHD1 regulation in EWS. Mechanistically, we demonstrate a requirement of EHD1 for endocytic recycling and Golgi to plasma membrane traffic of IGF-1R to maintain its surface expression and downstream signaling. Conversely, EHD1 overexpression-dependent exaggerated oncogenic traits require IGF-1R expression and kinase activity. Our findings define the RTK traffic regulation as a proximal mechanism of EHD1 overexpression-dependent oncogenesis that impinges on IGF-1R in EWS, supporting the potential of IGF-1R and EHD1 co-targeting.

Cellular functions and intrinsic attributes of the ATP-binding Eps15 homology domain-containing proteins

Several cellular processes rely on a cohort of dedicated proteins that manage tubulation, fission, and fusion of membranes. A notably large number of them belong to the dynamin superfamily of proteins. Among them is the evolutionarily conserved group of ATP-binding Eps15-homology domain-containing proteins (EHDs). In the two decades since their discovery, EHDs have been linked to a range of cellular processes that require remodeling or maintenance of specific membrane shapes such as during endocytic recycling, caveolar biogenesis, ciliogenesis, formation of T-tubules in skeletal muscles, and membrane resealing after rupture. Recent work has shed light on their structure and the unique attributes they possess in linking ATP hydrolysis to membrane remodeling. This review summarizes some of these recent developments and reconciles intrinsic protein functions to their cellular roles.

EHD1 and RUSC2 Control Basal Epidermal Growth Factor Receptor Cell Surface Expression and Recycling

Epidermal growth factor receptor (EGFR) is a prototype receptor tyrosine kinase and an oncoprotein in many solid tumors. Cell surface display of EGFR is essential for cellular responses to its ligands. While postactivation endocytic trafficking of EGFR has been well elucidated, little is known about mechanisms of basal/preactivation surface display of EGFR. Here, we identify a novel role of the endocytic regulator EHD1 and a potential EHD1 partner, RUSC2, in cell surface display of EGFR. EHD1 and RUSC2 colocalize with EGFR in vesicular/tubular structures and at the Golgi compartment. Inducible EHD1 knockdown reduced the cell surface EGFR expression with accumulation at the Golgi compartment, a phenotype rescued by exogenous EHD1. RUSC2 knockdown phenocopied the EHD1 depletion effects. EHD1 or RUSC2 depletion impaired the EGF-induced cell proliferation, demonstrating that the novel, EHD1- and RUSC2-dependent transport of unstimulated EGFR from the Golgi compartment to the cell surface that we describe is functionally important, with implications for physiologic and oncogenic roles of EGFR and targeted cancer therapies.

Mammalian Eps15 homology domain 1 potentiates angiogenesis of non-small cell lung cancer by regulating β2AR signaling

BACKGROUND

Non-small cell lung cancer (NSCLC) is a devastating disease with a heterogeneous prognosis, and the molecular mechanisms underlying tumor progression remain elusive. Mammalian Eps15 homology domain 1 (EHD1) plays a promotive role in tumor progression, but its role in cancer angiogenesis remains unknown. This study thus explored the role of EHD1 in angiogenesis in NSCLC.

METHODS

The changes in angiogenesis were evaluated through human umbilical vein endothelial cell (HUVEC) proliferation, migration and tube formation assays. The impact of EHD1 on β2-adrenoceptor (β2AR) signaling was evaluated by Western blotting, quantitative real-time polymerase chain reaction (qRT-PCR) analysis, and enzyme-linked immunosorbent assay (ELISA). The interaction between EHD1 and β2AR was confirmed by immunofluorescence (IF) and coimmunoprecipitation (Co-IP) experiments, and confocal microscopy immunofluorescence studies revealed that β2AR colocalized with the recycling endosome marker Rab11, which indicated β2AR endocytosis. Xenograft tumor models were used to investigate the role of EHD1 in NSCLC tumor growth.

RESULTS

The microarray analysis revealed that EHD1 was significantly correlated with tumor angiogenesis, and loss- and gain-of-function experiments demonstrated that EHD1 potentiates HUVEC proliferation, migration and tube formation. EHD1 knockdown inhibited β2AR signaling activity, and EHD1 upregulation promoted vascular endothelial growth factor A (VEGFA) and β2AR expression. Interestingly, EHD1 interacted with β2AR and played a novel and critical role in β2AR endocytic recycling to prevent receptor degradation. Aberrant VEGFA or β2AR expression significantly affected EHD1-mediated tumor angiogenesis. The proangiogenic role of EHD1 was confirmed in xenograft tumor models, and immunohistochemistry (IHC) analysis confirmed that EHD1 expression was positively correlated with VEGFA expression, microvessel density (MVD) and β2AR expression in patient specimens.

CONCLUSION

Collectively, the data obtained in this study suggest that EHD1 plays a critical role in NSCLC angiogenesis via β2AR signaling and highlight a potential target for antiangiogenic therapy.