Quantification of EGFR-HER2 Heterodimers in HER2-Overexpressing Breast Cancer Cells Using Liquid-Phase Electron Microscopy

Effect of HER2 expression status on the prognosis of patients with HR+/HER2‑ advanced breast cancer undergoing advanced first‑line endocrine therapy

The present study aimed to retrospectively assess the effects of human epidermal growth factor receptor 2 (HER2) expression on the diagnosis of patients with hormone receptor (HR)⁺/HER2^- late-stage breast cancer undergoing advanced first-line endocrine-based treatment. A total of 72 late-stage breast tumor cases from June 2017 to June 2019 were selected from the Department of Surgical Oncology, Shaanxi Provincial People's Hospital (Xi'an, China) and included in the present study. The expression of estrogen receptor, progesterone receptor and HER2 was detected by immunohistochemistry. The subjects were divided into two groups: the HER2-negative (0) cohort (n=31) and the HER2 low expression cohort (n=41). The age, BMI, Karnofsky Performance Status (KPS) score, tumor size, lymph node metastasis, pathological type, Ki-67 expression and menopausal status of the patients were obtained through the electronic medical record system of Shaanxi Provincial People's Hospital. Progression-free survival (PFS) and overall survival (OS) were evaluated for all patients. The median PFS and OS of the HER2(0) cohort were longer than those of the HER2 low expression cohort (all P<0.05). It was shown that age (hazard ratio, 6.000 and 5.465), KPS score (hazard ratio, 4.000 and 3.865), lymph node metastasis (hazard ratio, 3.143; 2.983) and HER2 status (hazard ratio, 3.167 and 2.996) were independent influencing factors of the prognosis of patients with HR⁺/HER2^- advanced breast cancer (ABC) (all P<0.05). Three models (model 1, no parameters adjusted; model 2, BMI, tumor size, pathological type, Ki-67 and menopausal status adjusted; and model 3, age, KPS functional status score and lymph node metastasis adjusted based on model 2) were established within the HER2(0) cohort as the reference for statistical analysis using the multivariate Cox's regression test. In models 2 and 3, the risk of poor prognosis of ABC within the HER2 low expression cohort was significantly higher compared with that in the HER2(0) cohort (hazard ratio, 3.558 and 4.477; 95% CI, 1.349-9.996 and 1.933-11.586; P=0.003 and P<0.001). The HER2 expression status of patients with HR⁺/HER2^- ABC receiving advanced first-line endocrine therapy may affect PFS and OS.

Structure and dynamics of the EGFR/HER2 heterodimer

HER2 belongs to the human epidermal growth factor receptor tyrosine kinase family. Its overexpression or hyperactivation is a leading cause for multiple types of cancers. HER2 functions mainly through dimerization with other family members, such as EGFR. However, the molecular details for heterodimer assembly have not been completely understood. Here, we report cryo-EM structures of the EGF- and epiregulin-bound EGFR/HER2 ectodomain complexes at resolutions of 3.3 Å and 4.5 Å, respectively. Together with the functional analyses, we demonstrate that only the dimerization arm of HER2, but not that of EGFR, is essential for their heterodimer formation and signal transduction. Moreover, we analyze the differential membrane dynamics and transient interactions of endogenous EGFR and HER2 molecules in genome-edited cells using single-molecule live-cell imaging. Furthermore, we show that the interaction with HER2 could allow EGFR to resist endocytosis. Together, this work deepens our understanding of the unique structural properties and dynamics of the EGFR/HER2 complex.

Challenges for the application of EGFR-targeting peptide GE11 in tumor diagnosis and treatment

Abnormal regulation of cell signaling pathways on cell survival, proliferation and migration contributes to the development of malignant tumors. Among them, epidermal growth factor receptor (EGFR) is one of the most important biomarkers in many types of malignant solid tumors. Its over-expression and mutation status can be served as a biomarker to identify patients who can be benifit from EGFR tyrosine kinase inhibitors and anti-EGFR monocloncal antibody (mAb) therapy. For decades, researches on EGFR targeted ligands were actively carried out to identify potent candidates for cancer therapy. An ideal EGFR ligand can competitively inhibit the binding of endogenous growth factor, such as epidermal growth factor (EGF) and transforming growth factor-α(TGF-α) to EGFR, thus block EGFR signaling pathway and downregulate EGFR expression. Alternatively, conjugation of EGFR ligands on drug delivery systems (DDS) can facilitate targeting delivery of therapeutics or diagnostic agents to EGFR over-expression tumors via EGFR-mediated endocytosis. GE11 peptide is one of the potent EGFR ligand screened from a phage display peptide library. It is a dodecapeptide that can specifically binds to EGFR with high affinity and selectivity. GE11 has been widely used in the diagnosis and targeted delivery of drugs for radiotherapy, genetherapy and chemotherpy against EGFR positive tumors. In this review, the critical factors affecting the in vivo and in vitro targeting performance of GE11 peptide, including ligand-receptor intermolecular force, linker bond properties and physiochemical properties of carrier materials, are detailedly interpreted. This review provides a valuable vision for the rational design and optimization of GE11-based active targeting strategies for cancer treatment, and it will promote the translation studies of GE11 from lab research to clinical application.