New Gain-of-Function Mutations Prioritize Mechanisms of HER2 Activation.

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• The ERBB2 (HER2) oncogene is implicated in various cancers, with amplification being a known driver in breast cancer.
• Missense mutations in ERBB2 can also affect its function, but comprehensive functional analysis of these variants is limited.

Purpose of the Study:

• To functionally characterize a large set of ERBB2 missense mutations using a high-throughput assay.
• To identify novel gain-of-function (GOF) mutations in ERBB2 and understand their mechanisms.
• To investigate the potential clinical relevance of identified HER2 GOF mutations.

Main Methods:

• Utilized the GigaAssay, a high-throughput one-pot system, to measure the molecular function of thousands of ERBB2 genetic variants.
• Classified the activities of 5,886 ERBB2 mutations, including previously unreported variants.
• Performed retrospective analysis of patient outcomes from the Genomic Data Commons.

Main Results:

• Assessed the functional impact of 5,886 ERBB2 missense mutations, identifying 112 new in vitro and 9 new in vivo gain-of-function (GOF) mutations.
• Observed spatial clustering of GOF mutations in sequence and structure, suggesting mechanisms involving heterodimerization with EGFR and juxtamembrane domain release of inhibition.
• Retrospective analysis indicated that newly identified HER2 GOF variants may be associated with increased patient survival.

Conclusions:

• The GigaAssay provides a powerful platform for comprehensive functional profiling of cancer-related genes like ERBB2.
• Identified novel HER2 GOF mutations offer insights into oncogene activation mechanisms.
• Newly discovered HER2 GOF variants show potential as predictive biomarkers for improved patient survival.