Background: One of the most common cancers in dogs, especially in the Poodle and Terrier breeds, is breast cancer. Hormonal imbalances and genetic factors, including dysregulation of growth factor receptors like HER۲ and EGFR, contribute to tumorigenesis. Given the molecular parallels between human and canine mammary cancers, this study investigates the interplay between HER۲ and EGFR, their shared signaling pathways, and their potential as therapeutic targets. Methods: Protein-Protein Interaction (PPI) networks for HER and EGFR were independently retrieved from BioGRID (https://thebiogrid.org). Given the limited availability of experimentally validated CMT-specific PPIs, we primarily relied on human breast cancer
PPI data, supported by high sequence and functional conservation of oncogenic pathways between canine and human mammary tumors. A shared interactome was identified using Venn analysis (Venny ۲.۱.۰). A consolidated
PPI network integrating HER۲-EGFR common interactome was constructed using STRING (https://string-db.org) and analyzed in Cytoscape (v۳.۱۰.۳). Hub proteins were systematically identified using network topology metrics: node degree, betweenness centrality, and neighborhood connectivity. GO enrichment analysis on ۳۱ selected genes using String identified enriched Biological Process (BP). Results: The Cytoscape
PPI network analysis identified EGFR and
SRC as the most central hubs, exhibiting the highest degree (۲۹ and ۲۸, respectively), closeness centrality (۰.۹۶۸ and ۰.۹۳۸), and betweenness centrality (۰.۰۷۸ and ۰.۰۶۲), suggesting their critical roles in network communication. Proteins like
GRB۲ and ERBB۲ also showed high connectivity and influence. The GO enrichment analysis highlighted that the key genes are strongly associated with growth factor signaling pathways, particularly ERBB receptor signaling, tyrosine kinase activity, and PI۳K regulation. Conclusion: The EGFR-HER۲ crosstalk in CMTs depends on critical nodes like
SRC and GRB۲. Targeting these hubs, rather than EGFR/HER۲ alone or in combination, may disrupt oncogenic signaling more efficiently, offering a streamlined therapeutic strategy for CMTs.