Construction of PPI network and identification of hub genes

A public online database, named STRING (https://string-db.org/), can be used to search for and predict PPIs. This inclusive resource facilitates the investigation of direct physical associations between proteins, as well as the detection of indirect functional connections unveiled through correlation analyses[22]. When common DEGs between different groups were identified, they were uploaded to STRING’s official website (https://cn.string-db.org/) and the interactions between DEGs and STRING database proteins were then assigned (with a minimum needed interaction score of 0.40). We followed the method of Liu et al[23], in which PPI interaction networks were visualized using Cytoscape (Version 3.6.1). Cytoscape is from National Institute of General Medical Sciences, United States. We used CytoHubba (Version 0.1) to identify hub genes using a maximal clique centrality algorithm.