Additionally, among downregulated hub genes, the expression of acyl-CoA oxidase 1 (ACOX1), apolipoprotein A2 (APOA2), apolipoprotein B (APOB), fibrinogen alpha chain (FGA), and fibrinogen gamma chain (FGG) were negatively correlated with the tumor stage of CCA patients. Here, APOA2 is linked to cholangiocarcinoma.