Fig 2: Targeting cholesterol synthesis in TNBC cells in the lung to inhibit metastasis formation(A and B) Migration (A) and tube formation (B) assays of isolated mouse lung endothelial cells. The HMGCR inhibitor simvastatin or cholesterol was added to the culture medium. (C and D) Migration (C) and tube formation (D) assays of isolated mouse lung endothelial cells. The geranylgeranyltransferase inhibitor GGTI-2133, farnesyltransferase inhibitor FTI-277, or squalene synthase inhibitor YM-53601 was added to the culture medium. (E) Syngeneic mouse models to evaluate lung metastasis formation. 0.5 × 106 4T1 cells were injected into BALB/c wild-type mice through the tail vein (n = 5). PBS or HPK-simvastatin (10 µg/mouse/daily) nanoparticles were administered intranasally beginning 48 h after tumor cell injection. Mouse lungs were collected 2 weeks after injection. Metastatic nodules were counted (right panel), and lung sections were stained by hematoxylin and eosin (left panel). (F) Representative images of CD31 staining of blood vessels in mouse lung metastases. The blood vessel density was quantified by ImageJ software (n = 15 view fields). Magnification, 400×. (G) Schematic illustrating a proposed model of the cross-talk among primary tumor cells, lung fibroblasts, and disseminated tumor cells during TNBC lung metastasis formation. *p < 0.05, ***p < 0.001.