Spontaneous Breast Cancer Metastasis Mouse Model

NOD-SCID mice (6–8 weeks, Female, SPF degree, 22 ± 3 g) were purchased from Beijing HFK Bioscience Co (Beijing, China). All mice were housed and maintained under specific pathogen-free (SPF) conditions as our described previously (12, 13). All procedures were approved by the Institutional Animal Care and Use Committee of Children’s Hospital of of Chongqing Medical University. A spontaneous BC metastasis mouse model was established as previously described (11). Briefly, 4T1 cells (1 × 10⁵) in 100 µl PBS buffer were subcutaneously injected into in the left mammary fat pad of NOD-SCID mice. After 3 to 5 days, 4T1-bearing mice were randomly divided into two groups to receive 0.9% NaCl or 15 mg/kg Sax orally daily (n = 3–5 mice/group). For ALA intervention in vivo, 4T1-bearing mice were randomly divided into two groups to receive intraperitoneal (i.p.) administration of 0.9% NaCl or ALA (80 mg/kg in 0.9% NaCl) three times per week (n = 3–5 mice/group). At the end of experiments, experimental mice were sacrificed, and liver and lung tissues were harvested for the analysis of H&E and immunohistochemistry staining.