Construction of tumor-bearing mice model

BC cells in good condition were adjusted at a dose of 1×10⁶/mL. Healthy BALB/c nude mice with 5 or 6 weeks old were randomly assigned into sh-NC group (n=9) or sh-LINC00668 1# group (n=9). Right chest fat pad of nude mouse was sterilized with 75% ethanol and 100 μL of BC cell suspension transfected with sh-NC or sh-LINC00668 1# was administrated. Mice were observed every 3 days. The long diameter and transverse diameter of BC tumor were measured using the vernier caliper. Volume of the BC tumor was calculated: V (mm³) =0.5× long diameter (mm) × transverse diameter² (mm²). Mice were sacrificed 3 weeks later, and tumor samples were harvested for weight recording. The staining results were independently scored by the author and a pathologist to minimize subjectivity, and the experiments were approved by the Animal ethics committee of Naval Military Medical University.