Xenograft Tumor Model for OCT4 Regulation

Animal experiments were performed as described previously [49 (link)]. Briefly, BALB/c-nu mice (female, 6–8 weeks old; Orient Bio, Seongnam, South Korea) were used to establish a tumor xenograft model. NTERA-2 Tet-on-shOCT4 OCT WT- and S236D-rescued cells (5.0 × 10⁶/each in opposite flanks) were inoculated subcutaneously. After 4–5 weeks, when the tumor sizes reached 50–100 mm³, the mice were randomly divided into two groups, a control group and a Dox group. Dox (1 mg/mL, #631311; Clontech Laboratories, Mountain View, CA, USA) was fed 5% sucrose drinking water. The primary tumor size and body weight were measured every week using calipers and a balance, respectively. The tumor volume was calculated using the formula V = (A × B²)/2, where V is the volume (mm³), A is the long diameter, and B is the short diameter. Mice were killed in a 7.5% CO₂ chamber, and the tumors were harvested for further analysis. All mice were attended under specific pathogen-free conditions at the National Cancer Center Research Institute Animal Facility. This study was reviewed and approved by the Institutional Animal Care and Use Committee of the National Cancer Center Research Institute (NCC-17-401), an Association for Assessment and Accreditation of Laboratory Animal Care International-accredited facility.