In vivo xenograft tumor model

BALB/c nude mice (4–6 weeks old, male) were purchased from the Experimental Animal Centre of Southern Medical University and maintained under standard pathogen-free conditions, with 6 mice in each group. A sample of 1 × 10⁷ HeLa cells with stable SKA3 overexpression or SKA3 knockdown or control plasmid re-suspended in 200 µL of PBS was injected into the left, middle or right dorsal flank of the mice, respectively. To analyze tumor growth, tumor size was measured using calipers for 6 weeks according to the following formula: L*W*W*π/6, where L is the length and W is the width of the tumor. The tumor tissues were harvested, fixed, and paraffin-embedded before 4-mm tissue sections were obtained. All sections were subjected to immunohistochemistry (IHC) staining. All animal studies (including the mouse euthanasia procedure) were performed in compliance with the regulations and guidelines of Southern Medical University Institutional Animal Care and according to AAALAC and IACUC guidelines.