2.9. In Vivo Xenograft Experiments

Cells (5 × 10⁵) were suspended in 100 μL of serum-free media and mixed with an equivalent volume of Matrigel (BD Biosciences). The aforementioned mixture was subcutaneously injected into the dorsal flanks of 6–8 weeks old nude mice (obtained from the Taiwan National Laboratory Animal Center, Taipei, Taiwan). Once the tumors grew to 100–150 mm³, mice were intraperitoneally treated with PR-619 (10 mg/kg/day, n = 5), cisplatin (10 mg/kg, three times/week, n = 5), or the combination of cisplatin with PR-619 (n = 5) for three weeks. The tumor sizes were measured using calipers every week. The tumor volume was calculated as follows: Longest tumor diameter × (shortest tumor diameter)²/2. Tumors were abscised and photographed. The study involving animal experiments complied with the ARRIVE guidelines and was approved by the National Taiwan University College of Medicine and College of Public Health Institutional Animal Care and Use Committee (IACUC, No. 20180483).