In Vivo Evaluation of miR-491-3p and uMtCK in Tumor Growth

Athymic BALB/c mice (4-6 weeks old) were obtained from Charles River (Beijing, China) and maintained under pathogen-free conditions. All mice were raised at a 12 h dark/light cycle, at 24 ± 2 °C, and were given free access to food and water. Animal experiments were carried out in approval of the Experimental Animal Committee of Panyu District Central Hospital (PYRC-2021-113), and conducted under the 3R principle to reduce suffering of mice. SW480 cells (5 × 10⁶) treated with miR-491-3p mimic, control miRNA mimic or both miR-491-3p mimic and pcDNA-uMtCK were resuspended in 100 µL of PBS and injected into right flank of mice (n = 3). Tumor growth was half-quantified with a caliper in a blinded fashion at the indicated time (0, 14, 21, and 35 days). Tumor volume was estimated through the formula length ×width² ×0.5, as previously described (Hart et al., 2012 (link); Khare et al., 2019 (link)). At the end of studies, all mice were euthanatized by cervical dislocation under inhalation anesthesia (2% isoflurane), and tumor tissues were collected. During the experiment, once any mouse suffering from unexpected disease or over-sized tumor (>1 cm) will be euthanatized as described earlier.