Xenograft model for growth delay and survival studies

RT112 cells were prepared in phenol red-free Matrigel (BD Biosciences) and phosphate-buffered saline 1:1; 100 μL (5 × 10⁶ cells) was injected into the flank of 6- to 7-week-old female CD1-nude mice. Mice were randomized in Excel (Microsoft) using RAND function into 4 groups: vehicle (5% DMSO in dH₂O), romidepsin (4 mg/kg, single dose, intraperitoneally), IR (using a Gulmay-320 cabinet, 6 Gy, single dose), and romidepsin + IR (6 hours after romidepsin treatment). They received the corresponding treatment when the tumors reached 50 mm³. Tumors were measured 3-dimensionally 3 times a week with a manual calipers, and tumor volume was calculated using the formula (width × length × height × [π/6]). Mice were sacrificed when the tumors reached the limit size of 350 mm³.