Bladder tumor model in mice

All animal protocols were approved by the Ethical Committee of The First Affiliated Hospital of Harbin Medical University and adhered to the Guide for the Care and Use of Laboratory Animals (NRC 2011, 8th Edition). Male, 8-week-old C57BL/6 mice were obtained from The First Affiliated Hospital of Harbin Medical University. Mice were housed in a temperature-controlled environment with 12-h light/dark cycles and unrestricted access to food and drinking water. To induce carcinogenesis in mouse bladder, 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN; Tokyo Chemical Industry Co Ltd, Japan) was added to the drinking water for 17 weeks until tissue harvesting. BBN-free water (vehicle) was added in the drinking water in equal volume for 17 weeks as control treatment. The induction of bladder cancer was histologically confirmed at tissue harvesting.