Gene expression changes associated with metastasis in mice with bladder cancer

Prognosis for bladder cancer is dependent on both tumor stage and grade. In patients with non-muscle invasive bladder cancer, the tumor invariably recurs and may progress. Patients who subsequently develop metastatic disease have a worse prognosis. The purpose of this study was to detect and find differences in patterns of gene expression between the primary tumor and common metastatic sites in a mouse model of bladder cancer to identify possible triggering events that result in metastasis.Five to six-week-old female C57BL/6 mice were orthotopically implanted with MB49-PSA (murine bladder cancer cells secreting human prostate-specific antigen as a tumor marker). At termination (up to 78 days after tumor implantation), bladders, kidneys, lymph nodes and lungs were snap frozen and RNA was extracted by homogenising the tissue in Trizol. Tumor presence in the tissues were confirmed by PSA gene expression which was quantified by real-time PCR. Gene expression level profiling of the transcriptome was analysed via RNA sequencing of samples from 4 bladders, 4 kidneys, 3 lymph nodes and 2 lungs.