Depression Induced by CUMS Leads to Bladder Cancer Development and Local Tumor Immunosuppression in Mice

Depression is a common mental disease in bladder cancer patients, leading to a loss of happiness, an increase in the suicide rate, and higher mortality. However, the influence of depression on bladder tumor tissue remains unknown. In this current study, a subcutaneous bladder cancer xenograft model was established on male C57 mice with mouse bladder cell line MB49. Chronic unpredictable mild stress (CUMS) was established to simulate depression in bladder cancer patients. The depression caused by CUMS was confirmed by testing sucrose preference and plasma cortisol and adrenocorticotropic hormone (ACTH) levels. Then, we measured and weighed tumors to demonstrate the promotion of tumor growth by CUMS. Immune-related cells and molecules were examined to reveal the mechanism. There is a significant decrease of CD8⁺/CD4⁺T cells ratio, NK cells, IL-2, and IFN-γ and a significant increase of T regs, IL-6, IL-1β, TNF-α, IL-10, and PGE2 in CUMS group, indicating the inhibition of immunity in the tumor microenvironment. Our results supported the perspective that depression exacerbated bladder cancer and revealed a possible mechanism. We suggest attaching importance to the psychological health of bladder cancer patients to prevent a worse prognosis induced by depression.