Culture supernatant of <i>Toxoplasma gondii</i> tachyzoites inhibits the proliferation and metastasis of bladder cancer cells

Bladder cancer is the most common type of tumor in the urinary system and has a high incidence and mortality rate. Protozoan parasites have recently gained popularity as a research topic for cancer therapy. The present study aimed to evaluate the effect of <i>T. gondii</i> tachyzoite culture supernatants on bladder cancer cells. Bladder cancer 5637 cells were infected with two different genotypes of <i>T. gondii</i> tachyzoite culture supernatants, RH and ToxoDB#9. The effects of <i>T. gondii</i> tachyzoite culture supernatant on cell proliferation were detected using a Cell Counting Kit-8 assay. The effects on cell migration and invasion were evaluated using wound healing and Transwell assays. The effect on the apoptosis rate of the cells was assessed using a TUNEL assay, while the protein levels of Bax and Bcl-2 were analyzed by western blotting. The results indicated that the culture supernatant of <i>T. gondii</i> tachyzoites altered the morphology of bladder cancer 5637 cells, inhibited cell proliferation, reduced cell migration and invasion and promoted apoptosis. The ToxoDB#9-type experimental group showed higher efficacy than the RH-type experimental group in inhibiting bladder cancer cell proliferation, reducing cell migration and invasion and promoting apoptosis. These results indicated that the culture supernatant of <i>T. gondii</i> tachyzoites could be a promising therapeutic agent for the treatment of bladder cancer.