The aim of the present study was to investigate the effects of Pseudomonas aeruginosa-mannose-sensitive hemagglutinin (PA-MSHA) on inhibiting the proliferation of bladder cancer cell lines and to further define its functional mechanisms. T24 and 5637 cells were treated with PA-MSHA at various concentrations and times. Cell proliferation was analyzed using Cell Counting Kit-8 (CCK-8) assays. The cell cycle distribution and apoptosis induced by PA-MSHA were measured by flow cytometry with propidium iodide (PI) and annexin V-fluorescein isothiocyanate (FITC) staining. Western blotting was used to evaluate the expression levels of the apoptosis-related molecules and PI3K-AKT-mTOR signaling pathway proteins. A time- and concentration-dependent cytotoxic effect of PA-MSHA was observed in the T24 and 5637 cells. Flow cytometry with PI and annexin V-FITC staining showed that the various concentrations of PA-MSHA were all able to induce the apoptosis and G0-G1 cell cycle arrest of the bladder cancer cells. Cleaved caspase-8 and -9 and Fas protein expression levels were markedly associated with an increase in the apoptosis of the bladder cancer cells. The cells stimulated with PA-MSHA also exhibited a downregulation of PI3K-AKT-mTOR signaling. PA-MSHA inhibits proliferation and induces apoptosis in the T24 and 5637 bladder cancer cell lines by modulating caspase family proteins and affecting the cell cycle regulation machinery. The PI3K-AKT-mTOR signaling pathway may be important in the direct anticancer cytotoxic effect of PA-MSHA.
Keywords: Pseudomonas aeruginosa-mannose-sensitive hemagglutinin vaccine; apoptosis; bladder cancer; caspase.