The regulatory effects of polyporus polysaccharide on the nuclear factor kappa B signal pathway of bladder cancer cells stimulated by Bacillus Calmette-Guerin.

Objective: To detect the effects of Polyporus polysaccharide (PPS), Bacillus Calmette-Guerin (BCG), and their combination on the nuclear factor kappa B (NF-κB) signaling pathway associated-gene expression and investigate the molecular mechanisms of the toxic-reducing effect of PPS in coordination with BCG against bladder cancer.

Methods: After T739 cells were treated with PPS, BCG and their combination, the changes in mRNA and protein expression of inhibitor of kappa B kinase beta (IKKβ), NF-κB subunit p65 (NF-κB p65), intracellular adhesion molecule 1 (ICAM1) and chemokine (C-c motif) ligand 2 (CCL2) in bladder cancer cell line T739 were determined by relative quantitative real-time PCR, Western blot, and flow cytometry (FCM). NF-κB p65 DNA-binding activity in T739 cell was detected by biotinylated probe-ELISA, and NF-κB p65 nuclear expression in T739 cell was observed by immunohistochemistry.

Results: Compared with the T739 control group, the mRNA expression of IKBKB (IKKβ), Rel A (NF-κB p65), ICAM1 and CCL2 in T739 cells treated with BCG were increased obviously (Ratio>2.0), as well as the expression of IKKβ, CCL2 and ICAM1 proteins. Meanwhile, NF-κB p65 DNA-binding activity and NF-κB p65 nuclear expression in T739 cells treated with BCG were up-regulated significantly (P<0.05). Compared with the control, the increased expression in T739 cells were simultaneously down-regulated after PPS treatment, except for ICAM1 protein expression. With cells treated with a combination of BCG and PPS, the expression of genes associated with the NF-κB signaling pathway, such as IKBKB, ICAM1 and CCL2, were all down-regulated compared to the BCG group, as well as Rel A mRNA expression, NF-κB p65 DNA-binding activity and NF-κB p65 nuclear expression.

Conclusions: PPS could inhibit the over-activation of the NF-κB signaling pathway induced by BCG in bladder cancer cells and accordingly attenuate the adverse reactions to BCG therapy.