Jonathan Rockoff¹, Akhil Saji¹, Jonathan Kroop¹, Muhammad Choudhury¹, Sensuke Konno^1,

To seek for a more effective way to treat bladder cancer with the poor outcomes, we have been working on natural products with anticancer activity for a decade. Recently, we came across the bioactive extract of Agrocybe chaxingu mushroom, CHX, which had been shown to have anticancer activity with few side/adverse effects. Accordingly, we then investigated if CHX might have anticancer effect on the relatively less aggressive human bladder cancer 5637 cells (grade 2) in vitro. Cells were treated with varying concentrations of CHX (0-500 μg/ml) for 72 h, and cell viability was determined by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide) assay to assess anticancer effect. To explore the anticancer mechanism of CHX, we also examined induction of oxidative stress (OXS), cell cycle, and apoptosis. We first found a significant (~50%) cell viability reduction in 5637 cells with 350 μg/ml of CHX, indicating its anticancer effect. Lipid peroxidation (LPO) assay revealed the significantly (~2.2-fold) increased oxidative stress (OXS) level as well. CHX also led to a G₁ cell cycle arrest with a ~37% increase in G₁-phase cell number and a ~44% decrease in S-phase cell number, compared to those in controls. This was further confirmed by the up-regulation of two G₁-specific cell cycle regulators, p21^WAF1 and p27^Kip1, with CHX treatment. Consequently, 5637 cells were found to undergo apoptosis, indicated by the down-regulation of anti-apoptotic bcl-2 concomitant with the up-regulation of pro-apoptotic Bax with CHX. In conclusion, CHX has anticancer effect on human bladder cancer 5637 cells, significantly reducing their cell viability. This is presumably attributed to elevated OXS, a G₁ cell cycle arrest, and ultimate apoptosis. Therefore, it is plausible that CHX may offer an alternative therapeutic option for low-grade bladder cancer cases.

bladder cancer, Agrocybe chaxingu, anticancer, oxidative stress, cell cycle arrest, apoptosis