Ailanthone inhibits cell growth and migration of cisplatin resistant bladder cancer cells through down-regulation of Nrf2, YAP, and c-Myc expression.

Ailanthone (Aila) is a natural active compound isolated from the Ailanthus altissima, which has been shown to possess an "in vitro" growth-inhibitory effect against several cancer cell lines. Advanced bladder cancer is a common disease characterized by a frequent onset of resistance to cisplatin-based therapy. The cisplatin (CDDP) resistance is accompanied by an increase in Nrf2 protein expression which contributes to conferring resistance. Recently, we demonstrated a cross-talk between Nrf2 and YAP. YAP has also been demonstrated to play an important role in chemoresistance of bladder cancer. We analyzed the antitumor effect of Aila in sensitive and CDDP-resistant bladder cancer cells and the molecular mechanisms involved in Aila activity. Sensitive and CDDP-resistant 253J B-V and 253J bladder cancer cells, intrinsically CDDP-resistant T24 bladder cancer cells and HK-2 human renal cortex cells were used. Cells were treated with diverse concentrations of Aila and proliferation, cell cycle, apoptosis and gene expressions were determined. Aila toxicity and proliferation were determined by MTT and colony forming methods, respectively. Cell cycle was determined by cytofluorimetric analysis through PI staining method. Apoptosis was detected using Annexin V and PI double staining followed by quantitative flow cytometry. Expressions of Nrf2, Yap, c-Myc, and house-keeping genes were determined by western blot with specific antibodies. Cell migration was detected by wound healing and Boyden chamber analysis. Aila inhibited the growth of sensitive and CDDP-resistant bladder cancer cells with the same effectiveness. On the contrary, the growth of HK-2 cells was only slightly reduced by Aila. Cell cycle analysis revealed an accumulation of Aila-treated bladder cancer cells in the G0/G1 phase. Interestingly, Aila strongly reduced Nrf2 expression in these cell lines. Moreover, Aila significantly reduced YAP, and c-Myc protein expression. The random and the oriented migration of bladder cancer cells were strongly inhibited by Aila treatment, in particular in CDDP-resistant cells. Aila inhibited proliferation and invasiveness of bladder cancer cells. Its high effectiveness in CDDP resistant cells could be related to the inhibition of Nrf2, YAP, and c-Myc expressions. Aila could represent a new tool to treating CDDP-resistant bladder cancers.