Leflunomide Inhibits Proliferation and Induces Apoptosis via Suppressing Autophagy and PI3K/Akt Signaling Pathway in Human Bladder Cancer Cells

Abstract

Introduction

Bladder cancer is a lethal human malignancy. Currently, treatment for bladder cancer is limited. The anti-tumor effects of leflunomide have attracted much more concern in multiple human cancers.

Materials and Methods

This study evaluated the anti-tumor effects of leflunomide on cell viability, colony formation, apoptosis, and cell cycle in two human bladder carcinoma cell lines, 5637 and T24. Meanwhile, the underlying mechanism including PI3K/Akt signaling pathway and autophagy modulation was also identified.

Results

Leflunomide markedly inhibited the growth of both bladder cancer cell lines and induced apoptosis and cell cycle arrest in S phase. The phosphorylation levels of Akt and P70S6K in both cell lines were significantly down-regulated with leflunomide treatment. Furthermore, the deceased formation of autophagosomes and the accumulation of LC3II and P62 suggested the blockade of autophagy by leflunomide. Modulation of autophagy with rapamycin and chloroquine markedly attenuated and enhanced the cytostatic effects of leflunomide, respectively.

Conclusion

Leflunomide significantly reduced the cell viability of bladder cancer cells via inducing apoptosis and cell cycle arrest and suppressing the PI3K/Akt signaling pathway. In addition, the blockade of autophagy was observed, and autophagy inhibition enhanced leflunomide-mediating anti-tumor effects. Our data presented here offer novel ideas for comprehensive therapeutic regimes on bladder cancer.

Keywords:

• leflunomide
• autophagy
• PI3K/Akt pathway
• anti-tumor
• bladder cancer

Disclosure

The abstract of this paper was presented at the ESMO 2019 Congress as a poster presentation. The poster’s abstract was published in ‘Poster Abstracts’ in Annals of Oncology: [https://www.annalsofoncology.org/article/S0923-7534(19)58295-3/pdf; https://www.researchgate.net/publication/336193248_61PAutophagy_inhibition_enhances_leflunomide-induced_cytotoxicity_in_human_bladder_cancer_cells]. The authors declare no conflicts of interest in this work.