Zoledronic acid inhibits the pentose phosphate pathway through attenuating the Ras-TAp73-G6PD axis in bladder cancer cells.

Zoledronic acid (ZA) is the current standard of care for the therapy of patients with bone metastasis or osteoporosis. ZA inhibits the prenylation of small guanosine-5'- triphosphate (GTP)-binding proteins, such as Ras, and thus inhibit Ras signaling. The present study demonstrated that ZA inhibited cell proliferation and the pentose phosphate pathway (PPP) in bladder cancer cells. In addition, the expression of glucose-6-phosphate dehydrogenase (G6PD, the rate-limiting enzyme of the PPP) was found to be inhibited by ZA. Furthermore, the stability of TAp73, which activates the expression G6PD was decreased in zoledronic acid treated cells. Decreased levels of Ras-GTP and phosphorylated-extracellular signal-regulated kinase 1/2 were also observed following treatment with ZA. This may be due to the fact that activated Ras was reported to stabilize TAp73 inducing its accumulation. The inhibition of Ras activity by PT inhibitor II also significantly reduced the levels of TAp73 and G6PD and the PPP flux. Moreover, knockdown of TAp73, attenuated the PPP flux and eliminated the affection of ZA on the PPP flux. In conclusion, it was proposed that ZA can inhibit stability of TAp73 and attenuate the PPP via blocking Ras signaling in bladder cancer cells. [ABSTRACT FROM AUTHOR]