N1-guanyl-1,7-diaminoheptane sensitizes bladder cancer cells to doxorubicin by preventing epithelial-mesenchymal transition through inhibition of eukaryotic translation initiation factor 5A2 activation.
Bottom Line: Drug resistance greatly reduces the efficacy of doxorubicin-based chemotherapy in bladder cancer treatment; however, the underlying mechanisms are poorly understood.It significantly inhibited activity of eIF5A2, suppressed doxorubicin-induced epithelial-mesenchymal transition in BIU-87 cells, and promoted mesenchymal-epithelial transition in J82 and UM-UC-3 cells.Combination therapy with GC7 may enhance the therapeutic efficacy of doxorubicin in bladder cancer by inhibiting eIF5A2 activation and preventing epithelial-mesenchymal transition.
Affiliation: Department of Radiation Oncology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.Show MeSH
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Mentions: Deoxyhypusine synthase is specifically inhibited by GC7 in mammalian cells, which catalyzes the post-translation modifications required to activate eIF5A2. Thus, to ascertain the role of eIF5A2 in doxorubicin-induced EMT, we used RNAi to knockdown eIF5A2 expression in bladder cancer cells. The siRNA-transfected bladder cancer cells were incubated with doxorubicin or doxorubicin plus GC7 for 48 h. The CCK8 assay and EdU incorporation assay revealed that the eIF5A2 siRNA significantly enhanced the cytotoxicity of doxorubicin in bladder cancer cells (Fig. 5, Table 3). Western blotting also revealed the upregulation of E-cadherin and downregulation of vimentin in eIF5A2 siRNA-transfected BIU-87 cells, and the contrary alteration of E-cadherin and vimentin expression in J82 and UM-UC-3 cells treated with doxorubicin for 48 h, compared to doxorubicin-treated cells transfected with the negative control siRNA (Fig. 6). We also preliminarily investigated the relationship between eIF5A2 and Twist-1 in bladder cancer cells. Knockdown of eIF5A2 decreased expression of Twist-1 in bladder cancer cells in the presence of doxorubicin (Fig. 6). Analogously, inhibition of activation of eIF5A2 by GC7 also showed similar effects (Fig. 3b). These results indicated that eIF5A2 is an important factor in the pathway involved in EMT regulations of bladder cancer cells. Twist-1, the E-cadherin repressor, may serve as an important downstream target of the eIF5A2 pathway in bladder cancer cells.
Affiliation: Department of Radiation Oncology, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.