Synergistic antitumor effects of combined treatment with HSP90 inhibitor and PI3K/mTOR dual inhibitor in cisplatin-resistant human bladder cancer cells

Hyung Joon Kim, Mi Kyung Gong, Cheol Yong Yoon, Jaeku Kang, Mijin Yun, Nam Hoon Cho, Sun Young Rha, Young Deuk Choi

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: The current study aimed to investigate the synergistic antitumor effect of combined treatment with 17-DMAG (HSP90 inhibitor) and NVP-BEZ235 (PI3K/mTOR dual inhibitor) on cisplatin-resistant human bladder cancer cells. Materials and Methods: Human bladder cancer cells exhibiting cisplatin resistance (T24R2) were exposed to escalating doses of 17-DMAG (2.5-20 nM) with or without NVP-BEZ236 (0.5-4 µM) in combination with cisplatin. Antitumor effects were assessed by CCK-8 analysis. Based on the dose-response study, synergistic interactions between the two regimens were evaluated using clonogenic assay and combination index values. Flow cytometry and Western blot were conducted to analyze mechanisms of synergism. Results: Dose- and time-dependent antitumor effects for 17-DMAG were observed in both cisplatin-sensitive (T24) and cisplatin- resistant cells (T24R2). The antitumor effect of NVP-BEZ235, however, was found to be self-limiting. The combination of 17- DMAG and NVP-BEZ235 in a 1:200 fixed ratio showed a significant antitumor effect in cisplatin-resistant bladder cancer cells over a wide dose range, and clonogenic assay showed compatible results with synergy tests. Three-dimensional analysis revealed strong synergy between the two drugs with a synergy volume of 201.84 µM/mL2%. The combination therapy resulted in G1-phase cell cycle arrest and caspase-dependent apoptosis confirmed by the Western blot. Conclusion: HSP90 inhibitor monotherapy and in combination with the PI3K/mTOR survival pathway inhibitor NVP-BEZ235 shows a synergistic antitumor effect in cisplatin-resistant bladder cancers, eliciting cell cycle arrest at the G1 phase and induction of caspase-dependent apoptotic pathway.

Original languageEnglish
Pages (from-to)587-596
Number of pages10
JournalYonsei medical journal
Volume61
Issue number7
DOIs
Publication statusPublished - 2020

Bibliographical note

Funding Information:
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2012R1A1A2043 965).

Publisher Copyright:
© Yonsei University College of Medicine 2020.

All Science Journal Classification (ASJC) codes

  • Medicine(all)

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