413P - Sensitization of melanoma cells to nitrosourea treatment by ROS-inducing IKKβ inhibitor

Date 18 December 2016
Event ESMO Asia 2016 Congress
Session Poster lunch
Topics Cytotoxic agents
Cancer biology
Skin cancers
Presenter Anfernee Kai-Wing Tse
Citation Annals of Oncology (2016) 27 (suppl_9): ix126-ix129. 10.1093/annonc/mdw589
Authors A.K. Tse, Y.J. Chen, X.Q. Fu, T. Su, T. Li, H. Guo, P.L. Zhu, H.Y. Kwan, B.C.Y. Cheng, H.H. Cao, S.K.W. Lee, W.F. Fong, Z.L. Yu
  • School Of Chinese Medicine, Hong Kong Baptist University, N/A - Hong Kong/HK

Abstract

Background

Nitrosoureas such as fotemustine and carmustine have been demonstrated to exert significant antitumor effects in malignant melanoma. However, treatment with nitrosoureas caused severe systemic side effects and therefore hamper its clinical use. In light of this, identification of sensitizing agents capable of increasing cytotoxic effects by nitrosoureas is important to facilitate alkylating agents-based melanoma therapy. Here we demonstrate that ROS-inducing IKKβ inhibitor sensitizes melanoma cells to nitrosoureas and propose a mechanism that involves the modulation of DNA crosslink and DNA damage signaling.

Methods

Cytotoxicity of nitrosoureas and/or ROS-inducing IKKβ inhibitor was determined by standard cell growth assay. Apoptosis and cell cycle distribution were detected by flow cytometry. DNA crosslink efficiency was determined by in vitro DNA crosslink assay and modified alkaline comet assay. DNA damage signaling was detected by Western Blot analysis of p-H2AX. The in vivo effects of nitrosourea/ROS-inducing IKKβ inhibitor combination were assessed in melanoma xenografts-bearing mice.

Results

ROS-inducing IKKβ inhibitor significantly sensitized various melanoma cells, but not normal fibroblasts, to nitrosourea-mediated cell death. The combination of ROS-inducing IKKβ inhibitor and nitrosourea caused cell cycle arrest, apoptosis and enhanced DNA damage responses. ROS induction increased DNA crosslink levels triggered by nitrosoureas and IKKβ inhibition increased DNA damage signals and sensitizes nitrosourea-induced cell death. Moreover, we confirm that ROS-inducing IKKβ inhibitor cooperates with nitrosourea to reduce tumor size and malignancy in vivo.

Conclusions

Overall, our results demonstrate a new direction in nitrosourea treatment, and reveal that the combination of ROS-inducing IKKβ inhibitor with nitrosoureas can be potentially used for melanoma treatment.

Clinical trial indentification

Legal entity responsible for the study

Hong Kong Baptist University

Funding

HMRF-Food and Health Bureau of Hong Kong; FRG-Hong Kong Baptist University; GRF-Research Grants Council of Hong Kong

Disclosure

All authors have declared no conflicts of interest.