Topically applied Melaleuca alternifolia (tea tree) oil causes direct anti-cancer cytotoxicity in subcutaneous tumour bearing mice

Ireland, D.J., Greay, S.J., Hooper, C.M., Kissick, H.T., Filion, P., Riley, T.V. and Beilharz, M.W. (2012) Topically applied Melaleuca alternifolia (tea tree) oil causes direct anti-cancer cytotoxicity in subcutaneous tumour bearing mice. Journal of Dermatological Science, 67 (2). pp. 120-129.

Abstract

Background: Melaleuca alternifolia (tea tree) oil (TTO) applied topically in a dilute (10%) dimethyl sulphoxide (DMSO) formulation exerts a rapid anti-cancer effect after a short treatment protocol. Tumour clearance is associated with skin irritation mediated by neutrophils which quickly and completely resolves upon treatment cessation. Objective: To examine the mechanism of action underlying the anti-cancer activity of TTO. Methods: Immune cell changes in subcutaneous tumour bearing mice in response to topically applied TTO treatments were assessed by flow cytometry and immunohistochemistry. Direct cytotoxicity of TTO on tumour cells . in vivo was assessed by transmission electron microscopy. Results: Neutrophils accumulate in the skin following topical 10% TTO/DMSO treatment but are not required for tumour clearance as neutrophil depletion did not abrogate the anti-cancer effect. Topically applied 10% TTO/DMSO, but not neat TTO, induces an accumulation and activation of dendritic cells and an accumulation of T cells. Although topical application of 10% TTO/DMSO appears to activate an immune response, anti-tumour efficacy is mediated by a direct effect on tumour cells . in vivo. The direct cytotoxicity of TTO . in vivo appears to be associated with TTO penetration. Conclusion: Future studies should focus on enhancing the direct cytotoxicity of TTO by increasing penetration through skin to achieve a higher . in situ terpene concentration. This coupled with boosting a more specific anti-tumour immune response will likely result in long term clearance of tumours.

Item Type:	Journal Article
Publisher:	Elsevier Ireland Ltd
Copyright:	© 2012 Japanese Society for Investigative Dermatology.
URI:	http://researchrepository.murdoch.edu.au/id/eprint/34779

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