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

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• 作者：Demelza J. Irel ; Sara J. Greay ; Cornelia M. Hooper ; Haydn T. Kissick ; Pierre Filion ; Thomas V. Riley ; Manfred W. Beilharz
• 关键词：Tea tree oil ; Cancer ; Immune response ; Cytotoxicity ; Penetration
• 刊名：Journal of Dermatological Science
• 出版年：2012
• 出版时间：August, 2012
• 年：2012
• 卷：67
• 期：2
• 页码：120-129
• 全文大小：2529 K

文摘

Background

m>Melaleuca alternifoliam> (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 m>in vivom> 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 m>in vivom>. The direct cytotoxicity of TTO m>in vivom> 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 m>in situm> terpene concentration. This coupled with boosting a more specific anti-tumour immune response will likely result in long term clearance of tumours.