Inhibition of established subcutaneous murine tumour growth with topical Melaleuca alternifolia (tea tree) oil

Abstract

TTO combined with an effective carrier significantly inhibited the growth of aggressive, subcutaneous, chemo-resistant tumours in immunocompetent mice. Taken together, these findings highlight the potential of topical TTO as an alternative topical antitumour treatment.

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

“…Ltd., Chinderah, NSW (Batch A352) [2]. A 10% solution of TTO was made by dissolving TTO in DMSO Hybri-max (Sigma Chemical Co., St Louis, MO).…”

“…Mice with shaved flanks and established tumours measuring 9 mm 2 (approximately 12-14 days post tumour inoculation) were treated topically with either 10% TTO/DMSO (50 ml), neat TTO (5 ml: an amount equivalent to that found in 10% TTO/DMSO), or vehicle control (50 ml: 10% H 2 O/DMSO) applied by pipetting the required volume onto the tumour and surrounding skin and gentle rubbing [2]. Treatments were applied once daily (at the same time each day) for 4 consecutive days.…”

“…All cells were maintained at 37 8C in 5% CO 2 in 75 cm 2 or 225 cm 2 tissue culture flasks in supplemented RPMI-1640 media and subcultured as previously described [2,13].…”

“…More recently, TTO and some of its components have been examined for anti-tumour activity [7][8][9][10]. When applied topically in a specific formulation to fully immune-competent, subcutaneous, tumour-bearing mice, TTO showed in vivo anti-tumour activity [2]. Four, daily, topical treatments of 10% TTO/DMSO caused subcutaneous AE17 mesotheliomas in mice to regress for a period of 10 days and significantly retarded the growth of subcutaneous B16-F10 melanomas.…”

“…Preclinical and clinical studies of plant derived terpene agents, including ingenol mebutate derived fromthesap of Euphorbia peplus [1] andMelaleuca alternifolia (teatree) oil [2], have demonstrated the potential for these topical chemotherapies to exert a rapid anti-cancer effect after a relatively short treatment protocol. Long treatment regimes, incomplete clearance rates, poor cosmetic outcomes and systemic toxicity have unfortunately limited patient satisfaction with currently approved topical chemotherapeutics such as imiquimod and 5-fluorouracil [3,4].…”