Modulation of chemotherapeutic drug sensitivity by frankincense.

The development of chemoresistance is a serious problem applicable to many types of cancer; ovarian cancer is a particular tumour type that can show intrinsic and acquired resistance to first-line chemotherapy. Second-line chemotherapy is used to treat recurrent ovarian cancer, e.g. liposomal doxorubicin (Jayson et al, 2014). A number of dose dependent side effects are reported from prolonged and repeated exposure to liposomal doxorubicin (Iwamoto, 2013). Reduction of the required dose for doxorubicin treatment using another agent that could also potentiate doxorubicin anti-cancer activity could be therapeutically valuable. Frankincense (from Boswellia sp.) has been used in traditional medicine for centuries primarily to treat diseases with an inflammatory aetiology. Bioactive components unique to Boswellia sp. (pentacyclic triterpenes in particular boswellic acids) responsible for many of the therapeutic actions of frankincense have been investigated more recently in the context of anticancer activity. Some reports show that 3-O-acetyl-11-keto-β-boswellic acid (AKBA) can modulate chemotherapeutic drug toxicity, although this has not been well explored. The identification of individual components in frankincense that can modify the anti-cancer actions of existing chemotherapeutic drugs or otherwise yield unexpected anticancer effects would be useful. This work examines the potential utility and mechanisms of action of AKBA for modifying cancer chemotherapeutic drug activity, using ovarian cancer cells as a model. Preliminary data (Fig. 1) show that a minimally cytotoxic dose of AKBA in combination with doxorubicin significantly (p < 0.01) enhances the EC50 of doxorubicin on A2780 and A280cis (cisplatin resistant) ovarian cancer cells. Work is funded by The Saudi Arabian Cultural Bureau: PhD scholarship awarded to IAH.

Fig. 1: Cytotoxicity of doxorubicin on ovarian cancer A2780 cells treated with and without AKBA. Cells were treated with doxorubicin alone (squares) or simultaneously with 26µM AKBA and doxorubicin (circles) for 24 hours at 37 °C, 5% v/v C0₂. Viability assessed using the MTT assay. The mean ± SEM for n = 3 independent experiments shown.

Iwamoto, T, Biology Pharmacy Bulletin, 2013, 36, 715 – 718. doi: 10.1248/bpb.b12 – 01102.

Jayson, G. C, Kohn, E. C, Kitchener, H. C. and Ledermann, J. A, The Lancet. Elsevier Ltd, 2014, 384(9951), 1376 – 1388. doi: 10.1016/S0140 – 6736(13)62146 – 7.