Biological evaluation of Pheroid® formulated plant bio-actives against oestrogen active breast cancer

Abstract

Cancer is a serious public health complication worldwide. Annually 115 000 South Africans are diagnosed with cancer, where men have a lifetime risk of 1:7 and women a lifetime risk of 1:8. The most frequently diagnosed and common cause of cancer-associated deaths in women is breast cancer, of which the predominant form is oestrogen active breast cancer. For these cancers, antineoplastic drugs that specifically inhibit oestrogen binding -- such as tamoxifen -- are frequently used as prophylactic and chemo-therapy treatments. A frequent complication of these treatments are severe side effects, as well as drug resistance. Thus, there is a great need to explore alternative treatment options, including adjuvant or supplementary treatments. There are many known plant bio-active compounds and extracts that have shown potential as adjuvant anticancer treatments. The limitation of many of the plant-based remedies is their poor physico-chemical and biopharmaceutical properties. The research aim of this study was to evaluate the potential anticancer activity of turmeric (Curcuma longa) and ginger (Zingiber officinale) extracts formulated in a Pheroid® drug delivery system. This was achieved using in vitro evaluations on the oestrogen active human breast cancer cell line (MCF-7), and an in vivo study using a MCF-7 tumour bearing rodent model. Unformulated concentrations of both extracts were used to determine potencies, which were incorporated into the formulations. The formulations were characterised in terms of particle size and electro-kinetic stability. The anti-proliferation effects of these formulations were gauged against the cancer line, while determining the cytotoxicity in a non-cancer cell line -- to prove anticancer effects. The potential anticancer effects were supported by calculating the cancer selectivity index (CSI). Additionally, the ability of the formulations to induce apoptosis was measured using flow cytometry. To establish whether the induced apoptosis was due to oestrogen inhibition, the T47D-KBluc reporter gene bioassay was used. Based on the results of the formulation characterisation and in vitro assays there were multiple candidates as adjuvant treatments. The most suitable candidate as the final formulation was selected specifically based on the CSI and apoptotic induction. The anticancer effects in vivo was to be determined using MCF-7 xenografts. The effects of the final formulation treatment alone, and as adjuvant to a known anticancer drug (cisplatin) would have been assessed over a period of 15 days, compared to a control. However, after the inoculation of the animals no tumours formed after 21 days. This led to this section of the study to be prematurely concluded. Even so, the results from the in vitro study have shown that the Pheroid® formulated extracts are promising anticancer agents against oestrogen active breast cancer.