Strategies to evaluate the clinical potential of botanical agents for breast cancer

Botanical therapies are commonly used worldwide for the treatment of cancer, yet laboratory and clinical evaluations have not been systemically conducted. We assessed 69 botanical agents based on traditional Chinese Medicine practice patterns for breast cancer. Aqueous extracts from these materials, prepared as a tea in the traditional manner, were evaluated in vitro on four human breast cancer cell lines (SKBR3, MCF7, MDA-MB231, and BT474) and one murine breast cancer cell line (MCNeuA) using the anti-proliferative crystal violet assay. Nineteen of the 71 extracts (27%), tested at a 1:10 dilution, demonstrated >50% growth inhibition on three or more of the five cell lines. Sixteen of the 69 extracts (23%) exhibited pronounced effects (>75% growth inhibition) on at least one of the five cell lines. Dose/response curves were obtained for several of the most potent extracts and demonstrated IC50 values ranging from <10 μg/ml to >1 mg/ml. The 12 most active extracts also demonstrated growth inhibitory activity on other cancer cell types (lung, prostate, pancreatic, and lymphoid). DNA flow cytometry analysis on whole herbal extracts suggests multiple and complex actions, with some extracts resulting in G2/M arrest. Six of 7 extracts tested induced high molecular weight DNA fragmentation while one caused low molecular weight fragment. ion. Multiplex RT-PCR analysis for apoptosis-related gene expression suggested no alterations in the expression of caspase-3, p53, or bcl-2 and related genes (bcl-xL and Bax). For one extract, Vaccaria Segatalis, fractionation using solvent partitioning as well as sizing, anion exchange and high performance liquid chromatography (HPLC) columns has yielded very high specific antiproliferative activity (> 10,000 fold), suggesting that most of this activity resides within a few candidate compounds. Mass spectroscopy (MS) of the active fraction shows a few low molecular sized peaks and efforts are underway to characterize these single compounds. We are commencing clinical trials with selected aqueous herbal extracts with antiproliferative activity (e.g. Ban Zhi Lian) and also continuing efforts to isolate novel molecules with activity against human breast cancer from other active botanical extract fractions.