Laboratory Testing of Chinese Herbs Used for Breast Cancer

Institution: University of California, San Francisco
Investigator(s): Debasish Tripathy, M.D. -
Award Cycle: 1999 (Cycle V) Grant #: 5JB-0068 Award: $85,754
Award Type: IDEAS II
Research Priorities
Detection, Prognosis and Treatment>Innovative Treatment Modalities: search for a cure

Initial Award Abstract (1999)
Traditional Chinese Medicine (TCM) is a treatment modality that has been used for centuries to cure cancer, prolong life, increase the quality of life for cancer patients, and more recently to ameliorate the side effects of Western therapies. The lack of evidence-based clinical trials coupled with the proliferation of anecdotal and case report studies of TCM make it an important treatment modality for further study. TCM use in the Bay Area is widespread and frequently used by our patient population, thus it can be studied using standard research models at our institution. There is a high degree of conformity among TCM practitioners in terms of both diagnoses and treatments due to the extensive historically-based documentation of TCM treatment modalities. We propose to obtain laboratory data on herbs commonly used for breast cancer in order to prioritize herbal formulae for future Phase I/II clinical trials.

We plan to perform laboratory analysis of a number of botanical agents that have been traditionally prescribed by TCM practitioners for metastatic breast cancer (MBC) patients. We have pilot data on a few herbal compounds that show anti-tumor activity, and we will use a similar expanded methodology to screen approximately 50 more botanical agents. We will test for the ability of these compounds to cause breast cancer cells to divide using an MTT assay, to commit suicide (apoptosis) using APO-BRDU and to grow using clonogenic assays. The compounds will be tested for their effects using both pulsed and continuous exposure. For herbal extracts with activity, the responsible components will be identified using salt exchange column and high performance liquid chromatography fractions. Promising herbs or combinations could then be entered into Phase I/II clinical trials using tumor response endpoints.

Final Report (2001)
Using an ethnopharmacological approach, seventy one substances that are used in traditional Chinese medicine for the treatment of cancer were obtained and evaluated for their effects on the growth of breast cancer cell lines in culture. Each herb was boiled in water and the resulting "tea" was tested for growth inhibitory activity on four human breast cancer cell lines (SK BR 3, MCF7, MDA MB 23 1, and BT 474) and one mouse breast cancer cell line (MCNeuA). 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 71 extracts (23%) exhibited pronounced effects (>75% growth inhibition) on at least one of the five cell lines.

We determined the dosage range for cell growth inhibition obtained for several of the most potent extracts and demonstrated ID50 values (the median effective doses) ranging from less than 10g/ml to greater than 1 mg/ml. Seven of these active extracts were also evaluated with respect to their ability to cause cell death (apoptosis). Six induced cell death as evidenced by high molecular weight DNA fragmentation and one of these produced low molecular weight DNA fragments as well. Cell cycle analysis of two herbal extracts demonstrated that they caused the cells to stop dividing (cell cycle arrest in G2/M), as well as some to begin dying (as indicated by a sub G0/G1 population). We have also performed bioassay guided fractionation of two of the active herbs, to begin to identify their active constituents. One of these we have purified to a single major peak (and a few minor peaks) on HPLC. Future studies with these crude aqueous extracts will improve our understanding of how these herbs may be acting in cancer patients and may also lead to the isolation of novel active anti-tumor compounds.