An investigation of the effects of selected Chinese herbal remedies on cancer cells 'in vitro'
Chinese herbal remedies (CHRs) are commonly prescribed for the treatment of cancer, however their use is often based on the belief systems of traditional Chinese medicine (TCM), and there is relatively little information regarding their efficacy or biological action. Thus, the aim of this investigation was to select a range of CHRs with some suggestion of tumour modulatory activity, and to devise and implement a strategy with which to investigate their direct toxicity to cancer cells, in an attempt to elucidate their potential efficacy and mode of action. The CHRs ‘OldenIandia diffusa’ (OD), Long Dan Xie Gan Wan (LD), ‘Polygonum multiflorum’ (PM) and ‘Polyporus umbellatus’ (PU) were selected for this investigation, and their direct cytotoxic potential against cancer cells examined using an ‘in vitro’ cell-based system. Initially, water and ethanol extracts of each CHR were made and their toxicity evaluated against a range of cancer cell lines (HL60, HT29, HCT-8, HeLa and CHO). The results of this study suggested that water extracts of OD, LD and PM, but not PU, were significantly toxic to a range of cancer cell types. Further investigation (using the HL60 and HT29 cell lines) suggested that OD and LD induced apoptosis in cancer cell lines ‘in vitro’ through activation of the intrinsic pro-apoptotic signalling pathway (characterised by activation of caspase 9), possibly through the induction of genotoxic damage, and that this activity was related to the combined actions of a number of cytotoxic compounds, and not to a single constituent. Furthermore, OD and LD were found to be less toxic to cultured primary blood lymphocytes (PBLs), thus further suggesting that there may be some scientific basis for their use in the treatment of cancer. Further investigation into the cytotoxic action of water extracts of PM revealed that it was inducing necrosis in cancer cell lines and not apoptosis, thus suggesting that PM does not possess anticancer activity. Overall, the results of this investigation suggest that OD and LD may be a source of novel chemotherapeutic agents, and that there may be some scientific basis for their traditional use in the treatment of cancer.