Lignans' prostate cancer protection gets study boost
prostate cancer by acting at the genetic level, suggests new
research that deepens our understanding of the topic.
An in vitro study, led by Mark McCann from AgResearch Grasslands in New Zealand, reports that enterolactone beneficially regulated several key genes, producing important effects on programmed cell death of prostate cancer cells. McCann, in collaboration with researchers from the University of Ulster, Belfast City Hospital, Cork Institute of Technology, and the University of Reading, reports the data in the journal Molecular Nutrition & Food Research. Plant lignans come from sources such as flax seed, whole grain cereals, berries, vegetables and fruits. Several hundred individual lignans have been discovered but the main research has focussed on lignans from flaxseed (Linum usitatissimum), with a small but growing number of studies on lignans from Norwegian spruce bark (Picea abies). When these lignans are metabolised by microflora in the human gut they form the mammalian lignan enterolactone (ENL), amongst other things. For the new study, McCann and co-workers tested the effects of ENL on the LNCaP human prostate cancer cell line. Using a concentration that was not considered toxic to the cells (non-cytotoxic) the researchers found that the density of the prostate tumour was reduced by 57.5 per cent, the metabolic activity of the tumour cells by 55 per cent, and cut secretion of prostate specific antigen (PSA) by 48.5 per cent. PSA is a marker commonly used to screen for prostate cancer and for tracking the disease after its diagnosis. Moreover, in mammalian lignan was found to induce apoptosis, or programmed cell death, of the cancer cells 8.33-fold compared to cancer cells not exposed to the lignan. Beneficial regulation of key genes, including MCMs and CDKs, which play key roles in cell and DNA replication, was also noted by the researchers. "The data suggest that the anti-proliferative activity of ENL is a consequence of altered expression of cell cycle associated genes and provides novel molecular evidence for the anti-proliferative properties of a pure lignan in prostate cancer," concluded the researchers. Over half a million news cases of prostate cancer are diagnosed every year world wide, and the cancer is the direct cause of over 200,000 deaths. More worryingly, the incidence of the disease is increasing with a rise of 1.7 per cent over 15 years. Benefits for ladies, too Lignans are well-known phytoestrogens - active substances derived from plants that have a weak oestrogen-like action, and have been linked before to breast health, as well as offering benefits for postmenopausal women. Last year, French researchers reported that a high intake of lignans from the diet could reduce the risk of breast cancer by almost 30 per cent. Results of this prospective study were published in the Journal of the National Cancer Institute. Source: Molecular Nutrition & Food Research Published online ahead of print, 8 April 2008, doi: 10.1002/mnfr.200700052 "Enterolactone restricts the proliferation of the LNCaP human prostate cancer cell line in vitro" Authors: M.J. McCann, C.I.R. Gill, T. Linton, D. Berrar, H. McGlynn, I.R. Rowland
