No abstract

Epidemiological evidence together with preclinical data from animal and in vitro studies strongly support a correlation between soy isoflavone consumption and protection towards breast and prostate cancers. The biological processes modulated by isoflavones, and especially by genistein, have been extensively studied, yet without leading to a clear understanding of the cellular and molecular mechanisms of action involved. This review discusses the existing gaps in our knowledge and evaluates the potential of the new nutrigenomic approaches to improve the study of the molecular effects of isoflavones. Several issues need to be taken into account for the proper interpretation of the results already published for isoflavones. Too often knowledge on isoflavone bioavailability is not taken into account; supra-physiological doses are frequently used. Characterization of the individual variability as defined by the gut microflora composition and gene polymorphisms may also help to explain the discrepancies observed so far in the clinical studies. Finally, the complex inter-relations existing between tissues and cell types as well as cross-talks between metabolic and signalling pathways have been insufficiently considered. By appraising critically the abundant literature with these considerations in mind, the mechanisms of action that are the more likely to play a role in the preventive effects of isoflavones towards breast and prostate cancers are reviewed. Furthermore, the new perspectives opened by the use of genetic, transcriptomic, proteomic and metabolomic approaches are highlighted.

Recent data support the notion that a group of key transcriptional regulators involved in tumorigenesis, including MYC, p53, E2F1, and BMI1, share an intriguing capacity to simultaneously regulate metabolism and cell cycle. Here, we show that another factor, the multifunctional protein E4F1, directly controls genes involved in mitochondria functions and cell-cycle checkpoints, including Chek1, a major component of the DNA damage response. Coordination of these cellular functions by E4F1 appears essential for the survival of p53-deficient transformed cells. Acute inactivation of E4F1 in these cells results in CHK1-dependent checkpoint deficiency and multiple mitochondrial dysfunctions that lead to increased ROS production, energy stress, and inhibition of de novo pyrimidine synthesis. This deadly cocktail leads to the accumulation of uncompensated oxidative damage to proteins and extensive DNA damage, ending in cell death. This supports the rationale of therapeutic strategies simultaneously targeting mitochondria and CHK1 for selective killing of p53-deficient cancer cells.

We selected edible and inedible mushrooms growing in the Mediterranean area of France to screen their biological activity: Caloboletus calopus, Rubroboletus lupinus, R. pulchrotinctus, R. satanas, Gyroporus castaneus, Suillus luteus, and Omphalotus olearius. Mushrooms were sequentially extracted using cyclohexane, chloroform, ethanol, and water. The antiproliferative activity against the HCT116 colon adenocarcinoma cell line and the antioxidant properties (DPPH radical scavenging assay, Folin-Ciocalteu assay, and oxygen radical absorbance capacity) of the Boletales extracts were evaluated and compared. Among the 28 mushroom extracts evaluated, 11 presented antiproliferative activity against HCT116 cells. These activities were not linked to antioxidant capacity. Among the antioxidant extracts, most were aqueous extracts in the oxygen radical absorbance capacity assay, whereas the highest values on the Folin-Ciocalteu and DPPH assays were noted for chloroform, ethanol, or aqueous extracts, depending on the mushroom species. Further studies are necessary to identify bioactive compounds and to valorize the mushrooms-for edible species, directly as health foods, or, for inedible mushrooms, as ingredients in the pharmaceutical and food industries.