Cactus pear: a natural product in cancer chemoprevention

BACKGROUND: Cancer chemoprevention is a new approach in cancer prevention, in which chemical agents are used to prevent cancer in normal and/or high-risk populations. Although chemoprevention has shown promise in some epithelial cancers, currently available preventive agents are limited and the agents are costly, generally with side effects. Natural products, such as grape seed, green tea, and certain herbs have demonstrated anti-cancer effects. To find a natural product that can be used in chemoprevention of cancer, we tested Arizona cactus fruit solution, the aqueous extracts of cactus pear, for its anti-cancer effects in cultured cells and in an animal model. METHOD: Aqueous extracts of cactus pear were used to treat immortalized ovarian and cervical epithelial cells, as well as ovarian, cervical, and bladder cancer cells. Aqueous extracts of cactus pear were used at six concentrations (0, 0.5, 1, 5, 10 or 25%) to treat cells for 1, 3, or 5 days. Growth inhibition, apoptosis induction, and cell cycle changes were analyzed in the cultured cells; the suppression of tumor growth in nude mice was evaluated and compared with the effect of a synthetic retinoid N-(4-hydroxyphernyl) retinamide (4-HPR), which is currently used as a chemoprevention agent. Immunohistochemistry staining of tissue samples from animal tumors was performed to examine the gene expression. RESULTS: Cells exposed to cactus pear extracts had a significant increase in apoptosis and growth inhibition in both immortalized epithelial cells and cancer cells in a dose- and time-dependent manner. It also affected cell cycle of cancer cells by increasing G1 and decreasing G2 and S phases. Both 4-HPR and cactus pear extracts significantly suppressed tumor growth in nude mice, increased annexin IV expression, and decreased VEGF expression. CONCLUSION: Arizona cactus pear extracts effectively inhibited cell growth in several different immortalized and cancer cell cultures, suppressed tumor growth in nude mice, and modulated expression of tumor-related genes. These effects were comparable with those caused by a synthetic retinoid currently used in chemoprevention trials. The mechanism of the anti-cancer effects of cactus pear extracts needs to be further studied

Loss of c-Met Disrupts Gene Expression Program Required for G2/M Progression during Liver Regeneration in Mice

conditional knockout mice to determine the effects of c-Met dysfunction in hepatocytes on kinetics of liver regeneration. primary hepatocytes and partially restored expression levels of mitotic cell cycle regulators albeit to a lesser degree as compared to control cultures.In conclusion, our results assign a novel non-redundant function for HGF/c-Met signaling in regulation of G2/M gene expression program via maintaining a persistent Erk1/2 activation throughout liver regeneration

Re-evaluation of the cold face test in humans

The cold face test has been found to be a simple clinical test to elicit the diving reflex, which assesses function of the sympathetic and parasympathetic nerve systems at the same time. However, there is no consensus about how the test should be performed without confounding the results by eliciting other reflexes, such as the oculocardiac reflex. The object of this study was to compare and standardize methods for per forming the cold face test. Reproducibility of results was assessed. Groups of 6 to 11 subjects participated in each protocol. To act as a cold stimulus a bag filled with iced-water and having a wet surface was used. The effects of allowing breathing to continue, of different masses of the bag, and of avoiding ocular pressure by wearing diving goggles were investigated. Blood pressure and heart rate were measured beat to beat using an automatic blood pressure measuring device. The cold stimulus used in this study was too small to elicit the oculocardiac reflex: wearing diving goggles and different masses of the bag had no influence on the response. The prevention of breathing, however, tended to enhance the fall ill heart rate during the cold stress. Reproducibility was highest when the subjects were habituated to the intensity of the stimulus. We recommend practising the test method in advance and performing it in a setting where the subject is unable to breathe