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A signalling pathway that influences how sensitive cancer cells are to the beneficial effects of dietary restriction is described in this week's Nature. Dietary restriction - eating less calories while maintaining essential vitamins and minerals - can extend lifespan, and reduce cancer incidence and growth. But some types of cancer cell are more sensitive to the anti-growth effects of dietary restriction than others, Nada Kalaany and David Sabatini report. The effect hinges on the activity of the phosphatidylinositol-3-kinase (PI3K) pathway. If the pathway is active, dietary restriction has no effect on cancer cells. However, if the pathway is inactive, tumours are sensitive to dietary restriction.

Dichloroacetate (DCA) sensitizes both wild-type and over expressing Bcl-2 prostate cancer cells in vitro to radiation. Cao W, Yacoub S, Shiverick KT, Namiki K, Sakai Y, Porvasnik S, Urbanek C, Rosser CJ. Prostate. 2008 Aug 1;68(11):1223-31. PMID: 18465755 DOI: 10.1002/pros.20788

Berberine, a natural product, induces G1-phase cell cycle arrest and caspase-3-dependent apoptosis in human prostate carcinoma cells. Mantena SK, Sharma SD, Katiyar SK. Mol Cancer Ther. 2006 Feb;5(2):296-308. PMID: 16505103 doi: 10.1158/1535-7163.MCT-05-0448 The effectiveness of berberine in checking the growth of androgen-insensitive, as well as androgen-sensitive, prostate cancer cells without affecting the growth of normal prostate epithelial cells indicates that it may be a promising candidate for prostate cancer therapy. The evaluation of ancient herbal medicines may indicate novel strategies for the treatment of prostate cancer, which remains the leading cause of cancer-related deaths in American men (1). In our present investigation, we show that a naturally occurring isoquinoline alkaloid, berberine, significantly inhibits the proliferation and reduces the viability of DU145 and PC-3 as well as LNCaP cells (Fig. 1), which suggests that berberine may be an effective chemotherapeutic agent against both androgen-sensitive and androgen-insensitive prostate cancer cells. Importantly, we found that berberine did not exhibit toxicity to nonneoplastic human prostate epithelial cells under the conditions used, except for a moderate reduction in cell viability at higher concentrations when cells were treated in vitro for an extended period of time. In conclusion, the results of the present study indicate that berberine inhibits proliferation and induces G1-phase arrest and apoptosis in human prostate cancer cells but not in normal human prostate epithelial cells. In addition, we provide mechanistic evidence that berberine-induced apoptosis in prostate carcinoma cells, particularly hormone-refractory prostate carcinoma cells, is mediated through enhanced expression of Bax, disruption of the mitochondrial membrane potential, and activation of caspase-3.

Tumours with PI3K activation are resistant to dietary restriction. Nada Y. Kalaany & David M. Sabatini Nature. Published online 11 March 2009 doi:10.1038/nature07782

Glucose restriction can extend normal cell lifespan and impair precancerous cell growth through epigenetic control of hTERT and p16 expression. Li Y, Liu L, Tollefsbol TO. FASEB J. 2009 Dec 17. [Epub ahead of print] PMID: 20019239 doi: 10.1096/fj.09-149328 Cancer cells metabolize glucose at elevated rates and have a higher sensitivity to glucose reduction. However, the precise molecular mechanisms leading to different responses to glucose restriction between normal and cancer cells are not fully understood. We analyzed normal WI-38 and immortalized WI-38/S fetal lung fibroblasts and found that glucose restriction resulted in growth inhibition and apoptosis in WI-38/S cells, whereas it induced lifespan extension in WI-38 cells. Moreover, in WI-38/S cells glucose restriction decreased expression of hTERT (human telomerase reverse transcriptase) and increased expression of p16(INK4a). Opposite effects were found in the gene expression of hTERT and p16 in WI-38 cells in response to glucose restriction. The altered gene expression was partly due to glucose restriction-induced DNA methylation changes and chromatin remodeling of the hTERT and p16 promoters in normal and immortalized WI-38 cells. Furthermore, glucose restriction resulted in altered hTERT and p16 expression in response to epigenetic regulators in WI-38 rather than WI-38/S cells, suggesting that energy stress-induced differential epigenetic regulation may lead to different cellular fates in normal and precancerous cells. Collectively, these results provide new insights into the epigenetic mechanisms of a nutrient control strategy that may contribute to cancer therapy as well as antiaging approaches.

Inhibition of suppressor T lymphocytes (Ts) by cimetidine. Sahasrabudhe DM, McCune CS, O'Donnell RW, Henshaw EC. J Immunol. 1987 May 1;138(9):2760-3. PMID: 2952721 Cyclophosphamide (CY) is the most extensively studied inhibitor of suppressor T lymphocyte (Ts) function. However, repeated administration of CY can abrogate sensitization. Therefore, we were interested in identifying noncytotoxic inhibitors of Ts function as adjuncts in the immunotherapy of Ts-inducing murine tumors. The effect of cimetidine (a histamine type 2 receptor antagonist) and diphenhydramine (a histamine type 1 receptor antagonist) on the Ts mediating tolerance to 2,4-dinitrofluorobenzene was studied. We report our data regarding the specific inhibition of Ts by cimetidine.

Derived from the bulb or clove of the plant. Garlic is used as a spice and to treat hyperlipidemia, hypertension, atherosclerosis, cancer, and infections. Processing can have a substantial effect on the chemical content in garlic; the volatile oil components are sensitive to heat and certain enzymes are acid-labile. Several oral garlic formulations are available, and clinical studies have addressed a variety of the proposed claims. Placebo-controlled trials on the cholesterol lowering effect of garlic yielded mixed results (16) (17) (18) (21) (22) (26). Studies evaluating the antithrombotic effects repeatedly have shown modest reduction in platelet aggregation, but varying levels of fibrinolytic activity. Research shows mixed effects with regard to reductions in blood glucose, blood pressure, or risk of cardiovascular disease (23). Frequently reported adverse events include bad breath, headache, fatigue, GI upset, diarrhea, sweating, and possible hypoglycemia (9). Because garlic is known to decrease platelet aggregation and potentially elevate the INR, it should not be used with anticoagulants or in patients with platelet dysfunction (15). Garlic appears to induce cytochrome p450 3A4 and may enhance metabolism of many medications (e.g. cyclosporin and saquinavir) (12). An analysis of several case-control studies in Europe suggests an inverse association between garlic consumption and risk of common cancers (25).

ScienceDaily (June 15, 2009) - Using a highly sensitive new test, scientists in Europe are reporting "convincing evidence" that marijuana smoke damages the genetic material DNA in ways that could increase the risk of cancer.

Israeli 'cancer shift' over heart disease mortality may be led by greater risk in women with high intake of n-6 fatty acids. Shapira N. Eur J Cancer Prev. 2007 Oct;16(5):486-94. PMID: 17923822 doi: 10.1097/CEJ.0b013e3280145b6d Population studies of Israeli Jews, Arabs, and women support the association of high n-6 polyunsaturated fatty acid intake with increased cancer risk and higher female sensitivity. Research findings suggest that gender and sex hormones may influence n-6 polyunsaturated fatty acid metabolism and carcinogenesis. This appears to be the first time gender has been proposed to modulate national cancer epidemiology, suggesting implications for differential nutritional prevention, warranting further research.

Differential effects of selenium on benign and malignant prostate epithelial cells: stimulation of LNCaP cell growth by noncytotoxic, low selenite concentrations. Kandaş NO, Randolph C, Bosland MC. Nutr Cancer. 2009;61(2):251-64. PMID: 19235042

University of Illinois researcher Elizabeth Jeffery has learned how to maximize the cancer-fighting power of broccoli. It involves heating broccoli just enough to eliminate a sulfur-grabbing protein, but not enough to stop the plant from releasing an important cancer-fighting compound called sulforaphane. The discovery of this sulfur-grabbing protein in the Jeffery lab makes it possible to maximize the amount of the anticarcinogen sulforaphane in broccoli.