Green tea and the risk of prostate cancer: A systematic review and meta-analysis.

Prostate cancer (PCa) now remains the 2nd most frequently diagnosed cancer. In recent years, chemoprevention for PCa becomes a possible concept. Especially, many phytochemicals rich foods are suggested to lower the risk of cancer. Among these foods, green tea is considered as effective prevention for various cancers. However, clinical trials and previous meta-analyses on the relationship between green tea consumption and the risk of PCa have produced inconsistent outcomes. This study aims to determine the dose-response association of green tea intake with PCa risk and the preventive effect of green tea catechins on PCa risk. Seven observational studies and 3 randomized controlled trials were retrieved from Cochrane Library, PubMed, Sciencedirect Online, and hand searching. The STATA (version 12.0) was applied to analyze the data. The relative risks (RRs) and 95% confidence intervals were pooled by fixed or random effect modeling. Dose-response relations were evaluated with categories of green tea intake. Although there was no statistical significance in the comparison of the highest versus lowest category, there was a trend of reduced incidence of PCa with each 1 cup/day increase of green tea (P = 0.08). Our dose-response meta-analysis further demonstrated that higher green tea consumption was linearly associated with a reduced risk of PCa with more than 7 cups/day. In addition, green tea catechins were effective for preventing PCa with an RR of 0.38 (P = 0.02). In conclusion, our dose-response meta-analysis evaluated the association of green tea intake with PCa risk systematically and quantitatively. And this is the first meta-analysis of green tea catechins consumption and PCa incidence. Our novel data demonstrated that higher green tea consumption was linearly reduced PCa risk with more than 7 cups/day and green tea catechins were effective for preventing PCa. However, further studies are required to substantiate these conclusions.

Two Membrane-Anchored Aspartic Proteases Contribute to Pollen and Ovule Development.

Aspartic proteases are a class of proteolytic enzymes with conserved aspartate residues, which are implicated in protein processing, maturation, and degradation. Compared with yeast and animals, plants possess a larger aspartic protease family. However, little is known about most of these enzymes. Here, we characterized two Arabidopsis (Arabidopsis thaliana) putative glycosylphosphatidylinositol (GPI)-anchored aspartic protease genes, A36 and A39, which are highly expressed in pollen and pollen tubes. a36 and a36 a39 mutants display significantly reduced pollen activity. Transmission electron microscopy and terminal-deoxynucleotidyl transferase-mediated nick end labeling assays further revealed that the unviable pollen in a36 a39 may undergo unanticipated apoptosis-like programmed cell death. The degeneration of female gametes also occurred in a36 a39 Aniline Blue staining, scanning electron microscopy, and semi in vitro guidance assays indicated that the micropylar guidance of pollen tubes is significantly compromised in a36 a39 A36 and A39 that were fused with green fluorescent protein are localized to the plasma membrane and display punctate cytosolic localization and colocalize with the GPI-anchored protein COBRA-LIKE10. Furthermore, in a36 a39, the abundance of highly methylesterified homogalacturonans and xyloglucans was increased significantly in the apical pollen tube wall. These results indicate that A36 and A39, two putative GPI-anchored aspartic proteases, play important roles in plant reproduction in Arabidopsis.

Lycopene and Risk of Prostate Cancer: A Systematic Review and Meta-Analysis.

Prostate cancer (PCa) is a common illness for aging males. Lycopene has been identified as an antioxidant agent with potential anticancer properties. Studies investigating the relation between lycopene and PCa risk have produced inconsistent results. This study aims to determine dietary lycopene consumption/circulating concentration and any potential dose-response associations with the risk of PCa. Eligible studies published in English up to April 10, 2014, were searched and identified from Pubmed, Sciencedirect Online, Wiley online library databases and hand searching. The STATA (version 12.0) was applied to process the dose-response meta-analysis. Random effects models were used to calculate pooled relative risks (RRs) and 95% confidence intervals (CIs) and to incorporate variation between studies. The linear and nonlinear dose-response relations were evaluated with data from categories of lycopene consumption/circulating concentrations. Twenty-six studies were included with 17,517 cases of PCa reported from 563,299 participants. Although inverse association between lycopene consumption and PCa risk was not found in all studies, there was a trend that with higher lycopene intake, there was reduced incidence of PCa (P = 0.078). Removal of one Chinese study in sensitivity analysis, or recalculation using data from only high-quality studies for subgroup analysis, indicated that higher lycopene consumption significantly lowered PCa risk. Furthermore, our dose-response meta-analysis demonstrated that higher lycopene consumption was linearly associated with a reduced risk of PCa with a threshold between 9 and 21 mg/day. Consistently, higher circulating lycopene levels significantly reduced the risk of PCa. Interestingly, the concentration of circulating lycopene between 2.17 and 85 µg/dL was linearly inversed with PCa risk whereas there was no linear association >85 µg/dL. In addition, greater efficacy for the circulating lycopene concentration on preventing PCa was found for studies with high quality, follow-up >10 years and where results were adjusted by the age or the body mass index. In conclusion, our novel data demonstrates that higher lycopene consumption/circulating concentration is associated with a lower risk of PCa. However, further studies are required to determine the mechanism by which lycopene reduces the risk of PCa and if there are other factors in tomato products that might potentially decrease PCa risk and progression.