A method to study the expression of DNA methyltransferases in aging systems in vitro

CDH1 promoter methylation correlates with decreased gene expression and poor prognosis in patients with breast cancer

The E-cadherin gene (CDH1) is associated with poor prognosis and metastasis in patients with breast cancer, and methylation of its promoter is correlated with decreased gene expression. However, there is currently no direct evidence that CDH1 promoter methylation indicates poor prognosis in patients with breast cancer. In the present study, methylation-specific polymerase chain reaction (PCR) was applied to detect the methylation status of the CDH1 promoter in 137 primary breast cancer, 85 matched normal breast tissue and 13 lung metastasis specimens. Reverse transcription-quantitative PCR was used to assess the relative expression levels of CDH1 mRNA, and correlation analysis between CDH1 methylation status, and gene expression, clinicopathological characteristics and patient survival was performed. Methylation of CDH1 was identified in 40.9% (56/137) of primary breast cancer specimens, 61.5% (8/13) of lung metastasis specimens and none of the matched normal breast specimens. The downregulation of CDH1 mRNA and E-cadherin protein expression were identified to be significantly correlated with CDH1 methylation (P<0.05). In addition, CDH1 methylation was significantly associated with lymph node metastasis and estrogen receptor status of patients (P<0.05). In univariate analyses, patients with CDH1 methylation exhibited poor overall survival (OS) and disease-free survival (DFS; P<0.05). Furthermore, multivariate analyses revealed that CDH1 methylation was an independent prognostic factor predicting poor OS (HR, 1.737; 95% CI, 0.957-3.766; P=0.041) and DFS (HR, 2.018; 95% CI, 2.057-3.845; P=0.033) in patients with breast cancer. Therefore, the present study suggests that CDH1 promoter methylation may be correlated with breast carcinogenesis and indicates poor prognosis in patients with breast cancer.

A possible role of an anthocyanin filter in low-intensity light stress-induced flowering in Perilla frutescens var. crispa

The red-leaved form of Perilla frutescens var. crispa was induced to flower by low-intensity light stress. The leaves of this form are normally red, but turned green under low-intensity light due to anthocyanin depletion in the epidermis. Flowering did not occur when plants were grown under light passed through a red-colored cellophane paper, which has an absorption spectrum similar to that of anthocyanins. High-concentration anthocyanins may play the role of a red-colored optical filter under normal light conditions, and this filter effect may be lost under low-intensity light, causing a change in the wavelength characteristics of the light with which the mesophyll cells are irradiated. This change may induce a photobiological effect leading to flowering. The gene expression and enzyme activity of phenylalanine ammonia-lyase (PAL), the key enzyme for anthocyanin biosynthesis, decreased under low-intensity light. L-2-aminooxy-3-phenylpropionic acid (AOPP), which is widely used as a PAL inhibitor, inhibited low-intensity light stress-induced flowering and increased PAL activity and anthocyanin content. The inhibition of flowering by AOPP in P. frutescens may be through different mechanisms than PAL inhibition.

Old age as a privilege of the "selfish ones"

In the past couple of centuries, scientists proposed great number of aging theories but neither of them appears to be fully satisfactory. In the statistical sense, we are dealing with an even greater challenge because large array of factors affects the aging process. Although at this point the most of these factors are well known, it is the very fact of their innumerability that complicates approaches to the issue at hand. Both in life and in medicine, the cause behind an effect can rarely be unequivocally determined. Thus, it appears that through out human history longevity has been primarily affected by eradication of diseases, especially by eradication of infectious diseases and introduction of the vaccines. For that reason, maybe we should not be referring to this issue as the «fountain of youth» but rather as the «vaccine of youth». The postulate that genetic instability is the precipitating factor both of aging and cancer has withstood many tests and keeps on being reaffirmed. For this reason, it is legitimate to pose a question of whether long-lived individuals may be those with «selfish» genes and more stable genetic material. They certainly cannot avoid aging, but aging in such individuals could be delayed due to steady character of their genome, which is less susceptible to mutations. On the population level, they constitute minority because stable genome would represent an obstacle to successful evolution of the species. If this was not the case, we might not be writing all these texts today.

Cancer chemoprevention by dietary polyphenols: promising role for epigenetics

Epigenetics refers to heritable changes that are not encoded in the DNA sequence itself, but play an important role in the control of gene expression. In mammals, epigenetic mechanisms include changes in DNA methylation, histone modifications and non-coding RNAs. Although epigenetic changes are heritable in somatic cells, these modifications are also potentially reversible, which makes them attractive and promising avenues for tailoring cancer preventive and therapeutic strategies. Burgeoning evidence in the last decade has provided unprecedented clues that diet and environmental factors directly influence epigenetic mechanisms in humans. Dietary polyphenols from green tea, turmeric, soybeans, broccoli and others have shown to possess multiple cell-regulatory activities within cancer cells. More recently, we have begun to understand that some of the dietary polyphenols may exert their chemopreventive effects in part by modulating various components of the epigenetic machinery in humans. In this article, we first discuss the contribution of diet and environmental factors on epigenetic alterations; subsequently, we provide a comprehensive review of literature on the role of various dietary polyphenols. In particular, we summarize the current knowledge on a large number of dietary agents and their effects on DNA methylation, histone modifications and regulation of expression of the non-coding miRNAs in various in vitro and in vivo models. We emphasize how increased understanding of the chemopreventive effects of dietary polyphenols on specific epigenetic alterations may provide unique and yet unexplored novel and highly effective chemopreventive strategies for reducing the health burden of cancer and other diseases in humans.

Epigenetics and cancer

Epigenetic modifications are central to many human diseases, including cancer. Traditionally, cancer has been viewed as a genetic disease, and it is now becoming apparent that the onset of cancer is preceded by epigenetic abnormalities. Investigators in the rapidly expanding field of epigenetics have documented extensive genomic reprogramming in cancer cells, including methylation of DNA, chemical modification of the histone proteins, and RNA-dependent regulation. Recognizing that carcinogenesis involves both genetic and epigenetic alterations has led to a better understanding of the molecular pathways that govern the development of cancer and to improvements in diagnosing and predicting the outcome of various types of cancer. Studies of the mechanism(s) of epigenetic regulation and its reversibility have resulted in the identification of novel targets that may be useful in developing new strategies for the prevention and treatment of cancer.