Different types of cell death in organismal aging and longevity: state of the art and possible systems biology approach.

Cell death is as important as cell proliferation for cell turn-over, and susceptibility to cell death is affected by a number of parameters that change with time. A time-dependent derangement of such a crucial process, or even the simple cell loss mediated by cell death impinges upon aging and longevity. In this review we will discuss how cell death phenomena are modulated during aging and what is their possible role in the aging process. We will focus on apoptosis and autophagy, which affect mostly proliferating and post-mitotic cells, respectively, and on mitochondrial degradation in long living cells. Since the "decisional process" that leads the cell to death is very complex, we will also discuss the possibility to address this topic with a systems biology approach.

(-)-Epigallocatechin-3-gallate downregulates estrogen receptor alpha function in MCF-7 breast carcinoma cells.

BACKGROUND: (-)-Epigallocatechin-3-gallate (EGCG) is the most active catechin present in green tea, demonstrated to have chemopreventive action and to kill cancer cells selectively. As a previous study found that catechins could compete with 17-beta-estradiol for binding to estrogen receptor alpha (ERalpha), we asked whether EGCG could regulate ERalpha action. METHODS: We used MCF-7, a breast carcinoma cell line having a high level of ERalpha expression. The cells were treated with various EGCG concentrations and cell viability was evaluated by MTT assay. ERalpha and pS2 expression were analyzed by RT-PCR after RNA extraction. To better define EGCG action in relation to ERalpha, we studied EGCG cytotoxicity on MCF-7 resistant to tamoxifen (MCF-7tam), MCF-7 treated with 10(-7)M ICI 182,780 for 8 days and on MDA-MB-231, a cell line that lacked ERalpha by flow cytometry (FCM). RESULTS: Both ERalpha and pS2 mRNA were expressed in samples treated with low EGCG concentration (30 microg/ml). At this concentration, no cell change was detectable. In contrast, pS2 expression was lost in samples treated with 100 microg/ml EGCG for 24h, indicating ERalpha alteration. EGCG cytotoxicity was lower when ERalpha was not present (MDA-MB-231) or inactivated (by tamoxifen or ICI 182,780). CONCLUSIONS: Functionally active ERalpha may have a role in EGCG cytotoxicity, increasing the sensitivity to the drug. As higher EGCG concentrations also killed cells resistant to tamoxifen or treated by 10(-7)M ICI 182,780, EGCG ought to be better investigated in breast carcinoma cells treated with drugs targeted to steroid receptors, as a potential complement of therapy.

p53 codon 72 alleles influence the response to anticancer drugs in cells from aged people by regulating the cell cycle inhibitor p21WAF1.

A common polymorphism at codon 72 in p53 gene leads to an arginine to proline aminoacidic substitution which affects in an age-dependent manner the susceptibility of cells to undergo apoptosis after oxidative stress. Here we report that dermal fibroblasts from Proline allele carriers (Pro+) display a higher expression of p21WAF1 gene, in both basal conditions and after treatment with doxorubicin or camptothecin. This phenomenon is accompanied by a lower susceptibility of Pro+ cells to undergo apoptosis, a lower capability to over cross G1-S transition and an increased propensity to express markers of cell senescence, with respect to fibroblasts from Arginine homozygotes (Pro-). All these phenomena are particularly evident in cells from centenarians. We conclude that the functional difference between the two p53 codon 72 alleles exerts a broad impact on the capability of cell from aged people to respond to stressors such as cytotoxic drugs.

Retention of the p53 codon 72 arginine allele is associated with a reduction of disease-free and overall survival in arginine/proline heterozygous breast cancer patients.

PURPOSE: The arginine to proline substitution at codon 72 represents a common aminoacidic polymorphism of the p53 protein. Recent data suggest that p53 codon 72 may modulate the response to cancer therapy. The aim of this study was to test the hypothesis that the p53 codon 72 genotype, evaluated in the tumor tissue and in the disease-free lymph node, is related to differences in disease-free and overall survival among breast cancer-affected patients. EXPERIMENTAL DESIGN: We assessed the p53 codon 72 genotype in DNA from disease-free lymph nodes and neoplastic tissues obtained from 67 women affected by breast cancer who underwent surgical resection at the Bologna Breast Cancer Surgical Unit from 1993 to 1995. RESULTS: We found that the retention of the p53 codon 72 arginine allele in the tumor tissue of proline/arginine heterozygous breast cancer patients is associated with statistically significant reduced disease-free and overall survivals. CONCLUSIONS: Our findings suggest that the genotyping for p53 codon 72 locus in both the tumor tissue and in the lymph node of breast cancer patients could contribute to identify a subset of arginine/proline heterozygous patients who have a reduced survival that is associated with the specific retention of the arginine allele in the tumor tissue.

p53 codon 72 genotype affects apoptosis by cytosine arabinoside in blood leukocytes.

A wide difference in the susceptibility to undergo in vitro apoptosis exists among individuals, and this fact has potential implications in predicting the in vivo response to apoptotic agents, such as those employed in chemotherapy. In this report, we addressed the question whether the natural variability at p53 locus (the proline-arginine substitution at codon 72) affects the capacity of peripheral-blood mononuclear cells from healthy subjects to undergo in vitro apoptosis in response to the cytotoxic drug cytosine arabinoside. We found that cells from subjects carrying the arginine/arginine genotype undergo in vitro apoptosis at a higher extent in comparison to those from arginine/proline subjects. This finding suggests that naturally occurring genetic variability at p53 gene explains part of the inter-individual difference in the in vitro susceptibility to a chemotherapeutic drug, thus resulting as an eligible predictor marker of in vivo response to chemotherapy and its adverse effects.

What studies on human longevity tell us about the risk for cancer in the oldest old: data and hypotheses on the genetics and immunology of centenarians.

Centenarians are people who escaped from major common diseases, including cancer, and reached the extreme limits of human life-span. The analysis of demographic data indicates that cancer incidence and mortality show a levelling off around the age of 85-90 years, and suggests that oldest old people and centenarians are protected from cancer onset and progression. In this paper, we review data of recent literature on the distribution in centenarians of germ-line polymorphisms, which are supposed to affect the individual susceptibility to cancer (p53, HRAS1, BRCA1, glutathione transferases, cytochrome oxidases, steroid-5 alpha-reductase enzyme type II). Moreover, we add new data on two p53 polymorphisms in a total of 1086 people of different age, including 307 centenarians. In addition, we put forth the hypothesis that the remodelling of the immune system occurring with age is capable of creating a hostile environment for the growth of cancer cells in these exceptional individuals. We conclude that future studies on centenarians regarding the germ-line variability of genes involved in the control of the immune response, including apoptosis (ApoJ), are likely to be of fundamental importance in understanding the basic mechanisms for cancer, aging and their complex relationship.

An allele of HRAS1 3'variable number of tandem repeats is a frailty allele: implication for an evolutionarily-conserved pathway involved in longevity.

The human HRAS1 belongs to an evolutionarily-conserved family of genes which enrolls among its members the yeast RAS2, a gene which regulates stress response and longevity in the Saccharomyces cerevisiae. In this paper we report that the frequency of the a3 allele of HRAS1 3'variable number tandem repeat (HRAS1 3'VNTR) decreases in centenarians in respect to young people, and we estimate that during aging a3 carriers have a relative mortality risk of 1.126 (95% CI=1.044-1.213). We propose that the germ-line variability at the HRAS1 locus impacts on the individual's capacity to reach the extreme limits of human life-span. Furthermore, we provide suggestive evidence that a3 HRAS1 3'VNTR allele and inherited variants of the mitochondrial genome (mtDNA haplogroups) do not affect independently human longevity, thus recalling the nucleus-mitochondrion interaction which regulates stress response and life-span in the yeast.