Biology of aging and cancer

Rapamycin extends maximal lifespan in cancer-prone mice

Aging is associated with obesity and cancer. Calorie restriction both slows down aging and delays cancer. Evidence has emerged that the nutrient-sensing mammalian target of rapamycin (mTOR) pathway is involved in cellular and organismal aging. Here we show that the mTOR inhibitor rapamycin prevents age-related weight gain, decreases rate of aging, increases lifespan, and suppresses carcinogenesis in transgenic HER-2/neu cancer-prone mice. Rapamycin dramatically delayed tumor onset as well as decreased the number of tumors per animal and tumor size. We suggest that, by slowing down organismal aging, rapamycin delays cancer.

Circadian disruption induced by light-at-night accelerates aging and promotes tumorigenesis in young but not in old rats

We evaluated the effect of exposure to constant light started at the age of 1 month and at the age of 14 months on the survival, life span, tumorigenesis and age-related dynamics of antioxidant enzymes activity in various organs in comparison to the rats maintained at the standard (12:12 light/dark) light/dark regimen. We found that exposure to constant light started at the age of 1 month accelerated spontaneous tumorigenesis and shortened life span both in male and female rats as compared to the standard regimen. At the same time, the exposure to constant light started at the age of 14 months failed to influence survival of male and female rats. While delaying tumors in males, constant light accelerated tumors in females. We conclude that circadian disruption induced by light-at-night started at the age of 1 month accelerates aging and promotes tumorigenesis in rats, however failed affect survival when started at the age of 14 months.

High sensitivity to carcinogens in the brain of a mouse model of Alzheimer's disease

Cancer and Alzheimer's disease (AD) are commonly found among elderly patients. Chronic inflammation is the characteristic of both diseases. Amyloid-beta peptide is the main inducer of inflammation in AD. Moreover, chronic inflammation promotes cancer, suggesting that AD patients may be more prone to develop cancer than non-demented people. To test this hypothesis, we injected the carcinogen 20-methylcholanthrene in the brain of transgenic mice overexpressing the mutant forms of amyloid precursor protein (APP) and presenilin 1 (PS1), as a model of AD, and their wild-type (WT) littermates. Mutant mice developed tumors faster and with higher incidence than their WT counterparts. Expression of the inflammatory markers interleukin (IL)-1alpha, IL-1beta, IL-6, IP-10 and tumor necrosis factor-alpha (TNF-alpha) was measured in AD and WT mice of 3 and 12 months of age that had not been exposed to the carcinogen. These cytokines were elevated in older AD mice, indicating the existence of a highly inflammatory milieu in these animals. We also found elevated expression of a mutated form of p53 in older AD mice, suggesting an alternative mechanism for the predisposition of AD brains to develop brain tumors. Clinical studies reporting comorbidity of AD and brain cancer are needed to understand whether our observations hold true for humans.

Psychogenic carcinogenesis: carcinogenesis is without exogenic carcinogens

The history of researches of a problem of cancer has cleared a number of key cellular-molecular-genetic mechanisms of carcinogenesis, however process of carcinogenesis, is still out of control and a world forecast is unfavorable despite the advanced pathogenetically focused medication and excellent results of cancer treatment in vivo. Numerous researches have shown that chronic psycho-emotional stress by means of stressful hormones and endogenous mutagens (reactive oxygen and nitrogen species) are capable to damage cells DNA and to compromise immune system. Actually, chronic psycho-emotional stress is capable to activate the key mechanisms of carcinogenesis. It specifies an opportunity of existence psychogenic carcinogenesis--"carcinogenesis is without carcinogens" which can function as independent and in a combination with physical, chemical and biological carcinogens, strengthening their carcinogenic effect. At cancer patients with psychogenically induced carcinogenesis use only the somatically focused therapy of a cancer (surgery, radiotherapy, chemotherapy, immunotherapy), apparently, is not enough for achievement of steady remission. At psychogenically induced carcinogenesis creation of effective anticarcinogenic medicines is also apparently problematic. The presented hypothesis allows to hope for search in the future of diagnostic criteria of revealing of persons with psychogenic also and development of new strategy of the second prophylactic, treatments and rehabilitations such cancer patients. The hypothesis psychogenic carcinogenesis expands existing representations about pathogenesis of malignant tumors and forms holistic approach to the decision of problems of a cancer at the person.

Clinicopathological features, background liver disease, and survival analysis of HCV-positive patients with hepatocellular carcinoma: differences between young and elderly patients

BACKGROUND

The aim of this retrospective study was to determine the incidence and characteristics of hepatocellular carcinoma (HCC) in hepatitis C virus (HCV) antibody-positive elderly patients with chronic hepatitis without cirrhosis.

METHODS

The study included 65 patients who developed HCC at >or=75 years of age and who received their first HCC therapy at Toranomon Hospital between 1985 and 2005. Their clinicopathological and laboratory data were analyzed and compared with those of 33 patients who developed HCC at <or=50 years of age during the same period.

RESULTS

The ratio of women patients in the elderly group (M: F = 1.1: 1) was higher than in the younger group (M: F = 5.6: 1). Also, patients in the elderly group had better liver function and prothrombin activity (P = 0.001), and lower total bilirubin (P = 0.002) than the young group. Only 11 of 65 elderly patients were diagnosed with liver cirrhosis by biopsy or peritoneoscopy before or at the time of development of HCC. Based on a discriminate score using gamma-globulin, hyaluronate level, platelet count, and sex, 27 (41.5%) elderly patients were considered to have chronic hepatitis, compared with six of 33 (18.1%) patients in the young group (P = 0.025). There were no differences in tumor number or size or tumor markers between the two groups. Survival rate was higher in the younger patients (P = 0.002), who were more likely to receive radical treatment.

CONCLUSIONS

Our results showed distinct differences in HCV-related HCC between elderly and young patients and suggested that elderly patients (especially women) could develop HCC even when liver histology shows chronic hepatitis and lack of cirrhosis.

How to minimize formation and growth of tumours: potential benefits of decapod crustaceans for cancer research

Tumours have only rarely been observed in the decapod crustaceans, a large animal group of more than 10,000 species that includes the commercially important and well investigated shrimp, lobsters, crayfish and crabs. Analysis of the literature and information from cancer and diseases data bases revealed a total of 15 incidences, some of them being questionable. Even in the long-lived species, which can reach life spans of almost 100 years, neoplasias are virtually unknown. The data published so far suggest that the strikingly different frequencies of carcinogenesis between decapods and other well investigated animal groups like mammals, fish, insects and molluscs is based on differences of the metabolic pathways for carcinogens, the immune systems, and the regulation of stem cells. Therefore, representatives of the Decapoda may serve as useful models to study how organisms can successfully prevent or control spontaneously and environmentally induced cell proliferation. A particularly promising candidate for in-depth investigation of these topics is the marbled crayfish, a rather new clonal lineage that is presently being introduced as a laboratory model in development and epigenetics.

Aging and neutrophils: there is still much to do

Human neutrophils are activated by a wide array of compounds through their receptors. This elicits their classical functions, such as chemotaxis, phagocytosis, and the production of reactive oxygen species (ROS). Upon stimulation, neutrophils also produce lipid and immune mediators and can present antigen through the major histocompatibility complex I (MHC-I). The age-related impairment of the classical functions of neutrophils is well described, but experimental evidence showing alterations in the production of mediators and antigen presentation with aging are lacking. This review highlights the role of neutrophils in age-related pathologies such as Alzheimer's disease, atherosclerosis, cancer, and autoimmune diseases. Furthermore, we discuss how aging potentially affects the production and release of mediators by human neutrophils in ways that may contribute to the development of these pathologies.

Immunological, Hematological, and Glycemia Effects of Dietary Supplementation withAgaricus sylvaticuson Patients’ Colorectal Cancer

Objective: The aim of this study was to evaluate the effects of dietary supplementation with Agaricus sylvaticus fungus on hematological, immunological, and glycemia levels of postsurgical patients with colorectal cancer. Methods: A randomized, placebo-controlled, clinical trial was conducted at the General Hospital of Brazil for 6 months. Fifty-six patients with colorectal cancer (stages I, II, and III) were divided into 2 groups: A. sylvaticus (30 mg/kg/day) and placebo. Complete hemogram, serum iron, and fasting glycemia evaluations were carried out throughout the treatment course. Subjects were divided according to body mass index (BMI), sex, and stage of colorectal cancer. Data were analyzed using SPSS 14.0 programs, Student’s t test, and F statistical test, with P ≤ 0.05 considered significant. Results: After 6 months of supplementation, the group that received A. sylvaticus showed significant increases in hemoglobin ( P = 0.0001), hematocrit ( P = 0.0001), erythrocytes ( P = 0.01), mean cell volume ( P = 0.01), mean cell hemoglobin ( P = 0.0001), mean cell hemoglobin concentration ( P = 0.0001), and neutrophil levels ( P = 0.0001). The platelet count was significantly reduced ( P = 0.03), but remained within normal levels. No significant alterations were observed in the placebo group. The study group was composed of 32 women (57.1%) and 24 men (42.9%). Mean BMI was 24.65 kg/m2. Glycemia levels in the placebo group (average age 59.14 ± 12.95 years) were: initial, 94.36 ± 15.34 mg/dl; 3 months, 98.12 ± 15.54 mg/dl ( P = 0.03); and 6 months, 98.52 ± 9.03 mg/dl ( P = 0.01). Glycemia levels in the supplemented group (average age 56.34 ± 15.53 years) were: initial, 95.92 ± 11.64 mg/dl, 3 months, 94.88 ± 12.24 mg/dl ( P = 0.65); and 6 months, 92.86 ± 6.82 mg/dl ( P = 0.01). Conclusions: The results of this study suggest that supplementation with A. sylvaticus produces benefits in hematological and immunological parameters and can reduce glycemia levels in patients with colorectal cancer.

Treating elderly patients with hormone sensitive breast cancer: what do the data show?

Elderly patients with breast cancer frequently present with one or more comorbid conditions in addition to their cancer, and this can complicate clinicians' treatment decisions. Declining estrogen levels increase the risk for conditions such as cardiovascular disease and osteoporosis in the elderly. Evidence from clinical trials suggests that the elderly are frequently underrepresented; this may be due to an inherent reluctance among physicians to prescribe the latest, most effective therapies and/or recommend elderly patients for participation in clinical trials. Nonetheless, there is evidence that breast cancer in the elderly is generally more indolent than in younger patients, with a low proliferative and invasive capacity and a high degree of hormone responsiveness, making elderly patients ideal candidates for adjuvant endocrine therapies. The aromatase inhibitors, including anastrozole, letrozole, and exemestane, have proven to be well tolerated and superior alternatives to tamoxifen for post-menopausal women with hormone-sensitive breast cancer, whether used upfront or sequentially with adjuvant tamoxifen. Although the elderly have also been underrepresented in clinical trials of the aromatase inhibitors, evidence from the major trials has not shown any decrement in efficacy or major safety concerns when these drugs are used in older populations. While recently published data from MA.17 and the Breast International Group 1-98 showed letrozole to be effective irrespective of age, clinicians should carefully consider underlying comorbidities when prescribing adjuvant endocrine treatments to elderly patients with breast cancer.

A statistical model for the identification of genes governing the incidence of cancer with age

The cancer incidence increases with age. This epidemiological pattern of cancer incidence can be attributed to molecular and cellular processes of individual subjects. Also, the incidence of cancer with ages can be controlled by genes. Here we present a dynamic statistical model for explaining the epidemiological pattern of cancer incidence based on individual genes that regulate cancer formation and progression. We incorporate the mathematical equations of age-specific cancer incidence into a framework for functional mapping aimed at identifying quantitative trait loci (QTLs) for dynamic changes of a complex trait. The mathematical parameters that specify differences in the curve of cancer incidence among QTL genotypes are estimated within the context of maximum likelihood. The model provides testable quantitative hypotheses about the initiation and duration of genetic expression for QTLs involved in cancer progression. Computer simulation was used to examine the statistical behavior of the model. The model can be used as a tool for explaining the epidemiological pattern of cancer incidence.

Deficiency in Poly(ADP-ribose) Polymerase-1 (PARP-1) Accelerates Aging and Spontaneous Carcinogenesis in Mice

Genetic and biochemical studies have shown that PARP-1 and poly(ADP-ribosyl)ation play an important role in DNA repair, genomic stability, cell death, inflammation, telomere maintenance, and suppressing tumorigenesis, suggesting that the homeostasis of poly(ADP-ribosyl)ation and PARP-1 may also play an important role in aging. Here we show that PARP-1(-/-) mice exhibit a reduction of life span and a significant increase of population aging rate. Analysis of noninvasive parameters, including body weight gain, body temperature, estrous function, behavior, and a number of biochemical indices suggests the acceleration of biological aging in PARP-1(-/-) mice. The incidence of spontaneous tumors in both PARP-1(-/-) and PARP-1(+/+) groups is similar; however, malignant tumors including uterine tumors, lung adenocarcinomas and hepatocellular carcinomas, develop at a significantly higher frequency in PARP-1(-/-) mice than PARP-1(+/+) mice (72% and 49%, resp.; P < .05). In addition, spontaneous tumors appear earlier in PARP-1(-/-) mice compared to the wild type group. Histopathological studies revealed a wide spectrum of tumors in uterus, ovaries, liver, lungs, mammary gland, soft tissues, and lymphoid organs in both groups of the mice. These results demonstrate that inactivation of DNA repair gene PARP-1 in mice leads to acceleration of aging, shortened life span, and increased spontaneous carcinogenesis.

Reactive species: a cell damaging rout assisting to chemical carcinogens

Reactive oxygen and nitrogen species (ROS and RNS) are known to contribute as pathogenic factors to the development of chronic progressive diseases at various stages. The present review discusses the role of oxidative stress in chemically induced cancer development and progression. Reactive species are capable of inducing DNA damage that eventually may contribute to cell transformation and tumor initiation. ROS and RNS are also associated with tumor promotion and progression. Both endogenous processes and redox-cycling of xenobiotic compounds have been shown to result in oxidative DNA damage. In addition, several exocyclic DNA adducts represent secondary DNA damage caused by products of lipid peroxidation in the course of oxidative cellular stress. Due to their intrinsic ability to catalyze redox reactions, transition metals, and quinones from various classes of xenobiotics or endogenous compounds are important mediators of oxidative stress and thus likely of being involved in DNA damage, lipid peroxidation, cell transformation, and tumor development.

Carcinogenesis and aging 20 years after: escaping horizon

Carcinogenesis is a multistage process: neoplastic transformation implies the engagement of a cell through sequential stages, and different agents may affect the transition between continuous stages. Multistage carcinogenesis is accompanied by disturbances in tissue homeostasis and perturbations in nervous, hormonal, and metabolic factors which may affect antitumor resistance. The development of these changes depends on the susceptibility of various systems to a carcinogen and on the dose of the carcinogen. Changes in the microenvironment may condition key carcinogenic events and determine the duration of each carcinogenic stage, and sometimes they may even reverse the process of carcinogenesis. These microenvironmental changes influence the proliferation rate of transformed cells, the total duration of carcinogenesis and, consequently, the latent period of tumor development. Aging may increase or decrease the susceptibility of various tissues to initiation of carcinogenesis and usually facilitates promotion and progression of carcinogenesis. Aging may predispose to cancer by two mechanisms: tissue accumulation of cells in late stages of carcinogenesis and alterations in internal homeostasis, in particular, alterations in immune and endocrine system. Aging is associated with number of events at molecular, cellular and physiological levels that influence carcinogenesis and subsequent cancer growth.

Progesterone effects on cell growth of U373 and D54 human astrocytoma cell lines

Astrocytomas are the most frequent primary brain tumors and constitute a leading cause of cancer-related deaths. We studied the effects of progesterone and its antagonist, RU486, on cell growth of two human astrocytoma cell lines with different evolution grade (U373, grade III; and D54, grade IV). Progesterone receptor expression was determined by Western blot. The effects of different doses of progesterone and RU486 on cell number, cell cycle, and apoptosis were analyzed for five consecutive days. Progesterone (10 nM) significantly increased the number of D54 cells from the second day of culture, and the number of U373 cells on days 3-5. RU486 (10 muM) blocked progesterone effects in both astrocytoma cell lines. Interestingly, RU486 administered without progesterone significantly reduced the number of cells from the second day of culture in both cell lines. Progesterone increased S phase of cell cycle in U373 cells (61%, on day 5). RU486 blocked the effects of progesterone on cell cycle but administered alone did not significantly change cell cycle profile. DNA fragmentation (TUNEL) assay showed that the diminution in the number of astrocytoma cells produced by RU486 was not by apoptosis. Progesterone receptor isoforms were detected in both cell lines. Our data suggest that progesterone induces cell growth of human astrocytoma cell lines through the interaction with its nuclear receptor.