Energy restriction and exercise differentially enhance components of systemic and mucosal immunity in mice.

The prevalence of obesity, an established risk factor for several chronic diseases, including cancer, has risen dramatically over the past 4 decades. Dietary change and/or increased physical activity are the most commonly recommended lifestyle-based strategies for preventing or reversing obesity. One of several physiological systems that may be enhanced by dietary change and exercise is the immune system. In this study, we examined the effects of energy restriction (ER; 30% reduction relative to control energy intake) and/or exercise (EX; voluntary wheel running) on systemic and mucosal immune function. Female C57BL/6 mice were randomized into 4 treatment conditions: 1) controls consumed ad libitum (AL); 2) AL with access to running wheels (AL + EX); 3) 30% ER; and 4) 30% ER with access to running wheels (ER + EX). Both ER and EX reduced spleen weight and the number of splenic T and B lymphocytes (P < 0.05). ER enhanced natural killer (NK) cell function, but reduced concanavalin A (Con A)-induced T-cell proliferation (P < 0.05). In contrast, EX enhanced Con A-induced proliferation and cytokine production from Peyer's patch cells (P < 0.05). These data suggest that ER and EX enhance some, but not all, components of the immune system and are likely working via different biological mechanisms to regulate NK and T-cell function.

Risk factors for HPV infection and cervical cancer among unscreened women in a high-risk rural area of China.

We report a prevalence rate of 23.6% human papillomavirus (HPV) infection with oncogenic subtypes and 2.4% cervical intraepithelial neoplasia (CIN) III and cervical cancer (CC) in rural middle-aged women in 2 counties with the highest CC mortality in Shanxi Province, China. We examined the association of risk factors to HPV infection and to CIN III and CC in 8,798 unscreened women aged 35-50 years. Multivariate odds ratios (OR) and 95% confidence intervals (CI) for each endpoint were obtained for risk factors after adjustment for covariates. The OR of oncogenic HPV were: 1.41 (95% CI = 1.25-1.60) and 1.42 (95% CI = 1.24-1.61) for the participant and her husband having multiple sexual partners, respectively; 1.67 (95% CI = 1.37-2.04), 1.15 (95% CI = 1.04-1.26), and 0.82 (95% CI = 0.72-0.94) for ever (vs. never) diagnosed with tuberculosis, cervical inflammation and vaginal trichomoniasis, respectively; while bathing in a public (v. private) facility had an OR of 1.23 (95% CI =1.11-1.35). Seasonal fluctuations in HPV infection, but not CC, appeared in Xiangyuan County, with OR of 1.23 (95% CI = 1.14-1.33) and 1.51 (95% CI = 1.35-1.67) in Spring and Winter compared to Summer, respectively. The OR of CIN III and CC in the HPV positives were: 2.03 (95% CI = 1.63-2.53) for ages > or =45 years (vs. <40); and 4.01 (95% CI = 1.46-11.0) for > or =3 (vs. no) home births. Public health interventions and control strategies for improving the reproductive health of women in these rural populations need to be developed to reduce risk of HPV and subsequent CC.

The utility of genetically altered mouse models for nutrition and cancer chemoprevention research.

The development of effective cancer preventive interventions is being enhanced by the use of relevant animal models to confirm, refine, and extend potential leads from clinical and epidemiologic studies. In particular, genetically altered mice, with specific cancer-related genes modulated, are providing powerful tools for studying carcinogenesis, as well as important conduits for translating basic research findings from the laboratory bench to the bedside. This review explores the utility of genetically altered mice for developing cancer preventive strategies that can offset increased cancer susceptibility resulting from specific genetic lesions. Examples will focus on preventing cancer by dietary interventions, particularly obesity prevention/energy balance modulation, as well as chemoprevention, in mice with alterations in genes such as the p53 or Apc tumor suppressors, components of the ErbB pathway, and other pathways frequently altered in human cancer.

Effects of energy balance on cancer in genetically altered mice.

Evidence has accumulated from laboratory-based animal experiments and population-based human epidemiological studies that lifestyle factors that affect energy balance, such as caloric intake, nutritional status, and exercise, act in concert with genetic susceptibility to influence cancer development and progression. The use of animal models with specific genetic alterations, in combination with lifestyle modifications that alter overall energy balance, has contributed to a greater understanding of the mechanistic changes occurring during carcinogenesis and to the identification of points of intervention. Studies in our laboratory focusing on the role of energy balance and genetic susceptibility in mice deficient in one (+/-) or both (-/-) alleles of the p53 tumor suppressor gene and mice with a mutant APC allele (APC(Min)) showed that calorie restriction decreases tumor burden, increases tumor latency, and decreases serum insulin-like growth factor (IGF)-1 and leptin levels. Data from our studies, combined with results from other animal and human studies, have established a role for IGF-1 in carcinogenesis. Studies using genetic models of cancer that have been interbred with mice with abnormal levels of IGF-1 will enable the examination of combined effects of energy balance and genetic alterations on the cancer process. Models that integrate lifestyle and genetic effects in a single system provide a physiologically intact system in which combination interventions and therapies for cancer prevention can be tested and validated, thus building a strong preclinical foundation that will inform the development of clinical trials and add perspective to epidemiological studies.

Combination of a poxvirus-based vaccine with a cyclooxygenase-2 inhibitor (celecoxib) elicits antitumor immunity and long-term survival in CEA.Tg/MIN mice.

The present study was designed to determine whether: (a) chronic administration of dietary celecoxib (Celebrex), a potent nonsteroidal anti-inflammatory drug, which targets the cyclooxygenase-2 (COX-2) enzyme, negatively impacts host immunity; and (b) celecoxib can be coupled with a poxvirus-based vaccine to impact tumor burden in a murine tumor model of spontaneous adenomatous polyposis coli. Naive mice fed the celecoxib-supplemented diets developed eosinophilia with lowered plasma prostaglandin E(2) levels and reduced COX-2 mRNA expression levels in their splenic T cells. Responses of splenic T, B, and natural killer cells to broad-based and antigen-specific stimuli were, for the most part, unchanged in those mice as well as COX-2 knockout mice; exceptions included: (a) reduced IFN-gamma production by concanavalin A- or antigen-stimulated T cells; and (b) heightened lipopolysaccharide response of naive B cells from mice fed a diet supplemented with 1000 ppm of celecoxib. When transgenic mice that express the human carcinoembryonic antigen (CEA) gene (CEA transgenic) were bred with mice bearing a mutation in the Apc(Delta850) gene (multiple intestinal neoplasia mice), the progeny (CEA transgenic/multiple intestinal neoplasia) spontaneously develop multiple intestinal neoplasms that overexpress CEA and COX-2. Beginning at 30 days of age, the administration of a diversified prime/boost recombinant CEA-poxvirus-based vaccine regimen or celecoxib (1000 ppm)-supplemented diet reduced the number of intestinal neoplasms by 54% and 65%, respectively. Combining the CEA-based vaccine with the celecoxib-supplemented diet reduced tumor burden by 95% and significantly improved overall long-term survival. Both tumor reduction and improved overall survival were achieved without any evidence of autoimmunity directed at CEA-expressing or other normal tissues. Celecoxib is prescribed for the treatment of familial adenomatous polyposis in humans, and the CEA-based vaccines have been well tolerated and capable of eliciting anti-CEA host immune responses in early clinical studies. The results suggest that the administration of a recombinant poxvirus-based vaccine is compatible with celecoxib, and this combined chemoimmuno-based approach might lead to an additive therapeutic antitumor benefit not only in patients diagnosed with familial adenomatous polyposis but, perhaps, in other preventive settings in which COX-2 overexpression is associated with progression from premalignancy to neoplasia.

Perturbations of the Ink4a/Arf gene locus in aflatoxin B1-induced mouse lung tumors.

Lung tumors from AC3F1 mice treated with aflatoxin B(1) (AFB(1)), were examined for loss of alleles, point mutations and hypermethylation of CpG sites within the promoters of the two genes in the Ink4a/Arf gene locus. Loss of microsatellite alleles in the Ink4a/Arf region occurred in 22 of 74 (30%) AFB(1)-induced lung tumors. Fifty-one of 61 (83%) tumors had at least partial methylation of CpG sites within the p16Ink4a promoter-exon 1alpha region. At least partial methylation of CpG sites was observed in 43 of 49 (88%) tumors analyzed for p19Arf promoter hypermethylation, with methylation of identified transcription factor binding sites or consensus sequences occurring in 21 tumors (DMP1/Ets in two tumors, CTCF in four tumors, E2F in three tumors, Sp1 in 16 tumors). Two tumors contained point mutations in the p19Arf promoter. Nuclear staining for p19(Arf) was decreased by 80-100% in 41 of 71 (58%) tumors. The concordance between p19Arf molecular perturbations and altered protein expression was 63%. However, upon comparing p19Arf promoter perturbations (i.e. methylation of functional transcription factor binding sites and point mutations) and altered p19(Arf) expression, the concordance was 86%, suggesting a mechanism for changes in protein expression in some tumors. There was an absence of a mutually exclusive relationship between disruption of p53 and p19(Arf), since the concordance was 62%. Similarly, no evidence was found of inverse relationships between perturbation of p16Ink4a and p19(Arf) (43% concordance) or p16Ink4(a) and p53 (37% concordance), suggesting that inactivation of these genes occurs independently and provides evidence that, although these genes may participate in cooperative cellular pathways, they also have functions in independent pathways that are important in mouse lung tumorigenesis.