Mechanistic insight into the ability of American ginseng to suppress colon cancer associated with colitis.

We have recently shown that American ginseng (AG) prevents and treats mouse colitis. Because both mice and humans with chronic colitis have a high colon cancer risk, we tested the hypothesis that AG can be used to prevent colitis-driven colon cancer. Using the azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model of ulcerative colitis, we show that AG can suppress colon cancer associated with colitis. To explore the molecular mechanisms of the anticancer effects of AG, we also carried out antibody array experiments on colon cells isolated at a precancerous stage. We found there were 82 protein end points that were either significantly higher (41 proteins) or significantly lower (41 proteins) in the AOM + DSS group compared with the AOM-alone (control) group. In contrast, there were only 19 protein end points that were either significantly higher (10 proteins) or significantly lower (9 proteins) in the AOM + DSS + AG group compared with the AOM-alone (control) group. Overall, these results suggest that AG keeps the colon environment in metabolic equilibrium when mice are treated with AOM + DSS and gives insight into the mechanisms by which AG protects from colon cancer associated with colitis.

Circadian disruption, Per3, and human cytokine secretion.

Circadian disruption has been linked with inflammation, an established cancer risk factor. Per3 clock gene polymorphisms have also been associated with circadian disruption and with increased cancer risk. Patients completed a questionnaire and provided a blood sample prior to undergoing a colonoscopy (n = 70). Adjusted mean serum cytokine concentrations (IL-6, TNF-alpha, gamma-INF, IL-1ra, IL-1-beta, VEGF) were compared among patients with high and low scores for fatigue (Multidimensional Fatigue Inventory), depressive symptoms (Beck Depression Inventory II), or sleep disruption (Pittsburgh Sleep Quality Index), or among patients with different Per3 clock gene variants. Poor sleep was associated with elevated VEGF, and fatigue-related reduced activity was associated with elevated TNF-alpha concentrations. Participants with the 4/5 or 5/5 Per3 variable tandem repeat sequence had elevated IL-6 concentrations compared to those with the 4/4 genotype. Biological processes linking circadian disruption with cancer remain to be elucidated. Increased inflammatory cytokine secretion may play a role.

Circadian clock manipulation for cancer prevention and control and the relief of cancer symptoms.

Life has evolved on this planet with regular daily spans of direct solar energy availability alternating with nocturnal spans of dark. Virtually every earth-borne life form has factored this circadian pattern into its biology to ensure the temporal coordination with its resonating environment, a task essential for its individual survival and that of its species. The first whole genome inspections of mutations in human colon and breast cancer have observed specific retained clock gene mutations. Single nucleotide polymorphisms within the genes of clock, clock-controlled, and melatonin pathways have been found to confer excess cancer risk or protection from cancer. Experimental studies have shown that specific core clock genes (Per2 and Per1) are tumor suppressors because their genetic absence doubles tumor numbers, and decreasing their expression in cancer cells doubles cancer growth rate, whereas their overexpression decreases cancer growth rate and diminishes tumor numbers. Experimental interference with circadian clock function increases cancer growth rate, and clinical circadian disruption is associated with higher cancer incidence, faster cancer progression, and shorter cancer patient survival. Patients with advanced lung cancer suffering greater circadian activity/sleep cycle disruption suffer greater interference with function, greater anxiety and depression, poorer nighttime sleep, greater daytime fatigue, and poorer quality of life than comparable patients who maintain good circadian integration. We must now determine whether strategies known to help synchronize the circadian clocks of normal individuals can do so in advanced cancer patients and whether doing so allows cancer patients to feel better and/or live longer. Several academic laboratories and at least 2 large pharmaceutical firms are screening for small molecules targeting the circadian clock to stabilize its phase and enhance its amplitude and thereby consolidate and coordinate circadian organization, which in turn is likely to help prevent and control human cancer. These drugs and strategies can, in turn, be used to make cancer patients with advanced disease feel and function more normally.

Circadian time-dependent tumor suppressor function of period genes.

The mammalian core clock genes, Periods (Per1 and Per2), have tumor suppressor properties. Decreased expression of Per1 and Per2 has been reported in several types of human cancers. On the other hand, overexpression of Per1 or Per2 inhibits cancer cell growth in culture. The authors have shown that downregulation of Per1 or Per2 enhances cancer growth in vitro. These genes also regulate the amount of cell proliferation-related molecules, many of which are therapeutic targets. In animals, tumors grow with clear circadian organization, and Per1 and Per2 exert their tumor suppressor functions in a circadian time-dependent manner. Downregulation of Per1 or Per2 increases tumor growth only at certain specific times of the day. Per1 and Per2 differentially regulate tumor growth rhythm in vivo. These data suggest that the therapeutic efficacy of antiproliferation agents depends on the time of day of drug delivery. The optimal times of day may be shifted in tumors that have mutant Period genes.

Clock genes and cancer.

Period genes ( Per2, Per1) are essential circadian clock genes. They also function as negative growth regulators. Per2 mutant mice show de novo and radiation-induced epithelial hyperplasia, tumors, and an abnormal DNA damage response. Human tumors show Period gene mutations or decreased expression. Other murine clock gene mutations are not associated with a tumor prone phenotype. Shift work and nocturnal light exposure are associated with circadian clock disruption and with increased cancer risk. The mechanisms responsible for the connection between the circadian clock and cancer are not well defined. We propose that circadian disruption per se is not uniformly tumor promoting and the mechanisms for tumor promotion by specific circadian clock disturbances will differ dependent upon the genes and pathways involved. We propose that Period clock gene mutations promote tumorigenesis by unique molecular pathways. Per2 and Per1 modulate beta-catenin and cell proliferation in colon and non-colon cancer cells. Per2 mutation increases intestinal beta-catenin levels and colon polyp formation. Per2 mutation also increases Apc(Min/+)-mediated intestinal and colonic polyp formation. Intestinal tumorigenesis per se may also alter clock function as a result of increased beta-catenin destabilizing PER2 protein. Levels and circadian rhythm of PER2 in Apc(Min/+) mouse intestine are markedly decreased, and selective abnormalities in intestinal clock gene and clock-controlled gene expression are seen. We propose that tumor promotion by loss of PERIOD clock proteins is unique to these clock genes as a result of altered beta-catenin signaling and DNA damage response. PERIOD proteins may offer new targets for cancer prevention and control.

American ginseng suppresses inflammation and DNA damage associated with mouse colitis.

Ulcerative colitis (UC) is a dynamic, idiopathic, chronic inflammatory condition associated with a high colon cancer risk. American ginseng has antioxidant properties and targets many of the players in inflammation. The aim of this study was to test whether American ginseng extract prevents and treats colitis. Colitis in mice was induced by the presence of 1% dextran sulfate sodium (DSS) in the drinking water or by 1% oxazolone rectally. American ginseng extract was mixed in the chow at levels consistent with that currently consumed by humans as a supplement (75 p.p.m., equivalent to 58 mg daily). To test prevention of colitis, American ginseng extract was given prior to colitis induction. To test treatment of colitis, American ginseng extract was given after the onset of colitis. In vitro studies were performed to examine mechanisms. Results indicate that American ginseng extract not only prevents but it also treats colitis. Inducible nitric oxide synthase and cyclooxygenase-2 (markers of inflammation) and p53 (induced by inflammatory stress) are also downregulated by American ginseng. Mucosal and DNA damage associated with colitis is at least in part a result of an oxidative burst from overactive leukocytes. We therefore tested the hypothesis that American ginseng extract can inhibit leukocyte activation and subsequent epithelial cell DNA damage in vitro and in vivo. Results are consistent with this hypothesis. The use of American ginseng extract represents a novel therapeutic approach for the prevention and treatment of UC.

Ginkgo biloba extract EGb 761 has anti-inflammatory properties and ameliorates colitis in mice by driving effector T cell apoptosis.

Ulcerative colitis is a dynamic, chronic inflammatory condition of the colon associated with an increased colon cancer risk. Ginkgo biloba is a putative antioxidant and has been used for thousands of years to treat a variety of ailments. The aim of this study was to test whether the standardized G.biloba extract, EGb 761, is an antioxidant that can be used to prevent and treat colitis in mice. Here, we show that EGb 761 suppresses the activation of macrophages and can be used to both prevent and treat mouse colitis. Markers of inflammation (iNOS, Cox-2 and tumor necrosis factor-alpha) and inflammatory stress (p53 and p53-phospho-serine 15) are also downregulated by EGb 761. Furthermore, we show that EGb 761 reduces the numbers of CD4+/CD25-/Foxp3- effector T cells in the colon. Interestingly, EGb 761 drives CD4+ effector T cell apoptosis in vitro and in vivo, providing a mechanistic explanation to the reduction in numbers of this cell type in the colon. This current study is in agreement with previous studies supporting a use of EGb 761 as a complementary and alternative strategy to abate colitis and associated colon cancer.

Seasonal modulation of post-resection breast cancer metastasis.

BACKGROUND: Human breast cancer incidence, histopathologic grade, invasiveness, and mortality risk vary significantly throughout each year. In order to better understand this seasonal cancer biology, we investigated the circannual pattern of post-resection breast cancer metastasis, under genetically and environmentally controlled conditions. METHODS: Over a span of 14 consecutive years, we conducted 22 similar experiments to investigate metastatic biology of breast cancer among 1,214 C3HeB/FeJ female mice. All mice were kept in temperature-controlled environment with 12 h light:12 h dark photoperiod, with food and water freely available, from birth until death. At 10-13 weeks of age, each mouse received 20,000 viable syngeneic mammary cancer cells subcutaneously and the tumor bearing leg was resected 10-12 days after tumor inoculation for potential cure. Once 10% of resected mice were found moribund, due to autopsy proven pulmonary metastases, all remaining mice were sacrificed and metastatic lung nodules were counted. RESULTS: The incidence of post-resection pulmonary metastasis was not randomly distributed throughout the year, but peaked prominently in Summer and Winter. Although tumor volume at resection was strongly associated with metastatic potential, a significantly higher probability of pulmonary metastasis was observed if surgery was performed in Summer and Winter, regardless of tumor volume at resection, compared to Spring and Fall. CONCLUSION: These results support the likelihood that human breast cancer seasonality is real and of biological origin. There are implications of this cancer chronobiology for breast cancer prevention, screening, diagnosis, and treatment.

Cancer chronomics III. Chronomics for cancer, aging, melatonin and experimental therapeutics researchers.

This position paper documents the merit of including for basic and clinical investigations the mapping of circadian and other rhythms and yet broader chronomes, time structures in and around us. Chronobiometry used herein relies on inferential statistical methods and on materials documented earlier. The circadian amplitude of melatonin is shown to relate both to cancer risk and to the presence of overt cancer, when no differences are found in the 24-hour average of melatonin. Optimization of treatment by timing, thoroughly documented along the circadian scale earlier, could be broadened to include optimization along the scale of the week, and eventually beyond. In both cases, reliance on marker rhythmometry is advocated. More generally, the limits of knowledge are expanded by considering already mapped spectral components and their characteristics that can be influenced by the dynamics of heliogeomagnetic signals heretofore unassessed.

Circadian timing in cancer treatment: the biological foundation for an integrative approach.

Despite the many innovations that have occurred in cancer treatment, the age-specific mortality for most adult tumors has remained stable during the past 30 years. There have been clinically significant improvements in the outcomes of young and middle-aged patients, yet the vast majority of cancer patients are more than 50 years of age, among whom we observe few improvements in clinical outcomes. Clearly, many of today's cytotoxic agents have been shown to be effective in-vitro and in animal model systems; however, few have proved efficacious in dramatically improving survival outcomes in adult cancer. There is now increasing evidence to suggest that the administration of cytotoxic agents, at the appropriate circadian phase, can significantly increase the therapeutic index of current cancer therapies.

Circadian chemotherapy for gynecological and genitourinary cancers.

The circadian timing of surgery, anticancer drugs, radiation therapy, and biologic agents can result in improved toxicity profiles, tumor control, and host survival. Optimally timed cancer chemotherapy with doxorubicin or pirarubicin (06:00h) and cisplatin (18:00h) enhanced the control of advanced ovarian cancer while minimizing side effects, and increased the response rate in metastatic endometrial cancer. Therapy of metastatic bladder cancer with doxorubicin-cisplatin was made more tolerable by this same circadian approach resulting in a 57% objective response rate. This optimally timed therapy is also effective in the adjuvant setting, decreasing the expected frequency of metastasis from locally advanced bladder cancer. Circadian fluorodeoxyuridine (FUDR) continuous infusion (70% of the daily dose given between 15:00h and 21:00h) has been shown effective for metastatic renal cell carcinoma resulting in 29% objective response and stable disease of more than 1 yr duration in the majority of patients. Toxicity is reduced markedly when FUDR infusion is modulated to circadian rhythms. In a multicenter trial in patients with metastatic renal cell cancer, patients were randomized to a flat or a circadian-modified FUDR infusion. This study confirmed a significant difference in toxicity and dose intensity, favoring the circadian-modified group. Hormone refractory metastatic prostate cancer has been treated with circadian-timed FUDR chemotherapy; however, without objective response. Biological agents such as interferon-alpha and IL-2 have shown low but effective disease control in metastatic renal cell cancer, however, with much toxicity. Each of these cytokines shows circadian stage dependent toxicity and efficacy in model systems. In summary, the timing of anthracycline, platinum, and fluoropyrimidine-based drug therapies during the 24h is relevant to the toxic therapeutic ratio of these agents in the treatment of gynecologic and genitourinary cancers.