Restraint stress reduces the antitumor efficacy of cyclophosphamide in tumor-bearing mice

Restraint stress abates the antioxidant potential of melatonin on dimethyl benz (a) anthracene (DMBA) induced carcinogenesis

Free radical involvement in initiation, promotion and progression of carcinogenesis, implicates that scavengers of free radicals may act as inhibitors in the carcinogenic process. Melatonin, an antioxidant was used in the present study to evaluate its effectiveness on skin carcinogenesis induced by DMBA both with and without chronic restraint stress (CRS). Fifty Swiss albino young male rats were divided into five groups of 10 rats each as controls, topical DMB alone, Pre CRS-DMBA, melatonin DMBA and Pre-CRS-DMBA-melatonin treated groups. After 18 weeks blood was collected along with liver and skin samples. These were used for antioxidant enzyme assay, DNA damage and fluorescent spectra analysis. Melatonin showed antioxidant potential in combatting DMBA induced skin carcinogenesis measured by free radical scavenging enzymes and in vivo antioxidant status, DNA damage. Sensitive detection of the DMBA induced micro biochemical changes was possible by fluorescent spectroscopy from the transformed ratio of fluorescent intensity (F1 530 nm/630 nm) otherwise found constant for normal tissues. By melatonin treatment this ratio was similar to control values. The decreased antioxidant biochemical parameters depicting oxidative stress were comparable to comet assay and fluorescent studies, endorsing the chemo-preventive efficacy of melatonin against skin carcinogenesis caused by DMBA. CRS pre-exposure diminished the chemo-preventive/antioxidant ability of melatonin and the results were same as DMBA alone treatment, showing stress affected both cancer development and chemoprevention. CRS decreased the antioxidant potential of melatonin. Hence, managing stress could be perceived in cancer chemoprevention. Further studies focusing on stress reduction are needed.

Stress hormone-mediated acceleration of breast cancer metastasis is halted by inhibition of nitric oxide synthase

Stress hormones have been shown to be important mediators in driving malignant growth and reducing treatment efficacy in breast cancer. Glucocorticoids can induce DNA damage through an inducible nitric oxide synthase (iNOS) mediated pathway to increase levels of nitric oxide (NO). Using an immune competent mouse breast cancer model and 66CL4 breast cancer cells we identified a novel role of NOS inhibition to reduce stress-induced breast cancer metastasis. On a mechanistic level we show that the glucocorticoid cortisol induces expression of keys genes associated with angiogenesis, as well as pro-tumourigenic immunomodulation. Transcriptomics analysis confirmed that in the lungs of tumour-bearing mice, stress significantly enriched pathways associated with tumourigenesis, some of which could be regulated with NOS inhibition. These results demonstrate the detrimental involvement of NOS in stress hormone signalling, and the potential future benefits of NOS inhibition in highly stressed patients.

Mechanisms underlying the effects of stress on tumorigenesis and metastasis (Review)

Stress is one of the fundamental survival mechanisms in nature. Although chronic or long-lasting stress can be detrimental to health, acute or short-term stress can have health benefits. The aim of the present review was to address the complexity and significance of stress in tumorigenesis. The review covers an evaluation of previously used and reported experimental animal models of stress, as well as the effects of stress on the neuroendocrine system, immune function, gut microbiota, and inflammation and multidrug resistance, all of which are closely associated with cancer occurrence, progression and treatment. The review concludes that understanding the efficacy of stress management (prevention and rehabilitation) is crucial to the development of comprehensive and individualized strategies for cancer prevention and treatment.

Neuroimmunology of Behavioral Comorbidities Associated With Cancer and Cancer Treatments

Behavioral comorbidities (depression, anxiety, fatigue, cognitive disturbances, and neuropathic pain) are prevalent in cancer patients and survivors. These mental and neurological health issues reduce quality-of-life, which is a significant societal concern given the increasing rates of long-term survival after various cancers. Hypothesized causes of behavioral comorbidities with cancer include tumor biology, stress associated with the cancer experience, and cancer treatments. A relatively recent leading mechanism by which these causes contribute to changes in neurobiology that underlie behavior is inflammation. Indeed, both basic and clinical research indicates that peripheral inflammation leads to central inflammation and behavioral changes in other illness contexts. Given the limitations of assessing neuroimmunology in clinical populations, this review primarily synthesizes evidence of neuroimmune and neuroinflammatory changes due to two components of cancer (tumor biology and cancer treatments) that are associated with altered affective-like or cognitive behaviors in rodents. Specifically, alterations in microglia, neuroinflammation, and immune trafficking to the brain are compiled in models of tumors, chemotherapy, and/or radiation. Evidence-based neuronal mechanisms by which these neuroimmune changes may lead to changes in behavior are proposed. Finally, converging evidence in clinical cancer populations is discussed.

Impact of stress on cancer metastasis

The influence of psychosocial factors on the development and progression of cancer has been a longstanding hypothesis since ancient times. In fact, epidemiological and clinical studies over the past 30 years have provided strong evidence for links between chronic stress, depression and social isolation and cancer progression. By contrast, there is only limited evidence for the role of these behavioral factors in cancer initiation. Recent cellular and molecular studies have identified specific signaling pathways that impact cancer growth and metastasis. This article provides an overview of the relationship between psychosocial factors, specifically chronic stress, and cancer progression.

Stress hormones mediate drug resistance to paclitaxel in human breast cancer cells through a CDK-1-dependent pathway

Chemotherapy comprises part of successful treatment regimens for breast cancer, however, up to 50% of patients develop resistance. Stress in cancer patients can equate to poor chemotherapeutic responses. We hypothesize that drug resistance may be associated with stress hormone-induced alterations in breast cancer cells. To test this hypothesis, MDA-MB-231 cells were cultured with paclitaxel and/or cortisol, norepinephrine and epinephrine and cytotoxicity, cell cycle analyses, genomic and proteomic analyses were performed. Paclitaxel-mediated cytotoxicity and G2/M cell cycle arrest were reversed significantly by stress hormones. Genomic and proteomic analyses revealed that stress hormones modulated beta-tubulin isotypes and significantly altered genes and proteins involved in regulation of the G2/M transition, including cyclin-dependent kinase-1 (CDK-1). Inhibition of CDK-1 abrogated stress hormone-mediated reversal of paclitaxel-induced cytotoxicity, indicating that the protective effect of stress hormones act through a CDK-1-dependent mechanism. These data demonstrate that stress hormones interfere with paclitaxel efficacy and contribute significantly to drug resistance.

Potential of a novel polysaccharide preparation (GLPP) from Anhui-grown Ganoderma lucidum in tumor treatment and immunostimulation

Growing evidence indicates the potential of developing novel polysaccharide-based adjuvant for tumor therapy from edible mushrooms, including Ganoderma lucidum. In the present study, a novel polysaccharide preparation (GLPP) was isolated from the fruiting body of G. lucidum grown in Anhui, China, and characterized for its physicochemical properties. GLPP had an average molecular weight of 6600 and a specific optical rotation of +25.6 degrees , contained 10.6% protein, and had a molar ratio of 0.9:15:1 for mannose, glucose, and galactose, respectively. GLPP was also investigated and compared with PSP (polysaccharopeptide preparation), a commercial antitumor and immunostimulating agent, for its antitumor and immunostimulation capacity, and potential in reducing the toxic effects induced by cyclophosphamide (Cy) treatment and Cobalt-60 ((60)Co) radiation in mice. GLPP at levels of 100 and 300 mg/kg body weight (BW)/d significantly inhibited the growth of inoculated S(180), Heps, and EAC tumor cells in mice. GLPP at a dose of 300 mg/kg BW/d showed stronger growth inhibition against all 3 tested tumor cells than PSP at 1 g/kg BW/d. GLPP also dose-dependently increased phagocytic index, phagocytic coefficient, and 50% hemolysin value in the EAC tumor-bearing mice, indicating its potential immunostimulating property. In addition, GLPP at 300 mg/kg BW/d was comparable to PSP at 1000 mg/kg BW/d in preventing the decrease of thymus index, spleen index, white blood cells, and bone marrow karyote numbers induced by Cy treatment and (60)Co radiation. These data demonstrated the potential utilization of GLPP as an adjuvant to conventional treatments of cancers and its use for cancer prevention.

Characterization and antitumor activity of pollen polysaccharide

The polysaccharide LBPP was extracted and isolated from the pollen of brassica napus L., and the antitumor activity was evaluated on Sarcoma 180-bearing mice and B16 melanoma-bearing mice through transplantable animal tumor. Mice were treated with three doses of the polysaccharide LBPP (50, 100 and 200 mg/kg body weight) for 10 days. Tumor weight, relative spleen and thymus weight, lymphocyte proliferation, natural killer cell activity, delayed type hypersensitivity (DTH), phagocytic function of monocyte, serum hemolysis antibody and peripheral blood of tumor-bearing mice were studied. At the doses of 100 and 200 mg/kg, a significant decrease (P<0.01) in tumor formation, a significant increase (P<0.05) in relative spleen and thymus weight, natural killer cell activity, phagocytic function of monocyte, lymphocyte proliferation, and serum hemolysis antibody, and a significant improvement of peripheral blood abnormality (P<0.05) and anemia (P<0.01) were observed. Results of these studies demonstrated that the polysaccharide LBPP had anti-tumor activity, which was mediated by immunomodulation and leukogenic and antianemic actions.

Temporal factors alter effects of social housing conditions on responses to chemotherapy and hormone levels in a Shionogi mammary tumor model

OBJECTIVE

To identify possible hormonal factors involved in the differential responses to chemotherapy observed in our tumor model, we investigated if the timing among tumor cell injection, rehousing, and chemotherapy administration differentially affects levels of corticosterone (CORT), growth hormone (GH), and testosterone and tumor and host responses to chemotherapy.

METHODS

Mice were reared either individually (I) or in groups (G). At 2 to 4 months, mice were injected with tumor cells and retained in their original housing conditions or rehoused into different experimental groups (GG, IG, II, GI) either immediately (experiment 1) or 14 days later (experiment 2); chemotherapy was administered when tumors weighed approximately 0.8 g.

RESULTS

In experiment 1, IG and GG mice had better responses to chemotherapy than GI mice. Chemotherapy increased CORT levels in II mice and decreased GH levels in GI mice compared with those of their drug vehicle-treated counterparts. Under the temporal conditions of experiment 2, IG and GG mice lost the advantage seen in experiment 1 in terms of tumor and host responses to chemotherapy. Before chemotherapy administration, CORT levels in IG mice and GH levels in GI mice were higher than those in mice in all other housing conditions. At 1 day after chemotherapy, CORT levels were higher for chemotherapy-treated than for drug vehicle-treated IG mice, and at 5 days post chemotherapy, GH levels were higher in GI than in IG mice.

CONCLUSIONS

Temporal relationships among tumor cell injection, rehousing, and chemotherapy administration critically influence responses to chemotherapy; these effects may be mediated, in part, by alterations in hormone levels.

Enhancement of pro-oxidant effect of 7,12-dimethylbenz (a) anthracene (DMBA) in rats by pre-exposure to restraint stress

The current study was designed to assess the effect of immobilization stress on liver toxicity induced by topical as well as oral administration of 7,12-dimethyl benz(a)anthracene (DMBA) in Swiss Albino rats. The experimental animals were divided into six groups. Group 1 animals were exposed to chronic restraint stress alone for 10 days (3h/day), shaved back of animals in group II were painted with 0.5% solution of DMBA twice a week for 4 weeks. Group III animals were first exposed to restraint stress similar to group I followed by DMBA application as in group II, group IV animals were orally administered four doses of 0.5% DMBA solution. (1ml/rat) at weekly intervals, while group V animals were first exposed to restraint stress as in group I followed by oral dose of DMBA similar to group IV. The untreated Group VI animals served as controls. Rats were sacrificed after a period of 4 weeks following DMBA administration. Biochemical measurements were carried out on liver tissues and serum/plasma of control and treated animals. Restraint stress was found to have marked effect on DMBA induced alteration of liver function as revealed by the increase in tissue marker enzymes viz glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), alkaline phosphatase (ALP), acid phosphatase (ACP), lactate dehydrogenase (LDH) with a significant further decrease in antioxidant enzymes catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST), glutathione reductase (GR) as compared to controls and DMBA alone(topical/oral) or stress alone treated rats. Increased lipid peroxidation was accompanied by a significant decrease in the level of total reduced glutathione (GSH). The changes in the levels of marker enzymes and in vivo antioxidants in serum/plasma were comparable to that of liver. The results of the present study indicate that immobilization stress markedly enhances DMBA induced alteration of liver and circulatory antioxidant status of the rats irrespective of the mode of DMBA administration though with a predominant effect on orally infused DMBA.

Enhanced Xenobiotic-Induced Hepatotoxicity and Kupffer Cell Activation by Restraint-Induced Stress

We tested the hypothesis that environmental stress is a predisposing factor for liver injury by examining the effect of acute restraint on liver injury provoked by carbon tetrachloride (CCl4) and allyl alcohol. Mice were immobilized using Plexiglas restraint cages, producing a form of psychogenic stress, whereas other animals were allowed to roam free. Serum alanine aminotransferase levels were elevated significantly in restrained animals after administration of varying doses of CCl4 or allyl alcohol that did not produce liver injury in unrestrained animals. This enhanced liver injury after CCl4 was seen in both male and female mice. The duration of acute restraint was found to be important because a period of 2.5 h of restraint enhanced hepatotoxicity, whereas shorter periods of restraint did not significantly increase liver injury. Serum corticosterone concentrations increased, whereas hepatic glutathione content decreased during and after acute restraint. In addition, delay in administration of CCl4 until 5 h after completion of restraint also produced an elevated level of liver injury compared with that seen in free roaming animals. Immunohistochemical examination of the livers showed significantly enhanced Kupffer cell activation in restrained mice compared with that of free roaming mice. These observations suggest that induction of psychogenic stress may increase the susceptibility to liver injury observed with classic hepatotoxicants and may represent an important predisposing factor to liver injury after xenobiotic exposure. The underlying mechanism seems to be increased macrophage activation in the liver, which may subsequently sensitize hepatocytes to xenobiotics and thus enhance hepatotoxicity.

Psychological stress induces chemoresistance in breast cancer by upregulating mdr1

Psychological distress reduces the efficacy of chemotherapy in breast cancer patients. The mechanism may be related to the altered neuronal or hormonal secretions during stress. Here, we reported that adrenaline, a hormone mediating the biological activities of stress, upregulates mdr1 gene expression in MCF-7 breast cancer cells via alpha(2)-adrenergic receptors in a dose-dependent manner. Mdr1 upregulation can be specifically inhibited by pretreatment with mdr1-siRNA. Consequently, adrenergic stimulation enhances the pump function of P-glycoprotein and confers resistance of MCF-7 cells to paclitaxel. In vivo, restraint stress increases mdr1 gene expression in the MCF-7 cancers that are inoculated subcutaneously into the SCID mice and provokes resistance to doxorubicin in the implanted tumors. The effect can be blocked by injection of yohimbine, an alpha(2)-adrenergic inhibitor, but not by metyrapone, a corticosterone synthesis blocker. Therefore, we conclude that breast cancers may develop resistance against chemotherapeutic drugs under psychological distress by over-expressing mdr1 via adrenergic stimulation.

Stress causes a further decrease in immunity to herpes simplex virus-1 in immunocompromised hosts

Physical or psychological stress can modulate immune responses in normal subjects. The effects of stress on immunity in immunocompromised hosts, however, have not been extensively investigated. Here we assess relationships among footshock stress (FS), infection with herpes simplex virus-1 (HSV-1), and immunosuppression by cyclophosphamide (CY) during the active immune response to virus in BALB/c mice. Without FS, CY significantly decreased survival and body weight gain, splenic leukocyte numbers, in vivo serum cytokine level and in vitro splenocyte cytokine production during HSV-1 infection. FS alone also significantly inhibited cell mediated anti-viral responses to HSV-1. However, FS in combination with certain CY doses led to a further significant decrease in host responses compared to either CY or FS treatment alone, including decreased survival rate, increased weight loss, lowered leukocyte numbers, reduced cytokine production in vivo and in vitro, and decreased numbers of cytokine-producing cells (IL-12 and IFNgamma). In contrast, CY, but not FS, significantly reduced in vivo anti-HSV-1 antibody secretion. These data support the hypothesis that stress can further reduce host immune responses in immunocompromised individuals. Thus, stress levels of patients should be taken into consideration prior to clinical treatment with immunosuppressants.

Noradrenergic responses of peripheral organs to cyclophosphamide in mice

To determine if the chemotherapeutic drug cyclophosphamide influences the activity of the sympathetic nervous system, the effects of cyclophosphamide on norepinephrine concentration in the heart, adrenal gland, spleen, and thymus gland were evaluated. Male BALB/cByJ mice were administered a single injection of cyclophosphamide (15, 50, or 100 mg/kg, i.p) or saline-vehicle. Organs were collected 72 or 120 h after injection and norepinephrine concentrations were determined by high pressure liquid chromatography with electrochemical detection. Cyclophosphamide reduced spleen, thymus gland, and heart mass while also elevating spleen and thymus gland norepinephrine concentrations (both pmoles/mg tissue and pmoles/mg protein) in a dose- and time-dependent manner. Norepinephrine concentrations in heart and adrenal gland were not altered by cyclophosphamide at any drug dose or time point. Dose- and time-dependent cyclophosphamide-mediated changes in peripheral norepinephrine levels in the spleen and thymus gland are interesting because subjects administered cyclophosphamide may be more susceptible to opportunistic infections, not only because the drug is antineoplastic, but also because the drug alters nervous system-immune system communication and the neurochemical milieu in which surviving cells interact.

Seasonal dependency of the effects of rotational stress and cyclophosphamide in mice bearing lewis lung carcinoma

The antitumor effects of cyclophosphamide were previously shown to be markedly reduced by the application of restraint stress in mice bearing Lewis lung carcinoma. The aim of this work was to determine the effects of rotational stress on the antitumor action of cyclophosphamide in the same animal-tumor system. Since the effects of rotational stress on metastasis were found to display a circannual rhythm, with a maximum in summer and a minimum in winter, the experiments were performed in June and February. Groups of 10 young female mice were kept under low stress housing conditions, with a 12-12 h light/dark cycle, starting 2 weeks before and during each experiment. Rotational stress caused an increase of metastasis volume to 361% of nonstressed controls in June and a decrease to 32.4% in February. In both seasons, the treatment with cyclophosphamide (240 mg/kg/day for 6 days) caused the absence of detectable metastasis at sacrifice in all mice; its combination with rotational stress caused the presence of metastases in similar proportions (6/10 and 10/10 for June vs February, respectively). The survival time of control mice was approximately twice as long in February as in June and was not appreciably modified by rotational stress; cyclophosphamide was similarly active in both seasons (4/10 and 6/10 long-term survivors for June vs February, respectively), and the number of long-term survivors was reduced to 0/10 in both seasons by rotational stress. The survival of the different experimental groups inversely correlated with the number of metastases as determined at sacrifice at the end of treatment and also with the number of CD3(+) and CD4(+) splenic T-lymphocyte subsets. These results do not appear to depend on the disruption of the circadian organization of the mice by rotational stress or by seasonal differences in cyclophosphamide activity. On the other hand, they can be interpreted assuming that cyclophosphamide reduces tumor metastasis and that T-lymphocyte-mediated immune responses of the host, amenable to modulation by stress and displaying seasonal differences uncoupled from circadian rhythms, further contribute to the tumor inhibitory effects of the drug. The observed differences in tumor metastasis caused by rotational stress and survival time in two different seasons, and the marked attenuation of cyclophosphamide antitumor action by rotational stress, appear of interest for their experimental and clinical implications.

Stress and chemotherapy. Combined effects on tumor progression and immunity in animal models

In mice bearing Lewis lung carcinoma, rotational and restraint stress specifically increases the formation of lung metastasis, and restraint stress markedly attenuates the antitumor effects of cyclophosphamide. The aim of this investigation was therefore to examine the effects of restraint stress on tumor metastasis in mice bearing MCa mammary carcinoma, and on the effectiveness of CCNU and DTIC. Restraint stress increases MCa mammary carcinoma metastasis, causes a marked reduction in cyclophosphamide activity, and a minor attenuation of the effects of CCNU and DTIC. The possible occurrence of seasonal factors, observed for the increase by rotational stress of Lewis lung carcinoma metastasis, was also determined for cyclophosphamide effectiveness. The survival time of control mice is longer in February than in June, and is not appreciably modified by rotational stress. The effects of cyclophosphamide are similar in both seasonal periods, and are similarly attenuated by rotational stress. The seasonal effects of rotational stress, and the reduction of the effects of cyclophosphamide caused by rotational stress, are accompanied by corresponding variations in the number of CD3+ and CD4+ splenic T-lymphocyte subsets and in the CD4+/CD8+ ratio, respectively. The reported effects of stress on tumor progression and on the effectiveness of cyclophosphamide thus appear to occur via modulation of immune responses of the host directed against the tumor. These data appear of interest for their experimental implications, and suggest the opportunity to consider the role that the stress during treatment may play in determining the effectiveness of clinical antitumor chemotherapy.

Oncology in neuroimmunomodulation. What progress has been made?

In 1987 in Dubrovnik, Yugoslavia, N.H. Spector named a new discipline: Neuroimmunomodulation. R. Ader called this new discipline psychoneuroimmunomodulation when the major emphysis was on its behavioral aspects. Neuroimmunomodulation (NIM) is devoted to the study of the interactions at different morphologic and functional levels among the immune, nervous, and endocrine systems. In fact, this science is the modern manifestation of an old science: in the words of B.D. Jankovic (1987), "Neuroimmunomodulation is a modern reflection in neurosciences and immunosciences of the ideas and experience of philosophers and ingenious observers of ancient Egypt, Greece, China, India, and other civilizations that the mind is involved in the defense against diseases." Twelve years ago NIM was regarded by many conventional scientists almost as a form of witchcraft. Today it may be the fastest growing area of biomedical science research in the world. Important clinical applications will not be far behind. NIM research has also progressed in the field of oncology research. Topics such as treatment of hormone-dependent cancer with analogues of hypothalamic hormones, the role of opioids and T cells in cancer, stress-cancer-immune connections, the anticancer role of melatonin and cytokines, immunotherapy of cancer, and the role of psychotherapy in cancer patients represent some lines of research that have been or are being investigated by scientists. Some areas remain to be thoroughly investigated such as the influence of physical exercise (sports), music (classical or modern), and/or relaxation techniques (e.g. yoga) on the development of human cancer. This paper reviews the role of NIM in oncology and provides some perspectives for further research and development of clinical applications.