Melatonin decreases bone marrow and lymphatic toxicity of adriamycin in mice bearing TLX5 lymphoma

Modulation Effect on Tubulin Polymerization, Cytotoxicity and Antioxidant Activity of 1H-Benzimidazole-2-Yl Hydrazones

1H-benzimidazol-2-yl hydrazones with varying hydroxy and methoxy phenyl moieties were designed. Their effect on tubulin polymerization was evaluated in vitro on porcine tubulin. The compounds elongated the nucleation phase and slowed down the tubulin polymerization comparably to nocodazole. The possible binding modes of the hydrazones with tubulin were explored by molecular docking at the colchicine binding site. The anticancer activity was evaluated against human malignant cell lines MCF-7 and AR-230, as well as against normal fibroblast cells 3T3 and CCL-1. The compounds demonstrated a marked antineoplastic activity in low micromolar concentrations in both screened in vitro tumor models. The most active were the trimethoxy substituted derivative 1i and the positional isomers 1j and 1k, containing hydroxy and methoxy substituents: they showed IC₅₀ similar to the reference podophyllotoxin in both tumor cell lines, accompanied with high selectivity towards the malignantly transformed cells. The compounds exerted moderate to high ability to scavenge peroxyl radicals and certain derivatives-1l containing metha-hydroxy and para-methoxy group, and 1b-e with di/trihydroxy phenyl moiety, revealed HORAC values high or comparable to those of well-known phenolic antioxidants. Thus the 1H-benisimidazol-2-yl hydrazones with hydroxy/methoxy phenyl fragments were recognized as new agents exhibiting promising combined antioxidant and antineoplastic action.

Potential role of melatonin in prevention and treatment of leukaemia

Leukaemia is a haematological malignancy originated from the bone marrow. Studies have shown that shift work could disrupt the melatonin secretion and eventually increase leukaemia incidence risk. Melatonin, a pineal hormone, has shown promising oncostatic properties on a wide range of cancers, including leukaemia. We first reviewed the relationship between shift work and the incidence rate of leukaemia and then discussed the role of melatonin receptors (MT1 and MT2) and their functions in leukaemia. Moreover, the connection between inflammation and leukaemia, and melatonin-induced anti-leukaemia mechanisms including anti-proliferation, apoptosis induction and immunomodulation are comprehensively discussed. Apart from that, the synergistic effects of melatonin with other anticancer compounds are also included. In short, this review article has compiled the evidence of anti-leukaemia properties displayed by melatonin and discuss its potential to act as adjunct for anti-leukaemia treatment. This review may serve as a reference for future studies or experimental research to explore the possibility of melatonin serving as a novel therapeutic agent for leukaemia.

Role of the Transcription Factor Yin Yang 1 and Its Selectively Identified Target Survivin in High-Grade B-Cells Non-Hodgkin Lymphomas: Potential Diagnostic and Therapeutic Targets

B-cell non-Hodgkin lymphomas (B-NHLs) are often characterized by the development of resistance to chemotherapeutic drugs and/or relapse. During drug-induced apoptosis, Yin Yang 1 (YY1) transcription factor might modulate the expression of apoptotic regulators genes. The present study was aimed to: (1) examine the potential oncogenic role of YY1 in reversing drug resistance in B-NHLs; and (2) identify YY1 transcriptional target(s) that regulate the apoptotic pathway in B-NHLs. Predictive analyses coupled with database-deposited data suggested that YY1 binds the promoter of the BIRC5/survivin anti-apoptotic gene. Gene Expression Omnibus (GEO) analyses of several B-NHL repositories revealed a conserved positive correlation between YY1 and survivin, both highly expressed, especially in aggressive B-NHLs. Further validation experiments performed in Raji Burkitt’s lymphomas cells, demonstrated that YY1 silencing was associated with survivin downregulation and sensitized the cells to apoptosis. Overall, our results revealed that: (1) YY1 and survivin are positively correlated and overexpressed in B-NHLs, especially in BLs; (2) YY1 strongly binds to the survivin promoter, hence survivin may be suggested as YY1 transcriptional target; (3) YY1 silencing sensitizes Raji cells to drug-induced apoptosis via downregulation of survivin; (4) both YY1 and survivin are potential diagnostic markers and therapeutic targets for the treatment of resistant/relapsed B-NHLs.

Deciphering the Molecular Basis of Melatonin Protective Effects on Breast Cells Treated with Doxorubicin: TWIST1 a Transcription Factor Involved in EMT and Metastasis, a Novel Target of Melatonin

Melatonin mitigates cancer initiation, progression and metastasis through inhibition of both the synthesis of estrogens and the transcriptional activity of the estradiol-ER (Estrogen receptor) complex in the estrogen-dependent breast cancer cell line MCF-7. Moreover, melatonin improves the sensitivity of MCF-7 to chemotherapeutic agents and protects against their side effects. It has been described that melatonin potentiates the anti-proliferative effects of doxorubicin; however, the molecular changes involving gene expression and the activation/inhibition of intracellular signaling pathways remain largely unknown. Here we found that melatonin enhanced the anti-proliferative effect of doxorubicin in MCF-7 but not in MDA-MB-231 cells. Strikingly, doxorubicin treatment induced cell migration and invasion, and melatonin effectively counteracted these effects in MCF-7 but not in estrogen-independent MDA-MB-231 cells. Importantly, we describe for the first time the ability of melatonin to downregulate TWIST1 (Twist-related protein 1) in estrogen-dependent but not in estrogen-independent breast cancer cells. Combined with doxorubicin, melatonin inhibited the activation of p70S6K and modulated the expression of breast cancer, angiogenesis and clock genes. Moreover, melatonin regulates the levels of TWIST1-related microRNAs, such as miR-10a, miR-10b and miR-34a. Since TWIST1 plays a pivotal role in the epithelial to mesenchymal transition, acquisition of metastatic phenotype and angiogenesis, our results suggest that inhibition of TWIST1 by melatonin might be a crucial mechanism of overcoming resistance and improving the oncostatic potential of doxorubicin in estrogen-dependent breast cancer cells.

Melatonin: does it have utility in the treatment of haematological neoplasms?

Melatonin, discovered in 1958 in the bovine pineal tissue, is an indoleamine that modulates circadian rhythms and has a wide variety of other functions. Haematological neoplasms are the leading cause of death in children and adolescents throughout the world. Research has demonstrated that melatonin is a low-toxicity protective molecule against experimental haematological neoplasms, but the mechanisms remain poorly defined. Here, we provide an introduction to haematological neoplasms and melatonin, especially as they relate to the actions of melatonin on haematological carcinogenesis. Secondly, we summarize what is known about the mechanisms of action of melatonin in the haematological system, including its pro-apoptotic, pro-oxidative, anti-proliferative and immunomodulatory actions. Thirdly, we discuss the advantages of melatonin in combination with other drugs against haematological malignancy, as well as its other benefits on the haematological system. Finally, we summarize the findings that are contrary to the suppressive effects of melatonin on cancers of haematological origin. We hope that this information will be helpful in the design of studies related to the therapeutic efficacy of melatonin in haematological neoplasms. LINKED ARTICLES: This article is part of a themed section on Recent Developments in Research of Melatonin and its Potential Therapeutic Applications. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v175.16/issuetoc.

Sex-dependent alteration of cardiac cytochrome P450 gene expression by doxorubicin in C57Bl/6 mice

BACKGROUND

There is inconclusive evidence about the role of sex as a risk factor for doxorubicin (DOX)-induced cardiotoxicity. Recent experimental studies have shown that adult female rats are protected against DOX-induced cardiotoxicity. However, the mechanisms of this sexual dimorphism are not fully elucidated. We have previously demonstrated that DOX alters the expression of several cytochrome P450 (CYP) enzymes in the hearts of male rats. Nevertheless, the sex-dependent effect of DOX on the expression of CYP enzymes is still not known. Therefore, in the present study, we determined the effect of acute DOX exposure on the expression of CYP genes in the hearts of both male and female C57Bl/6 mice.

METHODS

Acute DOX cardiotoxicity was induced by a single intraperitoneal injection of 20 mg/kg DOX in male and female adult C57Bl/6 mice. Cardiac function was assessed 5 days after DOX exposure by trans-thoracic echocardiography. Mice were euthanized 1 day or 6 days after DOX or saline injection. Thereafter, the hearts were harvested and weighed. Heart sections were evaluated for pathological lesions. Total RNA was extracted and expression of natriuretic peptides, inflammatory and apoptotic markers, and CYP genes was measured by real-time PCR.

RESULTS

Adult female C57Bl/6 mice were protected from acute DOX-induced cardiotoxicity as they show milder pathological lesions, less inflammation, and faster recovery from DOX-induced apoptosis and DOX-mediated inhibition of beta-type natriuretic peptide. Acute DOX exposure altered the gene expression of multiple CYP genes in a sex-dependent manner. In 24 h, DOX exposure caused male-specific induction of Cyp1b1 and female-specific induction of Cyp2c29 and Cyp2e1.

CONCLUSIONS

Acute DOX exposure causes sex-dependent alteration of cardiac CYP gene expression. Since cardiac CYP enzymes metabolize several endogenous compounds to biologically active metabolites, sex-dependent alteration of CYP genes may play a role in the sexual dimorphism of acute DOX-induced cardiotoxicity.

Preclinical combination therapy of the investigational drug NAMI-A(+) with doxorubicin for mammary cancer

AIM OF THE STUDY

The tumor metastases targeting ruthenium complex NAMI-A synergistically improves the activity of gemcitabine in combination therapies. High-throughput screening was used to identify other potential drug combinations from a library of FDA approved drugs. Doxorubicin was identified as a hit compound and was therefore evaluated in combination with NAMI-A in vitro and in a preclinical in vivo model.

RESULTS

High-throughput screening identified eight structurally diverse compounds that synergize with NAMI-A including doxorubicin. The combination index on MCF-7 cells showed synergism as the concentration of NAMI-A increases independent of the doxorubicin concentration. In MCa mammary carcinoma of CBA mice, NAMI-A (35 mg/kg/day i.p. on days 7-12) followed by doxorubicin (10 mg/kg i.p. on day 16), significantly increased the effects of the individual drugs on metastases with 70 % animals resulting free of macroscopically detectable tumor nodules in the lungs at sacrifice. NAMI-A, unlike doxorubicin, cured 60 % of the treated mice but the combination therapy was toxic to the animals.

CONCLUSIONS

The combined therapy of NAMI-A with doxorubicin synergizes on lung metastasis in a preclinical mouse model. The combination therapy at the maximum tolerated doses of the two drugs is toxic. Hence, this combination is not suitable for clinical studies using maximum tolerated doses.

Melatonin anticancer effects: review

Melatonin (N-acetyl-5-methoxytryptamine, MLT), the main hormone produced by the pineal gland, not only regulates circadian rhythm, but also has antioxidant, anti-ageing and immunomodulatory properties. MLT plays an important role in blood composition, medullary dynamics, platelet genesis, vessel endothelia, and in platelet aggregation, leukocyte formula regulation and hemoglobin synthesis. Its significant atoxic, apoptotic, oncostatic, angiogenetic, differentiating and antiproliferative properties against all solid and liquid tumors have also been documented. Thanks, in fact, to its considerable functional versatility, MLT can exert both direct and indirect anticancer effects in factorial synergy with other differentiating, antiproliferative, immunomodulating and trophic molecules that form part of the anticancer treatment formulated by Luigi Di Bella (Di Bella Method, DBM: somatostatin, retinoids, ascorbic acid, vitamin D3, prolactin inhibitors, chondroitin-sulfate). The interaction between MLT and the DBM molecules counters the multiple processes that characterize the neoplastic phenotype (induction, promotion, progression and/or dissemination, tumoral mutation). All these particular characteristics suggest the use of MLT in oncological diseases.

Amelioration of doxorubicin-induced myocardial oxidative stress and immunosuppression by grape seed proanthocyanidins in tumour-bearing mice

We have investigated the protective effects of grape seed proanthocyanidins on doxorubicin-induced toxicity in tumour-bearing mice. The intraperitoneal administration of doxorubicin (2 mg kg−1 every other day, cumulative dosage for 18 mg kg−1) significantly inhibited the growth of sarcoma 180, and induced myocardial oxidative stress with decreased superoxide dismutase and glutathione peroxidase activity while increasing malondialdehyde formation in the heart or serum. Doxorubicin-induced myocardial oxidative stress also reduced lactate dehydrogenase and creatine kinase activity in the heart and elevated their levels in the serum. Doxorubicin also affected immune functions of tumour-bearing mice with significantly decreased interleukin-2 (IL-2) and interferon-γ (INF-γ) production, and slightly decreased natural killer (NK) cell cytotoxicity, lymphocyte proliferation and CD4+/CD8+ ratio. It markedly increased the percentages of cytotoxic T cells (CD3+CD8+), helper T cells (CD3+CD4+), IL-2R+CD4+, and IL-2R+ cells as compared with untreated tumour-bearing mice. The intragastric administration of proanthocyanidin (200 mg kg−1 daily) significantly inhibited tumour growth, and increased NK cell cytotoxicity, lymphocyte proliferation, CD4+/CD8+ ratio, IL-2 and INF-γ production. Moreover, proanthocyanidin strongly enhanced the anti-tumour effect of doxorubicin and the above immune responses, and completely eliminated myocardial oxidative stress induced by doxorubicin. In conclusion, intragastric administration of proanthocyanidin could enhance the anti-tumour activity of doxorubicin and ameliorate doxorubicin-induced myocardial oxidative stress and immunosuppression in tumour-bearing mice.

The role of melatonin in immuno-enhancement: potential application in cancer

Melatonin, a neurohormone produced mainly by the pineal gland, is a modulator of haemopoiesis and of immune cell production and function, both in vivo and in vitro. Physiologically, melatonin is associated with T-helper 1 (Th1) cytokines, and its administration favours Th1 priming. In both normal and leukaemic mice, melatonin administration results in quantitative and functional enhancement of natural killer (NK) cells, whose role is to mediate defenses against virus-infected and cancer cells. Melatonin appears to regulate cell dynamics, including the proliferative and maturational stages of virtually all haemopoietic and immune cells lineages involved in host defense - not only NK cells but also T and B lymphocytes, granulocytes and monocytes - in both bone marrow and tissues. In particular, melatonin is a powerful antiapoptotic signal promoting the survival of normal granulocytes and B lymphocytes. In mice bearing mid-stage leukaemia, daily administration of melatonin results in a survival index of 30-40% vs. 0% in untreated mice. Thus, melatonin seems to have a fundamental role as a system regulator in haemopoiesis and immuno-enhancement, appears to be closely involved in several fundamental aspects of host defense and has the potential to be useful as an adjuvant tumour immunotherapeutic agent.

Salubrious effects of lipoic acid against adriamycin-induced clastogenesis and apoptosis in Wistar rat bone marrow cells

Adriamycin (ADR), an anthracycline antibiotic, which is widely used as an antineoplastic drug in the treatment of various solid tumors, has been shown to induce genotoxicity in erythropoietic system. The aim of the present study was to investigate the protective efficacy of DL-alpha-lipoic acid (LA) on ADR-induced clastogenicity and apoptosis in the bone marrow of rats. The animals were randomly divided into eight groups consisting of six rats each. Five groups were administered ADR (20 mg/kg body weight, i.v.) to induce genotoxicity; four of these groups received a single intraperitoneal injection of LA at a dose of either 100 or 200 mg/kg body weight, and either 30 or 60 min prior to ADR administration. A vehicle treated control group and LA control groups were also included. The beneficial effects of LA were monitored by DNA strand breaks, chromosomal aberrations, micronucleus assay and apoptotic studies in the bone marrow cells of rats after 24 h following single dose of ADR treatment. ADR treatment caused significant clastogenicity and apoptosis in rat bone marrow cells. The treatment with LA showed significant reduction in the frequency of chromosomal aberrations, DNA strand breaks and apoptosis in bone marrow cells as well as decreased the micronuclei formation in bone marrow and peripheral blood of rats treated with ADR. The protective effect of LA was found to be stronger at a dose of 200 mg/kg body weight than 100 mg/kg body weight dosage with respect to the above results, indicating the dose dependent effect of LA. However, the protection by LA was not dependent on the time intervals between LA and ADR administration. The results of this study illustrate the protective effect of LA on ADR-induced clastogenicity and apoptosis in the erythropoietic system of rats.

Effects of melatonin in reducing the toxic effects of doxorubicin

Anthracycline antibiotics, such as doxorubicin and daunorubicin, constitute a group of wide spectrum therapeutic agents. Application of these drugs in chemotherapy is limited because of their toxic effects. Melatonin, the main secretory product of pineal gland, was recently found as a free radical scavenger and antioxidant. We decided to evaluate the tissue protective effect of melatonin against toxic effects of doxorubicin in six groups of rats. Rats were given doxorubicin (Dx) (45 mg/kg dose), melatonin (MEL) (10 mg/kg), first doxorubicin and then melatonin (DM), first melatonin and then doxorubicin (MD). The degree of kidney, lung, liver and brain cells' alterations were examined biochemically. In doxorubicin-treated group, malondialdehyde (MDA) levels of kidney, lung, liver and brain tissues were significantly increased but glutathione (GSH) levels were decreased compared to control rats. In the group in which first doxorubicin and then melatonin were given, MDA levels were significantly decreased compared to the doxorubicin-treated group. In doxorubicin-treated group, serum levels of creatinine, uric acid, blood urea nitrogen (BUN), Gamma-glutamyl transpeptidase (GGT) and Lactic acid dehydrogenase (LDH) were significantly increased while serum albumin and total protein levels were significantly decreased compared to control rats. Melatonin decreased the intensity of the changes produced by the administration of doxorubicin alone. Melatonin was quite efficient in reducing the formation of lipid peroxidation, restoring the tissue GSH contents and alterations of serum levels.

Effects of melatonin and vitamin E on oxidative-antioxidative status in rats exposed to irradiation

Bone marrow is known to be particularly susceptible to radiation. In this study, the effects of treatment with Vitamin E and melatonin and irradiation-induced lipid peroxidation and its association with antioxidant enzymes in the total bone (bone and bone marrow) and skeletal muscle of rats subjected to total body irradiation was investigated. Wistar-Albino rats were intraperitoneally treated with 100mg/kg Vitamin E or melatonin before exposure to 720cGy irradiation. Control, irradiation, Vitamin E plus irradiation, melatonin plus irradiation groups were sacrificed by decapitation under ether anaesthesia on the 10th day after irradiation exposure. Application of total body irradiation elevated malondialdehyde (MDA) levels in rat skeletal muscle (p<0.001), but glutathione peroxidase (GSH-Px) and catalase activities remained unchanged. Application of Vitamin E with irradiation or melatonin decreased the MDA levels in skeletal muscle (p<0.01), but did not affect the GSH-Px and catalase activity. MDA levels were found elevated in total bone (p<0.001), GSH-Px activity decreased (p<0.001) and catalase activity remained unchanged in the group treated with irradiation. Application of Vitamin E with irradiation increased the GSH-Px activity in total bone (p<0.01), but the activity of MDA and catalase remained unchanged. Treatment of the animals with melatonin concurrent with total body irradiation reduced the degree of lipid peroxidation and elevation in antioxidant enzymes in total bone (p<0.01). We conclude that melatonin may protect the total bone from the damaging effects of irradiation exposure, and its actions protect total bone from oxidative stress. However, protective effects of Vitamin E were not observed in this study.

Proanthocyanidin from grape seeds potentiates anti-tumor activity of doxorubicin via immunomodulatory mechanism

The purpose of this study was to investigate the anti-tumor activities of proanthocyanidin (PA) from grape seeds and doxorubicin (DOX) in vitro as well as in vivo, either alone or in combination and to explore the immunomodulatory mechanism in tumor-bearing mice. PA (12.5 approximately 200 mg/l) or DOX (0.01 approximately 1 mg/l) for 24 h significantly inhibited YAC-1 cell proliferation (IC(50) 57.53 or 0.198 mg/l, respectively) in a concentration-dependent manner using microculture tetrazolium (MTT) assay. Meanwhile, a combination of PA (12.5, 25 mg/l) with DOX strongly inhibited cell proliferation with IC(50) values of DOX decreasing by 0.09 and 0.045 mg/l, respectively. In mouse tumor xenograft models, intraperitoneal administrations of PA (10 mg/kg) daily or DOX (2 mg/kg) every other day for 9 days significantly inhibited the growth of sarcoma 180, whereas a combination of the two strongly inhibited tumor growth as compared with PA or DOX alone (p<0.01). In contrast to PA treatment, DOX inhibited Con A-stimulated lymphocyte proliferation, IL-2 and IFN-gamma productions, NK cell cytotoxicity and CD4+/CD8+ ratio, while the administration of PA combined with DOX significantly enhanced the above immune responses as compared with the tumor-bearing control (p<0.01). Taken together, these results suggest that PA has anti-tumor activity and increases the anti-tumor activity of DOX, and the mechanism might be related partially to immunopotentiating activities through the enhancements of lymphocyte proliferation, NK cell cytotoxicity, CD4+/CD8+ ratio, IL-2 and IFN-gamma productions.

Does melatonin play a disease-promoting role in rheumatoid arthritis?

The pineal neurohormone melatonin (MLT) has been widely shown to exert an immunostimulatory and antiapoptotic role, mainly by acting on Th cells and on T and B cell precursors, respectively. Thus, MLT might favor or promote autoimmune diseases by acting directly on immature and mature immunocompetent cells. In fact, preclinical and clinical evidence point to a disease-promoting role of MLT in rheumatoid arthritis (RA). MLT, whose concentration is increased in serum from RA patients, may act systemically or locally in the inflamed joints. The circadian secretion of MLT with a peak level during the night hours might be strictly correlated with the peculiar daily rhythmicity of the RA symptoms. In rat studies employing Freund's complete mycobacterial adjuvant (FCA) as a model of rheumatoid arthritis, pinealectomized rats turned arthritic and exhibited a significantly less pronounced inflammatory response, which was restored to normal by a low MLT dose and was aggravated by a pharmacological MLT dose, that augmented the inflammatory and immune response. Continued investigation will refine our understanding of these observations, which will possibly translate into improved therapeutic approaches.

Melatonin stimulates the activity of protective antioxidative enzymes in myocardial cells of rats in the course of doxorubicin intoxication

The study aimed at determining the effect of melatonin on the activity of protective antioxidative enzymes in the heart and of lipid peroxidation products in the course of intoxication with doxorubicin (DOX). The rats were categorized into four groups, receiving: 0.9% NaCl i.p. (NaCl control); melatonin [20 mg/kg body weight (b.w.)] s.c. (control Mel); DOX (2.5 mg/kg b.w.) i.p.; melatonin plus DOX in doses as above. All the substances were administered once in a week for four consecutive weeks. Homogenates of heart tissue were examined for activities of glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), levels of reduced glutathione (GSH) and of lipid peroxidation indices (MDA + 4-HDA). Administration of melatonin alone did not induce alterations in levels of MDA + 4-HDA, GSH, or in activity of GPx, SOD or CAT, as compared to the group receiving 0.9% NaCl. GSH levels decreased following DOX but remained at normal levels following DOX and melatonin. The level of MDA + 4-HDA increased following DOX, as compared with the control, a change prevented by the combination of DOX + melatonin. Activities of GPx, SOD and CAT were higher in groups receiving DOX and/or DOX plus melatonin than in control groups. Activity of CAT and the level of GSH in the group receiving DOX plus melatonin were significantly higher than in the group intoxicated with DOX alone. The obtained results demonstrate that, when given in parallel with DOX, melatonin protects cardiomyocytes from damaging effects of the cytostatic drug (reflected by the levels of MDA + 4-HDA). The protective effect resulted, in part from the augmented levels of GSH and from stimulation of CAT activity by melatonin in cardiomyocytes subjected to the action of DOX.

Melatonin: reducing the toxicity and increasing the efficacy of drugs

Melatonin (N-acetyl-5-methoxytryptamine) is a molecule with a very wide phylogenetic distribution from plants to man. In vertebrates, melatonin was initially thought to be exclusively of pineal origin recent studies have shown, however, that melatonin synthesis may occur in a variety of cells and organs. The concentration of melatonin within body fluids and subcellular compartments varies widely, with blood levels of the indole being lower than those at many other sites. Thus, when defining what constitutes a physiological level of melatonin, it must be defined relative to a specific compartment. Melatonin has been shown to have a variety of functions, and research in the last decade has proven the indole to be both a direct free radical scavenger and indirect antioxidant. Because of these actions, and possibly others that remain to be defined, melatonin has been shown to reduce the toxicity and increase the efficacy of a large number of drugs whose side effects are well documented. Herein, we summarize the beneficial effects of melatonin when combined with the following drugs: doxorubicin, cisplatin, epirubicin, cytarabine, bleomycin, gentamicin, ciclosporin, indometacin, acetylsalicylic acid, ranitidine, omeprazole, isoniazid, iron and erythropoietin, phenobarbital, carbamazepine, haloperidol, caposide-50, morphine, cyclophosphamide and L-cysteine. While the majority of these studies were conducted using animals, a number of the investigations also used man. Considering the low toxicity of melatonin and its ability to reduce the side effects and increase the efficacy of these drugs, its use as a combination therapy with these agents seems important and worthy of pursuit.

Role of exogenous melatonin in reducing the nephrotoxic effect of daunorubicin and doxorubicin in the rat

The aim of these studies was to examine the nephroprotective effect of melatonin following the anthracycline administration [daunorubicin (DNR); doxorubicin (DOX)] in rats. Application of these drugs in chemotherapy is limited because of their cardiotoxicity and nephrotoxicity. Rats of the Buffalo strain were divided into groups according to the cytostatic drug used, its dose and sequence of administration [DNR or DOX single (i.v.) dose of 10 mg/kg b.w., i.e. acute intoxication and 3 mg/kg b.w. (i.v.) weekly for 3 wk, subchronic intoxication]. Melatonin was administered subcutaneously before and after every injection of a cytostatic drug at a dose of 10 mg/kg b.w. The severity of renal alterations was examined both biochemically [levels of lipid peroxidation markers, malonyldialdehyde (MDA) and 4-hydroxyalkenals (4-HDA)], or histologically. A statistically significant decrease in renal damage was noted after melatonin administration to acutely or subchronically intoxicated DNR-treated and DOX-treated rats. Biochemical assays revealed significant decreases in MDA and 4-HDA levels following application of melatonin during subchronic DNR or DOX intoxication. In summary, melatonin was found to exert a protective effect on the kidney, which was particularly evident after subchronic DOX and DNR intoxication, using both histological or biochemical methods.

Role of exogenous melatonin in reducing the cardiotoxic effect of daunorubicin and doxorubicin in the rat

The aim of the studies was to examine the cardioprotective effect of melatonin during the anthracycline administration (daunorubicin, doxorubicin) in rats. Application of these drugs in chemotherapy is limited because of their cardiotoxicity. Rats of Buffalo strain were divided into groups according to the cytostatic drug used, its dose and sequence of administration (single intravenous [i.v.] dose of 10 mg/kg b.w., i.e., acute intoxication; 3 mg/kg b.w. weekly for 3 weeks, subchronic intoxication). Melatonin was administered subcutaneously before and after every injection of a cytostatic drug at a dose of 10 mg/kg b.w. The degree of cardiac muscle cell alterations was examined either histologically (Mean Total Score technique and the Billingham scale), or biochemically (levels of lipid peroxidation markers, malonyldialdehyde, and 4-hydroxyalkenals). Statistically significant decrease in cardiac muscle cell damage was noted with an aid of the Billingham scale after melatonin administration in acutely intoxicated doxorubicin-treated rats (p < 0.001). The similar phenomenon was observed using the Mean Total Score technique in case of acute daunorubicin or doxorubicin (p < 0.01 and p < 0.001, respectively) intoxications. A significant reduction in cardiac muscle cell lesions was detected either by the Billingham scale or by the Mean Total Score technique during subchronic intoxication with either of the anthracyclines when melatonin was given. Biochemical assays revealed significant decreases in malonyldialdehyde and 4-hydroxyalkenals levels following application of melatonin during either acute doxorubicin (p < 0.05) or subchronic daunorubicin (p < 0.01) intoxication. In summary, melatonin was found to exert a protective effect on the cardiac muscle cells, which was particularly evident after acute doxorubicin or subchronic daunorubicin intoxication, using either histological or biochemical methods.

Cyclophosphamide plus somatostatin, bromocriptin, retinoids, melatonin and ACTH in the treatment of low-grade non-Hodgkin's lymphomas at advanced stage: results of a phase II trial

PURPOSE

Somatostatin, prolactin, retinoids, melatonin and ACTH have been shown to influence the lymphatic growth, and the action of the cyclophosphamide in lymphoproliferative disorders is well known. This provided the rationale to conduct, in patients with low-grade non-Hodgkin's lymphomas (NHL), a phase II trial of a combined association of cyclophosphamide, somatostatin, bromocriptin, retinoids, melatonin and ACTH.

PATIENTS AND METHODS

Twenty patients with a diagnosis of low-grade NHL, stage III or IV, were included in this study. Patients received for one month the following treatment: cyclophosphamide, somatostatin, bromocriptin, retinoids, melatonin, and ACTH. The therapy was continued for two additional months in patients with stable or responding disease. After three months, the responding patients continued the therapy for three months and more.

RESULTS

Twenty patients were assessable for toxicity and response; 70% (14 of 20 patients; 95% confidence interval [CI], 50% to 90%) had a partial response; 20% (4 of 20) had stable disease, and 10% (2 of 20) progressed on therapy. Going on with the treatment, none of the 14 patients with partial response had a disease progression (average follow-up time of 21 months, range, 7 to 25), and 50% of these patients had a complete response; among 4 patients with stable disease, 25% (1 of 4) had a partial response and 75% (3 of 4) progressed on therapy (mean time to progression [TTP] 14.3 months, range, 7 to 21). The toxicity was very mild, the most common side effects being drowsiness, diarrhea and hyperglycemia.

CONCLUSIONS

The association of cyclophosphamide, somatostatin, bromocriptin, retinoids, melatonin, and ACTH is well tolerated and effective in treatment of low-grade NHL at advanced stage.

The immunotherapeutic potential of melatonin

The interaction between the brain and the immune system is essential for the adaptive response of an organism against environmental challenges. In this context, the pineal neurohormone melatonin (MEL) plays an important role. T-helper cells express G-protein coupled cell membrane MEL receptors and, perhaps, MEL nuclear receptors. Activation of MEL receptors enhances the release of T-helper cell Type 1 (Th1) cytokines, such as gamma-interferon (gamma-IFN) and IL-2, as well as of novel opioid cytokines. MEL has been reported also to enhance the production of IL-1, IL-6 and IL-12 in human monocytes. These mediators may counteract stress-induced immunodepression and other secondary immunodeficiencies and protect mice against lethal viral encephalitis, bacterial diseases and septic shock. Therefore, MEL has interesting immunotherapeutic potential in both viral and bacterial infections. MEL may also influence haemopoiesis either by stimulating haemopoietic cytokines, including opioids, or by directly affecting specific progenitor cells such as pre-B cells, monocytes and NK cells. MEL may thus be used to stimulate the immune response during viral and bacterial infections as well as to strengthen the immune reactivity as a prophylactic procedure. In both mice and cancer patients, the haemopoietic effect of MEL may diminish the toxicity associated with common chemotherapeutic protocols. Through its pro-inflammatory action, MEL may play an adverse role in autoimmune diseases. Rheumatoid arthritis patients have increased nocturnal plasma levels of MEL and their synovial macrophages respond to MEL with an increased production of IL-12 and nitric oxide (NO). In these patients, inhibition of MEL synthesis or use of MEL antagonists might have a therapeutic effect. In other diseases such as multiple sclerosis the role of MEL is controversial. However, the correct therapeutic use of MEL or MEL antagonists should be based on a complete understanding of their mechanism of action. It is not yet clear whether MEL acts only on Th1 cells or also on T-helper Type 2 cells (Th2). This is an important point as the Th1/Th2 balance is of crucial importance in the immune system homeostasis. Furthermore, MEL being the endocrine messenger of darkness, its endogenous synthesis depends on the photoperiod and shows seasonal variations. Similarly, the pharmacological effects of MEL might also be season-dependent. No information is available concerning this point. Therefore, studies are needed to investigate whether the immunotherapeutic effect of MEL changes with the alternating seasons.

Identification of highly elevated levels of melatonin in bone marrow: its origin and significance

Bone marrow is an important tissue in generation of immunocompetent and peripheral blood cells. The progenitors of hematopoietic cells in bone marrow exhibit continuous proliferation and differentiation and they are highly vulnerable to acute or chronic oxidative stress. In this investigation, highly elevated levels of the antioxidant melatonin were identified in rat bone marrow using immunocytochemistry, radioimmunoassay, high performance liquid chromatography with electrochemical detection and mass spectrometry. Night-time melatonin concentrations (expressed as pg melatonin/mg protein) in the bone marrow of rats were roughly two orders of magnitude higher than those in peripheral blood. Measurement of the activities of the two enzymes (N-acetyltransferase (NAT) and hydroxyindole-O-methoxyltransferase (HIOMT)) which synthesize melatonin from serotonin showed that bone marrow cells have measurable NAT activity, but they have very low levels of HIOMT activity (at the one time they were measured). From these studies we could not definitively determine whether melatonin was produced in bone marrow cells or elsewhere. To investigate the potential pineal origin of bone marrow melatonin, long-term (8-month) pinealectomized rats were used to ascertain if the pineal gland is the primary source of this antioxidant. The bone marrow of pinealectomized rats, however, still exhibited high levels of melatonin. These results indicate that a major portion of the bone marrow's melatonin is of extrapineal origin. Immunocytochemistry clearly showed a positive melatonin reaction intracellularly in bone marrow cells. A melatonin concentrating mechanism in these cells is suggested by these findings and this may involve a specific melatonin binding protein. Since melatonin is an endogenous free radical scavenger and an immune-enhancing agent, the high levels of melatonin in bone marrow cells may provide on-site protection to reduce oxidative damage to these highly vulnerable hematopoietic cells and may enhance the immune capacity of cells such as lymphocytes.