Martin Péč

Melatonin potentiates the anti-tumour effect of pravastatin in rat mammary gland carcinoma model

Previous studies in the field of cancer research have suggested a possible role for statins in the reduction of risk in certain malignancies. The purpose of these studies was to examine the chemopreventive effects of pravastatin alone and in combination with pineal hormone melatonin in the N‐methyl‐N‐nitrosourea‐induced mammary carcinogenesis model. Pravastatin was given orally (1 00 mg/kg) and melatonin was added to the water (20 μg/ml). Chemoprevention began seven days prior to carcinogen administration and subsequently continued for 15 weeks until autopsy. At autopsy, mammary tumours were removed and prepared for histopathological and immunohistochemical analysis. Parameters of experimental carcinogenesis, mechanism of action (biomarkers of apoptosis, angiogenesis and proliferation) and side effects after long‐term treatment in animals were assessed. Pravastatin alone suppressed tumour frequency by 20.5% and average tumour volume by 15% compared with controls. Combined administration of the drugs decreased tumour frequency by 69% and lengthened tumour latency by nine days compared with control animals. The ration between high and low grade carcinomas was apparently reduced in both treated groups. The analysis of carcinoma cells showed significant expression increase in caspase‐3 and caspase‐7 after pravastatin treatment; however, combined treatment even more pronounced increase in the expression of both caspases. Regarding VEGFR‐2 expression, a small effect in carcinomas of both treated groups was found. In plasma metabolism evaluation, pravastatin alone significantly decreased levels of glucose and triacylglycerols. Our results suggest a mild anti‐neoplastic effect of pravastatin in this rat mammary gland carcinoma model. Statins co‐administered with other suitable drug (e.g. melatonin) should be further evaluated for tumour‐preventive properties.

Pioglitazone in chemically induced mammary carcinogenesis in rats.

Data available from in-vitro and in-vivo studies suggest oncostatic properties of peroral antidiabetics, thiazolidinediones, in many types of cancer. This study is the first report on the chemopreventive effect of pioglitazone in mammary carcinogenesis in rats. Mammary carcinogenesis was induced by N-methyl-N-nitrosourea administered in two intraperitoneal doses per 50 mg/kg bodyweight on the 43rd and 50th postnatal days. Pioglitazone was administered in the diet at concentrations of 10 and 100 ppm, respectively, 12 days before the first carcinogen dose until the termination of the experiment. During the experiment, the animals were weighed weekly and palpated for the presence of mammary tumors, and the incidence, latency, tumor frequency, and tumor volume were recorded. The experiment was terminated 17 weeks after the first carcinogen dose; basic tumor growth parameters and metabolic and hormonal variables were evaluated. Pioglitazone at higher concentration decreased incidence and frequency per group from the 11th week of experiment when compared with the control group and a group receiving a lower dose. Pioglitazone at a higher dose decreased the final incidence by 38%, frequency per group by 63%, and extended latency period by 32% when compared with the control group. Our data suggest that pioglitazone and other glitazones should be further investigated for oncopreventive effects.

Immunohistochemical and histomorphological analysis of rat mammary tumors after simvastatin treatment

The results of experimental studies have indicated the pleiotropic effects of statins in organism, e.g. the influence on cell cycle, apoptosis or angiogenesis. In this study, the effects of simvastatin on selected parameters of apoptosis and proliferation in chemocarcinogen-induced mammary tumorigenesis in female rats were determined. Simvastatin was administered dietary at a dose of 18 mg/kg and highly effective dose of 180 mg/kg the entire experiment (18 weeks). At autopsy mammary tumors were removed and prepared for immunohistochemical and histomorphological analysis. In treated animals (simvastatin 180 mg/kg), significant decrease by 12% in Bcl-2 protein expression and non-significant decrease by 27% of Ki67 protein expression in tumor cells compared to tumor cells in control animals were observed after semiquantitative evaluation. Morphometrical analysis has shown significant proapototic shift in Bcl-2/Bax ratio in tumor cells. In high grade control carcinoma cells, the expression of Ki67 increased by 37% (non-significantly) in comparison with control low grade carcinomas. A histomorphological analysis of malignant tumors has revealed a shift from high grade to low grade carcinomas after simvastatin treatment. The noticeable decrease of mammary tumor frequency and incidence in rats after simvastatin treatment was accompanied with antiapoptotic Blc-2 protein decrease and proapoptotic Bax protein increase in this experiment.

Phaeohyphomycosis due to Alternaria spp. and Phaeosclera dematioides: a histopathological study

Summary. A case of phaeohyphomycosis caused by strains of both Alternaria spp. and Phaeosclera dematioides is presented. The biopsy material was studied using histological, immunohistochemical and transmission electron microscopy techniques. The agents dematiaceous mycelia are composed of thick‐walled hyphae, branched and unbranched, with terminal vesicular formations. All the described structures occur alone or in chains within multinuclear giant foreign body‐type cells or invading an abscess. Also present are budding forms. Immunostaining of histiocytic inflammatory cells in either diffuse or granulomatous infiltrates revealed cytoplasmic positivity for lysozyme and Ki‐M1P antibody. The lymphocytic infiltrates of the upper corium show predominantly small T lymphocytes (CD3 and CD45RO positive) and absence of CD20‐positive B cells. Plasma cells occurring within the infiltrates of the deeper parts show polyclonal expression of both Ig light chains.

Combination of Pitavastatin and melatonin shows partial antineoplastic effects in a rat breast carcinoma model.

Our previous results indicated significant tumor-suppressive effects of different statins in rat mammary carcinogenesis. The purpose of this experiment was to examine the chemopreventive effects of Pitavastatin alone and in combination with the pineal hormone melatonin in the model of N-methyl-N-nitrosourea-induced mammary carcinogenesis in female Sprague-Dawley rats. Pitavastatin was administered dietary (10mg/kg) and melatonin in an aqueous solution (20μg/ml). Chemoprevention began 7 days prior to carcinogen administration and subsequently continued for 15 weeks until autopsy. At autopsy, mammary tumors were removed and prepared for histopathological and immunohistochemical analysis. Compared to controls, Pitavastatin alone reduced average tumor volume by 58% and lengthened latency by 8 days; on the other hand, the drug increased tumor frequency by 23%. Combined administration of Pitavastatin with melatonin decreased tumor frequency by 23%, tumor volume by 44% and lengthened tumor latency by 5.5 days compared to control animals. The analysis of carcinoma cells showed significant increase in caspase-3 expression in both treated groups and a tendency of increased caspase-7 expression after Pitavastatin treatment alone. Significant expression decrease of Ki67 was found in carcinoma cells from both treated groups. Compared to control carcinoma cells, Pitavastatin alone increased VEGF expression by 41%, however melatonin totally reversed its undesirable effect. Pitavastatin combined with melatonin significantly increased femur compact bone thickness in animals. Pitavastatin alone decreased plasma triglycerides and total cholesterol levels, however it significantly increased levels of glucose. In summary, our results show a partial antineoplastic effect of Pitavastatin combined with melatonin in the rat mammary gland carcinoma model.

Young Barley Indicates Antitumor Effects in Experimental Breast Cancer In Vivo and In Vitro.

ABSTRACT The effect of dietary administered young barley containing a mixture of phytochemicals to female rats for the prevention of N-methyl-N-nitrosourea-induced mammary carcinogenesis was evaluated. After carcinogen administration (14 wk), mammary tumors were removed and prepared for histopathological and immunohistochemical analysis. Moreover, in vitro evaluation of possible mechanisms in MCF-7 breast cancer cell line was performed. Barley (0.3%) demonstrated mild antitumor effect in mammary carcinogenesis, yet 3% barley did not further improve this effect. Immunohistochemical analysis of rat tumor cells in treated groups showed significant increase in caspase-3 expression and significant reduction in Ki67 expression. In addition, 3% barley significantly decreased dityrosine levels versus control. Barley in higher dose significantly decreased serum low-density lipoprotein-cholesterol in rats. In vitro studies showed that barley significantly decreased survival of MCF-7 cells in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and significantly decreased 5-bromo-20-deoxyuridine incorporation versus control. Barley prevented cell cycle progression and extended incubation with barley showed significant increase in the percentage of annexin V/propidium iodide-positive MCF-7 cells. Our results propose an antitumor effect for the mixture of phytochemicals present in young barley in a breast cancer model.

Preventive effects of fluvastatin in rat mammary carcinogenesis

On the basis of preclinical and clinical evidence, statins lead to risk reduction of several types of neoplasia including breast cancer. This study is the first report on the preventive effects of fluvastatin in experimental breast cancer in vivo. In this experiment, the antineoplastic effects of fluvastatin in the chemoprevention of N-methyl-N-nitrosourea-induced mammary carcinogenesis in female rats were evaluated. The effects of fluvastatin on selected parameters of apoptosis, proliferation, and angiogenesis in mammary tumor cells were determined. The drug was dietary administered at two concentrations of 20 and 200 mg/kg. The experiment was terminated 17 weeks after carcinogen administration; mammary tumors were removed and prepared for histomorphological and immunohistochemical analysis. The basic parameters of experimental carcinogenesis, chosen metabolic variables, and side effects after long-term fluvastatin treatment in animals were assessed. Fluvastatin at higher concentrations suppressed tumor frequency by 63% and tumor incidence by 33% in comparison with the controls. After fluvastatin treatment, immunohistochemical analysis of tumor cells showed a decrease in vascular endothelial growth factor receptor-2 expression by 86% and an increase in caspase-3 by 8.5%. Fluvastatin in both treated groups significantly increased the parameters of serum lipid metabolism and significantly decreased femur compact bone thickness and body weight in animals. Our results suggest that fluvastatin and other statins should be further evaluated for tumor-preventive characteristics.

Antitumor effects of atorvastatin in the chemoprevention of rat mammary carcinogenesis

Epidemiological studies indicate that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors, or statins, play a role in inhibition of several human neoplasia including breast cancer. In this study, chemopreventive effects of atorvastatin in N-methyl-N-nitrosourea-induced mammary carcinogenesis in female rats were evaluated. Atorvastatin was administered in the diet at two concentrations: 10 mg/kg (ATOR 10) and 100 mg/kg (ATOR 100). Atorvastatin treatment began 8 days prior to carcinogen administration and subsequently continued for 15 weeks till the end of the experiment. Atorvastatin at a higher dose suppressed tumor frequency by 80.5% (P = 0.0008) and tumor incidence by 49.5% (P = 0.015), and extended latency period by 14 days (P = 0.076) when compared to the control group. Atorvastatin at a lower dose did not significantly alter tumor parameters in comparison with the control group. In the specimens of mammary tumors, atorvastatin (in the ATOR 100 group) significantly decreased mRNA expression of Bcl-2 gene but non-significantly increased Bax mRNA expression compared to control group. Atorvastatin administration did not alter serum concentration of triacylglycerols, total cholesterol, and LDL cholesterol in comparison with controls. This study is the first report on tumor suppressive effect of atorvastatin in rat mammary carcinogenesis.

Rosuvastatin in the chemoprevention of N-methyl-N-nitrosourea - induced mammary carcinogenesis in female rats.

The results of preclinical research have indicated anticarcinogenic effects of statins in diverse tumors including breast cancer. Lipophilic atorvastatin and simvastatin have demonstrated high anticarcinogenic effects in experimental breast cancer in our previous experiments. In this study, the chemopreventive potential of hydrophilic rosuvastatin in N-methyl-N-nitrosourea induced mammary carcinogenesis in female rats was evaluated. Chemoprevention started 7 days before carcinogen administration and subsequently continued 17 weeks – until the end of the experiment. Dietary administered rosuvastatin (250 mg/kg) decreased tumor frequency by 39% (p=0.146), average tumor volume by 64% (p=0.236), as well as lengthened the latency period by 11 days (p=0.143) compared to controls. Moreover, rosuvastatin (250 mg/kg) decreased average tumor volume by 85% (p=0.0082) compared to the group with rosuvastatin at lower dose in the diet (25 mg/kg). A histopathological analysis of mammary tumors has revealed a shift from poorly differentiated to well differentiated tumors after treatment with rosuvastatin (250 mg/kg). With the exception of HDL-cholesterol, the parameters of plasma lipid metabolism did not differ after rosuvastatin treatment. Rosuvastatin did not change the food intake and body weight in rats. This study is the first about rosuvastatin used in rat mammary carcinogenesis. Hydrophilic rosuvastatin have shown lower antineoplastic activity than lipophilic statins in this model of experimental breast cancer.

Melatonin enhanced bexarotene efficacy in experimental mammary carcinogenesis.

The aim of this paper was to test lower, safe bexarotene dose administered alone and in combination with melatonin to improve its efficacy. Mammary carcinogenesis was induced by N-methyl-N-nitrosourea in female Sprague-Dawley rats, administered in two doses intraperitoneally between 42.-54. postnatal days and chemoprevention was initiated 7 days prior to first N-methyl-N-nitrosourea injection and lasted 15 weeks. Bexarotene, particularly in combination with melatonin decreased mammary tumor incidence and frequency with a shift from poorly to well differentiated carcinomas. Bexarotene alleviated glycaemia and liver/heart muscle glycogen concentration decreased as well as liver/thymus malondialdehyde increased in comparison with control group. The combination of bexarotene and melatonin is therefore beneficial in preventive-curative model of experimental mammary carcinogenesis and may be applied in oncological practice as such.