Modifying effects of propolis on MeIQx promotion of rat hepatocarcinogenesis and in a female rat two-stage carcinogenesis model after multiple carcinogen initiation

Chemopreventive Action by Ethanol-extracted Brazilian Green Propolis on Post-initiation Phase of Inflammation-associated Rat Colon Tumorigenesis

BACKGROUND/AIM

Propolis has since long been utilized in numerous folk medicines with a variety of medicinal properties. In this study, the effects of ethanol-extracted (EEP) and water-extracted (WEP) Brazilian green propolis on the post-initiation phase of inflammation-associated rat colon tumorigenesis were directly compared.

MATERIALS AND METHODS

Male F344 rats at 6 weeks of age were subcutaneously injected with 1,2-dimethylhydrazine (DMH) at 40 mg/kg body weight twice during the first week, followed by 1% dextran sodium sulfate (DSS) in drinking water for one week. After a 1-week no-treatment period, animals were administered either basal Oriental MF powdered diet, or 1% EEP or 1% WEP in the basal diet until week 32.

RESULTS

Post-initiation treatment with EEP significantly reduced the multiplicity of colorectal carcinomas compared to the control (0.40±0.13/rat vs. 2.29±0.84/rat, respectively, p<0.05), and EEP also reduced the tumor volume. Immunohistochemically, expression of inflammation-associated proteins inducible nitric oxide synthase, tumor necrotic factor alpha, nuclear factor kappa B and glutathione peroxidase-2 were significantly diminished in colorectal tumors from EEP-treated rats.

CONCLUSION

Suppression of inflammation and oxidative stress, which had been triggered by DMH and promoted by DSS, was a primary mechanism by which EEP suppressed carcinogenesis.

Characterization of diethylnitrosamine-induced liver carcinogenesis in Syrian golden hamsters

The aim of this study was to characterize hepatocarcinogenesis in diethylnitrosamine (DEN)-treated hamsters. Syrian golden hamsters (n=36) were administered DEN by hypodermic injection and addition to drinking water. Morphological analyses, including light microscopy and immunohistochemistry of α-fetal protein (AFP), were performed on liver and lung tissues. Primary cell culture and tumor transplantation were carried out to evaluate the potential application in hepatocellular carcinoma (HCC) research. From 25 to 50 weeks of treatment, liver tumors, including macronodular HCC and ascites, were found in one-third (4/12) of the animals treated with DEN. HCC was characterized by poor differentiation, frequent mitosis, AFP reaction, vessel invasion and potential application in primary cell culture and xenotransplantation. Pre-neoplastic lesions were hyperplastic nodules comprised of clear cells, bile duct proliferation, fatty metamorphosis and multilocular cysts. The DEN-treated hamsters also showed lung tumors consisting of AFP-negative, well-differentiated neoplastic cells. Characterization of DEN-induced HCC in hamsters provides insights into human hepatocarcinogenesis. This animal model has potential applications in HCC research.

Absence of chemopreventive influence of propolis on the rat liver altered foci development

Propolis (bee glue) is a complex mixture of natural substances that exhibits a broad spectrum of biological activities. As the possibility exists that it may exert a chemopreventive role against cancer development, the present study aimed to evaluate the chemopreventive influence of a Brazilian aqueous propolis extract (APE) in a rat two-stage (initiation-promotion) medium-term bioassay for chemical liver carcinogenesis. Male Wistar rats were sequentially initiated with diethylnitrosamine (DEN, 200mg/kgb.w.) and, 2 weeks later, exposed to a diet containing hexachlorobenzene (HCB, 100ppm) and to APE 0.1% through drinking water for 6 weeks. Appropriate control groups were also established. The animals were sacrificed at the weeks 8th and 30th when liver samples were processed to evaluate the development of altered hepatocyte foci (AHF) identified under hematoxylin and eosin (H&E) staining and by the immunohistochemical expression of the enzyme glutathione S-transferase placental form (GST-P). The results indicate that APE 0.1% did not protect against the development of any of the differentially identified putative preneoplastic foci in DEN-initiated animals, exposed or not to the promoting agent HCB. Also, APE 0.1% by itself did not significantly induce any AHF, what is in line with its already known absence of genotoxic potential. Our results indicate that an aqueous extract of Brazilian propolis did not exert chemoprevention on the hepatocarcinogenesis process chemically induced in the rat.

The contribution of plukenetione A to the anti-tumoral activity of Cuban propolis

Increasing efforts are directed toward finding applications for natural products and their derivatives in the treatment of human diseases. Among such products, propolis, a resinous substance produced by honey bees from various plant sources, has been found to be a promising source of potential therapeutics. In the present work, we aimed at studying the perspective of Cuban propolis as a source of possible anti-cancer agents. We found an anti-metastatic effect in mice and considerable cytotoxicity without cross-resistance in both wild-type and chemoresistant human tumor cell lines. Plukenetione A--identified for the first time in Cuban propolis--induced G0/G1 arrest and DNA fragmentation in colon carcinoma cells. Furthermore, the activities of both topoisomerase I and DNA polymerase were inhibited, while the expression of topoisomerase II-beta, EGF receptor, and multidrug resistance-related protein genes was found repressed. We assume that plukenetione A contributes to the anti-tumoral effect of Cuban propolis mainly by targeting topoisomerase I as well as DNA polymerase.

The Interaction of New Plant Flavonoids with Rat Liver Mitochondria: Relation between the Anti- and Pro-oxydant Effect and Flavonoids Concentration

Flavonoids are polyphenols derivatives of plant origin that possesses a broad range of pharmacological properties, including protection of cells and tissues against the deleterious effects of reactive oxygen species. Their antioxidant activity results from scavenging of free radicals and other oxidizing intermediates, from the chelation of iron or copper ions and from inhibition of oxidases. But a number of studies have found both anti and prooxidant effects for many of these compounds. These reasons prompted us to investigate whether flavonoids compounds alone or combined flavonoids had antioxidant, free radical scavenger and antiapoptotic properties. The investigation was carried in vitro using rat hepatic mitochondria. Respiratory control ratio (RCR), oxygen consumption, adenosine tri phosphate (ATP) synthesis, scavenging action, enzymatic activities of involved complexes, superoxide anion and the release of cytochrome C were measured to assess the mechanisms of action of these drugs. Our data showed that the decrease of RCR induced by high concentrations (0.1 mM and 0.01 mM) of all flavonoids tested was due to a common inhibition of oxidative phosphorylation (State 4) and activation of state 3. At the opposite mitochondrial swelling was slightly induced only by low concentrations (10(-8) and 10(-9) M) of the flavonoids. They had no effects on the mitochondrial complexes (I to V) activity. Furthermore the mitochondrial membrane potential was not affected by any flavonoids. The effect of flavonoids on superoxide anion generation was variable. All the flavonoids studied acted between 10(-4) M and 10(-6) M with no effects at lower concentrations. These effects were similar on lipid peroxidation (malondialdehyde [MDA] levels). We remarked a concentration-dependent in the effect of flavonoids since they acted as antioxidant and also as uncoupler at high concentrations, which is a risk for the cells. We conclude that flavonoids extracted from algerian plants have some protecting effects against oxidative stress by protecting the mitochondria.

Therapeutic effect of paclitaxel and propolis on lipid peroxidation and antioxidant system in 7,12 dimethyl benz(a)anthracene-induced breast cancer in female Sprague Dawley rats

Breast cancer is one of the most common cancers in women of developed and developing countries. The optimum management of which requires a multidisciplinary approach including the use of certain biochemical and molecular markers. The effect of propolis along with paclitaxel on 7,12 dimethyl benz(a)anthracene (DMBA) induced experimental breast cancer was investigated in female Sprague Dawley rats. Female Sprague Dawley rats were divided into five groups of six animals each. Group I served as normal control animal. Group II animals received DMBA (20 mg in 0.5 ml sunflower oil and 0.5 ml of saline) i.p. to develop mammary tumor by the end of 90 days. Group III were breast cancer animals treated with 33 mg paclitaxel/kg body weight (bw) weekly once for 4 weeks. Group IV were breast cancer-bearing animals treated with 50 mg propolis/kg bw for 30 days. Group V were breast cancer-bearing animals treated with both paclitaxel and propolis as mentioned above. Administration of paclitaxel and propolis effectively suppressed breast cancer, which is revealed by the decrease in the extent of lipid peroxidation (LPO) with concomitant increase in the activities of enzymic antioxidants (superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)) and non-enzymic antioxidants (reduced glutathione (GSH), Vitamin C and Vitamin E) levels when compared to breast cancer-bearing animals treated with either paclitaxel or propolis alone. From our results, we conclude that propolis is a potent antioxidant and, when given in combination with paclitaxel, offers maximum protection against DMBA induced mammary carcinogenesis.

Peroral Application of Water-soluble Derivative of Propolis (WSDP) and Its Related Polyphenolic Compounds and Their Influence on Immunological and Antitumour Activity

Polyphenolic compounds are widely distributed in the plant kingdom and display a variety of biological activities, including chemoprevention and growth inhibition of tumours. Propolis contains a conglomerate of polyphenolic compounds. We investigated the effect of propolis and polyphenolic compounds, components of propolis, on the growth and metastatic potential of a transplantable mammary carcinoma (MCa) of the mouse. Metastases in the lung were generated by 2 x 10(5) tumour cells injected intravenously (i.v.). A water-soluble derivative of propolis (WSDP) and the polyphenolic compounds (caffeic acid (CA) and caffeic acid phenethyl ester (CAPE)) were given to mice perorally before or after tumour cell inoculation. WSDP, CA and CAPE reduced the number of metastases in the lung. This implies that the antitumour activities of the compounds used in these studies are mostly related to the immunomodulatory properties of the compounds, their cytotoxicity to tumour cells, and their ability to induce apoptosis and/or necrosis.

Inhibitory effect of water-soluble derivative of propolis and its polyphenolic compounds on tumor growth and metastasizing ability: a possible mode of antitumor action

Polyphenolic compounds are widely distributed in the plant kingdom and display a variety of biological activities, including chemoprevention and tumor growth inhibition. Propolis is made up of a variety of polyphenolic compounds. We compared how the routes of administration of polyphenolic compounds deriving from propolis and of propolis itself affect the growth and metastatic potential of a transplantable mammary carcinoma (MCa) of the CBA mouse. The influence of tested compounds on local tumor growth was also studied. Metastases in the lung were generated by 2 x 10(5) tumor cells injected intravenously (IV). A water-soluble derivative of propolis (WSDP) and polyphenolic compounds (caffeic acid, CA, and CA phenethyl ester, CAPE) were given to mice per os (PO) or intraperitoneally (IP) before or after tumor cell inoculation. Tested compounds significantly decreased the number of lung colonies. When mice were inoculated with 10(5) MCa cells in the exact site of subcutaneous injection of different doses of WSDP, CA, or CAPE, tumor growth was inhibited, and survival of treated mice was prolonged. Antitumor activity, according to the results obtained, is mostly related to the immunomodulatory properties of the compounds and their capacity to induce apoptosis and necrosis. In conclusion, results presented here indicate that WSDP, CA, and CAPE could be potential useful tools in the control of tumor growth in experimental tumor models when administrated PO; because PO administration is the easiest way of introducing a compound used for prevention and/or cure of any disease, it is likely that this article has reached the goal of the investigation.

Immunomodulatory and antimetastatic action of propolis and related polyphenolic compounds

The effect of polyphenolic compounds isolated from propolis and propolis itself was investigated on the growth and metastatic potential of a transplantable mammary carcinoma (MCa) of CBA mouse. Metastases in the lung were generated by intravenous injection of tumor cells (2 x 10(5)). A water-soluble derivative of proplis (WSDP), caffeic acid (CA), caffeic acid phenethyl ester (CAPE) and quercetin (QU) were given to mice per os before tumor cells inoculation. Tested compounds significantly decreased the number of tumor nodules in the lung. According to the results obtained the antitumor activity of tested compounds can be related to the immunomodulatory properties of the compounds, their cytotoxicity to tumor cells, and their capacity to induce apoptosis and necrosis. The experimental data support that WSDP, CA, CAPE and QU could be potentially useful in the control of tumor growth in experimental models.

Protective role of Egyptian propolis against tumor in mice

BACKGROUND

Propolis has numerous biologic activities including antibiotic, antifungal, antiviral and anti-inflammatory properties. The present work is aimed to study the effect of crude Egyptian propolis on tumor in mice induced by Ehrlich ascitis carcinoma (EAC) cell line.

RESULTS

The administration of propolis (160 mg/kg body weight), by gastric intubation 2 h before the intraperitoneal injection of EAC, effectively inhibited tumor growth and the proliferation of EAC. The tumor volume was markedly reduced from 7+/-0.9 ml in EAC-infected mice to 1.6+/-0.95 ml in propolis-treated mice. Also, the lipid peroxide level which was 13.3+/-1.24 nmol malodialdehyde (MDA)/mg protein in EAC infected mice was significantly decreased to 3.3+/-2.1 nmol MDA/mg protein. Reduced glutathione (GSH) and glutathione S-transferase (GST) concentrations were markedly increased in propolis-treated mice. This effect was associated with inhibition of cell cycle progression and induction of apoptosis. Administration of propolis 2 h before injection of EAC arrested cells in G0/G1 phase and resulted in a decrease in the viability, DNA, total RNA and protein level of tumor cells.

CONCLUSIONS

Crude Egyptian propolis has a strong inhibitory activity against tumors. The anti-tumor mechanism may be mediated by preventing oxidative damage and induction of apoptosis.