Prevention of peritoneal carcinomatosis in mice with combination hyperthermal intraperitoneal chemotherapy and IL-2.

PURPOSE: The purpose of this study was to investigate the effect of local chemoimmunotherapy and hyperthermal intraperitoneal chemotherapy (HIPEC) in a mouse model of induced peritoneal carcinomatosis. MATERIAL AND METHODS: Peritoneal carcinomatosis in mice was produced by intraperitoneal implantation of MCa cells (5 x 10(3)). Interleukin-2 (4.1 x 10(4) IU/mouse) was injected into the abdominal cavity of mice at day 7 and 3 before implantation of tumour cells. Immediately after implantation of MCa cells mice were treated twice with 2 ml of saline that was heated either at 37 degrees C or 43 degrees C and cytostatics (doxorubicin 20 mg kg(-1), cisplatin 10 mg kg(-1), mitomycin 5 mg kg(-1), or 5-FU 150 mg kg(-1)). We followed the survival of animals and side effects appearing with different forms of treatment. RESULTS: Combined treatment with Interleukin-2 (IL-2) and cytostatics (5-FU, CIS or MIT) significantly affected the development of peritoneal carcinomatosis and increased the survival of mice (ILS% - 37 degrees C = 29.88, 199.32, and 108.52, ILS% - 43 degrees C = 62.69, 260.50, and 178.05, respectively). However, intraperitoneal chemotherapy on survival time of mice with DOX + IL-2 was ineffective as compared with DOX alone. CONCLUSION: We would like to stress that treatment with IL-2 prior to tumour diagnosis is not clinically practical, rather, the manuscript attempts to describe an experimental proof of principle. Results suggest the synergistic effect of hyperthermia, chemotherapy and immunotherapy; IL-2 significantly increases antitumor activity of hyperthermic chemotherapy and survival rate of mice with peritoneal carcinomatosis.

Evaluation of radioprotective effects of propolis and its flavonoid constituents: in vitro study on human white blood cells.

This in vitro study aimed to evaluate the possible radioprotective effects of the natural substances WSDP, caffeic acid, chrysin and naringin on gamma-irradiated human white blood cells. The effectiveness of tested compounds was evaluated using the alkaline comet assay, the analysis of structural chromosome aberration and the cytokinesis-block micronucleus assay. The results obtained by the alkaline comet study indicate favourable toxicity profiles of propolis and its polyphenolic components, and confirmed the radioprotective abilities comparable to the chemical radioprotector AET. WSDP and its polyphenolic components were able to reduce the number of necrotic cells. None of tested compounds induced significant genotoxicity, but all of them offered a quite measurable protection against DNA damage. WSDP was found to be the most effective in diminishing the levels of primary and more complex cytogenetic DNA damage in white blood cells. Considering its complex composition, to undoubtedly explain the underlying mechanisms of cyto/radioprotective effects, further studies are needed.

Assessment by survival analysis of the radioprotective properties of propolis and its polyphenolic compounds.

The radioprotective effects of propolis and polyphenolic compounds from propolis on the radiation-induced mortality of mice exposed to 9 Gy of gamma-irradiation were studied. Intraperitoneal (i.p.) treatment of mice at doses of 100 mg kg(-1) body weight of propolis (water or ethanolic extract; WSDP or EEP) or its polyphenolic compounds (quercetin, naringin caffeic acid, chrysin) consecutively for 3 d before irradiation, delayed the onset of mortality and reduced the symptoms of radiation sickness. All test compounds provided protection against hematopoietic death (death within 30 d after irradiation). The greatest protection was achieved with quercetin; the number of survivors at the termination of the experiment was 63%. According to statistical analyses by the Kaplan-Meier method and the log-rank test, a significant difference between test components and control was found (p<0.001). Treatment with test components after lethal irradiation was ineffective. These results suggest that propolis and its polyphenolic compounds given to mice before irradiation protect mice from the lethal effects of whole-body irradiation.

Direct and indirect mechanism(s) of antitumour activity of propolis and its polyphenolic compounds.

The immunomodulatory actions of a water-soluble derivative of propolis (WSDP) and two components of propolis, caffeic acid (CA) and caffeic acid phenethyl ester (CAPE) were investigated. Oral administration (50 mg/kg) of WSDP, CA, and CAPE enhanced the weight and cellularity of the spleen (p<0.05, p<0.01) of treated mice. The response of spleen cells to polyclonal mitogens (PHA, Con A, PWM) was also increased in mice treated with WSDP as compared to control (p<0.01); in contrast, the response of spleen cells of mice treated with CA were significantly suppressed (p<0.001). The colony forming ability of HeLa cells plated on monolayers of macrophages was completely inhibited by peritoneal macrophages from mice receiving either WSDP, CAPE, or CA. Macrophages from treated mice also inhibited [3H]TdR incorporation into HeLa cells in vitro. Testing for the possible presence of NO in the supernatants of 24 hours cultured macrophages activated with either compound revealed that the toxicity of these cells to HeLa cells was in part due to the production of NO. Tumour growth was suppressed by WSDP and its polyphenolic compounds given orally to mice. Local presence of CA, and CAPE in the tissue, caused a significant delay of tumour formation. Based on these results, we postulate that the antitumour activity of the test compounds includes pronounced immunomodulatory activity mainly due to the augmentation of non-specific antitumour resistance in mice via macrophage activation and the production of soluble factors by those cells which may interfere with either cells of the immune system or directly by tumour cells.

Effects of local administration of propolis and its polyphenolic compounds on tumor formation and growth.

Many dietary constituents are chemopreventive in animal models, and experiments with cultured cells are revealing various potential mechanisms of action. Compounds classified as blocking agents can prevent, or greatly reduce, initiation of carcinogenesis, or suppressing agents can act on cell proliferation. Caffeic acid (CA) and caffeic acid phenethyl ester (CAPE), members of the polyphenolic compounds, are present in high concentrations in medicinal plants and propolis, a natural beehive product. A water-soluble extract of propolis (WSDP) and two components of propolis, CA and CAPE were investigated for direct antitumor activity in vivo and in vitro. The local presence of CA and CAPE in the tissue caused a significant delay in tumor formation and increased life span 29.30 to 51.73%, respectively. CA and CAPE, but not WSDP, significantly suppressed human HeLa cervical carcinoma cell proliferation in vitro. Based on these results, we postulate that the antitumor activity of polyphenolic compounds includes direct cytotoxic effects on tumor cells.

Water-soluble derivative of propolis and its polyphenolic compounds enhance tumoricidal activity of macrophages.

Many plants and the plant-derived honeybee propolis have shown biological activities like immunomodulation and antitumor effect. The effect of two water-soluble propolis derivatives (WSDP) from Croatia and Brazil, caffeic acid, quercetin, chrysin and naringenin which are present in WSDP was assessed on the development of Ehrlich ascites tumor (EAT). The compounds (50 mgkg(-1)) were given by gastric intubations (po) 2 h prior to the intraperitoneal injection of EAT (2x10(6)) cells. It was observed that WSDP and its compounds effectively inhibited tumor growth and proliferation of EAT. The volume of ascitic fluid induced by EAT cells and total number of cells present in the peritoneal cavity was markedly reduced in EAT-bearing mice treated with test components. Treatment with test components increased the number of polymorphonuclear (PMN) cells and decreased the number of macrophages in the peritoneal cavity of treated animals. The macrophage spreading activity revealed that WSDP and all test compounds affected the functional state of macrophages increasing their tumoricidal activity. The effect of WSDP was most pronounced suggesting synergistic effect of components present in WSDP. It is likely that part of the antitumor efficacy of the assayed components against EAT cells was the results of increased macrophage activity.

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.

Immunomodulation by water-soluble derivative of propolis: a factor of antitumor reactivity.

The antimetastatic efficacy of a water-soluble derivative of propolis (WSDP) was studied. Tumor was a transplantable mammary carcinoma of CBA mouse. Metastases in the lung were generated by 2 x 10(5) viable tumor cells i.v. WSDP was given intraperitoneally at doses of 50 or 150 mg/kg before or after tumor cell inoculation. Therapies reduced the number of metastases in the lung and tumor growth was suppressed significantly by WSDP. It is likely that antimetastatic activity of the WSDP is mainly mediated by immunomodulatory activity. Changes in several immunological parameters such as production of lymphocyte activating factor by peritoneal macrophages and the efficacy of those macrophages to kill tumor cell in vitro, responses of lymphocytes to mitogen, and weight and cellularity of spleen, respectively, correlated well with antimetastatic properties of the WSDP. Based on results we postulate that the antimetastatic activity of propolis includes a pronounced immunomodulatory activity mainly toward augmentation of nonspecific antitumor resistance in mice via macrophage activation.