Prevention of Distant Lung Metastasis After Photodynamic Therapy Application in a Breast Cancer Tumor Model.

The objective of this study was to investigate the activity of photodynamic therapy mediated by aluminum-chlorophthalocyanine contained in a polymeric nanostructured carrier composed by methyl vinyl ether-co-maleic anhydride (PVM/MA) against local subcutaneous breast cancer tumors and its effects against distant metastasis in a mouse tumor model. In our results, we observed a decrease in breast cancer tumor growth, prevention of distant lung metastases, and a significant increased survival in mice treated with photodynamic therapy. In addition to these results, we observed that tumor-bearing mice without treatment developed a significant extension of liver hematopoiesis that was significantly reduced in mice treated with photodynamic therapy. We hypothesized and showed that this reduction in (1) metastasis and (2) liver hematopoiesis may be related to the systemic activity of immature hematopoietic cells, specifically the myeloid-derived suppressor cells, which were suppressed in mice treated with photodynamic therapy. These cells produce a tolerogenic tumor environment that protects tumor tissues from immunological surveillance. Therefore, we suggest that photodynamic therapy could be employed in combination with other conventional therapies; such as surgery and radiotherapy, to improve the overall survival of patients diagnosed with breast cancer, as observed in our experimental resuIts.

Antitumor activity of photodynamic therapy performed with nanospheres containing zinc-phthalocyanine.

BACKGROUND: The increasing incidence of cancer and the search for more effective therapies with minimal collateral effects have prompted studies to find alternative new treatments. Among these, photodynamic therapy (PDT) has been proposed as a very promising new modality in cancer treatment with the lowest rates of side effects, revealing itself to be particularly successful when the photosensitizer is associated with nanoscaled carriers. This study aimed to design and develop a new formulation based on albumin nanospheres containing zinc-phthalocyanine tetrasulfonate (ZnPcS4-AN) for use in the PDT protocol and to investigate its antitumor activity in Swiss albino mice using the Ehrlich solid tumor as an experimental model for breast cancer. METHODS: Ehrlich tumor's volume, histopathology and morphometry were used to assess the efficacy of intratumoral injection of ZnPcS4-AN in containing tumor aggressiveness and promoting its regression, while the toxicity of possible treatments was assessed by animal weight, morphological analysis of the liver and kidneys, hemogram, and serum levels of total bilirubin, direct bilirubin, indirect bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transferase (GGT), alkaline phosphatase, creatinine and urea. In order to evaluate the efficacy of PDT, groups of animals treated with intratumoral injection of doxorubicin (Dox) were also investigated. RESULTS: Intratumoral injection of ZnPcS4-AN was found to be efficient in mediating PDT to refrain tumor aggressiveness and to induce its regression. Although tumor volume reduction was not significant, PDT induced a remarkable increase in the necrosis area seen in the tumor's central region, as in other experimental groups, including tumor and Dox treated groups, but also in the tumor's peripheral region. Further, PDT showed minimal adverse effects. Indeed, the use of ZnPcS4-AN in mediating PDT revealed anti-neoplastic activity similar to that obtained while using intratumoral Dox therapy. CONCLUSIONS: PDT mediated by the new formulation ZnPcS4-AN enhanced the inhibition of tumor growth while producing practically no adverse effects and thus emerges as a very promising nanotechnology-based strategy for solid cancer treatment.

Dextran-functionalized magnetic fluid mediating magnetohyperthermia combined with preventive antioxidant pequi-oil supplementation: potential use against cancer.

This work aimed to test a dextran-functionalized magnetic fluid (DexMF) sample in mediating magnetohyperthermia to treat an advanced clinical Ehrlich-solid-tumor, to verify the effects of oral antioxidant administration of pequi-oil on this treatment and to investigate the potential of these treatments for future use as an adjuvant in cancer therapy. Animals received the treatments: (a) filtered water (control); (b) tumor implantation and no treatment (tumor group); (c) tumor implantation followed by intratumoral injection of DexMF and alternating current magnetic field exposure (MHT group) for three consecutive days; (d) oral pequi-oil supplementation followed by tumor implantation and the same treatment as group MHT (PMHT group). Analyses took place 1 and 2 weeks after tumor implantation. Both treatments were effective in increasing the tumor necrosis process and controlling tumor growth, besides keeping lymphocyte-dependent immunity. Although the MHT treatment was more efficient after the first week in reducing DNA damage to blood peripheral leucocytes, PMHT therapy appeared to be more effective with the advance of the carcinogenesis process after the second week. Our findings evidence the potential use of DexMF mediating magnetohyperthermia in cancer treatment and also suggest that the preventive pequi oil administration could increase the efficiency of this process.

WITHDRAWN: Effects of oral administration of Bacillus thuringiensis as spore-crystal strains Cry1Aa, Cry1Ab, Cry1Ac or Cry2Aa on hematologic and genotoxic endpoints of Swiss albino mice.

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