Breast cancer is the second leading cause of cancer death worldwide. Nanotechnology approaches can overcome the side effects of chemotherapy as well as improve the efficacy of drugs. Dendrimers are nanometric size polymers which are suitable as drug delivery systems. To the best of our knowledge, studies on the application of PAMAM G4.5 (polyamidoamine half generation 4) dendrimers as potential drug delivery systems in breast cancer have not been reported. In this work we developed a PAMAM G4.5 dendrimer containing FITC (fluorescein isothiocyanate) dye to study their uptake by murine breast cancer cells and BALB/c mice breast tumors. We performed a reaction between FITC and PAMAM G4.5 dendrimers which were previously derivatized with piperazine (linker molecule), characterized them by 1H NMR (proton nuclear magnetic resonance) spectroscopy and MALDI-TOF (matrix-assisted laser desorption/ionization- time-of-flight) mass spectrometry. The experimental data indicated that 2 FITC molecules could be bound covalently at the PAMAM G4.5 dendrimer surface, with 17 FITC molecules probably occluded in PAMAM dendrimers cavity. PAMAM-FITC dendrimer (PAMAM G4.5-piperazinyl-FITC dendrimer) size distribution was evaluated by DLS (dynamic light scattering) and TEM (transmission electron microscopy). The nanoparticle hydrodynamic size was 96.3 ± 1.4 nm with a PdI (polydispersion index) of 0.0296 ± 0.0171, and the size distribution measured by TEM was 44.2 ± 9.2 nm. PAMAM-FITC dendrimers were neither cytotoxic in 4T1 cells nor hemolytic up to 24 h of incubation. In addition, they were uptaken in vitro by 4T1 cells and in vivo by BALB/c mice breast tumors. PAMAM G4.5-piperazinyl-FITC dendrimer intracellular distribution was observed through histologic analysis of the tumor by laser confocal microscopy. These results indicate that PAMAM G4.5 dendrimers enter tumor tissue cells, being good candidates to be used as antitumor drug delivery systems for breast cancer treatment and diagnosis.

Breast cancer is a solid tumor characterized by a high level of hypoxic areas which are difficult to treat. The rate of this disease in women is elevated, mainly in developing countries since the diagnosis is made in the later stages of the disease. We have developed bioreductive prodrugs under conditions of hypoxia in which the compound 2-amino-7(8)-fluorophenazine N 5 ,N 10 - dioxide (FNZ) stands out as a potent and selective anticancer agent. In order to improve the ADME properties the FNZ was vehiculated in physiological serum:tween (PS:T). This work presents the optimization of the synthesis of FNZ, the evaluation of the mutagenic potential in vitro (AMES test) and the acute toxicity (Up & Down) of free-FNZ and its encapsulated. The optimization of the procedure to scale-up 5 g was done according to the synthesis already described. Washing and drying conditions of the benzofuroxan intermediate and FNZ allowed an overall yield of 60 %, five times higher than the micro-scale procedure. We performed the Ames assay on five strains of Salmonella typhimurium (TA98, TA100, TA1535, TA1537, TA102) recommended for drug development. The preliminary results indicate that all the systems under study (Free-FNZ, PS:T/FNZ) exhibited mutagenicity in the five Salmonella strains. The most mutagenic system was the free-FNZ being the encapsulation using (PS:T) the least. The acute toxicity showed that the vehiculated FNZ had a maximum dose of 2000 mg/kg of mouse weight. The vehiculated FNZ was not toxic in the Up & Down assay transforming it in a good formulation to be used in vivo studies. Acknowledgement: The authors want to thank the ANII for financial support.

Our group has previously reported potential new radiopharmaceuticals, i.e. 99m Tc-tricarbonyl-(2-amino- 5,10-dioxide- 7(8)-fluorophenazine), Tc-FZ), with the ability to detect hypoxic tumoral tissues. Previously, this probe was used to detect solid tumors, employing a model of lung carcinoma generated by inoculation of 3LL Lewis murine cells in C57BL/6 mice. The results revealed an adequate tumor/muscle ratio, 3.8 at 2 h post-injection (p.i.), with lower tumor/blood ratio, i.e. 0.6 at 2 h p.i.. Due to some models of breast cancer also being characterized by hypoxic areas, herein we decided to analyze the behavior of Tc-FZ in BALB/c mice bearing mammary tumor induced with 4T1-mouse tumoral cell line. The studied ratios revealed to be slightly a little more unfavorable than in the lung tumor-porting animals, being tumor/muscle and tumor/blood ratios, at 2 h p.i., of 3.0 and 0.23, respectively. Additionally, animals in vivo images showed that the liver masked tumor signal. Acknowledgement The authors want to thank the ANII for financial support.