EFFECTS OF PEQUI OIL NANOEMULSIONS ON THE MORPHOLOGY AND PROLIFERATION PATTERN OF BREAST CANCER CELLS

The present study aimed to investigate the effects of Pequi oil nanoemulsions (Caryocar brasiliense) in morphologic aspects and proliferation (cell cycle pattern) of breast cancer cells (MCF-7) in vitro. Pequi oil nanoemulsions (NE) were prepared as following: different proportions of Pequi oil and surfactants were added in deionized water (for negatively charged NE-) or chitosan solution (2mg/mL) (for positively charged NE+) and submitted to sonication (20Hz) for 5 minutes under an ice bath. Physicochemical parameters and stability of NEs were analyzed by dynamic light scattering after 1, 7, 15, 30, and 60 days of storage at 4°C and room temperature. MCF-7 cells were seeded in 6-well plates (3×104 cells/well) and incubated with 168&#956;g/mL for 72h. Then, the cells were fixed with 4% paraformaldehyde and stained with Giemsa in order to analyze morphologic aspects of treated MCF-7. For cell cycle analysis, cells were resuspended in 0.1% sodium citrate, 0.1% Triton-X, 20µg/mL propidium iodide and evaluated by flow cytometry. Statistical analysis was performed with ANOVA (Tukey test). Nanoemulsions produced showed mean hydrodynamic diameter <300nm and average polydispersity <0.3. NEs remained stable during the period evaluated in both storage conditions. Regarding morphological aspects, MCF-7 cells treated with NE- presented a more pronounced cytoplasmic retraction than in NE+ treatment. Furthermore, microscopic analysis of cell colonies indicated lower cell growth in both treatments. Cell cycle analysis showed a slight increase of 5% in the proportion of cells at G2 phase and a 5% decrease in the proportion of cells at G1 phase (p<0.05) of treated cells. In conclusion, the present data show that Pequi NEs are stable formulations and affect the morphology and cell cycle of breast cancer cells suggesting their application as a promising therapeutic approach in breast cancer treatments. More studies aiming to investigate other mechanisms of action involved are underway.