However, it has been informed that at higher concentrations could induce breast cancer cell apoptosis [36]. This is an ER independent and nongenomic effect; it was found in ER negative breast cancer cells and other cell types such as malignant gliomas, pancreatic Dactolisib carcinomas, and melanomas. On the other hand, estradiol has an antiapoptotic influence in both, ER positive and negative cells, in addition to its proliferative effect on ER positive cells; the antiapoptotic effect has also been reported in MCF-7 Inhibitors,research,lifescience,medical breast cancer cell line [37]. From the results obtained in cell cultures,

it might conclude that all the compositions containing 20mM of TMX showed an important cytotoxic effect. This phenomenon would be related with the induction of cellular apoptosis described above; the effect was also observed in ME N° 1 and 4 containing 10mM TMX. The % of viable cells observed

Inhibitors,research,lifescience,medical would indicate that seven of the fifteen assayed compositions were able to solubilize an enough amount of TMX capable to show a modification in the apoptosis cellular induction. It is also interesting to remark that this phenomenon is observed in presence of the above demonstrated proliferative effect of Inhibitors,research,lifescience,medical estradiol. It can be concluded that formulations 1 and 4 had the best in vitro performance because they were able to show an important antiproliferative effect even when they were loading the intermediate dose. Another interesting observation to point out is that formulation

3 showed the highest percentage of cell viability at any TMX concentration; this formula is the one which has the highest PC (16%) concentration. Previous reports showed that PC content is increased in cancer Inhibitors,research,lifescience,medical cells and have an important role in their proliferation [38, 39]. So, it is expected that this stimulation on cell proliferation can be attributed to the levels of PC. Inhibitors,research,lifescience,medical This observation and the mechanism described above suggest that the proposed MEs would present a high cellular uptake; anyway, PC proliferation effect has to Calpain be considered in further pharmacotherapeutic evaluation. The obtained MEs are promising in the current state of increasing interest for nanocarriers that can be used for TMX delivery. For example, Chawla and Amiji, examined biodegradable polymeric nanoparticles uptake and distribution in MCF-7 breast cancer cell line. They compared TMX intracellular concentration when delivered by the nanoparticles and in solution, and they found that the drug uptake from the nanoparticles followed a saturable transport. Therefore, above certain concentration, TMX intracellular concentration was much higher when delivered by the solution [1]. On the contrary, MEs designed in this work did not show signs of limited transport in none of the selected drug concentrations.