Genotoxic evaluation of poly(anhydride) nanoparticles in the gastrointestinal tract of mice.

Gantrez® AN 119-based NPs have been developed as oral drug carriers due to their strong bioadhesive interaction with components of the gastrointestinal mucosa and to their adaptable surface. The use of mannosamine to coat Gantrez® AN 119-based NPs results in a high mucus-permeable carrier, able to reach the gastrointestinal epithelium. Although their efficacy to transport a therapeutic agent has been demonstrated, their safety has not yet been thoroughly studied. They have proved to be non-cytotoxic, non-genotoxic and non-mutagenic in vitro; however, the in vivo toxicity profile has not yet been determined. In this study, the in vivo genotoxic potential of Gantrez® AN 119 NPs coated with mannosamine (GN-MA-NP) has been assessed using the in vivo comet assay in combination with the enzyme formamidopyrimidine DNA glycosylase in mice, following the OECD test guideline 489. To determine the relevant organs to analyse and the sampling times, an in vivo biodistribution study was also carried out. Results showed a statistically significant induction of DNA strand breaks and oxidized bases in the duodenum of animals exposed to 2000 mg/kg bw. However, this effect was not observed at lower doses (i.e. 500 and 1000 mg/kg which are closer to the potential therapeutic doses) or in other organs. In conclusion, GN-MA-NP are promising nanocarriers as oral drug delivery systems.

Stefin B deficiency reduces tumor growth via sensitization of tumor cells to oxidative stress in a breast cancer model.

Lysosomal cysteine cathepsins contribute to proteolytic events promoting tumor growth and metastasis. Their enzymatic activity, however, is tightly regulated by endogenous inhibitors. To investigate the role of cathepsin inhibitor stefin B (Stfb) in mammary cancer, Stfb null mice were crossed with transgenic polyoma virus middle T oncogene (PyMT) breast cancer mice. We show that ablation of Stfb resulted in reduced size of mammary tumors but did not affect their rate of metastasis. Importantly, decrease in tumor growth was correlated with an increased incidence of dead cell islands detected in tumors of Stfb-deficient mice. Ex vivo analysis of primary PyMT tumor cells revealed no significant effects of ablation of Stfb expression on proliferation, angiogenesis, migration and spontaneous cell death as compared with control cells. However, upon treatment with the lysosomotropic agent Leu-Leu-OMe, cancer cells lacking Stfb exhibited a significantly higher sensitivity to apoptosis. Moreover, Stfb-ablated tumor cells were significantly more prone to cell death under increased oxidative stress. These results indicate an in vivo role for Stfb in protecting cancer cells by promoting their resistance to oxidative stress and to apoptosis induced through the lysosomal pathway.