| dc.description.abstract | Objective: Hypoxia is characteristic feature of solid tumors and the main obstacle for favorable anticancer effects in the clinic. In this regard, hypoxia-responsive systems can be used as smart nanoformulations for deep penetration into the tumor. In this study, we present the design and synthesis of nano-sized self-activating chitosan nanogel in the tumor microenvironment for the specific packaging and delivery of FTY720 (fingolimod), which is able to penetrate into the hypoxic core of tumor cells in MDA-MB-231 triple-negative breast tumoroids.
Materials and Methods: First, mPEG3000 was coupled with Azo300 linker through EDC/NHS to form mPEG-AZO. Then, mPEG-Azo was attached to the surface of chitosan nanoparticles through EDC/NHS. FTY720 was loaded physically and nanogel formation was promoted by TPP-mediated ionic gelation. The nanogel synthesis was characterized by FTIR, DLS, NMR, SEM and TEM. Hypoxia-responsive behavior was confirmed using a nitro reductase as well as two-dimensional hypoxia/normoxia cell culture to performe cytotoxicity assays and live/dead staining. Finally, the anticancer potential, mode of action, cell penetration and controlled drug delivery were evaluated using 3D tumor spheroids, live/dead fluorescence staining, DAPI staining and Real Time PCR to measure the expression levels of Notch1 and mTOR as two key targets of fingolimod and the key genes related to apoptosis, Bax and caspase3,
Results: Our results indicate the successful formulation of hypoxia-responsive chitosan nanogel with a size of 49.86 nm and a zeta potential of +3.22 mV, which increases to +30.3 mV after the separation of the PEG shell. This spherical nanogel has the ability of self-activation in the hypoxia microenvironment in laboratory conditions and 2D and 3D culture. This capability causes deep penetration in the core of hypoxic the microtumor and affords targeted drug. Treatment with lower doses of fingolimod (10 μg) significantly reduced MDA-MB-231 microtumor size by 15% and induced apoptosis by 88% within 72 hours after single-dose treatment.
Conclusion: Our results prove the effectiveness of the newly formulated hypoxia-responsive nanogel as a biocompatible and safe drug formulation platform for the controlled and selective delivery of effective anticancer drugs such as fingolimod, with promising anti-cancer potential to effectively eliminate invasive hypoxic solid tumors such as triple negative breast cancer.
Keywords: chitosan nanogel, tumor microenvironment, hypoxia responsive, tumor spheroid model; Fingolimod, breast cancer treatment | en_US |
