Developing porous silicon nanoparticles for the targeted treatment of uveal melanoma
Uveal melanoma (UM) is a rare and aggressive type of cancer occurring in the melanocytes of the eye. Treatment options, such as resection, enucleation, and radiation therapy, result in vision loss. Therefore, there is a need for a new targeted therapeutic approach that would preserve ocular tissue and visual function while achieving efficient tumor control. Our approach aims to use photoactivated porous silicon nanoparticles (pSiNPs) as a drug delivery vehicle to target UM while preserving vision. In this objective, pSiNPs have first been produced by electrochemical etching. Nanoparticle tracking analysis showed that the pSiNPs were uniform in size at ≈100 nm. Then, UM cells were incubated with pSiNPs and MTT assay showed that pSiNPs did not decrease cell viability at concentrations ≤50μg/mL. Interestingly, fluorescent imaging also showed that pSINPs were present inside the UM cells, suggesting efficient internalization. Second, we evaluated the efficacy and effect of IAP protein knockout in UM cells, an inhibitor of apoptosis overexpressed in many cancers. Western blot revealed that IAP protein level was lower in cells transfected with IAP siRNA compared to scramble control. Using MTT assay, we also showed that IAP siRNA-transfected cells displayed a higher sensitivity to doxorubicin compared to control cells (64% vs 44% survival, respectively). Third, different UM cells have also been screened for the presence of Mannose-6 Phosphate receptor (M6PR), a receptor often present in cancer cells due to their high affinity for carbohydrate molecules. Western blot showed that M6PR expression level in UM cells is similar to M6PR level in positive control, suggesting that M6PR is overexpressed in UM cells and could be used for a pSiNP-targeted approach. Finally, to test this approach in a physiologically relevant system, we aimed to develop and characterize UM spheroids. Among the ultra-low attachment (ULA) and hanging drop techniques, used in combination with different additives (xanthan gum, methylcellulose, Matrigel), the 5% Matrigel in ULA plates provided the most uniform and compact spheroids, as confirmed by the overexpression of E-cadherin, allowing us to establish robust and fast-growing spheroids to be used in organ-on-chip technology. This preliminary data (1) showed that pSiNPs are biocompatible and can be internalized, (2) identified a targeted siRNA-based therapeutic approach for UM and (3) developed protocol for UM spheroids formation. Future studies will now aim to conjugate M6PR ligand-IAP siRNA-pSiNPs to test the relevance of this approach on a UM-on-chip.
