Evaluation of a novel tool for the study of early metastasis based in B16F10 murine melanoma cells labeled with Cd-Te Quantum Dots

Many studies have proposed the use of fluorescent semiconductor nanoparticles or quantum dots (QDs) as new experimental tools to label cells and tumors due to their unique optical properties (high extinction coefficient,... [ view full abstract ]

Many studies have proposed the use of fluorescent semiconductor nanoparticles or quantum dots (QDs) as new experimental tools to label cells and tumors due to their unique optical properties (high extinction coefficient, stability, increased brightness, etc.) in comparison with organic dyes. However, the use of QDs is limited by their toxicity in biological systems, mostly associated with Cd+2 release and reactive oxygen species (ROS) generation. Also, little is known about the effects of QDs on the metastatic capacity of cancer cells. With this in mind, we developed a methodology that permits obtaining viable B16F10 cells(syngeneic murine melanoma cells with C57BL/6 mice, widely used in metastasis studies) labeled with QDs to then study their behavior in migration and metastasis assays.
The effects of QDs uptake on viability, proliferation, migration and invasiveness of B16F10 cells were determined in the absence or presence of N-acetylcysteine (NAC). Then, QDs-labeled B16F10 cells with in vitro migration parameters similar to control cells were selected and injected into C57BL/6 mice to evaluate their metastatic potential. Fluorescence levels associated with QDs uptake in different organs of the mice were determined at 5 min, 30 min, 1 h, 6 h and 24 h post injection.
Our results suggest that QD-labeling of B16F10 cells severely reduces viability but that treatment with NAC significantly improves both labeling of cells and viability. Migration of QDs-labeled B16F10 cells was enhanced due to the production of ROS, but treatment of labeled cells with NAC prior to the assays reduced these parameters to control levels. On the other hand, proliferation and invasion by QDs-labeled B16F10 cells was reduced even following NAC treatment. In vivo assays show that QDs-labeling permits short-term tracking of B16F10 cells in the lung following intravenous injection into the tail vein(attached image), but these cells were unable to generate lung metastasis after 21 days. Our results suggest that B16F10 cells labeled with QDs could be used for monitoring early steps in the process of lung metastasis.