Micro-PIXE reveals cisplatin uptake followed by Fe accumulation in U87 cells†

Cisplatin (Pt(NH₃)₂Cl₂) and other platinum-based drugs are widely used medications that treat several different cancers, including, but not limited to, ovarian, testicular, and neck. Here, we investigate the uptake of cisplatin in human glioblastoma U87 cells and its impact on other ions with the use of the micro-PIXE technique. Cells were treated with cisplatin at concentrations of 10, 20, and 100 μM for 24 hours. The micro-PIXE technique allowed the quantification of the elements in the cells and provided the generation of two-dimensional elemental maps with micrometric spatial resolution. By measuring the chlorine and platinum signals, we were able to identify single cells and detect those with higher platinum concentrations, respectively. Furthermore, the analysis of the whole PIXE spectra allowed the identification of an increase in iron in cells treated with 100 μM. This result is consistent with the hypothesis of cisplatin-induced ferroptosis, which was validated by lipid peroxidation using flow cytometry. We conclude that cell uptake of cisplatin is heterogeneous and that high uptake of cisplatin correlates with high Fe accumulation.