Fig. 3

Cis-Pt@PNPs-CL4 are more cytotoxic than free Cis-Pt and untargeted Cis-Pt-loaded nanovectors. (a-c) Representative IC50 curves for free Cis-Pt, Cis-Pt@PNPs, Cis-Pt@PNPs-SCR and Cis-Pt@PNPs-CL4 on MDA-MB-231 and MDA-MB-231 EGFR-KO. Cells were incubated with increasing concentration of free Cis-Pt, Cis-Pt@PNPs, Cis-Pt@PNPs-SCR or Cis-Pt@PNPs-CL4 (from 0.1 to 30 µM Cis-Pt, free or encapsulated in nanoparticles). After continuous 72 h-incubation (a, b) and after 40 min incubation followed by washes (WO = washout) and 72 h recovery (c), cell viability for each sample was determined and expressed as percent of viable treated cells with respect to mock-treated controls. Data were plotted in GraphPad Prism v.8.4.3 software to draw dose-response curve and to calculate IC50 values (d). IC50 was estimated on the basis of at least three different experiments. (e) BT-549 cells were incubated with Cis-Pt, Cis-Pt@PNPs-SCR or Cis-Pt@PNPs-CL4 at the indicated concentration of Cis-Pt for 72 h and cell viability for each sample was analyzed and expressed as percent of viable treated cells with respect to mock-treated controls. Each determination represents the average of three individual experiments and error bars represent SD. ^****P < 0.0001; ^***P < 0.001; ^*P < 0.05. (f) The apoptosis of MDA-MB-231 cells receiving 72-h treatment with Cis-Pt, Cis-Pt@PNPs-CL4 or Cis-Pt@PNPs-SCR was measured by Annexin-V/PI staining and flow cytometric analysis. The cell apoptosis data are shown on the right histograms. Values are shown relative to mock treatment, arbitrarily set to 1 (n = 3). ^***P < 0.001, ^**P < 0.01