Figure 1.

Primary Breast Cells Are More Sensitive to Cisplatin-Induced DNA Lesions Than Primary Lung Cells

(A) Overview of adapted MTT assay to measure cell death. Briefly, cells were seeded at 50% density and treated with high doses of cisplatin for 24 or 48 h. Treatment under these conditions results in cell death (e.g., compare the wells treated with 60 μM cisplatin at 24 and 48 h).

(B) Breast cells are more sensitive to cisplatin than lung cells. Human primary epithelial cells from six donors were treated with a range of cisplatin concentrations. After 48 h, the cell viability was determined by MTT assay. The concentration at which 50% loss of viability occurred (IC₅₀) was calculated (n = 3–6). A t-test was used to compare IC₅₀ values between breast and lung cells.

(C) Treatment with cisplatin results in apoptosis. Nuclear morphology of breast and lung cells was visualized by DAPI stain after 24-h exposure to 80 μM cisplatin (representative experiment, n = 4).

(D) Breast cells more frequently display apoptotic morphology (DAPI stain) after 24 h of cisplatin treatment than lung cells (representative experiment, n = 4). A two-way ANOVA with Bonferroni post-hoc test was carried out to compare differences (*p < 0.05, ***p < 0.001).

(E) Breast cells are more sensitive to equal amounts of cisplatin-induced DNA lesions at 48 h. The amount of DNA-bound platinum was determined after 48 h of cisplatin treatment (Figure S1A) and plotted against the cellular viability (MTT assay) at 48 h (representative experiment, n = 3). Regression analysis was used to test if the slope and intercept were different. Error bars represent the SD (n = 3).