Fig. 4
PPH overcomes PTX resistance. (a) PTX resistant phenotype of SKOV3 cells is confirmed by the increase of the EC50 value for PTX in SKOV3 PTX resistant cancer cells compared to parental SKOV3 cells. EC50 curve represents mean ± SD of three biologically independent experiments (N = 3) with each three technical replicates (n = 3). (b) PPH reduces viability of PTX resistant SKOV3 cells. EC50 curve represents mean ± SD of three biologically independent experiments (N = 3) with each three technical replicates (n = 3). (c,d) Real-time analysis of cell confluency of SKOV3 PTX resistant cells following PPH treatment. Microscopic pictures were taken every 6h and cell confluency was analyzed using IncuCyte software (indicated by yellow mask). Cell confluency curve represents mean ± SD of three biologically independent experiments (N = 3) with each 3 technical replicates (n = 3). Pictures are representative of three independent experiments. (e) Representative images and quantification of colony formation assay for SKOV3 PTX-resistant cells treated with PTX (1 nM, 3 nM and 10 nM) or PPH (0.1 µM, 1 µM and 2.5 µM) showing PPH overcomes PTX resistance. Samples were normalized to vehicle control (DMSO). Bar plot represents mean ± SD of three biologically independent experiments. Statistical significance between groups was determined with one-way ANOVA and Tukey’s multiple comparisons test. (f) Violin plot indicating the impact of 5-day treatment with PTX (0.1 µM) or PPH (50 µM) on ATP content of HGSOC ex vivo cultured tumor fragments. DMSO was used as vehicle control. Each symbol is a technical replicate (n = 22). Statistical significance between groups was determined with a Kruskal–Wallis test and Dunn’s multiple comparisons test. (g) Immunohistochemical K40 Ac of α-tubulin staining of ex vivo cultured patient-derived HGSOC tumor fragments after 5 days of PPH treatment (50 µM). Levels of statistical significance are indicated as * P ≤ 0.05, ** P ≤ 0.01, *** P ≤ 0.001, **** P < 0.0001. RI = resistance index. DMSO was used as vehicle control.
