Fig. 3: MSCs select for apoptotic resistant prostate cancer cell populations.

a Growth of parental PAIIIs (F0) and MSC PAIII cell lines selected after one (F1) or two rounds (F2) of exposure to MSC conditioned media (50% concentration). Cell growth was calculated as a percentage of controls grown in the absence of MSC CM (n ≥ 3 biologically independent samples). b Direct co-culture of F0 and F2 PAIIIs with MSCs at varying ratios (MSC:PAIII). Data obtained from n ≥ 3 biologically independent samples. Cell growth was calculated as a percentage of F0 and F2 PAIIIs seeded at equivalent numbers in the absence of MSCs. c Immunofluorescence (IF) analysis of cleaved caspase-3 positivity (green) in F0 and F2 PAIII cell lines treated for 6 h with MSC CM. Graphs illustrate the number of cleaved caspase-3 positive cells as a ratio of total cell number (nuclear DAPI-blue). Data obtained from n ≥ 3 fields of view from at least three independent experiments. Etoposide (ETX; 50 μM) was used as a positive control. Data shown as mean ± SD. d, e MSC CM (50%) selection of apoptosis resistant DU-145 prostate cancer cells (F2) and the response to etoposide (ETX; 50 μM). Cell growth was calculated by MTT assay with absorbance (ABS) at 490 nm used as a correlate for cell number (n ≥ 3 biologically independent samples). f IC₅₀ curves of PAIII F0 and MSC selected F2 cells treated with docetaxel for 48 h at a concentration range of 0–6.25 nM (n ≥ 3 biologically independent samples at each concentration used. Dots represent the mean combined with a nonlinear fit solid line. Error bars shown as mean ± SEM (a, b, d) or ±SD (c, e). Statistical analyses were generated from one-way ANOVA with multiple comparisons at 95% CI or unpaired t-test (e). Asterisks denotes statistical significance (*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001) while NS denotes not significant.