Fig. 2: Testosterone and AR-pathway activity interfere with docetaxel-induced target engagement and cell death.

a Acetylated-α-tubulin as a measurement for tubulin stabilisation in PC346C-DCC-K tumours obtained 3 days after docetaxel treatment, in castrate and testosterone-supplemented mice (DocCx n = 6 and DocTest n = 6, respectively). Acetylated-α-tubulin signal intensity was obtained by immunoblotting individual tumour samples and normalised to GAPDH loading control. Statistical comparison was performed by a two-sided T test. b Quantification of TUNEL stainings in short-term docetaxel-treated PC346C-DCC-K tumours from castrate and testosterone-supplemented mice (DocCx n = 6 and DocTest n = 6, respectively). TUNEL signal was compared to three tumours obtained from castrate mice (Cx) with no/low docetaxel accumulation (≤0.1 ng/mg tumour) after short-term treatment. Fraction of TUNEL-positive pixels was normalised to Hoechst signal, and data plotted is the median TUNEL-positive pixels of the individual tumour samples. ***P < 0.001 and *P < 0.05. n.s. Not significant. c Impact of androgen supplementation (R1881; orange data points) on docetaxel response as compared to androgen-deprived culture conditions (DCC; blue data points). Docetaxel sensitivity was assessed in the AR-positive CRPC cell lines PC346C-DCC-K (top panel) and VCaP-DCC-E (lower panel) (both n = 3). Docetaxel response was normalised to cell density at the start of docetaxel treatment (dashed line) and plotted as relative cell expansion. Data were fitted using a non-linear curve fit to compare the two culture conditions; P values are displayed. d Individual tumour growth curves of docetaxel-treated PC346C-DCC-K tumours under castrate conditions (from day 0, n = 7). Sixty days after docetaxel treatment, mice were supplemented with a testosterone implant (red data points) and tumour growth was monitored until tumours exceeded 1000 mm³, or a maximum follow-up of 21 days.