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. 2020 Nov 4;124(1):217–227. doi: 10.1038/s41416-020-01094-y

Fig. 5. PR expression is necessary for tumoursphere outgrowth in an endocrine-resistant model of ER+ breast cancer.

Fig. 5

a Primary and secondary tumoursphere formation of parental and tamoxifen-resistant (TamR) MCF-7 cells. b Protein expression of PR and ER in TamR MCF-7 cells pretreated with 1 nM E2 for 48 h, followed by acute R5020 treatment (1 h; 10 nM). c PR transcript levels were analysed in cells grown in adherent 2D conditions, as 3D primary or 3D secondary tumourspheres using RT-PCR analysis. d Single-cell phospho-PR levels were measured in 2D adherent cultures and 3D tumourspheres by phospho-specific flow cytometry. Flow plots are representative of n = 3 independent experiments. e KLF4, NOTCH2, ALDH1A1, and FOXO1 mRNA levels were measured by RT-PCR. f PR was silenced in endocrine refractory MCF-7 and T-47D cells using shRNA and tumoursphere formation tested. g Secondary tumoursphere formation was examined with Mifepristone (RU486; 100 nM) and/or NT157 (3 µM) treatment in MCF-7 and T-47D parental and TamR models. Error bars are S.E.M.; n = 3 biological replicates; *p < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.