Fig. 4

SERMs enhance microtubule stability by interacting with the taxane site. a hTERT-RPE1 cells were treated with 50 µM of selected SERMs or 500 nM of TAX (15) for 2 h and then subjected to 16 µM of nocodazole challenge for 50 min in the presence of the SERM. The cells were fixed and stained as described. Scale bars 20 µm, inset—800%. b Quantification of the proportion of cells in each condition that have microtubules in soluble or polymerized state. c Eight selected SERMs: RAL (7), LAS (13), 5C6 (3), 5C7 (1), TAM (14), OB3 (4), OB7 (5), 5JY (2) and controls, TAX (15) and VLB (17), were evaluated for their ability to enhance microtubule polymerization at 50 µM; asterisk (*) indicates treatment with 1 µM. Data were normalized to maximum polymerization readout from 10 µM of paclitaxel treatment (**). d hTERT RPE-1 cells were incubated with indicated drugs at 50 µM (except TAX at 2 µM), and SiR-tubulin at 500 nM in the presence of verapamil for 3 h. Representative SiR-tubulin signal for each is shown, outlines indicate cell boundary based on brightfield images (Supplementary Fig. 5). RAL (7), and TAM analogue, 5C6 (3), demonstrated the strongest displacement of SiR-Tubulin fluorescence signal, while LAS (13) showing minimal SiR-Tubulin redistribution. TAM (14), and its derivatives 5C7 (1) and 5JY (2) and OBHS analogues: OB3 (4) and OB7 (5) showed no displacement. Scale bar 35 μm