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. Author manuscript; available in PMC: 2018 Apr 1.
Published in final edited form as: Arterioscler Thromb Vasc Biol. 2017 Feb 2;37(4):664–674. doi: 10.1161/ATVBAHA.116.308791

Figure 5. Tamoxifen metabolite 4-hydroxytamoxifen inhibits platelet activation and alters release of stored factors.

Figure 5

To measure the effect of 4-Hydroxytamoxifen (4-OH) on platelet activation, platelets were isolated from healthy donors, pretreated with 25–50 µM of 4-OH or vehicle control, washed, exposed to agonists, (MCF-7 or MDA-MB-231 tumor cells or TRAP) and P-selectin was measured by flow cytometry (A). VEGF release was measured by ELISA (B). A membrane-based array was performed to further characterize changes in protein release caused by 4-OH (C–E). Platelets from normal, healthy donors were isolated, treated with 50 uM 4-OH or vehicle control, washed, then activated with 5 µM TRAP (C) or MCF-7 tumor cells (D) to generate releasates. Releasate were assayed for 43 proteins by membrane-based array. Proteins showing differences of more than 1.5-fold between vehicle control and 4-OH are shown (C-D). Summary of array results lists all proteins with a 1.5-fold or greater change between drug and vehicle control (E). Bars indicate SEM. P<*0.05, ***0.001 by ANOVA, n=3 independent replicates per treatment group for A–B. Releasates from 3 independent replicates were pooled for use in array.