Aspirin inhibition and recovery of cyclooxygenase activity and thromboxane biosynthesis in human megakaryocytes: a translational surrogate model

Figures

• 

  Fig. 1. Expression of COX-1 and -2 in MEG-01 and CHRF-288-11. (A) Immunoblot analysis of COX-1 and COX-2 expression in CHRF-288-11 cells. (B) Immunoblot analysis of COX-1 and COX-2 expression in MEG-01 cells. Two × 106 cells were lysed, and 20 μg of total proteins were subjected to 9% SDS-polyacrylamide gel. COX-1, COX-2, and β-actin were developed on the same blot (n = 3). (C) Immunocytochemistry of MEG-01 cells using selective anti-COX-1 and COX-2 antibodies. Representative images of immunostaining of COX-1 or COX-2 are shown; slides were analyzed by light microscopy using the PhenoImager HT 2.0 workstation system (Akoya Biosciences) at main magnification ×20. COX, cyclooxygenase.

• 

  Fig. 2. Effect of aspirin on TXB2 biosynthesis and kinetics of COX activity recovery in MEG-01 and CHRF-288-11 cells. (A, B) MK cells were treated with different concentrations of aspirin (0.1, 1, 3, 10, and 30 μM) for 30 min, followed by TXB2 measurement. The percentage of TXB2 in aspirin-treated cells vs vehicle-treated cells as control is plotted. (A) MEG-01 and (B) CHRF-288-11. Results are expressed as a mean ± SEM of experiments performed in triplicates in MEG-01 (n = 7) and CHRF-288-11 (n = 3), respectively. IC50 was determined by GraphPad Prism and calculated as 2.4 ± 0.5 and 2.8 ± 0.6 μM (mean ± SEM.) for MEG-01 and CHRF-288-11, respectively. (C, D) MK cell lines were treated with 10 μM aspirin or vehicle (0.1% ethanol, v/v) for 30 min and COX activity was determined. Washed cells were allowed to recover for 24, 48, 72, 96 and 120 hours. TXB2 levels in (C) MEG-01 and (D) CHRF-288-11 were measured after AA loading and expressed as % TXB2 of aspirin vs control (vehicle-treated cells). Results are expressed as a mean± SEM. of separate experiments for MEG-01 (n = 10) and for CHRF-288-11 (n = 8), performed each in triplicate. AA, arachiconic acid; COX, cyclooxygenase; TX, thromboxane.

• 

  Fig. 3. COX isoenzyme contribution in TXB2 biosynthesis after treatment with 10 μM aspirin in (A) MEG-01 and (B) CHRF-288-11 cells. All cells were treated with 10 μM aspirin for 30 min, and basal COX activity was determined (labelled ASA). Cells were next washed and plated for each time point (24, 48, and 72 hours), treated with either DMSO (0.1%; v/ v) (labeled Ctrl.), 10 μM SC-560 or 1 μM NS-398 for 30 min, before the addition of 10 μM AA (see the Methods section). TXB2 levels were measured as ng/million cells and expressed as % of control. Results are expressed as a mean ± SEM. of three experiments performed in triplicate for both MK cell lines, and statistical analysis was performed using 1-way ANOVA followed by Tukey test, comparing each inhibitor vs control at each time point. ∗∗∗P < .001; ∗∗∗∗P < .0001. AA, arachidonic acid; ASA, aspirin; Ctrl., Control; ns, nonsignificant; TX, thromboxane.

• 

  Fig. 4. Effect of daily treatment with aspirin on TXB2 biosynthesis in MEG-01. Cells were treated at day 0, washed, and treated daily with 10, 1, or 0.1 μM aspirin. COX activity was assessed each day by TXB2 expressed in ng/million cells and represented as a percentage of control (mean ± SEM, n = 3–4, performed in triplicate). Statistical analysis was performed using one-way ANOVA followed by Tukey test, ∗∗∗∗P < .0001. TX, thromboxane.