Abstract 4589: Perturbation of epidermal growth factor (EGF) receptor internalization by novel aspirin analogues in SW480 cells

BACKGROUND Colorectal cancer (CRC) is a global phenomenon with over 135 million new cases and over 600,000 deaths worldwide annually. The EGFR regulates normal growth and differentiation of cells, however its dysregulation is the cause of a wide range of cancers, including CRC. Activation of the EGFR requires phosphorylation at specific sites, which then leads to the recruitment of proteins and ultimately its internalization. The use of low-dose aspirin as a preventative agent is a controversial topic, particularly as the mechanism of action is hotly disputed. We have previously determined that novel aspirin analogues dramatically reduce EGFR phosphorylation in SW480 CRC cells; these cells express neither COX-1 nor COX-2, the perceived target for aspirin-like compounds. We have seen these aspirin analogues to also perturb the internalization of this receptor. METHODS SW 480 CRC cells were cultured in Leibovitz9s L-15 medium on glass slides and starved for 48 hours. The cells were then treated with 0.5 mM aspirin analogues (ortho-aspirin, meta-aspirin, para-aspirin, ortho-thioaspirin, meta-thioaspirin and para-thioaspirin) for 30 minutes and then treated with EGF-tagged with AlexaFluor 555 for an hour. The reaction was the quenched with cold PBS, fixed and mounted on microscope slides with VectaShield + DAPI. Confocal microscopy was used to study the effect of these aspirin analogues on EGFR internalization. RESULTS EGF increased phosphorylation at all sites tested. We have peviously shown that these effects were prevented by preincubation with thioaspirins more potently than with aspirin and its positional isomers. These novel thioaspirins are also more potent in inhibiting proliferation of SW480 CRC cells. We now show these analogues prevent the internalization of EGFR. Instead they permit the formation of clusters. Aspirin and its analogues can perturb EGFR internalization and signalling in SW 480 cells. CONCLUSION The EGFR signalling pathway is a target for aspirin and aspirin analogues. The inhibition of receptor phosphorylation is accompanied by the loss of receptor internalization. Citation Format: Asma’U I.J. Bashir, Sarah Jones, Christopher J. Perry, Stephen T. Safrany, Iain D. Nicholl. Perturbation of epidermal growth factor (EGF) receptor internalization by novel aspirin analogues in SW480 cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4589.