# Investigating the effects of platelets, platelet releasate and aspirin on colorectal cancer cell proliferation, migration and invasion

## TL;DR

This study explores how platelets and aspirin affect the behavior of colorectal cancer cells, finding that aspirin directly inhibits cancer cell growth but does not stop platelet activation.

## Contribution

The study reveals that aspirin's anti-cancer effects are direct and not mediated through platelet inhibition.

## Key findings

- Aspirin directly inhibits the proliferation of HCT15 and HCT116 colorectal cancer cell lines.
- Platelets and platelet releasate increase migration and invasion of HCT116 but not HCT15 cells.
- Aspirin does not inhibit platelet activation by colorectal cancer cells.

## Abstract

The aims of this study were to investigate the binding of platelets to colorectal cancer (CRC) cells, platelet activation by CRC cells, and determine the effect of platelets and platelet releasate containing extracellular vesicles on CRC cell proliferation, migration and invasion following aspirin pretreatment. Platelets from healthy individuals were pretreated with aspirin before co-incubation with CRC cells. Platelet activation by CRC cells was analysed by flow cytometry and the binding of platelets to CRC cells investigated using immunofluorescence microscopy. Platelet releasate containing extracellular vesicles was generated by centrifugation. The effect of platelets and platelet releasate on CRC cell proliferation was investigated using carboxyfluorescein succinimidyl esterand dimethylthiazol-carboxymethoxyphenyl-sulfophenyl-tetrazolium assays. Migration and invasion were examined using Transwell assays. HCT15 and HCT116 CRC cells activated platelets, with higher numbers of CRC cells activating more platelets, however aspirin was unable to inhibit platelet activation. Platelets are also able to bind to HCT15 and HCT116 cells. Platelets and platelet releasate did not affect HCT15 and HCT116 proliferation, however, aspirin directly inhibited the proliferation of both cell lines. Platelets and platelet releasate significantly increased the migration and invasion of HCT116, but not HCT15 cell lines. Platelets adhere to and are activated by CRC cells lines, with aspirin unable to inhibit this activation. CRC proliferation was not affected by platelets, however the effect on cancer cell migration and invasion was dependent upon the cell line, suggesting the effects of platelets and platelet releasate containing extracellular vesicles may be patient specific. The inhibitory effect of aspirin on colorectal cancer proliferation is a direct effect on the cancer cell and independent of platelets and extracellular vesicles.

The online version contains supplementary material available at 10.1007/s12032-026-03264-z.