Platelet-protein-profiling of healthy controls and patients with early- and late-stage colorectal cancers

Aims: Early tumor detection and intervention are important determinants of survival in patients with cancer. During early tumor growth, platelets actively and selectively sequester proteins and, as such, the platelet protein content can be used as a marker of early tumor growth. We therefore aimed at identifying differenzially expressed proteins of platelets that distinguish healthy controls from patients with early- and late-stage colorectal cancer. Such markers might serve for innovative early detection, prognosis and therapeutic intervention.

Material and methods: We compared multiplex-fluorescence two-dimensional gel electrophoresis (2-DE)-based protein expression pattern of platelets between healthy controls (n=12) and patients with early- (n=7) and late-stage (n=5) colorectal carcinoma. 2-DE results with differences in expression levels between the three groups were analyzed with SameSpot® software followed by principal component analysis (PCA).

Results: Comparing the platelet-proteome of healthy controls and patients with early and late colorectal carcinoma (p<0.05), 39 differenzially expressed proteins could be detected. Of those, 11 polypeptides were distinctly expressed between healthy controls and early-stage carcinomas only. A PCA-based cluster analysis showed clustering and good separation between the groups.

Conclusion: This study showed significant differences in protein expression of platelets from healthy controls and from patients with early- and late-stage colorectal cancers. These targets will be identified by mass spectrometry and further validated for their biomarker potential on large patient cohorts.