Login to Access Video or Poster Abstract: MP87-07
Sources of Funding: None

Introduction

The risk of developing venous thromboembolic events (VTE) is increased up to 4-fold in in men diagnosed with metastatic prostate cancer (PCa). While the precise reasons for this are unknown previous work has established the capacity of platelets (clot initiators) to absorb factors from the bloodstream that may alter platelet functions. Notably, one such factor, cell free DNA (cfDNA) has been shown to strongly correlate with disease severity and outcome. In this study, we sought to examine the effects of cfDNA from men with aggressive PCa on platelets in the context of clot formation and disease progression. _x000D_

Methods

Platelets were isolated from venous blood of 10 men with metastatic castration resistant prostate cancer (mCRPC). Platelet aggregation in response to agonists (i.e. thrombin and collagen) was established using platelet aggregometer. Platelet ability to bind to cancer cells (in vitro) was determined using flow cytometry. Platelet effect on prostate tumor growth in vivo was assessed using human platelet transfusions into 3 different PCa mouse models (intracardiac, subcutaneous, and orthotopic) in combination with standard bioluminescence techniques._x000D_

Results

We assessed the effects of tumor associated nucleic acids on circulating platelets. We found that PCa derived cfDNA - loaded platelets were more reactive to agonists (thrombin and collagen), vs. unloaded platelets, making them more susceptible to spontaneous clot formation. We established that platelets from men with mCRPC (10 men) were significantly (p<0.001) more adherent to cancer cells in vitro as compared to platelets from healthy controls. Addition of nucleic acids (i.e. DNA) to healthy donor platelets in vitro converted them to be more thrombogenic and similar to platelets from men with mCRPC. Finally, we observed that platelets from men with mCRPC strongly induced cell proliferation and tumor growth in vivo (p<0.005), as compared to platelets from healthy controls.

Conclusions

High levels of cancer associated cfDNA have been previously demonstrated to correlate with poor prognosis and increased risk of VTE in men with PCa. Intriguingly, we found that PCa associated cfDNA modulates platelet behavior, revealing, for the first time, a potential molecular basis for Trousseau syndrome in PCa. Further, our findings also shed new light on how cfDNA may alter cancer growth via modulating platelets in the tumor microenvironment. Taken together, our study provides novel insights into the possible biological consequences of cfDNA seen in the advanced cancer state. _x000D_

Funding

None