Vascular endothelial dysfunction and platelet activation play a key role in
tumor metastasis, and therefore, both of these processes are considered important therapeutic targets in
cancer. The aim of our studies was to analyze antimetastatic activity of combination
therapy using
nitric oxide donor DETA/NO and
antiplatelet drug clopidogrel.
Nitric oxide acts as a vasoprotective mediator, while
clopidogrel inhibits
ADP-mediated platelet aggregation. 4T1-luc2-tdTomato cell line transplanted intravenously (i.v.) and 4T1 cell line transplanted orthotopically were used as metastatic mammary gland
cancer models. Moreover, antiaggregation action of compounds was tested ex vivo on the blood samples taken from
breast cancer patients. We have shown that in selected dosage regimes,
DETA/NO combined with
clopidogrel significantly reduced lung metastatic foci formation in an i.v. model, and such inhibition was transiently observed also in an orthotopic model. The antimetastatic effect was correlated with a significant increase of
prostacyclin (PGI2) metabolite and reduction of
endothelin-1, sE-
selectin, sI-CAM, and TGF-β plasma levels as well as decreased V-CAM expression on the endothelium. Combination
therapy decreased
fibrinogen binding to the resting platelets at the early stage of
tumor progression (day 14). However, at the later stages (days 21 and 28), the markers of platelet activation were detected (increased JON/A antibody bound,
P-selectin level, binding of
fibrinogen, and vWf). Decreased aggregation as well as a lower release of TGF-β were detected in platelets incubated ex vivo with compounds tested from metastatic
breast cancer patients. Although combination
therapy increases
E-cadherin, the increase of
N-cadherin and α-SMA in
tumor tissue was also observed. The results showed that at the early stages of
tumor progression, combined
therapy with
DETA/NO and
clopidogrel improves vasoprotective and antiplatelet activity. However, in advanced
tumors, some adverse effects toward platelet activation can be observed.