Platelet VASP phosphorylation assessment in clopidogrel-treated patients: lack of agreement between Western blot and flow cytometry.

Vasodilator-stimulated phosphoprotein (VASP) 239 phosphorylation flow cytometric assessment has been reported as a tool to evaluate the responsiveness to clopidogrel in coronary heart disease (CHD) patients. We report for the first time the comparison between flow cytometry and two challenger assays, aggregometry and Western blot. We studied 21clopidogrel-treated CHD patients, and 28 healthy volunteers. Aggregometry showed platelet function inhibition inpatients. VASP 239 phosphorylation was assessed using flow cytometry and Western blot. ADP receptor response index (RI) were calculated using the formula (PGE1) - (PGE1 + ADP)/(PGE1) x 100. Flow cytometry was not able to detect clopidogrel intake, as RI were 99 +/- 10% [68-130] in healthy volunteers, and 91 +/- 17% [66-127] in treated patients (ns). On the contrary, RI mean in Western blot was 91 + 8% [76-127] in healthy volunteers, and 37 i 25% [4-80] in patients (p<0.05). The extreme values in Western blot revealed inter-individual variability in response to treatment. The comparison between both tests showed a total lack of agreement. Flow cytometric VASP 239 phosphorylation assay lacks sensitivity to detect clopidogrel intake, contrary to Western blot and aggregometry. Caution is required before classifying patients as 'low-responders' to thienopyridines using such method.

Assessment of the antiinvasive potential of the anthracycline aclacinomycin (Aclarubicin) in a human fibrosarcoma cell line.

Aclacinomycin (Aclarubicin) is a trisaccharide anthracycline anticancer drug active against a wide variety of solid tumors and haematological malignancies. We have evaluated its antimigrative and antiinvasive properties in a Boyden chamber with or without Matrigel and in wound repair assays. Aclacinomycin was demonstrated to inhibit HT-1080 cell migration and invasion while being more potent than the classical anthracycline doxorubicin. This decrease occurred in a dose-dependent manner and without affecting cell proliferation. Importantly, the antiinvasive effect was not associated to a modification in the production of the matrix-degrading enzymes MMP-2 and MMP-9 but rather to changes in cytoskeletal and focal contact formation. Indeed, the drug reduces cell polarity, impairs the actin-mediated membrane ruffling at the leading edge and decreases beta1 integrin expression and activation. Dramatic alterations in the distribution of vinculin and in the expression and phosphorylation state of both FAK and Src kinases were also detected. As a conclusion, these data suggest a novel application for this chemotherapeutic agent due to its ability to reduce tumor cell invasion. Combination of aclacinomycin with MMP inhibitors could have therapeutic potential in preventing tumor metastasis.