Dual antiplatelet therapy with clopidogrel and aspirin increases mortality in 4T1 metastatic breast cancer-bearing mice by inducing vascular mimicry in primary tumour

// Marta Smeda 1 , Anna Kieronska 1 , Bartosz Proniewski 1 , Agnieszka Jasztal 1 , Anna Selmi 1 , Krystyna Wandzel 1 , Agnieszka Zakrzewska 1 , Tomasz Wojcik 1 , Kamil Przyborowski 1 , Katarzyna Derszniak 1 , Marta Stojak 1 , Dawid Kaczor 1 , Elzbieta Buczek 1 , Cezary Watala 2 , Joanna Wietrzyk 3 and Stefan Chlopicki 1, 4 1 Jagiellonian Centre for Experimental Therapeutics, Jagiellonian University, Bobrzynskiego 14, Krakow 30-348, Poland 2 Department of Haemostasis and Haemostatic Disorders, Medical University of Lodz, Kosciuszki 4, Lodz 90-419, Poland 3 Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Department of Experimental Oncology, Rudolfa Weigla 4, Wroclaw 53-114, Poland 4 Chair of Pharmacology, Jagiellonian University, Medical College, Grzegorzecka 16, Krakow 31-531, Poland Correspondence to: Stefan Chlopicki, email: stefan.chlopicki@jcet.eu Keywords: mouse breast cancer; vascular mimicry; platelet inhibition; aspirin; clopidogrel Received: November 01, 2017 Accepted: February 25, 2018 Published: April 03, 2018 ABSTRACT Platelet inhibition has been considered an effective strategy for combating cancer metastasis and compromising disease malignancy although recent clinical data provided evidence that long-term platelet inhibition might increase incidence of cancer deaths in initially cancer-free patients. In the present study we demonstrated that dual anti-platelet therapy based on aspirin and clopidogrel (ASA+Cl), a routine regiment in cardiovascular patients, when given to cancer-bearing mice injected orthotopically with 4T1 breast cancer cells, promoted progression of the disease and reduced mice survival in association with induction of vascular mimicry (VM) in primary tumour. In contrast, treatment with ASA+Cl or platelet depletion did reduce pulmonary metastasis in mice, if 4T1 cells were injected intravenously. In conclusion, distinct platelet-dependent mechanisms inhibited by ASA+Cl treatment promoted cancer malignancy and VM in the presence of primary tumour and afforded protection against pulmonary metastasis in the absence of primary tumour. In view of our data, long-term inhibition of platelet function by dual anti-platelet therapy (ASA+Cl) might pose a hazard when applied to a patient with undiagnosed and untreated malignant cancer prone to undergo VM.