Platelet phenotype changes associated with breast cancer and its treatment

Abstract

Platelets and their granular contents influence both angiogenesis and breast cancer progression. This study was performed to assess the effect of breast cancer and its treatment on platelet biology and the response to inhibition of the platelet P2Y12 receptor. Receptor-specific platelet activation and inhibition was studied for three platelet-associated proteins important in cancer angiogenesis and progression, vascular endothelial growth factor (VEGF), thrombospondin1 (TSP1), and transforming growth factor beta 1 (TGF-β1).

Twenty-four women with active breast cancer and 10 healthy controls not receiving antiplatelet therapy participated in the study. Ex vivo activation of platelets in whole blood was accomplished using PAR1AP, PAR4AP, convulxin, and ADP. Platelet inhibition was accomplished using the P2Y12 receptor antagonist cangrelor (the in vitro equivalent of clopidogrel). VEGF, TSP1, and TGF-β1 were measured using standard ELISA.

Platelet activation by ADP, PAR1, PAR4, and collagen receptors increased VEGF, TSP1, and TGF-β1 secretion in patients with breast cancer. Agonist-induced release of VEGF was greater in cancer patients as compared to healthy controls (p = 0.02 for ADP, p < 0.001 for PAR1AP, PAR4AP, and convulxin) despite a decrease in the efficiency of VEGF secretion in patients with breast cancer. These differences were not observed for TSP1 and TGF-β1 secretion. P2Y12 receptor inhibition decreased VEGF, TSP1, and TGF-β1 secretion. In patients with cancer, cangrelor inhibited TSP1 release to a greater extent than VEGF and TGF-β1 release. In patients with breast cancer, the magnitude of platelet inhibition achieved by cangrelor was greater than that achieved with healthy controls for all agonists and platelet proteins studied.

While platelets are known to influence progression of breast cancer, our results show that breast cancer and its treatment influence the platelet phenotype by increasing the secretion of pro-angiogenic proteins following platelet activation, modulating the efficiency of platelet protein release as well as increasing the response to antiplatelet therapy.

Keywords:

• Platelets
• P2Y12 blockade
• TSP1
• TGF-β1 breast cancer
• VEGF

Acknowledgments

This study was funded by the American Cancer Society, the Vermont Cancer Center and the Lake Champlain Cancer Research Organization, the American Society of Hematology Trainee Award, and the Charles H. Smith Memorial Fund at the University of Vermont.

Declaration of Interest

C.E. Holmes: American Cancer Society, Lake Champlain Cancer Research Organization and the University of Vermont Cancer Center, Charles H. Smith Memorial Fund at the University of Vermont. J.E. Levis: American Cancer Society, Lake Champlain Cancer Research Organization and the University of Vermont Cancer Center, Charles H. Smith Memorial Fund at the University of Vermont. D. Sharma: The American Society of Hematology Trainee Award. I. Lal: Lake Champlain Cancer Research Organization and the University of Vermont Cancer Center. D.J. Schneider, N.M. Bambace, M.E. Wood, and H.B. Muss have no declaration of interests to report.

The authors have no competing interests to declare.

Additional information

Notes on contributors

Chris E. Holmes

C. Holmes (Guarantor) conceived of and designed the research study, performed and directed research, participated in data analysis and manuscript preparation. J. Levis aided in research design, performed research, performed data analysis, and participated in manuscript preparation. D. Schneider developed the protocols for flow cytometry, contributed to study design, and aided in manuscript preparation. N. Bambace participated in subject recruitment, performed research, and implementation of research protocols. D. Sharma participated in subject recruitment, data analysis, and implementation of research protocols. I. Lal participated in subject recruitment and implementation of research protocols. M. Wood participated in subject recruitment and aided in manuscript preparation. H. Muss participated in study design and recruitment and manuscript preparation.

Jamie E. Levis

C. Holmes (Guarantor) conceived of and designed the research study, performed and directed research, participated in data analysis and manuscript preparation. J. Levis aided in research design, performed research, performed data analysis, and participated in manuscript preparation. D. Schneider developed the protocols for flow cytometry, contributed to study design, and aided in manuscript preparation. N. Bambace participated in subject recruitment, performed research, and implementation of research protocols. D. Sharma participated in subject recruitment, data analysis, and implementation of research protocols. I. Lal participated in subject recruitment and implementation of research protocols. M. Wood participated in subject recruitment and aided in manuscript preparation. H. Muss participated in study design and recruitment and manuscript preparation.

David J. Schneider

C. Holmes (Guarantor) conceived of and designed the research study, performed and directed research, participated in data analysis and manuscript preparation. J. Levis aided in research design, performed research, performed data analysis, and participated in manuscript preparation. D. Schneider developed the protocols for flow cytometry, contributed to study design, and aided in manuscript preparation. N. Bambace participated in subject recruitment, performed research, and implementation of research protocols. D. Sharma participated in subject recruitment, data analysis, and implementation of research protocols. I. Lal participated in subject recruitment and implementation of research protocols. M. Wood participated in subject recruitment and aided in manuscript preparation. H. Muss participated in study design and recruitment and manuscript preparation.

Nadia M. Bambace

C. Holmes (Guarantor) conceived of and designed the research study, performed and directed research, participated in data analysis and manuscript preparation. J. Levis aided in research design, performed research, performed data analysis, and participated in manuscript preparation. D. Schneider developed the protocols for flow cytometry, contributed to study design, and aided in manuscript preparation. N. Bambace participated in subject recruitment, performed research, and implementation of research protocols. D. Sharma participated in subject recruitment, data analysis, and implementation of research protocols. I. Lal participated in subject recruitment and implementation of research protocols. M. Wood participated in subject recruitment and aided in manuscript preparation. H. Muss participated in study design and recruitment and manuscript preparation.

Deva Sharma

C. Holmes (Guarantor) conceived of and designed the research study, performed and directed research, participated in data analysis and manuscript preparation. J. Levis aided in research design, performed research, performed data analysis, and participated in manuscript preparation. D. Schneider developed the protocols for flow cytometry, contributed to study design, and aided in manuscript preparation. N. Bambace participated in subject recruitment, performed research, and implementation of research protocols. D. Sharma participated in subject recruitment, data analysis, and implementation of research protocols. I. Lal participated in subject recruitment and implementation of research protocols. M. Wood participated in subject recruitment and aided in manuscript preparation. H. Muss participated in study design and recruitment and manuscript preparation.

Inder Lal

C. Holmes (Guarantor) conceived of and designed the research study, performed and directed research, participated in data analysis and manuscript preparation. J. Levis aided in research design, performed research, performed data analysis, and participated in manuscript preparation. D. Schneider developed the protocols for flow cytometry, contributed to study design, and aided in manuscript preparation. N. Bambace participated in subject recruitment, performed research, and implementation of research protocols. D. Sharma participated in subject recruitment, data analysis, and implementation of research protocols. I. Lal participated in subject recruitment and implementation of research protocols. M. Wood participated in subject recruitment and aided in manuscript preparation. H. Muss participated in study design and recruitment and manuscript preparation.

Marie E. Wood

C. Holmes (Guarantor) conceived of and designed the research study, performed and directed research, participated in data analysis and manuscript preparation. J. Levis aided in research design, performed research, performed data analysis, and participated in manuscript preparation. D. Schneider developed the protocols for flow cytometry, contributed to study design, and aided in manuscript preparation. N. Bambace participated in subject recruitment, performed research, and implementation of research protocols. D. Sharma participated in subject recruitment, data analysis, and implementation of research protocols. I. Lal participated in subject recruitment and implementation of research protocols. M. Wood participated in subject recruitment and aided in manuscript preparation. H. Muss participated in study design and recruitment and manuscript preparation.

Hyman B. Muss

C. Holmes (Guarantor) conceived of and designed the research study, performed and directed research, participated in data analysis and manuscript preparation. J. Levis aided in research design, performed research, performed data analysis, and participated in manuscript preparation. D. Schneider developed the protocols for flow cytometry, contributed to study design, and aided in manuscript preparation. N. Bambace participated in subject recruitment, performed research, and implementation of research protocols. D. Sharma participated in subject recruitment, data analysis, and implementation of research protocols. I. Lal participated in subject recruitment and implementation of research protocols. M. Wood participated in subject recruitment and aided in manuscript preparation. H. Muss participated in study design and recruitment and manuscript preparation.