Clotting Breast Cancer

Institution: University of California, Irvine
Investigator(s): Michael Samoszuk, M.D. -
Award Cycle: 2002 (Cycle VIII) Grant #: 8IB-0009 Award: $98,986
Award Type: IDEA
Research Priorities
Detection, Prognosis and Treatment>Innovative Treatment Modalities: search for a cure

Initial Award Abstract (2002)
The presence of an intact blood supply permits breast cancer to grow and to spread by seeding malignant cells into the circulation. However, the tumor vasculature is not normal. For example, breast cancers have leaky blood vessels, sluggish blood flow, and abundant material that naturally promotes clotting of blood. Although these conditions would be expected to cause clotting within breast tumors, the blood generally remains fluid. Our hypothesis is that the tumor vasculature contains specific factors to prevent clotting. If ways could be devised to neutralize this process, then blockage of the vasculature would occur, shut off nutrients to the cancer, and prevent cancer from spreading.

We will test the hypothesis that an enzyme called tryptase, that is produced by allergic cells called mast cells, is responsible for preventing the blood from clotting in breast cancer. Tryptase is abundantly present in breast cancer tissues and rapidly destroys the key component of blood that is responsible for clotting. Another white blood cell, called eosinophils, promotes clotting by neutralizing the anti-coagulant, heparin. Our project has two main aims. First, we will test whether eosinophil granule proteins can neutralize mast cell typtase. We will examine standard parameters of blood clotting in a model system of mast cells and eosinophils that we think occurs in the tumor vasculature. The second aim is to test our hypothesis in animal models. We will grow tumors in mice with subcutaneous implants of 4T1 breast cancer cells and determine whether the drug gabexate mesylate (a synthetic inhibitor of serine proteases such as mast cell tryptase) will cause selective clotting (thrombosis) in tumor tissue vs. normal tissues. If our hypothesis regarding mast cell tryptase is correct, we expect that the drug will clot the blood supply to the breast cancer implants.

This project is innovative because it targets a novel and previously underexplored aspect of breast cancer biology: the control of blood clotting within the tumor. It also has the potential to be translated into a new, non-toxic approach for breast cancer treatment that targets the blood flow to the cancer and not the cancer cells themselves.

Final Report (2003)
This research project was intended to determine if certain drugs could produce blood clots in experimental breast cancer tumors in mice. Our hypothesis was that allergic cells, such as eosinophils and mast cells that naturally infiltrate human breast cancer are thought to regulate blood clotting in breast tumors. We reasoned that by interfering with the functions of the allergic cells, the drugs would be able to clot the blood supply to the tumor, thereby depriving it of nutrients and pathways for systemic spread. Our initial experiments confirmed that the allergic cells (eosinophils and mast cells) are, indeed, involved in regulating tumor blood clotting. The drugs we studied for tumor effects were as follows: sodium cromolyn (an FDA-approved drug that is commonly used to treat allergies); heparinase enzyme (a drug that is being tested for treatment of overdose with the blood thinner heparin); gabexate mesylate (a drug that is being used in Europe to treat patients with bleeding disorders and pancreatitis); and imatinib mesylate (Gleevec™) - a drug that is FDA-approved for the treatment of chronic myelogenous leukemia. We treated tumor-bearing mice with these drugs for five days and then removed the tumors for analysis. All of the tumors from the drug-treated mice had microscopic evidence of substantial blood clotting. Similar blood clotting was not observed in any of the tumors from the untreated control mice. Surprisingly, the average masses of the tumors from the treated mice (cromolyn 190 mg; heparinase 210 mg; gabexate mesylate 152 mg; imatinib mesylate 195 mg) were significantly higher than the average mass of the tumors from the untreated control mice (60 mg). In addition, the tumors from the drug-treated mice had microscopic evidence of oxygen deprivation. We conclude that drugs that inhibit allergic cells can produce blood clotting in breast cancer, and the blood clotting is associated with accelerated tumor growth and decreased oxygenation of the tumors.

Our results were published in four journal articles, and they suggest that allergic mast and eosinophil cells may play an important role in regulating blood clotting in breast cancer and promoting the growth of breast cancer. Our work also confirms previous studies that suggest that blood clotting actually promotes the growth of malignant tumors. Consequently, we believe that there is a need to better establish the link between blood clotting processes and the cells involved with breast tumor growth and therapeutic strategies. In the future, we will investigate the role of other naturally occurring anticoagulants that are produced by the connective tissue adjacent to the breast cancer cells.

Symposium Abstract (2003)
As the plague of breast cancer deaths continues, the need for new approaches to prevent this disease becomes increasingly apparent. With the perspective that cancer is a disease of uncontrolled cell growth, we need new agents to inhibit cancer cell growth. The family of molecules composed of vitamin A derivatives (retinoids) is an excellent set of candidates. Retinoids are currently used in the treatment of epithelial cancer and acute promyelocytic leukemia and have been evaluated as preventive and therapeutic agents for a variety of human cancers. Several studies show that retinoids are also capable of inhibiting breast cancer cell growth. However, their anti-breast cancer activity is mainly seen in early stage breast cancer cells and upon progression of the disease, breast cancer cells become refractory to retinoids. This phenomenon of retinoid resistance has been one of the major drawbacks in retinoid therapy. Unfortunately, how anti-cancer activity of retinoids is lost in late stage breast cancer cells is unclear.

We propose to study the mechanism by which retinoids exert their anti-cancer activity in breast cancer cells and by which this effect is lost in resistant cancer cells. Results from these studies will provide us with an opportunity to increase retinoid sensitivity in retinoid-resistant breast cancer cells, and thereby enhance their therapeutic efficacy. The results will also provide a basis upon which to develop more effective anti-breast cancer retinoids with clinical value.

Mast cell inhibitor cromolyn increases blood clotting and hypoxia in murine breast cancer.
Periodical:International Journal of Cancer
Index Medicus: Int J Cancer
Authors: Samoszuk M, Corwin MA
Yr: 2003 Vol: 107 Nbr: Abs: Pg:159-163

Acceleration of tumor growth and peri-tumoral blood clotting by imatinib mesylate (Gleevec).
Periodical:International Journal of Cancer
Index Medicus: Int J Cancer
Authors: Samoszuk M, Corwin MA
Yr: 203 Vol: 106 Nbr: Abs: Pg:647-652

Effects of human mast cell tryptase on the kinetics of blood clotting.
Periodical:Thrombosis Research
Index Medicus: Thromb Res
Authors: Samoszuk M, Corwin M, Hazen SL
Yr: 2003 Vol: 109 Nbr: Abs: Pg:153-156

Effects of human mast cell tryptase and eosinophil granule proteins on the kinetics of blood clotting.
Periodical:American Journal of Hematology
Index Medicus: Am J Hematol
Authors: Samoszuk M, Corwin M, Hazen SL
Yr: 2003 Vol: 73 Nbr: Abs: Pg:18-25

Acceleration of mammary adenocarcinoma growth and blood clotting by mast cell inhibitors
Periodical:Proceedings of the American Association for Cancer Research
Index Medicus: Proc Am Assoc Cancer Res
Authors: Samoszuk M, Corwin M
Yr: 2003 Vol: 44 Nbr: Abs: #6252 Pg: