Cancer and thrombosis are common co-occurrences in healthcare today. Cancer is the second leading cause of death in the United States with thrombosis being the second leading killer of cancer patients behind tumor progression. Cancer patients as a whole are 4 to 7 times more likely to develop thrombosis and 20%-30% of all first-time thrombosis diagnoses are cancer-related. Risk assessment and treatment options have much room for improvement. The lack of success for conventional antithrombotic prophylaxis suggests that hyperthrombosis in cancer works through a discrete pathway.
A discovery by our group in recent years correlated the increased activity of Aryl hydrocarbon receptor (AHR) in the body to increase thrombotic phenotypes in patients with chronic kidney disease. Another group had published a manuscript about Kynurenine (Kyn), an activating ligand of the receptor that was produced by tumor cells to promote tumor growth through an AHR pathway (Opitz 2011). The link between the findings of these two groups could show that Kyn—AHR pathway is causing the increase in thrombosis in cancer patients. We used an animal model of thrombosis in cancer and created a new variation of it to test the Kyn—AHR pathway. We hypothesized that cancerous animals would show an increase in thrombosis and increased levels of AHR and Kyn along with downstream elements such as Tissue Factor (TF).
Cancer was induced on nude mice via xenograft injection of cancer cells and 4-5 weeks of incubation to allow the tumors to proliferate. After the incubation period, mice underwent inferior vena cava (IVC) ligation, and were then euthanized 48 hours later. Two types of cancer were tested: HT-29 colon adenocarcinoma and A549 non small cell lung adenocarcinoma. There were 4 animal groups: mice that were injected with cancer cells and operated on, mice that were injected with cancer cells but not operated on, mice that were not injected but were operated on, and mice that did not receive neither the injections or the operation. After euthanasia, blood, tumors, and major organs were harvested to assess markers and pathways of thrombosis associated with cancer.
We were able to successfully grow xenograft tumors in the nude mice. The HT-29 tumors grew very aggressively while A549 tumors experienced a small latent period before starting to proliferate. Animals with HT-29 and A549 xenograft tumors displayed greater thrombosis, measured by the weight of the blood clot formed in the IVC due to ligation (p=0.04 and p=0.05, respectively). HT-29 also displayed significant increases in Kyn, AHR activity, indoxyl sulfate (IS), and showed increased staining of tissue factor with immunohistochemistry. A549 did not have significant p-values in these experiments, but did show upward trends in all categories besides IS sera levels.
In summary, we developed a new animal model of thrombosis in colon adenocarcinoma and showed significant increases in thrombosis as well as multiple markers of thrombosis. This is an exciting and complex way to study thrombosis in cancer in an in vivo approach with opportunities for future therapeutic testing. / 2020-07-03T00:00:00Z
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/30806 |
| Date | 03 July 2018 |
| Creators | Roth, Daniel Michael |
| Contributors | Chitalia, Vipul C, Belghasem, Mostafa E |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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