Date of Award

5-2023

Degree Type

Thesis

Degree Name

Departmental Honors

Department

Biology

Abstract

Cancer is the second leading cause of death in the United States, exceeded only by heart disease. One of every five deaths in the United States is due to cancer. A growing area of research involves the analysis of cancer resistant traits in other species to understand their biological mechanisms and eventually make translations to human cancer research and clinical treatment. Because of their remarkable cancer resistance, the naked mole-rat (NMR) is a prime subject for this research, and various studies have already suggested that the immune mechanisms of the NMR might be harnessed for human cancer therapies1-4,7.

In both humans and NMRs, neutrophils are the most abundant type of immune cell. As part of the human immune response neutrophils release neutrophil extracellular traps (NETs) in a process referred to as NETosis8. The ejected NETs are a matrix of DNA and histone proteins that function as extracellular webs to trap and destroy pathogens9. Unfortunately, NETs also worsen the effects of many diseases, and increasing evidence significantly links NETs with cancer5,9,13-20. When cancer cells are surrounded by NETs, they are afforded a variety of benefits. NETs help improve tumor vascularity by creating space for blood vessels while simultaneously forming a physical barrier that shields tumors from the cytotoxicity of other immune responses. This protection and blood supply markedly improve tumor growth, local invasion, and metastasis to other locations13,15,16,19. These results are from studies involving both mouse models and human tissue samples, but the literature is void of any publications regarding the character of NET release in NMRs.

The object of this study was to establish a protocol for isolation and NETosis induction of NMR neutrophils and characterize NMR NET release in comparison to humans for the first time. We hypothesized that NMR neutrophils would be less sensitive to NET formation compared to human neutrophils and that a higher concentration of stimulants will be required to induce NETosis in NMR cells. Working with scientists in the Schiffman Lab at the University of Utah Huntsman Cancer Research Center, we first established a protocol for the isolation, stimulation, and quantification of human neutrophil NETosis. With this protocol, NMR blood was collected and then separated via cell sedimentation and density gradients to isolate neutrophils. Cells were counted and seeded onto plates for the stimulation of NETosis with the bacterial toxins ionomycin and lipopolysaccharide (LPS). Results were collected via a Sytox Green fluorescence assay and confocal microscopy. We used neutrophils isolated from human blood as an experimental control. We were able to successfully isolate NMR neutrophils, stimulate and characterize NETosis, and compared it to human neutrophil control. Strikingly, our preliminary data does indicate increased resistance to NET release in NMRs compared to humans. Although more sampling will be necessary to further confirm and quantify these differences, this initial success nonetheless helps to confirm the value of researching NMR NETosis and shows promise for future experiments.

Download

Included in

Biology Commons

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .

 

Faculty Mentor

Zhongde Wang

Departmental Honors Advisor

Sara Freeman