Homework 3 - Project Summary
Homework 3 - Project Summary ZOL 425
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This 3 page Class Notes was uploaded by Jacob Decker on Sunday February 14, 2016. The Class Notes belongs to ZOL 425 at Michigan State University taught by D. Bello-Deocampo in Spring 2016. Since its upload, it has received 37 views. For similar materials see Cells and Development (W) in Microbiology at Michigan State University.
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Date Created: 02/14/16
Decker 1 William Decker ZOL 425 2/07/16 Homework 3: Project Summary Outline Prostate cancer is one of the most common forms of cancer found in men in developed countries. The causes are still debatable, but recent research provides strong implications that chronic inflammation may be a vital contributor in the development of prostate cancer. Tolllike receptors (TLRs) are important ligands that mediate inflammatory responses by recognizing 1 specific pathogenic components. Based in the membranes of macrophages and dendritic cells, 2 TLRs induce proliferation of proinflammatory molecules such as cytokines. Among the family of TLRs, TLR4 is a specific receptor that has the responsibility of recognizing lipopolysaccharides (LPS). LPS is an endotoxin found on the membrane of gram negative bacteria, and when identified by TLR4 causes a proliferation of the TLR4 receptor itself 3 and other molecules involved in the inflammatory response. Interestingly, a recent study found that a miniscule mutation within TLR4 was associated with a 26% increased risk of prostate 4 cancer and a 39% increased chance of developing earlyonset prostate cancer. We can then rightfully ask ourselves, does stimulation of TLR4 lead to inflammation and how does this affect the development of TLR4 in cancer cells? To answer this, we were given PC3 cells, which are (Grade IV adenocarcinoma) human prostate cancer cells derived from a bone metastasis. To design an experiment aimed to answer this question, we will need a control _____________________________________________________ 1Kiyoshi Takeda and Shizuo Akira. “Tolllike receptors in innate immunity.” International 2Immunology, Vol. 17, No. 1, 2005): 2. Angelo M. De Marzo et al. “Inflammation in prostate carcinogenesis.” Nature Reviews Cancer (2007): 264. 3 Gerardo Gatti. “Expression of Tolllike receptor 4 in the prostate gland and its association with the severity of prostate cancer.” Prostate. 2009; 69: 1388. 4 5 De Marzo. “Inflammation in prostate carcinogenesis,” 264. Charbonneau, Amanda. "Hypothesis Testing and Project Intro." Laboratory Lecture Notes. MI, East Lansing. 26 Jan. 2016. Lecture. Decker 2 group and a test group, as most experiments require. To put our experimental proposal in general terms, we will vary the amount of LPS exposed to the cancer cells in a predetermined time schedule to observe how the cells will react in regards to the proliferation of TLR4. We decided to separate our cells into six petri dishes, in which there will be three distinctive treatments imposed. Two petri dishes will receive no exposure to LPS for our ‘negative control’, and will be referred to as treatment 1. The next two petri dishes will receive 50 microliters (L) of LPS for 3 hours for our ‘acute exposure’ and will be referred to as treatment 2. Finally, the last two petri dishes will be exposed to continuous LPS; 50 L LPS at 96 hours, 2448 hours, and 3 hours. These two petri dishes will be our cells that are chronically exposed to LPS, and will be referred to as treatment 3. We would not be following the true scientific method without forming some sort of hypotheses. As a class, two different hypotheses were produced. The first, or ‘Hypothesis A’, predicts that the cells with continual (chronic) LPS exposure would downregulate TLR4 proliferation and become tolerant of LPS. This was anticipated because LPS would become a normal part of the environment or because inflammation is maladaptive in most cases. Our 6 second prediction, or ‘Hypothesis B’, stated that cells with continual LPS exposure would up regulate TLR4 expression to induce inflammation and to ride the tissue of the endotoxin or hypothetical “bacteria”. 7 I expect that our chronicallyexposed prostate cancer cells will downregulate the proliferation of TLR4. This prediction is parallel to Hypothesis A, in which I think that LPS _____________________________________________________ 8 Oblak. “Tolllike receptor 4 activation in cancer progression and therapy.” Clin Dev Immunol 2011; 2011: 4. 9 Gatti. “Expression of Tolllike receptor 4 in the prostate gland and its association with the severity of prostate cancer.” 1394. Decker 3 would become tolerated be the cells and that, if inflammation occurs, would not be beneficially to the culture. In fact, Oblak et al. states that more metastatic human cancer lines (cancer cells that have spread throughout the body and are not part of the origin of the tumor), like our PC3 cells, express more TLR4 ligands than those more closely related to the primary site of the cancer 8 growth. Meaning that because our cells are derived from a metastasis, they should have relatively more expressed TLR4. It is also stated in many studies that there is less expression of TLR4 in more progressed cancerous tumors. In other words, the grade or severity of the cancer is inversely proportional to the level of TLR4 expressed on that cancer. Possibly due to the declined differentiation with more advanced cancer or the expression of TLR4 is mediated by other unknown factors, it is still undetermined what the cause of this is. Therefore, I would hypothesis that since our cells are a prostatecancer cell line derived from a bonemetastasis, the TLR4 expression would be reduced with chronic exposure to the endotoxin LPS. _____________________________________________________ 8 Oblak. “Tolllike receptor 4 activation in cancer progression and therapy.” Clin Dev Immunol 2011; 2011: 4. 9 Gatti. “Expression of Tolllike receptor 4 in the prostate gland and its association with the severity of prostate cancer.” 1394.