Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Effects of Vitamin A Metabolites on Apoptosis A.M. Campbell and R. Barra Dept. of Biological Sciences, University of Mary Washington Abstract Results Introduction Retinol is a vitamin A compound present in all mammalian cells (1). Dietary sources of retinol are consumed, processed as carotenoids, and stored as retinyl esters in the liver. In order to be used by mammalian cells, retinol must be metabolized (1); retinoic acid (RA) is the most useful metabolite of retinol. Retinol affects mammalian cells in a variety of ways. RA has been found to have an effect on normal, malignant and premalignant cells in both in vivo and in vitro studies (4). The concentration of RA is important when examining its effects on cell lines, which are said to be “dose-responsive” (9). There is an optimum range for administering retinol for each cell line as both high and low concentrations of RA can have unfavorable effects on development (2, 5). Retinol is metabolized to RA by a two-step mechanism; both steps consist of oxidation reactions. RA is the most active, functional metabolite (7) and it has the ability to alter the expression of many genes (5). Multiple cis and trans isomers of RA exist. An isomerization reaction must take place and act on retinol before the first oxidation reaction occurs in order for the end product to be a cis or trans isomer (6). The exact mechanism of action of RA is unknown (8). RA is an important regulator of morphogenesis, differentiation, and proliferation (3) in normal and tumor cells and is believed to act through the regulation of retinoid-responsive genes (4). Low concentrations of retinol cause cells to stop growing and die; however, the dead cells still have intact nuclei, so apoptosis is not the cause of the cell death (1). Two of the most common metabolites are 13-cis RA (13cRA) and all-trans RA (ATRA). 13cRA is the main compound found in the acne medication, Accutane. There is evidence that 13cRA is effective in re-differentiating therapy (3) and that is has the ability to prevent precancerous cells from becoming malignant and invasive (4). ATRA completely stopped the cell cycle during the G1 phase of development in human embryonic carcinoma cells. ATRA increased the rate of ubiquitination of cyclin D1; attaching ubiquitin to the cyclin D1 protein deactivates it (10). Decreasing levels of cyclin D1 are closely associated with G1 phase arrest (11). CD95 is a death receptor that belongs to the TNF-R Superfamily. Apoptosis in induced by death inducing signaling complex (DISC) formation. DISC is formed almost immediately after CD95 is activated by its ligand (CD95L) or by an agonistic antibody (13). There is evidence from various studies that RA can affect the cell cycle, can induce apoptosis, or can alter gene expression by DNA methylation, although the pathways involved have not been fully elucidated. In this study, I examined the effects of two main metabolites of Vitamin A, 13cRA and all-trans RA (ATRA), on cell cycle regulation, specifically CD95 expression and cytotoxicity on CRL-1790 epithelial cells. This is a normal epithelial cell line initially isolated from colon tissue. An enzyme-linked immunosorbent assay was used to determine CD95 expression and the MTT assay was used to determine cell viability. Experiment Design References Discussion 1) Buck, Jochen, Andrzej Myc, Annette Garbe, and Gieri Cathomas. "Differences in the Action and Metabolism between Retinol and Retinoic Acid in B Lymphocytes .ÓJournal of Cell Biology 115. (1991): n. pag. Web. 31 Mar 2011. 2) Sakai, Yasuo, Chikara M eno, Hideta Fujii, Jinsuke Nishino, and Hidetaka Shiratori. "The retinoic acid-inactivating enzyme CYP26 is essential for establishing an uneven distribution of retinoic acid along the anterio-posterior axis within the mouse embryo." Genes & Development 15.2 (2000): 213-25. Web. 31 M ar 2011. 3) Handkiewicz-Junak, Daria, Jozef Roskoz, Kornelia Hasse-Lazar, Sylwia Szpak Ulczok, and Zbigniew Puch . "13-cis-retinoic acid re differentiation therapy and recombinant human thyrotropin-aided radioiodine treatment of non-Functional metastatic thyroid cancer: a single-center, 53-patient phase 2 study." Thyroid Research Journal 2.8 (2009): n. pag. Web. 1 Apr 2011. 4) Guo, Xiaojia, and Lorraine Gudas. "Metabolism of all-trans-Retinol in Normal Human Cell Strains and Squamous Cell Carcinoma (SCC) Lines from the Oral Cavity and Skin: Reduced Esterification of Retinol in SCC Lines." American Association for Cancer Research (1998): 166 76. Web. 10 Mar 2011. 5) Ross, Catharine, and Reza Zolfaghari. "Regulation of Hepatic Retinol M etabolism: Perspectives from Studies on Vitamin A Status." Journal of Nutrition (2004): 269-75. Web. 30 Mar 2011. 6) Liden, Martin, and Ulf Eriksson. "Understanding Retinol Metabolism: Structure and Function of Retinol Dehydrogenases." Journal of Biochemistry (2006): 13001-4. Web. 31 M ar 2011. 7) Cerignoli, Fabio, Xiaojia Guo, Beatrice Cardinali, Christian Rinaldi, and Jessica Casaletto. "retSDR1, a Short-Chain Retinol Dehydrogenase/Reductase, Is Retinoic Acid-inducible and Frequently Deleted in Human Neuroblastoma Cell Lines." American Association for Cancer Research (2001): n. pag. Web. 10 Mar 2011. 8) Guo, Xiaojia, Beatrice Knudsen, Donna Peehl, Alberto Ruiz, and Dean Bok. "Retinol Metabolism and Lecithin: Retinol Acyltransferase Levels Are Reduced in Cultured Human Prostate Cancer Cells and Tissue Specimens." American Association for Cancer Research (2001): n. pag. Web. 10 Mar 2011. 9) Park, Eun Young, Alice Dillard, Elizabeth Williams, Erik Wilder, and M . Reese Pepper. "Retinol Inhibits the Growth of All-Trans-Retinoic Acid Sensitive and All-Trans-Retinoic Acid- Resistant Colon Cancer Cells through a Retinoic Acid Receptor- Independent M echanism." American Association for Cancer Research (2005): n. pag. Web. 10 Mar 2011. 10) Guidoboni, Massimo, Paola Zancai, Roberta Cariati, Silvana Rizzo, and Jessica Dal Col. "Retinoic Acid Inhibits the Proliferative Response Induced by CD40 and Interleukin-4 in Mantle Cell Lymphoma." American Association for Cancer Research (2004): n. pag. Web. 10 M ar 2011. 11) Spinella, M ichael, Sarah Freemantle , David Sekula, Jeffery Chang, and Allison Christie. "Retinoic Acid Promotes Ubiquitination and Proteolysis of Cyclin D1 during Induced Tumor Cell Differentiation." Journal of Biological Chemistry (1999): n. pag. Web. 11 Apr 2011. 12) "Accutane Lawsuit Settlement 2011 News." Accutane Side Effects Lawsuit Center. Fields Law Office, Ltd. , n.d. Web. 22 Apr 2011. http://www.accutanesideeffectslawsuit.com/. 13) Shatnyeva, Olga M., Andriy V. Kubarenko, Claudia E. M . Weber, Alexander Pappa, Reinhard Schwartz-Albiez, Alexander N. R. Weber, Peter H. Krammer, and Inna N. Lavrik. "Abstract." National Center for Biotechnology Information. U.S. National Library of Medicine, 18 May 2011. Web. 15 May 2012. http://www.ncbi.nlm.nih.gov /pmc/articles/PM C3097226/ I would like to thank the University of Mary Washington, College of Arts and Sciences for the funding for this opportunity in undergraduate research.