Molecular Effects of Iodine-Biofortified Lettuce in Human Gastrointestinal Cancer Cells |
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Authors: | Olga Sularz,Aneta Koronowicz,Cayla Boycott,Sylwester Smoleń ,Barbara Stefanska |
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Affiliation: | 1.Department of Human Nutrition and Dietetics, Faculty of Food Technology, University of Agriculture in Krakow, Balicka 122, 31-149 Krakow, Poland;2.Food, Nutrition and Health Program, Faculty of Land and Food Systems, The University of British Columbia, 2205 East Mall, Vancouver, BC V6T 1Z4, Canada;3.Department of Plant Biology and Biotechnology, Faculty of Biotechnology and Horticulture, University of Agriculture in Krakow, Al. 29 Listopada 54, 31-425 Krakow, Poland |
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Abstract: | Considering the growing number of cancer cases around the world, natural products from the diet that exhibit potential antitumor properties are of interest. Our previous research demonstrated that fortification with iodine compounds is an effective way to improve the antioxidant potential of lettuce. The purpose of the present study was to evaluate the effect of iodine-biofortified lettuce on antitumor properties in human gastrointestinal cancer cell lines, gastric AGS and colon HT-29. Our results showed that extracts from iodine-biofortified lettuce reduce the viability and proliferation of gastric and colon cancer cells. The extracts mediated cell cycle arrest which was accompanied by inactivation of anti-apoptotic Bcl-2 and activation of caspases, as assessed by flow cytometry. However, extracts from lettuce fortified with organic forms of iodine acted more effectively than extracts from control and KIO3-enriched plants. Using quantitative PCR, we detected the increase in pro-apoptotic genes BAD, BAX and BID in AGS cells whereas up-regulation of cell cycle progression inhibitor CDKN2A and downregulation of pro-proliferative MDM2 in HT-29 cells. Interestingly, lettuce extracts led to down-regulation of pro-survival AKT1 and protooncogenic MDM2, which was consistent for extracts of lettuce fortified with organic form of iodine, 5-ISA, in both cell lines. MDM2 downregulation in HT-29 colon cancer cells was associated with RB1 upregulation upon 5-ISA-fortified lettuce extracts, which provides a link to the epigenetic regulation of tumor suppressor genes by RB/MDM2 pathway. Indeed, SEMA3A tumor suppressor gene was hypomethylated and upregulated in HT-29 cells treated with 5-ISA-fortified lettuce. Control lettuce exerted similar effects on RB/MDM2 pathway and SEMA3A epigenetic activation in HT-29 cells. Our findings suggest that lettuce as well as lettuce fortified with organic form of iodine, 5-ISA, may exert epigenetic anti-cancer effects that can be cancer type-specific. |
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Keywords: | lettuce iodine gene expression DNA methylation gastrointestinal cancer |
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