Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2005
Publication Date: August 28, 2005
Citation: Finley, J.W. 2005. Selenium and sulforaphane from broccoli interact to alter gene expression and protection against oxidative stress in cultured cells [abstract]. Presented at the 230th ACS National Meeting, Washington DC, Aug 28 - Sep 1, 2005. Technical Abstract: Broccoli may be a dietary source of glucosinolates and selenium (Se), bioactive molecules that reduce oxidative stress. Glucosinolates may induce proteins with antioxidant function, including phase 2 proteins and thioredoxin reductase (TR); Se is essential for TR activity. Sulforaphane (Sf), a glucosinolate metabolite, transcriptionally induces multiple antioxidant genes through the promoter-bound Antioxidant Response Element (ARE). The interaction of Se and Sf on TR expression was studied in Hep-G2 cells containing a TR/firefly luciferase reporter gene construct. Sf, but not Se, induced reporter gene expression; point mutation constructs demonstrated an ARE in the promoter was the Sf-sensitive control element. Conversely, Se or Sf equally upregulated TR activity, but Se+Sf induced TR activity 2-fold beyond the individual compounds. These data suggest that TR is controlled transcriptionally and translationally by compounds from broccoli, and simultaneous activation of both controls additively increases TR activity. The antioxidant activity of Se, Sf, and Se/Sf-enriched broccoli extracts was studied by measuring DNA single-strand breaks in Hepa1C1C7 cells. Sf and Sf-enriched broccoli induced the phase 2 protein quinone reductase, but Se and Se-enriched broccoli was the most effective for reducing oxidative stress. These results demonstrate that Sf from broccoli induces antioxidant proteins, but Se-enriched broccoli is most efficacious for reduction of oxidative stress.