Abstract 5700: Establishing candidate biomarkers for the pharmacodynamic action of sulforaphane in the breast

Abstract

Abstract The goal of this study is the discovery of biomarkers reflecting the pharmacodynamic action of sulforaphane (SFN), initially in the normal human mammary epithelial MCF10A cell line and then in tissue obtained from healthy patients undergoing reduction mammoplasty surgery. SFN is formed by the hydrolysis of glucoraphanin, a water soluble glucosinolate found in cruciferous vegetables with especially high levels measured in 3 day old broccoli sprouts. Chemoprevention by SFN is achieved in part through the upregulation of cytoprotective enzymes via the Keap1/Nrf2 pathway. Preliminary dose response and time course studies in MCF10A cells established that SFN upregulated cytoprotective genes as indicated by increased levels of NQO1 transcripts, protein and activity. NQO1 induction is dependent on the Keap1/Nrf2 pathway since NQO1 transcripts, protein and activity were enhanced by KEAP1 siRNA knockdown in MCF10As. For the biomarker discovery phase isobaric tag for relative and absolute quantitation (iTRAQ) was used to quantify global protein changes using mass spectrometry. Two independent 8-plex iTRAQ experiments determined the pharmacological actions of SFN on protein expression, compared to a vehicle control, and the genetic regulation of protein expression following knockdown of KEAP1 compared to a non targeting control siRNA. In both experiments protein expression was analyzed at 12, 24, 48, and 72 hour time points after SFN treatment or KEAP1 knockdown. In addition to confirming NQO1 to be a good candidate biomarker, the iTRAQ analysis identified other upregulated candidates to be aldo-keto reductase family 1 member C1 (AKR1C1), DJ-1 protein, and thioredoxin. NQO1 and AKR1C1 transcripts were also elevated in the MCF10A cells, as assessed by microarray assay. Candidate biomarkers identified from microarray and iTRAQ studies reflecting the pharmacodynamic action of SFN in human cells will be analyzed by Western blot, qRT-PCR and enzyme assays in tissue from reduction mammoplasty patients. These women have been randomized in a clinical trial to receive either a broccoli sprout preparation containing 100 micomole SFN or a placebo beverage daily for 10 days prior to surgery. Supported by P50 CA088843, U54 RR020839 and BC073262. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5700.