Anticancer Effect of Chloroform Fraction from Broccoli (Brassica oleracea L.) Sprout on Breast Cancer Stem Cells

Abstract

Broccoli (Brassica oleracea L.) sprout is a cruciferous vegetable that contain a variety of bioactive components. In this study, crude methanol extract (ME) of broccoli sprout was fractioned by hexane, chloroform, ethyl acetate, butanol, and water to compare the anti-proliferative effect on breast cancer cells. Among the fractions, hexane fraction (HF) and chloroform fraction (CF) decreased the viability of MCF-7/SCs like breast cancer stem cells (BCSCs), and the CF had the highest antiproliferative activity (IC50 = 69.47 mg/mL). The CF also suppressed the stemness characteristics of MCF-7/SCs and induced apoptotic cell death. The most abundant characteristic peak in CF was identified as oleic acid (area = 35.05%) by gas chromatography-mass spectrometry (GC-MS). We found that oleic acid, a main component in the CF, exhibited antiproliferative activity in MCF-7/SCs and MDA-MB-231/IR cells compared to the parental MCF-7 and MDA-MB-231 cells. Oleic acid induced the apoptosis and impaired characteristics of BCSCs. Furthermore, oleic acid inhibited migration and invasion ability of MCF-7/SCs and MDA-MB-231/IR cells in a dose- and time- dependent manner and suppressed the expression of EMT-related markers including Slug, Snail, ZEB1 and Vimentin. This oleic acid increased the low-level reactive oxygen species (ROS) in BCSCs while decreasing expression of glutathione peroxidase 1 (GPx1). Mechanistically, reduction of GPx1 expression by oleic acid inhibited FAK/NF-κB activation. This study indicates that the CF and oleic acid, a major component of broccoli sprouts, contribute to its potent anticancer activity against BCSCs.