Role of Krüppel-like Factor 4-p21Axis in Breast Cancer Stem-like Cell Inhibition by Benzyl Isothiocyanate.
Cancer Prev Res (Phila). 2019 Mar ;12(3):125-134. Epub 2019 Feb 5. PMID: 30723175
Cancer chemoprevention by benzyl isothiocyanate (BITC), which is derived from cruciferous vegetables like garden cress, in a transgenic mouse model of breast cancer is associated with inhibition of breast cancer stem-like cells (bCSC), but the molecular regulators of this effect remain elusive. This study demonstrates a protective effect of Krüppel-like factor 4 (KLF4)-p21axis in bCSC inhibition by BITC. Exposure of human breast cancer cells (MCF-7, MDA-MB-231, and SUM159) to plasma-achievable concentrations of BITC resulted in a robust induction ofmRNA and its protein expression as determined by qRT-PCR and Western blotting or confocal microscopy. BITC-mediated suppression of bCSC markers, including aldehyde dehydrogenase 1 activity and mammosphere frequency, was significantly augmented by transient or stable knockdown of KLF4. Western blotting and IHC revealed relatively higher levels of KLF4 protein in mammary tumor sections from BITC-treated mice in comparison with controls, but the difference was insignificant. Analysis of the breast cancer RNA-Seq data from The Cancer Genome Atlas indicated significant positive correlation between expression ofand that of() but not(). Knockdown of p21protein also amplified BITC-mediated suppression of bCSC. Finally, KLF4 was recruited to the promoter ofas indicated by chromatin immunoprecipitation assay. These results indicate that induction of KLF4-p21axis attenuates inhibitory effect of BITC on bCSC self-renewal. Translational implication of these findings is that breast cancer chemoprevention by BITC may be augmented with a combination regimen involving BITC and an inhibitor of KLF4.