Dietary Chemopreventative Benzyl Isothiocyanate Inhibits Breast Cancer Stem Cells In Vitro and In Vivo

Abstract

A small subset of mammary tumor initiating cells (also known as breast cancer stem cells; bCSC), characterized by expression of different markers [CD44high/CD24low/epithelial specific antigen (ESA)+], aldehyde dehydrogenase-1 (ALDH1) activity, and ability to form mammospheres under ultra-low attachment culture conditions, are suspected to evade conventional therapies leading to disease recurrence. Elimination of both therapy-sensitive epithelial tumor cells and therapy-resistant bCSC is therefore necessary for prevention of breast cancer. We have shown previously that a nontoxic small-molecule constituent of edible cruciferous vegetables (benzyl isothiocyanate; BITC) inhibits mammary cancer development in mouse mammary tumor virus-neu (MMTV-neu) transgenic mice by causing epithelial tumor cell apoptosis. The present study demonstrates efficacy of BITC against bCSC in vitro and in vivo. Mammosphere formation frequency and CD44high/CD24low/ESA+ and/or ALDH1+ populations in cultured MCF-7 (estrogen-receptor positive) and SUM159 (triple-negative) human breast cancer cells were decreased significantly in the presence of plasma achievable concentrations of BITC. BITC administration in the diet (3 μmol BITC/g diet for 29 weeks) resulted in a marked decrease in bCSC in the MMTV-neu mice tumors in vivo. Overexpression of full-length Ron as well as its truncated form (sfRon), but not urokinase-type plasminogen activator receptor, conferred near complete protection against BITC-mediated inhibition of bCSC in MCF-7 cells. The BITC treatment downregulated protein levels of Ron and sfRon in cultured breast cancer cells and in tumor xenografts. Ron overexpression resulted in up-regulation of bCSC-associated genes Oct-4, SOX-2, and Nanog. In conclusion, the present study indicates that BITC treatment eliminates bCSC in vitro and in vivo.

Forkhead Box Q1 Is a Novel Target of Breast Cancer Stem Cell Inhibition by Diallyl Trisulfide

“…Mammosphere Formation Assay-The mammosphere assay was performed as described by us previously (26). Briefly, 1000 cells in medium supplemented with penicillin/streptomycin, B27, insulin, hydrocortisone, epidermal growth factor, basic fibroblast growth factor, 2-mercaptoethanol, and methylcellulose were plated on ultralow attachment plates.…”

“…However, these mice were included for tumor incidence and tumor volume calculations. For analysis of ALDH1 activity and mammosphere formation, primary tumors were processed as described by us previously (26). Briefly, tissues were digested in Dulbecco's modified Eagle's medium supplemented with 300 units/ml collagenase and 100 units/ml hyaluronidase for 3-4 h at 37°C.…”

Benzyl Isothiocyanate: Double Trouble for Breast Cancer Cells

“…Available data suggest that unanticipated adverse effects were associated with high dosages of the ITCs; however, the adverse effects occurred at doses that are several-fold higher than the normal physiologic doses. In that context, it is noteworthy that the studies by Kim and colleagues (29) showed significant chemopreventive effects at low dose levels corresponding to human exposure levels. A second issue that needs to be addressed is establishment of a formulation of pure BITC suitable for clinical investigation.…”

“…The article by Kim and colleagues (29) In an in vivo efficacy assay, chronic dietary administration of BITC (3 mmol BITC/g diet) resulted in a marked decrease in bCSCs in tumors of MMTV-neu mice. BITC-mediated inhibition of bCSCs was associated with decreased expression of fulllength receptor tyrosine kinase Ron as well as of its truncated activated form (sfRon), which drives stemness in breast cancer cells.…”

Radiations and biodegradation techniques for detoxifying Carica papaya seed oil for effective dietary and industrial use

“…The latter two benefits had been attributed to the presence of sulfurous compounds with chemopreventive properties known as benzyl isothiocyanate (Cowan 1999;Kim et al 2013;Lohiya et al 2008;Pedro et al 2011), The level ranging from 4.0 to 23.3 g/kg depending on the various processing methods for the pre-treatment of papaya seeds (Kermanshai et al 2001;Lee et al 2011). BITC is also found to have cancer preventive properties by controlling phase I drug-metabolizing enzymes and phase II detoxification enzymes (Kim et al 2013;Zhang et al 1992). However, its presence in extremely large quantities contributes to the limited culinary uses of the seed oil.…”