Phenethyl Isothiocyanate Suppresses Stemness in the Chemo- and Radio-Resistant Triple-Negative Breast Cancer Cell Line MDA-MB-231/IR Via Downregulation of Metadherin

Abstract

Resistance to chemotherapy and radiation therapy is considered a major therapeutic barrier in breast cancer. Cancer stem cells (CSCs) play a prominent role in chemo and radiotherapy resistance. The established chemo and radio-resistant triple-negative breast cancer (TNBC) cell line MDA-MB-231/IR displays greater CSC characteristics than the parental MDA-MB-231 cells. Escalating evidence demonstrates that metadherin (MTDH) is associated with a number of cancer signaling pathways as well as breast cancer therapy resistance, making it an attractive therapeutic target. Kaplan–Meier plot analysis revealed a correlation between higher levels of MTDH and shorter lifetimes in breast cancer and TNBC patients. Moreover, there was a positive correlation between the MTDH and CD44 expression levels in The Cancer Genome Atlas breast cancer database. We demonstrate that MTDH plays a pivotal role in the regulation of stemness in MDA-MB-231/IR cells. Knockdown of MTDH in MDA-MB-231/IR cells resulted in a reduction in the CSC population, aldehyde dehydrogenase activity, and major CSC markers, including β-catenin, CD44+, and Slug. In addition, MTDH knockdown increased reactive oxygen species (ROS) levels in MDA-MB-231/IR cells. We found that phenethyl isothiocyanate (PEITC), a well-known pro-oxidant phytochemical, suppressed stemness in MDA-MB-231/IR cells through ROS modulation via the downregulation of MTDH. Co-treatment of PEITC and N-Acetylcysteine (a ROS scavenger) caused alterations in PEITC induced cell death and CSC markers. Moreover, PEITC regulated MTDH expression at the post-transcriptional level, which was confirmed using cycloheximide, a protein synthesis inhibitor.

10-Gingerol Targets Lipid Rafts Associated PI3K/Akt Signaling in Radio-Resistant Triple Negative Breast Cancer Cells

“…According to our recent studies, the established MDA-MB-231/IR cells were found to possess enhanced chemo-and radio-resistance and several differentially regulated genes (DEGs) related to cell division, metabolism, drug resistance, metastasis, and stem-like properties, compared with parental MDA-MB-231 cells [12]. To assess the inhibitory effects of 10-gingerol on the proliferation of MDA-MB-231/IR cells, cells were exposed to different concentrations (200, 100, 50, 25, 12.5, and 6.25 µM) of 10-gingerol and incubated for 24 and 48 h. Docetaxel, a clinically used anti-cancer drug (an anti-mitotic agent), was used as the positive control.…”

“…A radio-resistant cell line (MDA-MB-231/IR) was recently developed in our laboratory [12]. Cell culture media [Dulbecco's modified Eagle's medium (DMEM)], fetal bovine serum (FBS), and antibiotics were purchased from Invitrogen (Carlsbad, CA, USA).…”

“…The MTT assay was used as the cell proliferation assay in the present investigation. MDA-MB-231, MDA-MB-231/IR, and MCF-10A cells were cultured in 96-well plates (5000 cells/well) and incubated for 24 h. Following incubation, cells were exposed to 10-gingerol (200, 100, 50, 25, 12.5, and 6.25 µM) for 24 and 48 h. MTT assay was conducted as described in our recent publication [12]. The percentage of cell viabilities of treated and untreated groups were calculated using the formula (control − treated) ÷ control) × 100%.…”

“…Trans-well cell invasion assay (Corning, Cambridge, MA, USA) was conducted as previously described by us [12]. After coating the upper chamber with 1% matrigel, MDA-MB-231/IR cells (1 × 10 5 cells/trans well) were transferred to the upper chamber (supplemented with or free of, 10-gingerol).…”

Perspective on dietary isothiocyanates in the prevention, development and treatment of cancer

“…Elimination of CSCs or tumor initiating cells would therefore constitute the ideal targets in chemoprevention and anti-tumor targeting during progression. There are documented studies showing targeting of tumor stem cells with good evidence [38,40,43,53] . Furthermore, considering all the hallmark features of cancer originally elaborated by Hanahan and Weinberg [54] and now reviewed and expanded on by Girotti et al [55] , who describe how galectins can affect tumor progression, it is obvious that ITCs can have a significant impact on all of these, including galectins [56] .…”