Inhibiting epidermal growth factor receptor signalling potentiates mesenchymal–epithelial transition of breast cancer stem cells and their responsiveness to anticancer drugs

Abstract

The recurrence of breast cancer in patients is a persistent challenge to the medical fraternity. Breast tumor contains a small population of cells with high tumor initiating and metastatic potential, known as cancer stem cells (CSCs), which are resistant to existing chemotherapeutics. CSCs contribute to the aggressiveness of triple negative breast cancers (TNBCs), thereby necessitating the identification of molecular targets on breast CSCs. TNBC cell line MDA-MB-231, in comparison with MCF-7, demonstrated a higher expression of epidermal growth factor receptor (EGFR). Thus, the naturally occurring flavanone, chrysin, with limited potential as a chemotherapeutic agent, was structurally modified by designing an analog with EGFR binding affinity using a molecular docking approach and subsequently synthesised. Chrysin analog CHM-09 and known EGFR inhibitors demonstrated a comparable anti-proliferative, anti-migratory activity along with the induction of apoptosis and cell cycle arrest in MDA-MB-231. Furthermore, sorted CD24 /CD44 -breast CSCs and CD24 -breast cancer cells from MDA-MB-231 demonstrated a markedly high expression of EGFR in the former than in the latter. CHM-09 and EGFR inhibitors could perturb EGF-induced EGFR signalling of breast CSC proliferation, migration, mammosphere formation and mesenchymal tri-lineage differentiation. CHM-09 or EGFR inhibitors not only led to inactivation of EGFR downstream signalling pathways such as Akt, extracellular signal regulated kinase and signal transducer and activator of transcription 3, but also induction of mesenchymal-epithelial transition as confirmed by decreased N-cadherin and increased E-cadherin expression. Finally, combinatorial treatment of EGFR inhibitors and doxorubicin led to significant increase in breast CSCs responsiveness to a chemotherapeutic drug. The results of the present study suggest that EGFR is a therapeutic target in breast CSCs and that abrogation of EGFR signalling along with chemotherapeutic drugs is an effective approach against breast cancer.

Glutathione S‐transferase omega 1 inhibition activates JNK‐mediated apoptotic response in breast cancer stem cells

“…We evaluated GSTO1 protein expression in sorted breast CSCs (CD24 − /CD44 + ) and cancer (CD24 + ) cells as described previously . Interestingly, CD24 − /CD44 + breast CSCs depicted markedly high expression of GSTO1 as compared with CD24 + cells (Fig.…”

“…Next, to validate the molecular docking interaction of S2E with GSTO1, we performed a cellular thermal shift assay (CETSA) as described previously . To assess the binding affinity, MDA‐MB‐231 cells were treated with vehicle control (DMSO) or S2E (25 μ m ) followed by detection of GSTO1 stabilization confirmed by immunoblotting.…”

“…The TNBC cell lines MDA‐MB‐231, MDA‐MB‐468, MDA‐MB‐453 and BT‐549 as well as control primary human embryonic kidney cells, HEK293, were cultured as described previously . TNBCs and control cells were treated for 48 h with chemotherapeutic drugs (doxorubicin, gemcitabine, docetaxel, tamoxifen), vehicle control or separately with either tamoxifen or compound S2E and/or a combination of both at different concentrations as mentioned in the figures.…”

Cellular crosstalk mediated by platelet-derived growth factor BB and transforming growth factor β during hepatic injury activates hepatic stellate cells

“…Immunoblot analysis: HepG2 cells were treated with either 30mM AAP or 75mM EtOH or 1% CCl 4 or 750µg/mL TAA for 24 h. The extracted protein lysates were subjected to sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), transferred onto polyvinylidene difluoride (PVDF) membrane followed by immunobloting with annexin V antibody and detected using chemiluminiscence reagent (Merck Millipore, USA) (Manupati at al. 2017).…”

“…Immunoblot analysis: PDGF-BB or TGFβ (10ng/mL) or CM of hepatotoxicant-treated HepG2 cells were treated to HSCs, protein lysates were resolved as described above and probed with antibodies against phosphorylated and total PDGFRβ, TGFRIIβ, FAK, and ERK1/2 as well as βtubulin antibody as loading control (Manupati et al 2017).…”