Cancer stem-like cells from head and neck cancers are chemosensitized by the Wnt antagonist, sFRP4, by inducing apoptosis, decreasing stemness, drug resistance and epithelial to mesenchymal transition

Abstract

Cancer stem cells (CSCs) of head and neck squamous cell carcinoma (HNSCC) are defined by high self-renewal and drug refractory potential. Involvement of Wnt/β-catenin signaling has been implicated in rapidly cycling cells such as CSCs, and inhibition of the Wnt/β-catenin pathway is a novel approach to target CSCs from HNSCC. In this study, we found that an antagonist of FrzB/Wnt, the secreted frizzled-related protein 4 (sFRP4), inhibited the growth of CSCs from two HNSCC cell lines, Hep2 and KB. We enriched the CD44(+) CSC population, and grew them in spheroid cultures. sFRP4 decreased the proliferation and increased the sensitivity of spheroids to a commonly used drug in HNSCC, namely cisplatin. Self-renewal in sphere formation assays decreased upon sFRP4 treatment, and the effect was reverted by the addition of Wnt3a. sFRP4 treatment of spheroids also decreased β-catenin, confirming its action through the Wnt/β-catenin signaling pathway. Quantitative PCR demonstrated a clear decrease of the stemness markers CD44 and ALDH, and an increase in CD24 and drug-resistance markers ABCG2 and ABCC4. Furthermore, we found that after sFRP4 treatment, there was a reversal in the expression of epithelial to mesenchymal (EMT) markers with the restoration of the epithelial marker E-cadherin, and depletion of EMT-specific markers twist, snail and N-cadherin. This is the first report demonstrating that the naturally occurring Wnt inhibitor, sFRP4, can be a potential drug to destroy CSC-enriched spheroids from HNSCCs. The repression of EMT and the decrease in stemness profile further strengthen the use of sFRP4 as a potent therapeutic against CSCs.

Cancer stem cell metabolism: a potential target for cancer therapy

“…CSCs are niche forming cells enriched with growth factors, and growing them in serum-free conditions containing growth factors, such as epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), maintains the undifferentiated stem cell state and induces the proliferation of self-renewing, unipotent CSCs from parental cell lines [4, 25, 26]. CSCs are characterised by specific surface markers such as CD133 + /CXCR4 + , CD24 + /CD44 + , CD24 + /CD44 + /ESA + , c-Met + /CD44 + , and ALDH1 + /CD133 + in pancreatic cancer [27, 28]; CD24 −/low /CD44 + in breast cancer; CD44 + in colon/ gastric/ head and neck/ovarian cancer; CD34 + /CD38 − in leukaemia cells; CD13/CD45/CD90 in liver cancer; CD117/CD90/EpCAM in lung cancer; CD20/CD166/Nestin in melanoma cancer; and CD133 + /ABCG2 + in Glioblastoma Multiforme [29, 30]. CSCs also express various markers such as CXCR4/ ESA and Nestin [27].…”

Decreased expression of the plasminogen activator inhibitor type 1 is involved in degradation of extracellular matrix surrounding cervical cancer stem cells

“…In cervical cancer, ALDH1-positive cells, like other solid tumors, are known to be more tumorigenic than negative ones, and we used ALDH1 as a marker of cervical CSCs (25)(26)(27)(28)(29)(30)(31)(32)(33)(34). First, using the cervical cancer cell line CaSki we confirmed that the expression of PAI-1 was significantly increased by changing coatings of culture plates as described (35), especially collagen IV-coating, confirmed by enzyme-linked immunosorbent assay (ELISA).…”

Wnt Signaling Inhibits the Growth of Primary Cilia and Activates CyclinD1, Snail and VEGFA Expression in Breast Cancer Cell Line MDA-MB-231

“…Recently, Snail was reported to trigger epithelial-mesenchymaltransition in tumor progression (37).SFRP4, another specifically Wnt antagonist, by inducing apoptosis, decreasing epithelial to mesenchymaltransion in head and neck cancer (38).…”