Genistein inhibits nasopharyngeal cancer stem cells through sonic hedgehog signaling.

Genistein, a soy derived isoflavanoid compound, exerts anticancer effects in various cancers. Nasopharyngeal cancer stem cells (NCSCs) are a small subpopulation of cancer cells which are responsible for initiation, progression, metastasis, and recurrence of nasopharyngeal cancer. The present study aimed to investigate the suppressive effects of genistein on NCSCs and its underlying mechanism. NCSCs were enriched from human nasopharyngeal cancer cell lines CNE2 and HONE1 through tumorsphere-forming assay. It was shown that genistein inhibited the tumorsphere formation capacity, decreased the number of EpCAM+ cells, downregulated the expression of NCSCs markers, suppressed cell proliferation, and induced apoptosis of NCSCs. Genistein suppressed the activity of Sonic hedgehog (SHH) signaling, which was important for the maintenance of NCSCs, while activation of SHH signaling by purmorphamine diminished the inhibitory effects of genistein on NCSCs. Our data suggested that genistein inhibited NCSCs through the suppression of SHH signaling. These findings support the use of genistein for targeting NCSCs.

Phenethyl isothiocyanate inhibits colorectal cancer stem cells by suppressing Wnt/ß-catenin pathway.

Cancer stem cells (CSCs) are considered to play essential roles in the process of origination, proliferation, migration, and invasion of cancer, and their properties are regulated by Wnt/ß-catenin pathway. Phenethyl isothiocyanate (PEITC) is a natural product obtained from cruciferous vegetables with anticancer activities. The present study aimed to investigate the inhibitory effect and the underlying mechanisms of PEITC on colorectal CSCs. In this study, we found that PEITC can significantly reduce the size and number of colorectal cancer cell spheroids in serum-free medium. With increasing PEITC concentrations (10-40 µM), the number of spheroids was reduced to about 10% of the control group, and the percentage of CD133+ cells was decreased by about 3-16 folds. PEITC also decreased the expression of CSC markers. Meanwhile, inhibition of proliferation as well as induction of apoptosis of colorectal CSCs was observed after PEITC treatment. Furthermore, through activating Wnt/ß-catenin pathway with LiCl, the inhibitory effects of PEITC on colorectal CSCs were diminished. Our data suggested that PEITC can be an effective inhibitor of colorectal CSCs by targeting Wnt/ß-catenin pathway.

(-)-Epigallocatechin-3-Gallate Inhibits Colorectal Cancer Stem Cells by Suppressing Wnt/ß-Catenin Pathway.

The beneficial effects of tea consumption on cancer prevention have been generally reported, while (-)-Epigallocatechin-3-gallate (EGCG) is the major active component from green tea. Cancer stem cells (CSCs) play a crucial role in the process of cancer development. Targeting CSCs may be an effective way for cancer intervention. However, the effects of EGCG on colorectal CSCs and the underlying mechanisms remain unclear. Spheroid formation assay was used to enrich colorectal CSCs from colorectal cancer cell lines. Immunoblotting analysis and quantitative real-time polymerase chain reaction were used to measure the alterations of critical molecules expression. Immunofluorescence staining analysis was also used to determine the expression of CD133. We revealed that EGCG inhibited the spheroid formation capability of colorectal cancer cells as well as the expression of colorectal CSC markers, along with suppression of cell proliferation and induction of apoptosis. Moreover, we illustrated that EGCG downregulated the activation of Wnt/ß-catenin pathway, while upregulation of Wnt/ß-catenin diminished the inhibitory effects of EGCG on colorectal CSCs. Taken together, this study suggested that EGCG could be an effective natural compound targeting colorectal CSCs through suppression of Wnt/ß-catenin pathway, and thus may be a promising agent for colorectal cancer intervention.

Curcumin Suppresses Lung Cancer Stem Cells via Inhibiting Wnt/ß-catenin and Sonic Hedgehog Pathways.

Cancer stem cells (CSCs) are highly implicated in the progression of human cancers. Thus, targeting CSCs may be a promising strategy for cancer therapy. Wnt/ß-catenin and Sonic Hedgehog pathways play an important regulatory role in maintaining CSC characteristics. Natural compounds, such as curcumin, possess chemopreventive properties. However, the interventional effect of curcumin on lung CSCs has not been clarified. In the present study, tumorsphere formation assay was used to enrich lung CSCs from A549 and H1299 cells. We showed that the levels of lung CSC markers (CD133, CD44, ALDHA1, Nanog and Oct4) and the number of CD133-positive cells were significantly elevated in the sphere-forming cells. We further illustrated that curcumin efficiently abolished lung CSC traits, as evidenced by reduced tumorsphere formation, reduced number of CD133-positive cells, decreased expression levels of lung CSC markers, as well as proliferation inhibition and apoptosis induction. Moreover, we demonstrated that curcumin suppressed the activation of both Wnt/ß-catenin and Sonic Hedgehog pathways. Taken together, our data suggested that curcumin exhibited its interventional effect on lung CSCs via inhibition of Wnt/ß-catenin and Sonic Hedgehog pathways. These novel findings could provide new insights into the potential therapeutic application of curcumin in lung CSC elimination and cancer intervention. Copyright © 2017 John Wiley & Sons, Ltd.