TY - JOUR
T1 - Epigallocathechin gallate, polyphenol present in green tea, inhibits stem-like characteristics and epithelial-mesenchymal transition in nasopharyngeal cancer cell lines
AU - Lin, Chien Hung
AU - Shen, Yao An
AU - Hung, Peir Haur
AU - Yu, Yuan Bin
AU - Chen, Yann Jang
N1 - Funding Information:
This project was supported by grants from the National Science Council, Taiwan (NSC-99-2314-B-010-006-MY3, NSC-96-2320-B-010-035-MY2), Department of Health, Taipei City (Grant No. 10001-62-030), and National Yang Ming University, Ministry of Education, Aim for the Top University Plan.
PY - 2012/10/30
Y1 - 2012/10/30
N2 - Background: Previous studies have demonstrated that the consumption of green tea inhibits the growth of various cancers. Most cancers are believed to be initiated from and maintained by a small population of cancer stem-like cells (CSC) or tumor-initiating cells (TIC) that are responsible for tumor relapse and chemotherapeutic resistance. Although epigallocathechin gallate (EGCG), the most abundant catechin in green tea, has been reported to induce growth inhibition and apoptosis in some cancer cells, its effect on CSC is undefined. In this study, we enriched CSC by the sphere formation, and provided an efficient model for further experiments. Using this method, we examined the effects of EGCG regulating the nasopharyngeal carcinoma (NPC) CSC and attempted to elucidate the possible mechanisms.Methods: NPC TW01 and TW06 cell lines were enriched by sphere formation and characterized their phenotypical properties, such as invasion capacity, epithelial-mesenchymal transition (EMT) and gene expression were analyzed by quantitative real-time reverse transcription polymerase chain reaction (q-RT-PCR). EGCG-induced growth inhibition in the parental and sphere-derived cells was determined by MTT and bromodeoxyuridine (BrdU) assay. EGCG-induced apoptosis was analyzed by flow cytometry with Annexin V and PI staining. The effects of EGCG on sphere-derived cell tumorigenicity, migration and invasion were determined by soft agar assay, wound healing, and cell invasion assay. The alternation of protein expression regulated by EGCG on these sphere-derived cells was assessed by immunofluorescence staining and western blot.Results: NPC sphere-derived cells grown in serum-free non-adherent culture showed increased expression of stem cell markers and EMT markers compared to parental cells grown in conventional culture. Although EGCG induced growth inhibition and apoptosis in the parental cells in a dose-dependent manner, it was not as effective against spheres. However, EGCG potently inhibited sphere formation and can eliminate the stem cell characteristics of NPC and inhibit the epithelial-mesenchymal transition (EMT) signatures.Conclusions: Overall, these findings show that NPC cells with sphere formations possess the properties of CSC. Using this model, we found that EGCG regulated NPC CSC, their self-renewal capacity, and inhibited their invasive characteristics. It supports the pivotal role of EGCG as a dietary compound targeting NPC and may decrease recurrence and metastasis in nasopharyngeal carcinoma cells.
AB - Background: Previous studies have demonstrated that the consumption of green tea inhibits the growth of various cancers. Most cancers are believed to be initiated from and maintained by a small population of cancer stem-like cells (CSC) or tumor-initiating cells (TIC) that are responsible for tumor relapse and chemotherapeutic resistance. Although epigallocathechin gallate (EGCG), the most abundant catechin in green tea, has been reported to induce growth inhibition and apoptosis in some cancer cells, its effect on CSC is undefined. In this study, we enriched CSC by the sphere formation, and provided an efficient model for further experiments. Using this method, we examined the effects of EGCG regulating the nasopharyngeal carcinoma (NPC) CSC and attempted to elucidate the possible mechanisms.Methods: NPC TW01 and TW06 cell lines were enriched by sphere formation and characterized their phenotypical properties, such as invasion capacity, epithelial-mesenchymal transition (EMT) and gene expression were analyzed by quantitative real-time reverse transcription polymerase chain reaction (q-RT-PCR). EGCG-induced growth inhibition in the parental and sphere-derived cells was determined by MTT and bromodeoxyuridine (BrdU) assay. EGCG-induced apoptosis was analyzed by flow cytometry with Annexin V and PI staining. The effects of EGCG on sphere-derived cell tumorigenicity, migration and invasion were determined by soft agar assay, wound healing, and cell invasion assay. The alternation of protein expression regulated by EGCG on these sphere-derived cells was assessed by immunofluorescence staining and western blot.Results: NPC sphere-derived cells grown in serum-free non-adherent culture showed increased expression of stem cell markers and EMT markers compared to parental cells grown in conventional culture. Although EGCG induced growth inhibition and apoptosis in the parental cells in a dose-dependent manner, it was not as effective against spheres. However, EGCG potently inhibited sphere formation and can eliminate the stem cell characteristics of NPC and inhibit the epithelial-mesenchymal transition (EMT) signatures.Conclusions: Overall, these findings show that NPC cells with sphere formations possess the properties of CSC. Using this model, we found that EGCG regulated NPC CSC, their self-renewal capacity, and inhibited their invasive characteristics. It supports the pivotal role of EGCG as a dietary compound targeting NPC and may decrease recurrence and metastasis in nasopharyngeal carcinoma cells.
KW - Cancer stem cells
KW - Epigallocathechin gallate
KW - Epithelial-mesenchymal transition
KW - Nasopharyngeal carcinoma
KW - Stem cells
UR - http://www.scopus.com/inward/record.url?scp=84867895444&partnerID=8YFLogxK
U2 - 10.1186/1472-6882-12-201
DO - 10.1186/1472-6882-12-201
M3 - Article
C2 - 23110507
AN - SCOPUS:84867895444
SN - 1472-6882
VL - 12
JO - BMC Complementary and Alternative Medicine
JF - BMC Complementary and Alternative Medicine
M1 - 1263
ER -