title: Identification of label-retaining cells in nasopharyngeal epithelia and nasopharyngeal carcinoma tissues.
abstract: Adult stem cells can be identified by label-retaining cell (LRC) approach based on their ability to retain nucleoside analog, such as bromodeoxyuridine (BrdU). We hypothesized that mouse nasopharynx contains a small population of epithelial stem/progenitor cells that may be detected by the LRC technique. To identify LRCs in mice nasopharyngeal epithelia, neonatal mice were intraperitoneally injected with BrdU twice daily for 3 consecutive days. After an 8-week chase, long-term BrdU-labeled LRCs (approximately 2% of cells) were detected in the adult mice nasopharyngeal epithelia by immunostaining with BrdU antibody and some of LRCs (approximately 12% of cells) were found to be recruited into the S phase of cell cycle with an additional radioactive thymidine-labeling technique, indicating that the stem cells also divide, most likely asymmetrically. To further investigate whether the LRCs existed in human nasopharyngeal carcinoma (NPC) tissues, three NPC cell lines (5-8F, 6-10B and TMNE) were labeled with BrdU in vitro and then individually engrafted into the back of nude mice, which developed tumors. Again, label-retaining stem cells were found in all the three kinds of NPC xenograft tumors (approximately 0.3% of cells), around 16% of which were also labeled with radioactive thymidine. Thus, this study has demonstrated for the first time the presence of epithelial LRCs in mouse nasopharynx and human NPC tissues and these stem-like LRCs are not completely quiescent, as they will be recruited into the cell cycle to participate physiological or pathological process at any moment. More importantly, our data showed that NPC also contained stem cells, which are most likely the cause for NPC spread, metastasis and recurrence.
authors.affiliation: Cancer Research Institute, Xiang-Ya School of Medicine, Central South University, Changsha, Hunan 410078, China.
authors.forename: Hong-Bo
authors.initials: HB
authors.lastname: Zhang
authors.forename: Cai-Ping
authors.initials: CP
authors.lastname: Ren
authors.forename: Xu-Yu
authors.initials: XY
authors.lastname: Yang
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.forename: Ming
authors.initials: M
authors.lastname: Zhao
authors.forename: Hong
authors.initials: H
authors.lastname: Yang
authors.forename: Kai-Tai
authors.initials: KT
authors.lastname: Yao
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D001345:Autoradiography; D001973:Bromodeoxyuridine / Q000378:metabolism; D002277:Carcinoma / Q000473:pathology*; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D004847:Epithelial Cells / Q000145:classification* / Q000166:cytology / Q000378:metabolism*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007553:Isotope Labeling; D051379:Mice; D008807:Mice, Inbred BALB C; D008815:Mice, Inbred Strains; D008819:Mice, Nude; D009303:Nasopharyngeal Neoplasms / Q000473:pathology*; D009305:Nasopharynx / Q000166:cytology*; D009368:Neoplasm Transplantation; D013234:Stem Cells / Q000166:cytology; D013936:Thymidine / Q000378:metabolism; D014183:Transplantation, Heterologous
chemical_list: D001973:Bromodeoxyuridine; D013936:Thymidine