title: Repression of telomerase activity during in vitro differentiation of osteosarcoma cells.
abstract: In this report, we studied the relationship between telomerase activity and in vitro differentiation of osteosarcoma cells. Human osteosarcoma cells (HOS-8603) were treated with all-trans-retinoic acid (RA) and dexamethasone (DEX). Cell cycle phase, alkaline phosphatase (AP) activity, telomerase activity, and human telomerase RNA (hTR) in treated cells were detected. The results showed that the treated cells underwent morphologic differentiation. AP activity of the cells increased significantly. The proportion of the cells in S and G2/M phases was increased. A pronounced decline in telomerase activity was observed, but no significant difference in the amount of hTR expressed, when compared with the control. This study demonstrates that: (1) both RA and DEX can inhibit cell growth and induce morphologic and functional differentiation of HOS-8603 cells; (2) telomerase is an enzyme system regulated during induced differentiation of HOS-8603 cells; (3) significantly decreased telomerase activity may be an indicator of differentiation but does not parallel the expression level of hTR; and (4) the regulation of telomerase is directly linked to cell differentiation not cell cycle.
authors.affiliation: Department of Pathology, Sun Yat-Sen University of Medical Sciences, Guangzhou, People's Republic of China. pathol@gzsums.edu.cn
authors.forename: Jianming
authors.initials: J
authors.lastname: Wen
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.forename: Meng
authors.initials: M
authors.lastname: Zhang
authors.forename: Dan
authors.initials: D
authors.lastname: Xie
authors.forename: Laibao
authors.initials: L
authors.lastname: Sun
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D015152:Blotting, Northern; D001859:Bone Neoplasms / Q000201:enzymology*; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation; D006801:Humans; D012516:Osteosarcoma / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D019098:Telomerase / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D012333:RNA, Messenger; D014212:Tretinoin; D003907:Dexamethasone; D019098:Telomerase; D000469:Alkaline Phosphatase