title: Differential effects of TGF-beta1 on telomerase activity in thyroid carcinoma cell lines.
abstract: The aim of the present study was to investigate the effect of transforming growth factor-beta1 (TGF-beta1) on telomerase activity in a panel of human anaplastic thyroid carcinoma (ATC) cell lines. Addition of TGF-beta1 decreased the telomerase activity in HTh 74 and KTC-1 cells, while in C 643 and HTh 7 an increased activity was observed. The decreased telomerase activity appeared to be due to transcriptional repression of the hTERT promoter. Addition of a PI-3 kinase inhibitor (LY294002) abrogated the stimulatory effect of TGF-beta1 on the telomerase activity, indicating the possible involvement of hTERT activation via phosphorylation. Furthermore, the MEK-inhibitor U0126 had similar effects suggesting dual regulatory mechanisms. Interestingly, the cell lines differed genetically in that ATC cell lines responding with increased telomerase activity harbored a p53 mutation. In conclusion, TGF-beta1 exerts opposing effects on telomerase activity in ATC cell lines, possibly reflecting deregulation of TGF-beta1 signaling in a more malignant genotype.
authors.affiliation: Department of Genetics and Pathology, Uppsala University Hospital, Rudbeck Laboratory, SE-751 85 Uppsala, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Lindkvist
authors.forename: Asa
authors.initials: A
authors.lastname: Franzén
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Ren
authors.forename: Nils-Erik
authors.initials: NE
authors.lastname: Heldin
authors.forename: Ylva
authors.initials: Y
authors.lastname: Paulsson-Karlsson
mesh_terms: D045744:Cell Line, Tumor; D015536:Down-Regulation / Q000187:drug effects; D005838:Genotype; D006801:Humans; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011401:Promoter Regions, Genetic / Q000235:genetics; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*; D013964:Thyroid Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
chemical_list: D020929:Mitogen-Activated Protein Kinase Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D019098:Telomerase; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D016159:Tumor Suppressor Protein p53; C489427:MYC protein, human; C508960:TGFB1 protein, human