Hormonal regulation of thyroid peroxidase in normal and transformed rat thyroid cells.
The hormonal induction of thyroid peroxidase (TPO) mRNA is studied in the functional rat thyroid cell line FRTL-5 and compared to the induction of thyroglobulin (TG) mRNA and I- uptake. TPO and TG mRNAs are regulated by TSH and by insulin-like growth factor I (IGF-I) and/or insulin. However, while TPO is more sensitive to TSH regulation (5- to 6-fold increase vs. 2- to 3-fold increase by IGF-I), TSH and IGF-I are equally potent in increasing TG mRNA levels (3- to 4-fold). Regulation of I- uptake appears to be different: thus TSH greatly (15-fold) increases I- uptake, while IGF-I or insulin are completely ineffective. TPO and TG mRNAs and I- transport display different sensitivity to transformation of rat thyroid cells. Thus, when another differentiated rat thyroid cell line, the PC cells, are transformed by human c-myc (PC myc), TPO and TG mRNAs are both present at normal levels, while I- uptake is slightly decreased; in the PC cells transformed by polyomavirus middle-T-antigen (PC PyMLV) TPO mRNA is undetectable and I- uptake is greatly decreased, while TG mRNA is present at normal levels. All three differentiated functions are switched off in PC cells transformed by the cooperation of c-myc and polyomavirus middle-T-antigen (PC myc + PyMLV).
Zarrilli
R
R
Centro di Endocrinologia ed Oncologia Sperimentale del C.N.R., Dipartimento di Biologia e Patologia Cellulare e Molecolare, II Facoltà di Medicina e Chirurgia, Napoli, Italy.
Formisano
S
S
Di Jeso
B
B
D000818:Animals; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D015342:DNA Probes; D006728:Hormones / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007453:Iodide Peroxidase / Q000096:biosynthesis*; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013961:Thyroid Gland / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D013972:Thyrotropin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D015342:DNA Probes; D006728:Hormones; D007328:Insulin; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D013972:Thyrotropin; D007453:Iodide Peroxidase