The effect of thyrotropin receptor antibodies on the proliferation of FRTL-5 cells and the expression of protooncogene c-fos mRNA.
OBJECTIVE
Hyperthyroidism and a diffuse goiter are the main symptoms of Graves' disease (GD) associated with autoantibodies to thyroid-stimulating hormone (TSH) receptor (TRAb). The present study was conducted to evaluate effects of autoantibodies in patients with GD (TRAb-IgG) on induction of the proliferation and c-fos mRNA expression in FRTL-5 cells (Fisher rat thyroid cell line).


METHODS
Highly purified IgG fractions were isolated from 11 patients with GD, TRAb-IgG and 15 normal individuals (normal controls) with Protein A Sepharose CL-4B affinity column chromatograph. FRTL-5 cells, which had been grown to subconfluency and deprived of TSH for a few days. Then, these cells were used for measuring cAMP content, 3H-thymidine incorporation in cells and the expression of c-fos mRNA respectively.


RESULTS
After stimulation of TRAb-IgG, the cAMP production and 3H-thymidine incorporation in FRTL-5 cells were much higher than those from normal controls (P < 0.05 respectively). Using 32P labelled v-fos probe by the Northern Blot method, the expression of c-fos mRNA could be induced by IgGs from patients with GD.


CONCLUSIONS
These data suggest that the stimulation of TRAb-IgG followed by cAMP production and 3H-thymidine incorporation is related to the induction of c-fos mRNA and, thus, to the growth of FRTL-5 cells.
Fang
P
P
Tianjin Institute of Endocrinology, Tianjin Medical University, China.
Lü
M
M
Zhou
W
W
Li
J
J
Xu
B
B
Tang
T
T
Tan
Y
Y
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001323:Autoantibodies / Q000276:immunology*; D002455:Cell Division; D002478:Cells, Cultured; D016762:Genes, fos; D006111:Graves Disease / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011916:Rats, Inbred F344; D011989:Receptors, Thyrotropin / Q000276:immunology*; D013961:Thyroid Gland / Q000166:cytology*
D000906:Antibodies; D001323:Autoantibodies; D007074:Immunoglobulin G; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D011989:Receptors, Thyrotropin