(Am J Public Health 1987; 77:674-678.)

Review of treatment-related symptoms prompted policies to reduce toxicity including amifostine pretreatment for 131I therapy and thyrotropin (synthetic TSH) use in place of iatrogenic hypothyroidism for thyroglobulin testing and scanning.

A patient with widely metastatic differentiated thyroid cancer who had been heavily pretreated with (131)I was given recombinant human thyroid stimulating hormone (rhTSH) prior to (131)I treatment. Clinical and physical data from both this case and the literature suggest that the recombinant hormone, not the (131)I, may have caused a significant portion of the tumor swelling, which in turn was the most likely cause of the patient's symptoms. The potential effect of (131)I-induced tumor swelling and direct radiation effect on the lung is also analyzed. We review the potential hazards associated with rhTSH in patients with metastasis and propose means of minimizing this risk.

Three regions within the 5'-flanking region of the TSH beta gene have A-T-rich sequences which have sequence similarity to binding sites for the pituitary-specific POU domain transcription factor Pit-1/GHF-1. These three regions have been termed TSH A (-274 to -258 bp), TSH B (-336 to -326 bp), and TSH C (-402 to -384 bp). TSH A and TSH C are able to confer 2-6-fold TRH stimulation to the heterologous viral thymidine kinase (tk) promoter in transient expression assays in GH3 pituitary cells; TSH C can confer a 3-10-fold increase in basal enhancer activity as well. TSH A, B, and C DNAs all bound Pit-1 from GH3 cell nuclear extracts, based on gel mobility shift analysis in which antibody against Pit-1 prevented the formation of specific DNA-GH3 nuclear protein complexes. TSH A and TSH C also each formed several additional DNA-nuclear protein complexes which were not observed with TSH B. Some of these complexes may contain Pit-1 as their formation was inhibited by the addition of Pit-1 antibody; other complexes, however, were not altered by antibody treatment. All three A-T-rich elements bound in vitro translated Pit-1, with calculated affinities of 360 (A), 125 (B), and 38 (C) nM, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Two TRH-responsive elements have been identified in the rat TSH beta gene by deletion/mutation analysis of the 5'-flanking region of the gene and transfection of TSH beta-luciferase constructs into the GH3 pituitary cell line. Biological responsiveness was confirmed by inserting synthetic oligonucleotides next to the heterologous viral thymidine kinase (tk) promoter in tk luciferase (tkLUC) constructs. Both DNA regions, termed TSH A (at -274 to -258 bp) and TSH C (-402 to -385 bp), have a high level of sequence similarity to binding sites for the POU domain pituitary transcription factor Pit-1/GHF-1. In transfection assays, the TSH A region had no basal enhancer activity, but did confer 3- to 6-fold TRH- and PMA-stimulated transcriptional responses to the tk promoter. The TSH C region conferred basal enhancer activity (3- to 10-fold above control tkLUC) as well as a 2- to 3-fold TRH or PMA response. Combinations of TSH A and TSH C elements conferred both enhancer activity and a TRH- or PMA-stimulated response, but more than two copies of the regions resulted in no further stimulatory effect. Both TSH beta gene regions bound to nuclear proteins from GH3 cells, as determined by gel retardation analysis. The TSH A region DNA formed three prominent DNA-protein complexes, ranging from slowly to rapidly migrating bands and with calculated affinities of 32, 0.5, and 208 nM, respectively. The TSH C region formed two major complexes, which corresponded on the basis of mobility to the most slowly and rapidly migrating complexes formed by TSH A, but with calculated affinities of 3.1 and 33 nM. TSH C also formed a rapidly migrating minor complex unique for this gene region. The more rapidly migrating complexes appeared to be specific to nuclear proteins from GH3 cells. Treatment of cells with TRH did not significantly alter the affinity of protein binding. Mutation of TSH A and TSH C DNA by T to G substitutions abolished the ability of the DNA to confer a TRH response and severely inhibited the ability of the DNA to bind to GH3 nuclear proteins. Thus, transcriptional regulation of the rat TSH beta gene by TRH is correlated with the ability of the two TRH-sensitive elements to bind nuclear proteins. The differences noted in basal enhancer activity or the degree of TRH responsiveness may be related to some unique proteins bound to each DNA or to the differences in affinity of binding of the proteins common to both elements.