Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lithium has been reported to alter thyroid function and cause goiter in some patients. To explain the mechanism of lithium action in the thyroid gland, we studied the effect of lithium on thyroid function and cell growth in FRTL-5 rat thyroid cells and on de novo thyroid hormone formation in primary cultures of porcine thyroid follicles. TSH-induced iodide uptake was suppressed at 2 mM lithium in both FRTL-5 cells and porcine follicles. In porcine thyroid follicles, iodide uptake stimulated by 8-bromo-cAMP, iodine organification, and de novo thyroid hormone formation were also reduced by lithium; however, 2 mM lithium did not inhibit TSH-induced cAMP production. In FRTL-5 cells, lithium also inhibited forskolin-stimulated iodide uptake. These results suggested that lithium exerts its effect at a step involving cAMP signal transduction rather than inhibiting cAMP production. In both FRTL-5 thyroid cells and porcine follicles, lithium enhanced cell growth in basal states (lacking TSH) and with TSH treatment. In porcine thyroid cells, the protein kinase C activator, tetradecanoyl phorbol-13-acetate, increased cell growth, and lithium had an additive effect with tetradecanoyl phorbol-13-acetate on cell growth. To examine the possibility that the action of lithium was mediated by the protein kinase C pathway, porcine cells were incubated with lithium and H7, a selective protein kinase C inhibitor. Lithium-induced cell growth was suppressed to the basal level by H7. These results suggest that lithium exerts its growth-promoting effect through the protein kinase C system.
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PMID:Effect of lithium on function and growth of thyroid cells in vitro. 164 47

We report immunohistochemical evidence for the overexpression of protein kinase C in various proliferative diseases of human thyroid. Immunohistochemical characterization of various surgically removed thyroid tissues, viz., cancer tissues: papillary carcinoma and follicular carcinoma; adenoma tissues: tubular, trabecular and colloid adenomas; adenomatous goiter; and normal thyroid was done using the monospecific monoclonal antibodies MC-1a, MC-2a and MC-3a, each of which is specific for types I, II and III isozymes of protein kinase C, respectively. For protein kinase C type II, a remarkable difference in staining intensity was noted between the cancerous and normal tissues. The cytoplasm of papillary and follicular carcinoma cells stained more intensely than that of normal thyroid cells. In the benign tumor and adenomatous goiter tissues, stronger staining was noted in the papilliform-proliferating portion and cubic epithelial cells. In the normal thyroid tissues, epithelial cells of greater height were more strongly stained than simple squamous epithelial cells. These results indicated that protein kinase C type II isozyme is expressed in larger amounts in cancerous and proliferative tissues of the human thyroid.
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PMID:Immunohistochemical evidence for the overexpression of protein kinase C in proliferative diseases of human thyroid. 180 90

To study the growth control of human thyroid cells in different stages of differentiation, we established two human thyroid cell lines of adenomatous goiter and papillary carcinoma. A 59-year-old female patient with adenomatous goiter was operated in September 1991, and a 27-year-old female patient with papillary carcinoma in May 1990. The thyroid cell lines were established by successive passage without cellular or genetic manipulations such as fusing other cell lines or oncogenic viral infection. These cell lines, human adenomatous goiter cells (hAG) and human papillary thyroid carcinoma cells (hPTC), exhibited a flattened polygonal shape and proliferated as a monolayer in cell culture. The doubling time of the hAG cells was 60 h in Ham's F12 medium supplemented with 10% fetal bovine serum, and that of the hPTC cells, 18 h in the same medium. Both cell lines expressed mRNA for TSH receptor and secreted cAMP into the medium during incubation with thyrotropin (TSH) at concentrations as low as 0.01 mU/mL. The effects of activators of protein kinase A (PKA), protein kinase C (PKC), tyrosine kinase (TK), and estradiol (E2) on proliferation of the hAG cells and the hPTC cells were assessed by measuring cellular DNA content in 24-well plates with diaminobenzoic acid. TSH stimulated proliferation of the hAG cells, but it inhibited proliferation of the hPTC cells. Since TSH activates two signaling pathways, the adenyl cyclase-PKA system and phospholipase C-PKC system, we tested effects of dibutylyl cAMP (dBC) and phorbol myristate 13-acetate (PMA), separately. dBC stimulated proliferation of the hAG cells, but it inhibited that of the hPTC cells.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Different growth control of the two human thyroid cell lines of adenomatous goiter and papillary carcinoma. 778 32

Long-term administration of lithium is one of the well-known causes of goiter. It can stimulate DNA synthesis in rat thyroid cells (FRTL-5) treated with thyroid-stimulating hormone (TSH). To investigate the mitogenic signal transduction system activated by lithium, lithium-induced DNA synthesis and Ca2+ influx were studied using two protein kinase inhibitors, genistein as a specific tyrosine kinase inhibitor and staurosporine as a potent inhibitor of protein kinase C. Genistein but not staurosporine blocked the DNA synthesis induced by lithium in TSH-primed cells but neither compound had any effect on the Ca2+ entry stimulated by lithium. Genistein clearly attenuated the phosphotyrosine content of the 175 kDa substrate in the presence of lithium but staurosporine failed to do so. Moreover, lithium could also stimulate DNA synthesis in protein kinase C down-regulated cells. These data demonstrate that lithium may require the activation of a particular genistein-sensitive kinase, possibly a tyrosine kinase, to induce cell proliferation. It is suggested that the phorbol ester-sensitive protein kinase C family might not participate in the mitogenic signal transduction pathway activated by lithium.
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PMID:Genistein but not staurosporine can inhibit the mitogenic signal evoked by lithium in rat thyroid cells (FRTL-5). 782 87