Growth suppression of thyroid cancer cells by adenylcyclase activator.

Thyroid stimulating hormone (TSH) is known to increase intracytoplasmic cyclic adenosine monophosphate (cAMP) and to regulate the growth of normal follicular cells. The aim of this study was to explore the role of the cAMP-mediated signaling pathway stimulated by TSH as a cell growth modulator in human thyroid cancer cells. One papillary thyroid cancer cell line, K1 cells and two anaplastic thyroid cancer cell lines, TTA1 and TTA2 cells were treated with forskolin, which directly activates adenyl cyclase to raise the level of intracellular cAMP. Forskolin suppressed thyroid cancer cell proliferations, especially in K1 cells, in a dose-dependent manner and induced growth arrest at the G0/G1 phase of the cell cycle. We also examined the expression of mitogen activated protein kinase (MAPK) after the forskolin treatment. Forskolin reduced the activation of growth factor induced MAPK activity. In conclusion, we demonstrated that forskolin was involved in G1 arrest and MAPK activation in K1 thyroid cancer cells. Our study suggests that the TSH signal mediated by cAMP acts as a negative regulator in thyroid cancer cells, unlike that in normal follicular cells.

Genetic analyses in patients with familial isolated hyperparathyroidism and hyperparathyroidism-jaw tumour syndrome.

BACKGROUND: A subset of familial isolated primary hyperparathyroidism (FIHP) is a variant of hyperparathyroidism-jaw tumour syndrome (HPT-JT). AIM/PATIENTS AND METHODS: We investigated the involvement of the HRPT2, MEN1 and CASR genes in 11 provisional FIHP families and two HPT-JT families. RESULTS: Germline mutations of HRPT2 were found in two of the 11 FIHP families and one of the two HPT-JT families. One FIHP family with parathyroid carcinoma and atypical adenomas and another FIHP family with cystic parathyroid adenoma had novel frameshift mutations of 518-521del and 62-66del, respectively. In a patient with HPT-JT, a de novo germline mutation of 39delC was detected. Novel somatic HRPT2 mutations of 70-73del and 95-102del were found in two of five parathyroid tumours in a family with a 518-521del mutation. Biallelic inactivation of HRPT2 by a combination of germline and somatic mutation was confirmed in the parathyroid tumours. The finding that two families diagnosed with FIHP carried HRPT2 mutations suggests that they have occult HPT-JT. In the remaining 10 families, one family had a missense MEN1 mutation. No mutations of CASR were detected. CONCLUSION: Our results confirm the need to test for HRPT2 in FIHP families, especially those with parathyroid carcinomas, atypical adenomas or adenomas with cystic change.

Expression of heterogeneous nuclear ribonucleoproteins A2 and b1 in the thyroid follicular cells.

Several proteins implicated in hormonogenesis of the thyroid have alternatively spliced isoforms. Alternative splicing of pre-mRNA is considered to be important to regulate the hormonal activity. Heterogeneous nuclear ribonucleoproteins (hnRNP) A2 and B1 are two of the abundant nuclear RNA-binding proteins involved in alternative splicing. We examined the expression of hnRNP A2 and B1 in the thyroid, paying particular attention to the relationship between their function and the cellular morphology. B1 was expressed more frequently in cuboidal follicular cells that are hormonally active than in flat follicular cells in normal thyroid, although A2 expression showed no significant difference in two cell types. In Graves' disease, the patients who had high serum levels of triiodothyronine and thyroxine showed significantly increased expression of B1. B1 expression did not differ significantly between normal thyroids and thyroid neoplasms, except undifferentiated (anaplastic) carcinoma. Conclusively, B1 expression varied in relation to hormonal activity in thyroid follicular cells. B1 protein is a good immunohistological marker to detect hormonal activity of follicular cells, and may provide a key to elucidate the splicing mechanisms involved in thyroid hormonogenesis.

Altered expression patterns of heterogeneous nuclear ribonucleoproteins A2 and B1 in the adrenal cortex.

Several proteins implicated in hormonogenesis of the adrenal cortex have alternatively spliced isoforms, which respond differently to adrenocorticotropic hormone (ACTH). Heterogeneous nuclear ribonucleoproteins A2 and B1 are among the abundant pre-mRNA-binding proteins involved in alternative splicing. We examined the expression of A2 and B1 in normal adrenal cortex and tumors. B1 was variably expressed in the zona fasciculata-reticularis, although A2 was diffusely expressed in the three zones. B1 was more abundant in compact cells than clear cells, and B1 expression was frequent in the zona reticularis, which consists mainly of compact cells. In three kinds of cortical adenomas autonomously producing hormones, B1 was generally overexpressed and there were no significant differences among them. In cortisol-producing tumors, non-tumor parts of the cortex, which were generally atrophic due to low ACTH, had less B1 protein than normal adrenals. These results suggested a correlation between B1 expression and the hormonal activity responding to ACTH. In vitro ACTH stimulation induced a biphasic expression of B1 in an H295R cortical carcinoma cell line, and it paralleled hormonogenesis. Conclusively, B1 expression varied in relation to the hormonal activity responding to the ACTH, and it may provide a key to elucidating the splicing mechanisms involved in hormonogenesis.

Gene expression profiling identifies platelet-derived growth factor as a diagnostic molecular marker for papillary thyroid carcinoma.

PURPOSE: Cancer diagnostics and therapeutics are often based on clinically relevant markers that are expressed specifically in a malignant tissue at levels higher than in normal tissue. We examined potential markers for papillary thyroid carcinoma (PTC) by monitoring PTC-specific gene expression using cDNA microarray. EXPERIMENTAL DESIGN: Gene expression profiles for PTC tissue, normal thyroid tissue, and healthy peripheral blood cells were compared by use of a human 4000-gene cDNA microarray. Protein expressions of the up-regulated genes in PTC were examined in thyroid tissues by immunohistochemistry. RESULTS: Sixty-four genes were overexpressed in PTC tissue relative to normal thyroid tissue and healthy peripheral blood cells. The genes that were up-regulated in PTC were involved in cell cycle regulation, DNA damage response, angiogenesis, and oncogenesis. Among these genes, basic fibroblast growth factor and platelet-derived growth factor were identified by immunochemical methods as proteins that are specifically expressed at high levels in thyroid neoplasms. Basic fibroblast growth factor, which has been identified as a biomarker for PTC, was overexpressed in 54% of PTC cases, 67% of follicular thyroid carcinomas, and 36% of benign thyroid neoplasms. Platelet-derived growth factor was overexpressed in 81% of PTC cases and 100% of follicular carcinomas, but was immunonegative in normal thyroid tissues and benign thyroid neoplasms. CONCLUSIONS: Platelet-derived growth factor may be a potential biomarker for PTC and follicular carcinoma. Expression profile analysis using a microarray followed by immunohistochemical study can be used to facilitate the development of molecular biomarkers for cancer.

Expression of vascular endothelial growth factor (VEGF) and its cognate receptors in human pheochromocytomas.

Pheochromocytomas are well-vascularized tumors, suggesting that a potent angiogenic factor may be involved in the mechanism of their formation. As vascular endothelial growth factor (VEGF) is a potent mitogen for vascular endothelial cells, here we have investigated the mRNA and protein expression of VEGF and the mRNA expression of its two receptors (Flt-1 and Flk-1/KDR) in pheochromocytomas tissue. An increase in VEGF mRNA (mainly isoforms VEGF(121) and VEGF(165)) and in VEGF protein expression were observed by semi-quantitative RT-PCR and Western blot, respectively, compared to normal adrenomedullary tissue. Flk-1/KDR, and Flt-1 levels of mRNA were also increased markedly in tumors and correlated with levels of VEGF mRNA. Therefore, we speculate that upregulation of VEGF expression and its receptors might be important in the pathogenesis of pheochromocytomas.

The intraductal component of breast cancer is poorly responsive to neo-adjuvant chemotherapy.

Neo-adjuvant chemotherapy has been used for locally advanced breast cancers. With special attention to the proportion of intraductal component, we pathologically studied 25 patients that underwent neo-adjuvant chemotherapy via intra-arterial infusion or intravenous injection. In general, neo-adjuvant chemotherapy had a favorable effect on tumor reduction. The effectiveness varies depending on the predominance of intraductal component. The cases with a high proportion of intraductal component had lower response to the chemotherapies. The larger number of cancer cells remained within the mammary ducts. The residual cancer cells conserved proliferative activity. Intraductal component is poorly responsive to neoadjuvant chemotherapy.