Human Thyroid Peroxidase Activity in Benign and Malign Thyroid Disorders

Fragu, P.; Nataf, B

doi:10.1210/jcem-45-5-1089

Cited by 45 publications

(16 citation statements)

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“…Second, this study showed that TPO is strongly underexpressed in PTCs. Previous reports on TPO activity in thyroid carcinomas have stated that TPO activity in thyroid carcinoma tissues was very low [6,7], although no confirmation was provided by immunohistochemical studies [16][17][18][19] or Northern blot studies [20][21][22] It is not clear, however, why the two FTCs were histochemically positive for the two enzymes.…”

Section: Discussionmentioning

confidence: 99%

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Differential Expression of Dipeptidyl Peptidase IV (CD26) and Thyroid Peroxidase in Neoplastic Thyroid Tissues.

et al. 1996

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Section: Discussionmentioning

confidence: 99%

“…TPO activity in thyroid carcinoma tissues was greatly reduced [6,7], and increased DPPIV/CD26 activity was observed in nearly 100% of differentiated thyroid carcinomas which account for more than 95% of all thyroid cancer cases [8]. These two enzymes can be detected histochemically on tissue sections.…”

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confidence: 96%

Differential Expression of Dipeptidyl Peptidase IV (CD26) and Thyroid Peroxidase in Neoplastic Thyroid Tissues.

et al. 1996

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“…Although papillary and follicular thyroid carcinomas retain the majority of biological properties of normal thyroid cells, a variety of biochemical defects has been demonstrated (28)(29)(30). Indeed, impaired intrathyroidal iodine metabolism represents one of the most peculiar abnormalities present in thyroid neoplastic tissue.…”

Section: Alteration Of Iodine Metabolism In Cancer Tissuementioning

confidence: 99%

Sodium/iodide symporter: a key transport system in thyroid cancer cell metabolism

Filetti¹,

Bidart

Arturi³

et al. 1999

European Journal of Endocrinology

252

144

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The recent cloning of the gene encoding the sodium/iodide symporter (NIS) has enabled better characterization of the molecular mechanisms underlying iodide transport, thus opening the way to clarifying its role in thyroid diseases. Several studies, at both the mRNA and the protein expression levels, have demonstrated that TSH, the primary regulator of iodide uptake, upregulates NIS gene expression and NIS protein abundance, both in vitro and in vivo. However, other factors, including iodide, retinoic acid, transforming growth factor-b, interleukin-1a and tumour necrosis factor a, may participate in the regulation of NIS expression. Investigation of NIS mRNA expression in different thyroid tissues has revealed increased levels of expression in Graves' disease and toxic adenomas, whereas a reduction or loss of NIS transcript was detected in differentiated thyroid carcinomas, despite the expression of other specific thyroid markers. NIS mRNA was also detected in non-thyroid tissues able to concentrate radioiodine, including salivary glands, stomach, thymus and breast.The production of specific antibodies against the NIS has facilitated study of the expression of the symporter protein. Despite of the presence of high levels of human (h)NIS mRNA, normal thyroid glands exhibit a heterogeneous expression of NIS protein, limited to the basolateral membrane of the thyrocytes. By immunohistochemistry, staining of hNIS protein was stronger in Graves' and toxic adenomas and reduced in thyroid carcinomas.Measurement of iodide uptake by thyroid cancer cells is the cornerstone of the follow-up and treatment of patients with thyroid cancer. However, radioiodide uptake is found only in about 67% of patients with persistent or recurrent disease. Several studies have demonstrated a decrease in or a loss of NIS expression in primary human thyroid carcinomas, and immunohistochemical studies have confirmed this considerably decreased expression of the NIS protein in thyroid cancer tissues, suggesting that the low expression of NIS may represent an early abnormality in the pathway of thyroid cell transformation, rather than being a consequence of cancer progression.The relationship between radioiodine uptake and NIS expression by thyroid cancer cells require further study. New strategies, based on manipulation of NIS expression, to obtain NIS gene reactivation or for use as NIS gene therapy in the treatment of radiosensitive cancer, are also being investigated. European Journal of Endocrinology 141 443-457 Role of iodine in thyroid physiology and pathophysiology Iodine in thyroid physiologyIodine represents an essential element in thyroid physiology, being a critical component of thyroxine and tri-iodothyronine molecules, and a key regulator of thyroid gland function. Thus dietary iodide supply influences the functional activity of the thyroid gland, iodine deficiency being the main cause of endemic goiter. Furthermore, iodine directly modulates thyroid sensitivity to thyroid-stimulating hormone (TSH), and intrathyroidal iodin...

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“…Recently, TPO gene and protein expression in thyroid carcinoma has been analysed, with results indicating low enzymatic activity (Valenta et al, 1973;Valenta, 1976;Fragu and Nataf, 1977;Mizukami and Matsunaga, 1981), and impaired solubility (Neary et al, 1978). Mutated TPO genes were found in some differentiated thyroid carcinomas (Smanik et al, 1994).…”

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confidence: 99%

Is there loss or qualitative changes in the expression of thyroid peroxidase protein in thyroid epithelial cancer?

et al. 2001

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Summary There is disagreement concerning the expression of thyroid peroxidase (TPO) in thyroid cancer, some studies finding qualitative as well as quantitative differences compared to normal tissue. To investigate TPO protein expression and its antigenic properties, TPO was captured from a solubilizate of thyroid microsomes by a panel of murine anti-TPO monoclonal antibodies and detected with a panel of antihuman TPO IgGκ Fab. TPO protein expression in 30 samples of malignant thyroid tissue was compared with TPO from adjacent normal tissues. Virtual absence of TPO expression was observed in 8 cases. In the remaining 22 malignant thyroid tumours the TPO protein level varied considerably from normal to nearly absent when compared to normal thyroid tissue or tissues from patients with Graves' disease (range less than 0.5 to more than 12.5 µg mg -1 of protein). When expressed TPO displayed similar epitopes, to that of TPO from Graves' disease tissue. The results obtained by the TPO capturing method were confirmed by SDS-PAGE and Western blot analysis with both microsomes and their solubilizates. The present results show that in about two-thirds of differentiated thyroid carcinomas, TPO protein is expressed, albeit to a more variable extent than normal; when present, TPO in malignant tissues is immunologically normal.

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Human Thyroid Peroxidase Activity in Benign and Malign Thyroid Disorders

Cited by 45 publications

References 0 publications

Differential Expression of Dipeptidyl Peptidase IV (CD26) and Thyroid Peroxidase in Neoplastic Thyroid Tissues.

Differential Expression of Dipeptidyl Peptidase IV (CD26) and Thyroid Peroxidase in Neoplastic Thyroid Tissues.

Sodium/iodide symporter: a key transport system in thyroid cancer cell metabolism

Is there loss or qualitative changes in the expression of thyroid peroxidase protein in thyroid epithelial cancer?

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