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Published on: April 12, 2017
Local thyroid renin-angiotensin system in experimental breast cancer
M P Carrera-González1, M J Ramírez-Expósito, M D Mayas
1Experimental and Clinical Physiopathology Research Group, Department of Health Sciences, Faculty of Experimental and Health Sciences, University of Jaén, Jaén, Spain.
Unlabelled:
An association between breast cancer and thyroid dysfunction exists although the underlying mechanisms remain to be elucidated. Numerous studies have characterized the role of thyroid hormones in controlling the synthesis and secretion of renin-angiotensin system (RAS) components, but little information is available on the putative role of the local RAS on thyroid function.
Aims:
Here we analyze several soluble and membrane-bound RAS-regulating aminopeptidase activities in thyroid gland from rats with mammary tumors and the relationship with the circulating levels of thyroid stimulating hormone (TSH) and free thyroxin (fT4).
Main Methods:
We analyze soluble and membrane-bound RAS-regulating aminopeptidase activities fluorometrically using their corresponding aminoacyl-β-naphthylamide as the substrate.
Key Findings:
We have found in rats with mammary tumors a concomitant change of thyroid RAS-regulating enzymes and thyroid hormone production.
Significance:
We suggest that existence of alterations in the regulatory mechanisms mediated by the angiotensins of the local tissue RAS as a consequence of the carcinogenic process which could act alone or in combination with alterations at a higher level of regulation such as the hypothalamus-pituitary axis.
Insights
Breast cancer in rats alters thyroid function by affecting local renin-angiotensin system (RAS) enzymes and hormone production. These changes in thyroid RAS may contribute to dysfunction alongside broader regulatory axis alterations.
Area of Science:
- Endocrinology
- Oncology
- Molecular Biology
Background:
- The relationship between breast cancer and thyroid dysfunction is established, but mechanisms are unclear.
- Thyroid hormones influence the renin-angiotensin system (RAS), yet the local RAS role in thyroid function is understudied.
Purpose of the Study:
- To investigate soluble and membrane-bound RAS-regulating aminopeptidase activities in the thyroid glands of rats with mammary tumors.
- To examine the correlation between these enzymatic activities and circulating levels of thyroid stimulating hormone (TSH) and free thyroxine (fT4).
Main Methods:
- Analysis of soluble and membrane-bound RAS-regulating aminopeptidase activities.
- Fluorometric assay using aminoacyl-β-naphthylamide substrates.
Main Results:
- Rats with mammary tumors exhibited concurrent alterations in thyroid RAS-regulating enzymes.
- Thyroid hormone production levels were found to change concomitantly with these enzymatic changes.
Conclusions:
- Carcinogenesis-induced alterations in local tissue RAS regulatory mechanisms may impact thyroid function.
- These local RAS changes could act independently or in conjunction with hypothalamic-pituitary axis dysregulation.
