Publicado 4 números por año
ISSN Imprimir: 2155-014X
ISSN En Línea: 2155-0158
Nitric Oxide Synthase Activity and Nitric Oxide Concentration in the Tissues of Human Thyroid Carcinomas
SINOPSIS
The study of constitutive nitric oxide synthase (cNOS) activity has revealed that in papillary thyroid carcinomas it corresponds to that in unchanged peritumoral tissue, while the enzyme activity in follicular carcinomas is half lesser. At the same time, the activity of inducible nitric oxide synthase (iNOS) was higher in both papillary and follicular carcinomas. Such changes in enzyme activities were associated with the high level of nitric oxide in papillary carcinomas and minor changes in follicular carcinomas. In medullary carcinomas, the parameters under study corresponded to those in unchanged tissues, while in the papillary carcinoma metastases, the level of nitric oxide formation was much higher against the background of unchanged enzyme activity. Increased nitric oxide content and iNOS activity in papillary thyroid carcinomas did not depend significantly on the aggression characteristics of the latter. However, there were no signs of changes in nitric oxide content in T4 category of tumors against the background of reduced cNOS activity, and it was less expressed in tumors surrounded by the tissue with the availability of chronic thyroiditis. Furthermore, in papillary carcinomas of papillary or follicular pattern of growth, nitric oxide content did not differ from the normal value, being slightly higher in tumors of solid or heterogeneous structure with the presence of solid areas, whereas in carcinomas of papillary and follicular structure it was twice higher, and in the tissue of solid-insular structure three times higher. iNOS hyperactivity was observed in carcinomas of different patterns of growth, except for tumors of solid structure, where the enzyme activity turned out to be within normal range, and tumors of solid-insular structure where it was significantly higher (as well as cNOS activity) compared with tumors of other structure. Nitric oxide generating system is involved in the transformation of thyroid cells and progression of tumor growth, for example, through apoptosis regulation, which is evident from the results, obtained both in the present and previous studies. Meanwhile, the nature of nitric oxide involvement in papillary thyroid carcinomas with dissimilar histological structure is different.