Constitutive Expression of Nitric Oxide Synthases in Cancerous Follicle Cell of Human Thyroid Gland

초록

Unlike the normal follicle cells in human thyroid gland,cancerous follicle cells in papillary thyroid carcinoma(PTC)tissues were found to express all 3 isoforms of nitric oxide synthases(NOS;nNOS,eNOS,and iNOS)upon immuno-histochemical analysis. Semiquantitative RT-PCR results indicated that although constitutive expression of iNOS mRNA could not be detected in the normal thyroid gland tissues,constitutive expression of nNOS and eNOS mRNAs could be detected.In the carcinoma tissues,however,in addition to the constitutive expression of iNOS mRNA,the expressed levels of nNOS and eNOS mRNAs were significantly greater than those observed in the thyroid gland tissues.Molecular weights of the 3 NOS isoenzymes found in thyroid carcinoma tissues examined by Westen-blot analysis showed that the weights of eNOS(-125kDa)proeins were of standard sizes. However,the weight of in nNOS(-80kDa)appeared to be different from that of standard size(-160KDa).Combined these results indicate that immuno-histochemical detection of all 3 NOSs in follicle cells of thyroid tissue may serve as a diagnostic tool for the presence of thyroid carcinoma.