Gene Expression of Nitric Oxide Synthases in Thyroid Papillary Carcinoma / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: Nitric oxide (NO) is an important bioactive signalling molecule mediating several actions. Increased NO production may contribute in the pathogenesis of variety of disorders including cancer. Until now, the role of NO in cancer biology is unclear. The expressions of nitric oxide synthase (NOS) in thyroid carcinoma had not been fully determined yet and its role in that kind of tumor is still poorly understood. The aim of this study was to determine the expression and production of NOS in thyroid papillary carcinoma. MATERIALS AND METHOD: We investigated expressions of each NOS mRNA in 2 cases of surgical specimen of human thyroid papillary carcinoma by reverse transcriptase-polymerase chain reaction (RT-PCR). Western blot analysis using a polyclonal antibody directed against each NOS recognized immunoreactive NOS specific protein. Using the same antibody, the distribution of each NOS was examined in 10 formalin-fixed paraffin embedded samples by immunohistochemistry. RESULTS: RT-PCR analysis showed that the NOS mRNA expression in carcinoma tissues is elevated significantly in comparison with that in noncarcinoma tissue. The nNOS and eNOS specific proteins were found in papillary carcinoma but not in normal tissue. The iNOS specific protein was not detected in either carcinoma or normal tissues. Interestingly, the nNOS specific protein, which was analyzed by N-terminal antibody, was detected with several seperated bands. nNOS and eNOS were localized in papillary carcinoma cells but not in the normal thyroid tissue. iNOS was weakly stained in papillary carcinoma in comparison with nNOS and eNOS. CONCLUSION: All isoforms of NOS mRNA were expressed in papillary carcinoma but their specific proteins were only identified by the specific antibodies of nNOS and eNOS. Some low molecular weight protein bands detected in carcinoma seems to be a manifestation of possible structural diversity. Further DNA sequencing and activity study are needed for understanding its role in thyroid cancer.