The Expression of the Bcl-2 Family Proteins in Thyroid Neoplasms / 대한내분비학회지

ABSTRACT

BACKGROUND: Proteins of the Bcl-2 family are intracellular membrane-associated proteins that regulate programmed cell death either positively or negatively by as yet unknown mechanism. Bcl-2 family proteins have an antiapoptotic function, such as the Bcl-2, the long form of Bcl-x and Mcl-l, or a proapoptotic function, like the short form of Bcl-x and Bax. To investigate the potential role of Bcl-2 family proteins in thyroid tumorigenesis, the authors examined the pattern of expression of the Bel-2 family proteins in various thyroid neoplasms. METHODS: Bcl-2 family proteins, including Bcl-2, Bcl-x, Mcl-1 and Bax proteins were immunohistochemically stained in 57 cases of various thyroid neoplasms using formalin-fixed and paraffin embedded tissues; 18 cases of papillary carcinoma, 6 cases of medullary carcinoma, 4 cases of anaplastic carcinoma, 10 cases of follicular adenoma, 9 cases of adenomatous goiter, and 10 autopsy cases of fetal thyroid galnd. The intensity and frequency of the immunostaining were evaluated with the program of Image-Pro Plus Version 3.0 for image analysis. RESULT: Consistent expression of Bcl-2, Mcl-1, and Bax proteins were present in the surrounding normal thyroid tissue, however the expression of Bcl-x protein was not observed. Compare to the expression patterns of adenomatous goiter, and fetal and surrounding normal thyroid tissues, papillary and anaplastic carcinomas showed the decreased Bcl-2 and increased Bcl-x protein expressions(p (0.05). Medullary carcinoma revealed the increased Bcl-x protein expression only(p 0.05). CONCLUSION: These data suggest that combined patterns of decreased Bcl-2 and increased Bcl-x protein expressions may eontribute to the carcinogenesis of thyroid cancers originated from thyroid follicular cells, and an increased expression of Bcl-x protein may be related to the pathogenesis of medullary carcinoma from parafollicular C cells.