Sonic Hedgehog Protein Expression in Various Thyroid Tissues and Its Clinical Implication / 대한내분비외과학회지

PURPOSE: The Hedgehog (Hh) signaling pathway is important in embryonic development including cell differentiation and proliferation. Recently, activation of this pathway has been implicated in several forms of solid cancers. We investigated sonic hedgehog (Shh) protein expression and its relation to differentiation and clinicopathologic characteristics in thyroid cancer cell lines and tissues. METHODS: FTC-236, FTC-238, and XTC-1. We made tissue microarray slides using 80 thyroid surgical specimen: 40 benign and 40 malignant lesions. Immunohistochemical staining was performed using anti-Shh antibody. mRNA expression of NIS, thyroglobulin, and CD97 were evaluated by RT-PCR. Cyclopamine was used as a Shh signal inhibitor. RESULTS: Shh expression was more prominent in TPC-1, FTC-133, and XTC-1 cell lines than the others. Cyclopamine downregulated CD97 and upregulated thyroglobulin mRNA expression, but did not induce mRNA expression of NIS. Thyroid tissues showed varied expression of Shh in both benign and malignant diseases. Shh expression was detected in 38 of 50 (76%) normal, in 18 of 25 (72%) non-neoplastic benign, in nine of 15 (60%) benign tumors, and in 31 of 40 (77%) malignant tumors. Shh over-expression was significantly less frequent in papillary thyroid carcinomas than in normal or benign thyroid tissues. In addition, Shh protein expression did not relate to clinicopathologic characteristics in papillary thyroid carcinomas. CONCLUSION: Thyroid tissues and cell lines vary in expression of Shh. Cyclopamine can induce redifferentiation in thyroid cancer cell lines. Shh protein expression, however, is unrelated to clinicopathologic characteristics in papillary thyroid carcinomas.

Cyclopamine Inhibits Cancer Cell Proliferation in Thyroid Cancer Cell Lines / 대한내분비외과학회지

PURPOSE: The Hedgehog (HH) signaling pathway is important in development. Recently,ectopic activation of this pathway has been implicated in several forms of solid cancer including basal cell carcinoma, pancreatic cancer, colon cancer, and prostate cancer. There are three HH proteins involved in the pathway: Sonic HH, Indiana HH, and Desert HH. Cyclopamine disrupts Sonic HH signaling by inhibition of the seven-transmembrane receptor Smoothened (SMO). Whereas cyclopamine is cytotoxic to several human cancer cells, its effect on thyroid cancer cellsis unknown. We therefore investigated the effect of cyclopamine on cell proliferation in human thyroid cancer cell lines. METHODS: We used fivethyroid cancer cell lines: TPC-1 (papillary), FTC-133, FTC-236, FTC-238 (follicular), and XTC-1 (Hurthle cell). The MTT assay and cell cycle analysis were used to evaluate anti-proliferative effects. Tomatidine, a structural analogue of cyclopamine, was used as a control agent. Statistical significance was tested by ANOVA. RESULTS: After 4 days of treatment, the percent inhibition of growth with a concentration of 5, 10, and 20 M cyclopamine in the cell lines were 23.6±4.9%, 66.4±4.7% and 69.3±1.3% in TPC-1 7.5±2.8%, 10.7±3.2% and 49.6±6.4% in FTC-133, 19.2±9.5%, 50.4±4.8% and 60.4±2.0% in FTC- 236 22.8±4.2%, 53.4±5.5% and 63.7±4.8% in FTC- 238 7.6±5.8%, 16.6±2.2%, 24.0±4.3% in XTC-1. Treatment with tomatidine at the same concentrations did not significantly affect cell growth. Exposure to cyclopamine, however, did not affect the cell cycle significantly CONCLUSION: Cyclopamine inhibits cancer cell proliferation in a dose dependent manner in thyroid cancer cell lines. The Hh signaling pathway might be a useful therapeutic target for thyroid cancer.