Smoothened Regulates Migration of Fibroblast-Like Synoviocytes in Rheumatoid Arthritis via Activation of Rho GTPase Signaling.

Fibroblast-like synoviocytes (FLSs) acquire aggressive phenotypes characterized with enhanced migration abilities and inherent invasive qualities in rheumatoid arthritis (RA). Smoothened (Smo) is a key component of sonic hedgehog (Shh) signaling and contributes to tumor cell invasion and metastasis. The objective of this study is to investigate the role of Smo in the modulation of cell migration and explore the underlying molecular mechanism(s). FLSs were isolated from RA synovium. Shh levels were regulated by a Smo agonist (purmorphamine), Smo antagonist (KAAD-cyclopamine), or small interfering RNA targeting the Smo gene (Smo-siRNA) in RA-FLSs. Expression of Smo was detected by real-time PCR and western blot analysis. Cell migration was examined by Transwell assay and activation of Rho GTPases was measured by pull-down assays. Incubation with purmorphamine resulted in a significant increase of cell migration and activation of Rho GTPase signaling compared to controls (P < 0.05). However, treatment with KAAD-cyclopamine or transfection with Smo-siRNA suppressed migration of RA-FLSs and showed an inhibitory effect of Rho GTPase signaling. Together, these results suggest that Smo plays an important role in RA-FLSs migration through activation of Rho GTPase signaling and may contribute to progression of RA, thus, targeting Shh signal may have a therapeutic potential in patients with RA.

Inhibition of smoothened decreases proliferation of synoviocytes in rheumatoid arthritis.

Fibroblast-like synoviocytes (FLSs) contribute to synovial hyperplasia in rheumatoid arthritis (RA). Smoothened (Smo) is a key component of sonic hedgehog (Shh) signaling and contributes to tumor cell proliferation. The objective of this study was to investigate the role of Smo in RA synoviocyte proliferation. FLSs were isolated from RA synovium. Shh signaling was studied using a Smo antagonist (GDC-0449) and small interfering RNA (siRNA) targeting the Smo gene in FLSs. Cell proliferation was quantified by using kit-8 assay and cell cycle distribution and apoptosis were evaluated by flow cytometry. Cell cycle-related genes and proteins were detected by real-time PCR and western blot. FLSs treated with GDC-0449 or Smo-siRNA showed significantly decreased proliferation compared to controls (P < 0.05). Incubation with GDC-0449 or transfection with Smo-siRNA resulted in a significant increase of G1 phase cells compared to controls (P < 0.05). Cell cycle arrest was validated by the significant increase in cyclin D1 and E1 mRNA expression, decrease in cyclin-dependent kinase p21 mRNA expression in Smo-siRNA transfected cells (P < 0.05). Protein expression of cyclin D1 was also downregulated after Smo gene knockdown (P < 0.05). The results suggest that Shh signaling plays an important role in RA-FLSs proliferation in a Smo-dependent manner and may contribute to synovial hyperplasia. Targeting Shh signaling may help control joint damage in patients with RA.

Sonic hedgehog signalling pathway regulates apoptosis through Smo protein in human umbilical vein endothelial cells.

OBJECTIVE: The aim of this study was to investigate the expression of smoothened protein (Smo), a sonic hedgehog (Shh) signalling component, in synovium of RA and its role in the survival and apoptosis of endothelial cells. METHODS: The expression of Smo pxrotein in RA synovial tissue was examined by immunohistochemistry. Real-time PCR and western blotting techniques were employed to measure the expression of Shh signalling components in EA.hy926 endothelial cells exposed to TNF-α in the presence or absence of cyclopamine (a Smo-specific antagonist). Lastly, the effect of cyclopamine and Smo small interfering RNA on apoptosis induced by TNF-α and actinomycin D (ActD) was determined. RESULTS: We found that Smo was highly expressed in synovial tissues of RA, especially in endothelial cells, compared with the trauma group. TNF-α significantly increased the expression of Shh signalling components in EA.hy926 endothelial cells, while cyclopamine decreased the expression of Shh signalling components. EA.hy926 endothelial cells treated with various concentrations of cyclopamine (2-8 µmol/l) showed a significant decrease in cell viability and cell survival rate, and an increase in the rate of cell apoptosis compared with endothelial cells treated with TNF-α and ActD (P < 0.05). EA.hy926 endothelial cells transfected with Smo-siRNA also showed a lower cell survival rate and higher apoptotic rate, compared with cells in the control group (P < 0.05). CONCLUSION: The Shh signalling pathway plays a role in regulating endothelial cell apoptosis in a Smo-dependent manner.

[Cytodiagnosis and cytomorphologic analysis of hematolymphoid malignancy in serous effusion: a study of 23 cases].

OBJECTIVE: To evaluate the value of cytomorphologic and immunocytochemical approaches in the diagnosis of hematologic neoplasms in serous effusion. METHODS: The cytospin and Thinprep smears of effusion specimens were prepared from 23 cases of lymphoid malignancies with histological confirmation and 30 cases of benign effusions used as control. Morphological assessment of the cellular components was conducted, including the ratio of mesothelium to lymphocyte, karyomorphism of lymphoid cell and the presence of apoptosis and mitosis. Immunocytochemical study was performed in all the cases, with flow cytometry in one case. RESULTS: Among the 23 tumor cases, 14 represented disease relapse, and in the remaining nine cases, the serous effusion was the primary manifestation. The proportion of mesothelium was low in the tumor group, being less than 10% in 20 cases (87.0%, 20/23). It was more than 10% in most of benign cases (20/30, 66.7%). Lymphoid cells were prominent (> 80% cells) in 69.6% of the tumor cases, and the cellular component in some control cases (63.3%, 19/30) showed fewer lymphocytes. Nipple-like projection of lymphocytic nuclei could be detected in almost all the tumor cases (91.3%, 21/23), but was occasionally found in the control group (26.7%, 8/30). Apoptosis and mitosis were obvious in lymphomatous effusion, but observed in only 6.7% of the control cases. Significant difference of the previously mentioned cytomorphologic features existed between the tumor and control groups (P < 0.01). The results of immunocytochemical staining in cell block were identical to the corresponding immunohistochemistry, and one case of mantle cell lymphoma was confirmed by flow cytometry. The cytologic findings seen in all the 23 studied cases were in agreement with the corresponding histologic diagnosis. CONCLUSIONS: Some cytomorphologic features, including decreased number of mesothelium, increased number of lymphoid cells, nuclear nipple-like projection, and the presence of apoptosis and mitosis, are very useful for diagnosing lymphoid malignancy in serous effusion. Immunocytochemistry is an important approach to the cytodiagnosis and classification of lymphoma.