Abstract:

Objective To investigate the expression of Ptch-1 and Gli-1, hedgehog pathway-related genes in squamous cell carcinoma （SCC）, and the effect of cyclopamine, a specific inhibitor of hedgehog signaling pathway, on the proliferation of a SCC cell line Tca. Methods Skin samples were resected from 42 patients with SCC and 10 normal human controls. Immunohistochemistry and in situ hybridization were employed to study the expression and distribution of Ptch-1 and Gli-1 in these specimens. Tca cells were incubated with cyclopamine （1, 2, 5, 10 μmol/mL） for 48 hours, or cyclopamine （5 μmol/mL） for 1-8 days. The same concentrations of lycopersicin served as the control treatment. Then, MTT assay was performed to detect the proliferation of Tca cells. A fraction of Tca cells were cultured in the presence of 5 μmol/mL cyclopamine for 72 hours followed by BrdU assay for the evaluation of cell growth and proliferation. Results A significant increment was shown in the expression of both Patch-1 and Gli-1 by immunohistochemistry （χ2 = 5.656, 6.732, P < 0.05, 0.01, respectively） and in situ hybridization （χ2 = 6.787, 9.600, respectively, both P < 0.01） in SCC tissue compared with the control specimens. And both of them were predominantly distributed in the cytoplasm of SCC cells. As MTT assay revealed, cyclopamine notably inhibited the proliferation of Tca cells, and the effect increased with the concentration and action time of cyclopamine. Further more, the percentage of BrdU-positive cells was 26% in cyclopamine-treated Tca cells, significantly higher than that in the blank control cells （77%） and lycopersicin-treated cellls （72%）. Conclusions Hedgehog signaling pathway is activated in the lesions of SCC, and inhibition of the pathway may facilitate the treatment of SCC.

Key words: Hedgehog;signaling transduction;squamous cell carcinoma;cyclopamine