Effects of cyclopamine on the biological characteristics of human breast cancer MCF-7 cell line and its mechanism

Purpose: To observe the effects of cyclopamine on the biological characteristics of human breast cancer MCF-7 cell line and explore its mechanism. Materials and Methods: After human breast cancer MCF-7 cells were treated with different-concentration cyclopamine for different periods, MTT assay was used to detect the inhibitory effect of cyclopamine on MCF-7 cell proliferation, flow cytometry was used to determine the distribution of MCF-7 cell cycle and the effect of cyclopamine on MCF-7 apoptosis, and Western blot was used to measure the protein levels of cyclins D1 and p21 in MCF-7 cells. Results: In certain range, MCF-7 cell proliferation was inhibited by cyclopamine in a dose- and time-dependent manner, and the optimal inhibiting concentration was ten μmol/L and the optimal action time at 48 hours. With the time prolongation of cyclopamine action, the cells in G0/G1 phase were significantly increased, but the cells in S phase were significantly decreased (compared with blank control group, all p < 0.05). With the time prolongation of cyclopamine action, apoptosis rate of MCF-7 cells was also significantly increased (compared with blank control group, all p < 0.05). The level of cyclin D1 of MCF-7 cells was decreased, but cyclin p21 was increased (compared with blank control group, all p < 0.05). Conclusion: Cyclopamine inhibits MCF-7 cell proliferation via arresting MCF-7 cell transformation from G1 phase to S phase. This may be associated with the expressions of Hedgehog (Hh) signaling pathway-related cyclins.

Breast cancer; MCF-7; Cyclopamine; Cyclin.

[1] Katoh Y., Katoh M.: “Hedgehog signaling, epithelial-tomesenchymal transition ndmiRNA”. Int. J. Mol .Med., 2008, 22, 271.

[2] Yu C., Struhl G.: “Dual roles for patched in sequestering and transducing Hedgehog”. Cell, 1996, 87, 553.

[3] Incardona J.P., Lange Y., Cooney A., Pentchev P.G., Liu S.,Watson J.A., et al.: “Cyclopamine inhibition of Sonic hedgehog signal transduction is not mediated through effects on cholesterol transport”. Dev. Biol., 2000, 224, 440.

[4] van den Heuvel M., Ingham P.W.: “Smoothened encodes a receptorlike serpentine protein required for hedgehog signalling”. Nature, 1996, 382, 547.

[5] Qualtrough D., Buda A., Gaffield W., Williams A.C., Paraskeva C.: “Hedgehog signaling in colorectal tumour cells: induction of apop tosis with cyclopamine treatment”. Int. J. Cancer, 2004, 110, 831.

[6] Pasca di Magliano M., Hebrok M.: “Hedgehog signalling in cancer formation and maintenance”. Nat. Rev. Cancer, 2003, 3, 903.

[7] Zhang Su-qing, Li De-chun: “Expression ans significance of and Cyclin in hepatocellular carcinoma”. Jiangsu Medical Journal, 2004, 30, 26.

[8] Lebeau A., Unholzer A., Amann G., Kronawitter M., Bauerfeind I., Sendelhofert A., et al.: “EGFR,HER-2/neu,cyclinD1,p21 and p53 in correation to cell proliferation and steroid hormone receptor status in ductal carcinoma in situ of the breast”. Breast Cancer Res. Treat., 2003, 79, 187.