Abstract:

Objective To explore whether the Raptor can promote invasion and metastasis of breast cancer cells through Wnt3a/-catenin signaling pathway. Methods Using Western blotting to detect the protein expression of Raptor in breast cancer cells MDA-MB-231(MDA231) and MCF-7; Using RNAi technology to transfect small RNA interference plasmid into MDA231 breast cancer cells transiently. Overexpression of plasmid was transfected into MCF-7 breast cancer cells. Transwell and chemotaxis assay were used to detect the invasion and chemotaxis ability of breast cancer cells. Western blotting detected the expression of epithelial-mesenchymal transition(EMT) markers; Karyoplasm separation experiment tested the expression of β-catenin in nuclei. Results Western blotting result showed that the expression of Raptor was low in MCF-7, and high in MDA231. The protein expression of Raptor in SiRaptor/MDA231 was decreased obviously, and the protein expression of Raptor in MCF-7/Raptor was obviously higher. Transwell invasion and chemotaxis assay result showed that the invasion and chemotaxis ability of SiRaptor/MDA231 was decreased with the stimulation of Wnt3a, however, its capability of invasion and chemotaxis of MCF-7/Raptor was significantly enhanced. According to the result of Western blotting method with unused Wnt3a or at the same time stimulated with Wnt3a and Dkk1, the expression of E-cadherin was higher, and the expressions of vimentin and β-catenin were reduced in SiRaptor/MDA231, while in the MCF-7/Raptor, the expression of E-cadherin was reduced, and the expressions of vimentin and β-catenin were increased. Conclusion Through Wnt3a/β-catenin signaling pathway Raptor promotes the occurrence of EMT, thus to promote the invasion and metastasis of breast cancer cells.

Key words: Breast cancer, Raptor, Wnt3a/β-catenin, Epithelial-mesenchymal transition, Invasion, Western blotting