ABSTRACT
Metastasis is one of the main reasons causing death in cancer patients. It was reported that chemotherapy might induce metastasis. In order to uncover the mechanism of chemotherapy-induced metastasis and find solutions to inhibit treatment-induced metastasis, the relationship between epithelial-mesenchymal transition (EMT) and doxorubicin (DOX) treatment was investigated and a redox-sensitive small interfering RNA (siRNA) delivery system was designed. DOX-related reactive oxygen species (ROS) were found to be responsible for the invasiveness of tumor cells in vitro, causing enhanced EMT and cytoskeleton reconstruction regulated by Ras-related C3 botulinum toxin substrate 1 (RAC1). In order to decrease RAC1, a redox-sensitive glycolipid drug delivery system (chitosan-ss-stearylamine conjugate (CSO-ss-SA)) was designed to carry siRNA, forming a gene delivery system (CSO-ss-SA/siRNA) downregulating RAC1. CSO-ss-SA/siRNA exhibited an enhanced redox sensitivity compared to nonresponsive complexes in 10 mmol/L glutathione (GSH) and showed a significant safety. CSO-ss-SA/siRNA could effectively transmit siRNA into tumor cells, reducing the expression of RAC1 protein by 38.2% and decreasing the number of tumor-induced invasion cells by 42.5%. When combined with DOX, CSO-ss-SA/siRNA remarkably inhibited the chemotherapy-induced EMT in vivo and enhanced therapeutic efficiency. The present study indicates that RAC1 protein is a key regulator of chemotherapy-induced EMT and CSO-ss-SA/siRNA silencing RAC1 could efficiently decrease the tumor metastasis risk after chemotherapy.
Subject(s)
Female , Humans , Amines/chemistry , Antineoplastic Agents/adverse effects , Breast Neoplasms/pathology , Chitosan/chemistry , Doxorubicin/adverse effects , Drug Delivery Systems , Epithelial-Mesenchymal Transition/drug effects , MCF-7 Cells , Neoplasm Metastasis/prevention & control , Oxidation-Reduction , RNA, Small Interfering/administration & dosage , Reactive Oxygen Species/metabolism , rac1 GTP-Binding Protein/physiologyABSTRACT
Objective At present, there are few reports about the relationship between Chemerin and the occurrence and development of breast cancer. The aim of this study is to investigate Chemerin expression in breast cancer mice and its effect on proliferation and migration of breast cancer cells. Methods 30 Balb/c mice were randomly divided into two groups (Normal mice 15, Tumor-bearing mice 15). The 4T1 breast cancer cells were inoculated to construct breast cancer mice model. The expressions of Chemerin in peripheral blood and breast cancer tissue were detected by ELISA and Western blot, respectively. The relationship between Chemerin expression and breast cancer was analyzed. Breast cancer cells MCF-7 and MDA-MB-231 were treated with different concentrations of recombinant Chemerin protein and Chemerin neutralizing antibody. Three groups were set up in the experiment, including control group (1640 or DMEM culture medium, no cells), recombinant Chemerin protein group (100 μg/L, no dilution by serum-free medium) and Chemerin neutralizing antibody group (100 μg/L, no dilution by serum-free medium). The effects of Chemerin on cell proliferation and migration were detected by MTT assay and wound healing assay respectively. Results The expressions of Chemerin in peripheral blood and mammary gland of tumor bearing mice were significantly higher than that in normal mice (both P<0.05). The scratch mobility and MTT absorbance (OD) values of breast cancer cells treated with recombinant chemerin protein increased significantly with the increase of protein concentration (P<0.05).However, they significantly decreased after cells treated with chemerin neutralizing antibody (P<0.05). Conclusion Chemerin could promote the proliferation and migration of breast cancer cells in a concentration-dependent manner, thereby promotinge the occurrence and development of breast cancer.