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Gene delivery of cyclin-dependent kinase inhibitors p21 Waf1 and p27 Kip1 suppresses proliferation of MCF-7 breast cancer cells in vitro

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Because tumorigenesis depends on a variety of oncogenes, symphyseal study of combined genes may lead to more significant knowledge about tumorigenesis and progression. Combined deficiency of p21 and p27 proteins in mice is linked to more aggressive spontaneous tumorigenesis. We investigated the effect of the transfected p21 Waf1-p27 Kip1 gene on centrosome duplication, cell proliferation, and apoptosis of MCF-7, a breast cancer cell line.


The pIRES-p21 Waf1, pIRES-p27 Kip1, and pIRES-p21 Waf1-p27 Kip1 genes were transfected into MCF-7 cells by lipofection. The effect on proliferation was evaluated by MTT assay and clone-formation assay. Cell cycle and apoptosis were analyzed by flow cytometry. Apoptosis was tested by flow cytometry and TUNEL assay. Centrosome duplication was detected by use of indirect immunofluorescence microscopy.


The results showed that the pIRES-p21 Waf1, pIRES-p27 Kip1, and pIRES-p21 Waf1-p27 Kip1 significantly inhibited proliferation of MCF-7 cells, followed by accumulation of MCF-7 cells in cycle G1, induced apoptosis, and a decrease in the proportion of MCF-7 cells which contained abnormal centrosomes. Compared with p21 Waf1 or p27 Kip1 alone, combination of p21 Waf1 and p27 Kip1 had a much more significant effect (P < 0.05).


Altogether, these results indicate that the p21 Waf1-p27 Kip1 gene combination has a more obvious antitumor effect than p21 Waf1 or p27 Kip1 alone. This study provides preclinical evidence that combination of p21 Waf1 and p27 Kip1 could be a novel and promising therapeutic approach to treatment of breast cancer with suppressed p21 Waf1 and p27 Kip1 expression.

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This work was funded by grants from Natural Science Foundation of Shandong Province (y2007C134) and Natural Science Foundation of Qingdao Municipality (06-2-2-5-nsh-1). We thank Dr Zhang for his skillful statistical advice. We also thank Professor Liu from the Central Laboratory, The Affiliated Hospital of Qingdao Medical College, Qingdao University, for her technical support, and colleagues in the laboratory for helpful discussions.

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The authors declare that they have no conflict of interest.

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Correspondence to Funian Li.

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Jiang, D., Wang, X., Liu, X. et al. Gene delivery of cyclin-dependent kinase inhibitors p21 Waf1 and p27 Kip1 suppresses proliferation of MCF-7 breast cancer cells in vitro. Breast Cancer 21, 614–623 (2014).

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