Article

Validation of cyclin D1/CDK4 as an anticancer drug target in MCF-7 breast cancer cells: Effect of regulated overexpression of cyclin D1 and siRNA-mediated inhibition of endogenous cyclin D1 and CDK4 expression.

Oncology Research, Wyeth Research, Pearl River, NY 10965, USA.
Breast Cancer Research and Treatment (impact factor: 4.43). 02/2006; 95(2):185-94. DOI:10.1007/s10549-005-9066-y pp.185-94
Source: PubMed

ABSTRACT We have examined the role of cyclin D1 and cyclin-dependent kinase-4 (CDK4) in the cell cycle progression and proliferation of MCF-7 breast cancer cells. Forced expression of cyclin D1 using a tetracycline-regulated expression system, and suppression of endogenous cyclin D1 and CDK4 using small interfering RNA (siRNA) were used to validate this protein complex as a drug target in cancer drug discovery. Overexpression of cyclin D1 increased both phosphorylation of the retinoblastoma gene product (RB) and passage through the G1-S phase transition, resulting in increased proliferation of cells. When cyclin D1 expression was shut off, growth rates fell below those seen in control cell lines transfected with the vector, indicating an increased dependence on this protein for proliferation. Inhibition of endogenous cyclin D1 or CDK4 expression by RNA interference resulted in hypophosphorylation of RB and accumulation of cells in G1. These results support the prevailing view that pharmacological inhibition of cyclin D1/CDK4 complexes is a useful strategy to inhibit the growth of tumors. Furthermore, since MCF-7 cells appear to be dependent on this pathway for their continued proliferation, it is a suitable cell line to test novel cyclin D1/CDK4 inhibitors.

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Keywords

CDK4 expression
 
cell cycle progression
 
continued proliferation
 
control cell lines transfected
 
cyclin D1 expression
 
cyclin D1/CDK4 complexes
 
endogenous cyclin D1
 
Forced expression
 
growth rates
 
MCF-7 breast cancer cells
 
MCF-7 cells
 
pharmacological inhibition
 
prevailing view
 
protein complex
 
results support
 
RNA interference
 
suitable cell line
 
test novel cyclin D1/CDK4 inhibitors
 
tetracycline-regulated expression system
 
useful strategy
 

Mary Grillo