Expression of Polo-like Kinase 1 mRNA and Its Prognostic Value in Breast Cancer

Objective: To determine the expression of Plk1 mRNA and evaluate its prognostic value in breast cancer.Methods: Se-mi-quantitative RT-PCR assay was performed to detect the expression of Plk1 mRNA in three human breast cancer cell lines and one normal breast mammary epithelial cell line.Additionally,the expression of Plk1 mRNA in 84 breast cancer and corresponding normal breast epithelial tissues was also detected.Statistical analysis was performed to analyze the associations of Plk1 mRNA expression with clinicopathological factors of breast cancer patients including year,tumor size,tissue differentiation,lymph node metastasis,TNM stage and ER status.Finally,the association of Plk1 mRNA expression with prognosis of breast cancer patients was also analyzed.Results: The relative expression level of Plk1 mRNA in human breast cancer cells was significantly higher than that in normal mammary epithelial cell line(P0.05).Additionally,the relative level of Plk1 mRNA expression in breast cancer tissues(0.88±0.18) was significantly higher than that in corresponding normal breast epithelial tissues(0.22±0.10;P0.01).Statistical analysis showed that the level of Plk1 mRNA expression was significantly correlated with lymph node metastasis and TNM stage of breast cancer patients(P=0.009 and 0.007,respec-tively).Kaplan-Meier curves showed that the 5-year progression-free or overall survival rate of breast cancer patients with high Plk1 mRNA expression was significantly lower than that of breast cancer patients with low Plk1 mRNA expression(P=0.0026 or 0.0136).Further-more,Multivariate survival analysis using Cox's regression model showed that the status of Plk1 mRNA expression was an independent prognostic factor for breast cancer patients(HR=4.764,95% CI: 1.341~6.123,P=0.0025).Conclusion: Plk1 mRNA is highly expressed in human breast cancer tissues,and might be an important prognostic factor for breast cancer patients.