Purpose: The aim of this study was to investigate the expression of the PRL-3 in human invasive breast cancer and to evaluate its clinical and prognostic significance. Its potential role in the invasive-metastatic properties of invasive breast cancer was also investigated.
Methods: Protein expression of PRL-3 was evaluated by immunohistochemistry for a consecutive series of 82 invasive human breast cancer tissues and 63 matched lymph node metastases, including PRL-3 mRNA expression analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) in malignant, nonmalignant breast tissue samples and lymph node metastases. We investigated the correlation of PRL-3 with clinicopathologic features, Overall and recurrence-free survival distribution curves were assessed using the Kaplan-Meier test and log-rank statistics, followed by Cox proportional hazards regression model.
Results: We found that 70.7% patients expressed a high level of PRL-3 protein in their tumors, and its over expression was positive correlated with lymph node metastasis (LNM) (P = 0.011). Moreover, The PRL-3 mRNA expression was significantly higher in malignant compared to benign breast tissue, while increased expression of PRL-3 mRNA was significantly associated with LNM (P = 0.002). Univariate analysis showed that the positive expression of PRL-3 was a poor risk prognostic factor (OS, P = 0.045; RFS, P = 0.034). Multivariate analysis using the Cox regression model indicated that high PRL-3 expression was an independent unfavorable prognostic factor for RFS.
Conclusions: These results strongly suggest that PRL-3 expression can indicate the potential role of LNM to some extent. Increasing the risk of tumor metastasis (OR = 3.889). Our results also imply that PRL-3 might be a novel molecular marker for predicting relapse of invasive breast cancer.