High expression of Rac1 is correlated with partial reversed cell polarity and poor prognosis in invasive ductal carcinoma of the breast

Abstract

The change of cell polarity is usually associated with invasion and metastasis. Partial reverse cell polarity in IDC-NOS may play a role in lymphatic tumor spread. Rac1 is a kind of polarity related protein. It plays an important role in invasion and metastasis in tumors. We here investigated the expression of Rac1 and partial reverse cell polarity status in breast cancer and evaluated their value for prognosis in breast cancer. The association of the expression of Rac1 and MUC-1 with clinicopathological parameters and prognostic significance was evaluated in 162 cases of IDC-NOS paraffin-embedded tissues by immunohistochemical method. The Rac1 messenger RNA expression was measured by real-time polymerase chain reaction in 30 breast cancer patients, which was divided into two groups of partial reverse cell polarity and no partial reverse cell polarity. We found that lymph node metastasis of partial reverse cell polarity patients was higher than no partial reverse cell polarity patients (Z = −4.030, p = 0.000). Rac1 was upregulated in partial reverse cell polarity group than no partial reverse cell polarity group (Z = −3.164, p = 0.002), and there was correlationship between the expression of Rac1 and partial reverse cell polarity status (r s = 0.249, p = 0.001). The level of Rac1 messenger RNA expression in partial reverse cell polarity group was significantly higher compared to no partial reverse cell polarity group (t = −2.527, p = 0.017). Overexpression of Rac1 and partial reverse cell polarity correlates with poor prognosis of IDC-NOS patients (p = 0.011). Partial reverse cell polarity and lymph node metastasis remained as independent predictors for poor disease-free survival of IDC-NOS (p = 0.023, p = 0.046). Our study suggests that partial reverse cell polarity may lead to poor prognosis of breast cancer. Overexpression of Rac1 may lead to polarity change in IDC-NOS of the breast. Therefore, Rac1 could be a therapeutic target for breast cancer.