Combined use of immunoreactivities of RIG-I with Efp/TRIM25 for predicting prognosis of estrogen receptor-positive breast cancer patients

Abstract Background We previously identified Efp as an estrogen induced gene, and showed that the positive immunoreactivity of Efp is a poor prognostic factor for breast cancer patients. We also demonstrated that Efp has distinctive roles in innate immunity by activating pattern recognition receptor RIG-I. The clinical value of RIG-I protein expression in breast cancer had not been evaluated in relationship with patients’ prognosis. Patients and Methods Tissue samples of ER-positive invasive breast cancer were obtained from 145 female breast cancer patients who underwent surgical treatment. Immunoreactivities of RIG-I and Efp were analyzed with the antibodies generated for the present study. Results Positive immunoreactivity of RIG-I was correlated with lower disease-free survival (P = 0.032), and an independent poor prognostic factor (P = 0.043). RIG-I immunoreactivity was positively correlated with that of Efp (P = 0.0004). Patients with positive immunoreactivities of both RIG-I and Efp proteins were associated with lower disease-free survival rate (P = 0.005). Conclusions Positive immunoreactivity of RIG-I has clinical significance as poor prognostic factor in ER-positive breast cancer patients. Positive correlation of RIG-I and Efp immunoreactivities was observed and combination of their immunoreactivities can be used to predict patients’ prognosis.