Elevated Nuclear YB1 Expression Is Associated with Poor Survival of Patients with Early Breast Cancer

Background: Y-Box-Binding (YB1) protein represents a multifunctional protein, which plays a significant role in processes of proliferation, apoptosis and control of tumour cell response to toxic agents, including chemotherapy. The present study aimed at evaluating the prognostic significance of YB1 expression in breast cancer. Materials and Methods: We analyzed nuclear and cytoplasmic expression of YB1 in 101 patients with stage II breast cancer, with 17 years of follow-up. Immunohistochemical reactions were performed on paraffin sections of primary tumours, using monoclonal antibodies against YB1. Results were tested for their correlation with clinical and pathological data. Results: Patients with a pronounced expression of the nuclear form the YB1 protein demonstrated a highly significant shortening of disease-free survival, disease-specific survival and overall survival. The prognostic value of YB1 was also corroborated by multivariate analysis. Conclusion: We demonstrated that high nuclear expression of YB1 is associated with poor survival of patients with early-stage breast cancer. Breast cancer continues to be the most frequent occuring malignant tumour in women, while its manifestation demonstrates an increasing tendency all over Europe (1). In a standard manner, for most patients, even for those with low stages of the disease, surgery is used, associated with adjuvant therapy in the form of chemo/hormonal therapy and radiotherapy. Nevertheless, considering the real risk of relapse, a significant proportion of patients, particularly those with early stages of the disease, are needlessly subjected to supplementary therapy. This reflects the absence of reliable prognostic and predictive factors, thus making selection of patients suitable for supplementary therapy difficult. In recent years, several reports described the biological properties of breast cancer, with particular attention being given to prognostic and predictive factors which might promote an individualised approach to treatment of the patients. As a result, the panel of factors recognised by experts as being valuable both in stratification of patients and in the selection of appropriate therapy, was extended (2). One promising new direction of such tests involves evaluation of properties manifested by Y-Box-Binding (YB1) protein.