CXCR4/SDF1 expression in HER2/neu breast cancer biopsies and its relation to adjuvant treatment

Abstract

Background: Chemokines have a fundamental role in inflammation and in cancer progression. Chemokine receptor 4 (CXCR4) is a transmembrane receptor that belongs to the CXC chemokine receptor family and is the only known receptor for the Stromal Cell derived Factor­1(SDF­1). Many retrospective studies have documented that the expression of various chemokine receptors, particularly CXCR4, was associated with a poor prognosis in patients with breast cancer. In the present study, we proposed an SDF­1/CXCR4 induced expression in HER2/neu positive breast cancer biopsies. We, additionally, study its relation to patient’s treatment, prior and post adjuvant therapy. Methods: Immunohistochemical staining of her2/neu and ki64 were analyzed in mammary tumor biopsies. Reduction mammoplasty of normal patients were also studied as normal controls. Stained hematoxilyn and eosin slides where previously revised to confirm histological diagnostic and tumoral classification based on established criteria. Additional information considering biological markers such as estrogen receptor (ER), progesterone receptor (PR) expression were also observed in histopathological reports. Quantitative PCR was performed by amplifying a conserved region of the CXCR­4 and SDF­1 genes, and their correlation to Her2/neu expression and adjuvant therapy were analyzed. Statistical analysis was assess using appropriate parametric and nonparametric tests. Results: Her2/neu breast tumor specimens expressed SDF­1 at varying levels and differed upon tumor classification. Expression of the receptor correlates mainly with the tumor type and degree. Quantitative PCR showed low constitutive CXCR4 expression in normal breast tissue that increased in breast tumor tissue, particularly in those expressing her2/neu. Variations upon treatment correspond to those of tumor progression to malignancies and recurrence. Conclusions: We established a correlation between the expression of SDF1/CXCR4 and the tumoral characteristics prior and post adjuvant treatment. A more careful examination of experimental/clinical data may help to explain the mechanism(s) involving the SDF­1/CXCR4 signaling axis in the breast cancer pathophysiology.