Expression patterns among interferon regulatory factor-1, human X-box binding protein-1, nuclear factor kappa B, nucleophosmin, estrogen receptor-alpha and progesterone receptor proteins in breast cancer tissue microarrays.

Interferon regulatory factor-1 (IRF-1), human X-box binding protein-1 (hXBP-1), nuclear factor kappa B p65 (NFKB p65) and nucleophosmin (NPM) have been implicated in a signaling network of endocrine responsiveness. Expression of these proteins was measured by immunohistochemistry in tissue microarrays of 54 breast tumors. Correlations between each protein and established prognostic markers were assessed by Spearman's rank order correlation coefficient and partial correlation coefficient analyses. Moderate/strong staining is seen for hXBP-1 (79% of tumors) and NFKB p65 (57%). NPM exhibits nuclear staining (95%); IRF-1 exhibits both cytosolic (IRF-lc; 90%) and nuclear staining (IRF-ln; 51%). IRF-lc is associated with age (p=0.034); IRF-1n and PgR expression are correlated (p=0.014). NFKB p65 shows a borderline association with S phase (p=0.062). Coexpression of IRF-lc and hXBP1 (p=0.001), IRF-lc and NFKB (p=0.002), and hXBP-1 and NFKB (p=0.018) is observed. An inverse correlation exists between IRF-1n and NFKB (p=0.034). All four proteins are detected in breast tumors and their expression patterns support their role(s) in a key signaling network.