Evaluation of nuclear factor κB and chemokine receptor CXCR4 co-expression in patients with prostate cancer in the Radiation Therapy Oncology Group (RTOG) 8610

OBJECTIVE To determine the frequency of nuclear factor kappa B (NF kappa B) and the chemokine receptor CXCR4 co-expression in prostate cancer specimens from men with locally advanced disease. PATIENTS AND METHODS Paraffin-embedded samples from patients enrolled on the Radiation Therapy Oncology Group (RTOG) 8610 trial underwent immunohistochemical staining for NF kappa B and CXCR4. The amount of NF kappa B and CXCR4 was scored by a 'blinded' pathologist for the percentage of cells stained (0-100%) and staining intensity (0-3 +). Cox proportional hazard models were used for overall survival and disease-free survival to examine if NF kappa B and/or CXCR4 expression were associated with patient outcomes with and without adjustment for covariates. RESULTS Available material and successful staining allowed NF kappa B and CXCR4 status to be determined for 55 and 63 patients, respectively. Both NF kappa B and CXCR4 status were available for 51 patients. Of these, 53% were 2/3 + for cytoplasmic NF kappa B staining and 56% were 2/3 + for CXCR4. In all, 18 of the 51 patients were 2/3 + for both NF kappa B and CXCR4 (P = 0.129). Ten of 11 patients with 3 + NF kappa B had 2/3 + CXCR4 (P = 0.004). In this small study, neither NF kappa B nor CXCR4 were associated with prostate cancer outcomes. CONCLUSIONS High NF kappa B expression is associated with CXCR4 expression and they are co-expressed in about one third of patients with clinically localized prostate cancer. Larger studies to accurately determine the frequency of co-expression and prognostic utility of NF kappa B and CXCR4 alone and in combination are warranted.