Laurent Lessard

Nuclear Factor-κB Nuclear Localization Is Predictive of Biochemical Recurrence in Patients with Positive Margin Prostate Cancer

Purpose: Radical prostatectomy (RP) patients with positive surgical margins are at increased risk for recurrence, emphasizing the need for prognostic markers to stratify probable outcome for optimal patient management decisions. We tested the hypothesis that nuclear localization of nuclear factor (NF)-κB, a transcription factor involved in the regulation of cell growth, angiogenesis, invasion, and apoptosis, is associated with an increased risk of biochemical recurrence after RP. Experimental Design: Analyses addressed data from 42 patients (age range, 52–72 years; mean age, 63.7 years) who exhibited positive surgical margins after RP. Immunohistochemical analysis of NF-κB (p65) was performed on the positive margin tissue. A nuclear staining cutoff of >5% was considered positive. The relation between nuclear NF-κB expression and biochemical recurrence (prostate-specific antigen >0.3 ng/mL and rising) after RP was tested in univariate and multivariate Cox regression models. Results: Biochemical recurrence was recorded in 23 patients (54.8%; median follow-up, 3.2 years). Univariate Cox regression demonstrated a 4.9-fold (95% confidence interval, 1.5–16.7; P = 0.01) higher rate of recurrence in men with NF-κB > 5%. In the multivariate model, after controlling for primary (P = 0.004) and secondary (P = 0.7) Gleason patterns, lymph node (P = 0.06) and seminal vesicle invasion (P = 0.2), and preoperative prostate-specific antigen (P = 0.009), NF-κB > 5% was associated with a 6.2-fold higher risk of biochemical recurrence (95% confidence interval, 1.7–23.5; P = 0.007). Conclusions: In univariate and multivariate analysis, NF-κB nuclear expression was strongly predictive of biochemical recurrence in patients with positive surgical margins after RP. We propose that nuclear NF-κB may serve as a useful independent molecular marker for stratifying patients at risk for recurrence.

Expression and Nuclear Localization of ErbB3 in Prostate Cancer

Purpose: The ErbB1 and ErbB2 receptors have been implicated in prostate cancer progression, but less is known about the role and biology of other ErbB receptor family members in prostate cancer. The aim of this study was to analyze the expression and localization of ErbB3 in prostate tissues and prostate cancer cell lines. Experimental Design: Immunohistochemistry of ErbB3 was done on prostate cancer tissue sections from 143 patients and on a tissue microarray containing 390 cores of radical prostatectomy-derived specimens representing normal, prostatic intraepithelial neoplasia, and malignant tissues from 81 patients. ErbB3 subcellular localization was studied by Western blot analysis in LNCaP, 22Rv1, PC-3, and DU145 prostate cancer cell lines. Results: Immunohistochemistry analysis of prostate cancer tissues revealed that >90% of prostate cancer tissues displayed cytoplasmic ErbB3 staining. Minimal ErbB3 nuclear staining was observed in normal prostate tissues and benign prostatic hyperplasia tissues; in contrast, ErbB3 was frequently localized in the nucleus of cancerous tissues. This nuclear localization was more frequent (P < 0.001) in hormone-refractory tissues (17 of 17, 100%) compared with hormone-sensitive samples (37 of 92, 40.2%). Additionally, in the tissue microarray, increased nuclear ErbB3 was associated with increasing Gleason grade. Interestingly, Western blot analysis of cytoplasmic and nuclear subcellular fractions showed that ErbB3 nuclear localization was more prevalent in hormone-sensitive prostate cancer cell lines (LNCaP and 22Rv1) compared with hormone-insensitive cell lines (PC-3 and DU145). Conclusions: ErbB3 nuclear localization discriminates normal from malignant prostate tissues and between tumors from hormone-sensitive versus hormone-refractory prostate cancer. ErbB3 nuclear staining seems to be associated with risk of disease progression. The high frequency of ErbB3 nuclear localization in hormone-refractory tissues indicates that ErbB3 warrants further study to understand its association with prostate cancer disease progression.

Nuclear localization of nuclear factor-κB p65 in primary prostate tumors is highly predictive of pelvic lymph node metastases

Purpose: Lymph node invasion (LNI) is associated with increased risk of prostate cancer progression. Unfortunately, pelvic lymph node dissections are fraught with a high rate of false-negative findings, emphasizing the need for highly accurate markers of LNI. Because nuclear factor-κB (NF-κB) is a candidate marker of prostate cancer progression, we tested the association between nuclear localization of NF-κB in radical prostatectomy specimens and the presence of LNI. Experimental Design: NF-κB expression in radical prostatectomy specimens was assessed with a monoclonal NF-κB p65 antibody, in 20 patients with LNI and in 31 controls with no LNI and no biochemical relapse 5 years after radical prostatectomy. Univariate and multivariate logistic regression models were used. The accuracy of multivariate predictions with and without NF-κB was quantified with the area under the receiver operating characteristics curve and 200 bootstrap resamples were used to reduce overfit bias. Results: Univariate regression models showed a 7% increase in the odds of observing LNI for each 1% increase in NF-κB nuclear staining (odds ratio, 1.07; P = 0.003). In multivariate models, each 1% increase in NF-κB was associated with an 8% increase in the odds of LNI (odds ratio, 1.08; P = 0.03) and its statistical significance was only surpassed by the presence of seminal vesicle invasion (P = 0.003). Addition of NF-κB to all other predictors increased the accuracy of LNI prediction by 2.3% (from 84.8% to 87.1%; P < 0.001). Conclusion: This is the first study that shows that the extent of nuclear localization of NF-κB in primary prostate tumors is highly accurately capable of predicting the probability of locoregional spread of prostate cancer.

Low nuclear ErbB3 predicts biochemical recurrence in patients with prostate cancer.

To further evaluate the association between the cytoplasmic or nuclear localization of ErbB3 with biochemical recurrence (BCR) in patients with prostate cancer and positive surgical margins, as there is a greater risk of BCR for such patients after radical prostatectomy (RP).

Large-scale independent validation of the nuclear factor-kappa B p65 prognostic biomarker in prostate cancer

PURPOSE Over the last decade, we and others have uncovered a robust association between the nuclear localisation of nuclear factor-kappa B (NF-κB) p65, prostate cancer (PCa) aggressiveness and biochemical recurrence (BCR). Our goal was to validate these results in a large independent cohort of PCa patients who underwent radical prostatectomy. EXPERIMENTAL DESIGN A set of 1826 fully annotated prostate cancers treated by radical prostatectomy were analysed in a tissue microarray (TMA) format for NF-κB p65 immunohistochemistry-based protein expression. We performed standard Cox proportional hazard regression models for follow-up data, bootstrap procedure for model internal validation, Harrells concordance index for model discrimination and graphical assessment of predicted versus actual outcomes for model calibration. RESULTS We observed a significant association between an increase in the nuclear frequency of NF-κB p65 and Gleason score (P<0.001), overall BCR (P<0.001) and development of metastases (P=0.001). NF-κB was found to be an independent predictor of BCR (P<0.001, Cox regression). However its contribution to the predictive accuracy of a multivariate model, which included preoperative PSA, Gleason score, extraprostatic extension, lymph node invasion, seminal vesicle involvement and surgical margin status, was modest. CONCLUSIONS Our study offers validating results linking NF-κB p65 with disease progression using a large cohort of European men. However, the contribution of NF-κB to a post-surgical predictive model appears modest. Further validating work should focus on evaluating the contribution of NF-κB p65 in pre-treatment models.

Regulation of IκB kinase ε expression by the androgen receptor and the nuclear factor-κB transcription factor in prostate cancer

Although several genes have been associated with prostate cancer progression, it is clear that we are far from understanding all the molecular events implicated in the initiation and progression of the disease to a hormone-refractory state. The androgen receptor is a central player in the initiation and proliferation of prostate cancer and its response to hormone therapy. Nuclear factor-κB has important proliferative and antiapoptotic activities that could contribute to the development and progression of cancer cells as well as resistance to therapy. In this study, we report that IκB kinase ε (IKKε), which is controlled by nuclear factor-κB in human chondrocytes, is expressed in human prostate cancer cells. We show that IKKε gene expression is stimulated by tumor necrosis factor-α treatment in LNCaP cells and is inhibited by transfection of a dominant-negative form of IκBα, which prevents the nuclear translocation of p65. Furthermore, we found that tumor necrosis factor-α–induced IKKε expression is inhibited by an androgen analogue (R1881) in androgen-sensitive prostate cancer cells and that this inhibition correlates with the modulation of IκBα expression by R1881. We also noted constitutive IKKε expression in androgen-independent PC-3 and DU145 cells. To our knowledge, this is the first report of an IκB kinase family member whose expression is modulated by androgen and deregulated in androgen receptor–negative cells. (Mol Cancer Res 2007;5(1):87–94)