Androgen receptor CAG repeat length contraction in diseased and non-diseased prostatic tissues

To investigate contraction of CAG repeats within the androgen receptor gene (AR) as shorter CAG repeats have been implicated as a possible risk factor in prostate cancer (PCa). AR CAG repeat lengths were analyzed in DNA from microdissected diseased prostates, leukocytes from matched peripheral blood, and control non-diseased prostates. Consistently, all prostatic tissues, whether from benign or cancerous areas of diseased prostates, or from control prostates, showed multiple AR CAG repeat contractions. Germline DNA from blood leukocytes had single CAG repeat lengths in the normal range. AR CAG repeat length contraction may be involved in prostate carcinogenesis and may precede the pathological process.

ErbB3, Cyclin D1 and Ki67 nuclear staining predicts biochemical recurrence in prostate cancer treated by radical prostatectomy

10096

Background: The nuclear accumulation of growth factor receptor was reported to be associated to increased cell proliferation. Cyclin D1 and Ki67 are nuclear markers of cell proliferation. Deregulation of Cyclin D1 and Ki67 expression play a role in tumorigenesis and metastasis. Recently, we observed that nuclear localization of ErbB3 was associated with prostate cancer progression. The objective of this study was to determine if the association of cell proliferation markers and nuclear localization of ErbB3 could predict biochemical recurrence (BCR) in patients with prostate cancer following radical prostatectomy. Methods: Using immunohistochemistry we analyzed a tissue microarray containing 386 cores from 64 formalin-fixed paraffin embedded specimens from prostate cancer patients who had undergone radical prostatectomy. No patient had received hormone therapy prior to surgery and prior to BCR. Antibodies against Cyclin D1, ErbB3 and Ki67 proteins were used. Results: Nuclear staining was 60%, 67% and 86% for Cyclin D1, ErbB3 and Ki67 respectively. In our cohort, 29 of 64 PCa patients (45%) had a BCR after a median 3 years of follow-up. Thirty seven (37) percent of patients had positive nuclear staining for all three markers. BCR free survival probability at 3 years was not significant for each marker individually, except for ErbB3 in positive surgical margin patients. When all three markers were combined for nuclear staining Kaplan-Meier analysis BCR free was 0.4 and 0.1 for positive and negative nuclear staining respectively (p=0.0068). Univariate COX regression analysis shows a 2.98 fold (95% CI: 1.29 - 6.86, p=0.01) higher rate of BCR in patients positive for these three markers. In addition, in a multivariate model, including pre-operative PSA (p=0.19), pathologic stage (p=0.29), Gleason grade (p=0.40) and specimens that had positive nuclear staining for the 3 markers were associated with a 3.97 fold higher rate of BCR (95% CI: 1.54 - 10.25, p=0.0068). Conclusion: These results suggest that the association of cell proliferation markers and nuclear localization of ErbB3 could be useful in predicting recurrence following radical prostatectomy and guide therapeutic decisions. Large scale trials are needed to confirm these results.

No significant financial relationships to disclose.

Nuclear localization of NF-kappaB p65 in primary prostate tumors is predictive of pelvic lymph node metastases

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Background: Pelvic lymph node metastases are associated with a greater risk of prostate cancer recurrence and peripheral metastasis. Unfortunately, markers predictive of lymph node metastasis and/or recurrence after radical prostatectomy are limited and new molecular markers are needed to identify patients at higher risk of progression. NF-kB (p65) is a candidate molecular marker already associated with poor clinical outcomes such as biochemical recurrence and bone metastasis. We have also reported elevated nuclear p65 expression in prostate cancer lymph node metastasis. Pertinent to this issue, we tested whether the nuclear localization of p65 in radical prostatectomy specimens could predict the presence of lymph node metastases. Methods: Following informed consent, 51 patients who underwent radical prostatectomy were included in the study: 20 patients had lymph node metastasis at surgery and 31 patients had no evidence of lymph node metastasis and were used as the control group. All cases in the control group had no biochemical relapse 5 years following radical prostatectomy. NF-kB expression in prostate tumor sections was assessed by immunohistochemistry using a monoclonal NF-kB p65 antibody. The relation between nuclear p65 expression in primary tumors and lymph node metastasis was tested in univariate and multivariate Cox regression models. Results: Primary tumors of metastatic patients had an average of 21.25% of tumor cells with nuclear p65 expression as opposed to 9.42% of tumor cells of control patients (p=0.001). Univariate Cox regression demonstrated a 7.5% increased risk of having lymph node metastases for each percent increase in p65 nuclear staining (p=0.003). In the multivariate model, after controlling for pre-operative PSA (p=0.175), Gleason patterns (p=0.382), pathological stage (p=0.436), extracapsular extension (p=0.243) and seminal vesicle invasion (p=0.016), nuclear p65 was associated with an 8.8% increased risk for lymph node metastases (p=0.024). Conclusion: In univariate and multivariate analyses, p65 nuclear expression was strongly predictive of lymph node invasion. We propose that nuclear NF-kB (p65) may serve as a useful independent molecular marker for stratifying patients at risk for lymph node metastases.

No significant financial relationships to disclose.

Expression and localisation of Akt-1, Akt-2 and Akt-3 correlate with clinical outcome of prostate cancer patients

We investigated the correlation between the expression and localisation of Akt-1, Akt-2, Akt-3, phospho-Akt proteins and the clinicopathological parameters in 63 prostate cancer specimens. More than 60% of cancerous tissues overexpressed Akt-1, Akt-2 or Akt-3. Cytoplasmic Akt-1 expression was correlated with a higher risk of postoperative prostate-specific antigen (PSA) recurrence and shorter PSA recurrence interval. Cytoplasmic Akt-2 did not show any significant correlation with clinicopathological parameters predicting outcomes. Cytoplasmic Akt-3 was associated with hormone-refractory disease progression and extracapsular invasion. Nuclear Akt-1 and Akt-2 expression were correlated with favourable outcome parameters such as absence of lymph node and perineural invasion. Kaplan–Meier analysis and Cox regression model also showed that Akt-1 and Akt-2, but not Akt-3 or phospho-Akt was associated with a significantly higher risk of PSA recurrence. In contrast, nuclear Akt-1 was significantly associated with a lower risk of PSA recurrence. Multivariate analysis revealed that clinical stage, Gleason score and the combined cytoplasmic nuclear Akt-1 marker in cancerous tissues were significant independent prognostic factors of PSA recurrence. This is the first report demonstrating in patients with prostate cancer and the particular role of Akt-1 isoform expression as a prognostic marker depending of its localisation.