Faculty Bibliography

OBJECTIVE: The purpose of this study was to evaluate the utility of multiparametric MRI in localization of the index lesion of prostate cancer. MATERIALS AND METHODS: Fifty-one patients who underwent 3-T MRI of the prostate with a pelvic phased-array coil that included T2-weighted, diffusion-weighted, and dynamic contrast-enhanced sequences before prostatectomy were included. Six radiologists assessed all images to identify the lesion most suspicious of being the index lesion, which was localized to one of 18 regions. A uropathologist using the same 18-region scheme reviewed the prostatectomy slides to localize the index lesion. MRI performance was assessed by requiring either an exact match or an approximate match (discrepancy of up to one region) between the MRI and pathologic findings in terms of assigned region. RESULTS: The pathologist identified an index lesion in 49 of 51 patients. In exact-match analysis, the average sensitivity was 60.2% (range, 51.0-63.3%), and the average positive predictive value (PPV) was 65.3% (range, 61.2-69.4%). In approximate-match analysis, the average sensitivity was 75.9% (range, 65.3-69.6%), and the average PPV was 82.6% (range, 79.2-91.4%). The sensitivity was higher for index lesions with a Gleason score greater than 6 in exact-match (74.8% vs 15.3%, p < 0.001) and approximate-match (88.7% vs 36.1%, p = < 0.001) analyses and for index lesions measuring at least 1 cm in approximate-match analysis (80.3% vs 58.3%, p = 0.016). In exact-match analysis, 30.0%, 44.9%, and 79.1% of abnormalities found with one, two, and three MRI parameters represented the index lesion (p < 0.001). CONCLUSION: The sensitivity and PPV of multiparametric MRI for index lesion localization were moderate, although they improved in the setting of more aggressive pathologic features and a greater number of abnormal MRI parameters, respectively.

In prostate cancer, the signals that drive cell proliferation change as tumors progress from castration-sensitive (androgen-dominant) to castration-resistant states. While the mechanisms underlying this change remain uncertain, characterization of common signaling components that regulate both stages of prostate cancer proliferation is important for developing effective treatment strategies. Here, we demonstrate that paxillin, a known cytoplasmic adaptor protein, regulates both androgen- and EGF-induced nuclear signaling. We show that androgen and EGF promoted MAPK-dependent phosphorylation of paxillin, resulting in nuclear translocation of paxillin. We found nuclear paxillin could then associate with androgen-stimulated androgen receptor (AR). This complex bound AR-sensitive promoters, retaining AR within the nucleus and regulating AR-mediated transcription. Nuclear paxillin also complexed with ERK and ELK1, mediating c-FOS and cyclin D1 expression; this was followed by proliferation. Thus, paxillin is a liaison between extranuclear MAPK signaling and nuclear transcription in response to androgens and growth factors, making it a potential regulator of both castration-sensitive and castration-resistant prostate cancer. Accordingly, paxillin was required for normal growth of human prostate cancer cell xenografts, and its expression was elevated in human prostate cancer tissue microarrays. Paxillin is therefore a potential biomarker for prostate cancer proliferation and a possible therapeutic target for prostate cancer treatment.

Each histologic type of renal cell carcinoma (RCC) has different pathologic and clinical parameters; however, the independent role of histologic type in outcome prediction remains contested. Most studies show relevance for outcome of each histologic type when correlated with survival by univariate analysis, whereas few studies show differences in outcome once other key prognostic factors, such as stage and grade, are considered. These studies highlight the challenges to prove outcome relevance. Despite the contested independent value of type for outcome prediction, separation of RCC into types is well accepted and can be substantiated on clinical, pathologic, molecular, and general outcome differences.

Deng F-M, Mendrinos S E, Das K & Melamed J (2012) Histopathology 60, 1004-1008 Periprostatic lymph node metastasis in prostate cancer and its clinical significance Aims: To evaluate the potential of periprostatic lymph node (LN) as a staging indicator, particularly with the use of methods for enhanced detection of micrometastasis. Methods and results: We retrieved cases with periprostatic LN from radical prostatectomy specimens accrued between 1997 and 2007 at our institution. Twenty-one (0.8%) of 2663 radical prostatectomy specimens had periprostatic LNs (total number of LNs = 22). LN size ranged from 0.8 to 4.7 mm. Most of the periprostatic LNs were located close to the posterior base. Seven (32%) of 22 LNs were involved by metastatic prostate cancer (PCa), including five detected on routine haematoxylin and ceosin slides and an additional two detected only by immunohistochemistry. Cases with periprostatic LNs had a significantly higher metastatic rate (29%; six of 21) compared to those with pelvic LNs sampled at radical prostectatomy in our institution (1.9%). When compared to cases with negative periprostatic LNs (n = 15), the tumour characteristics of cases with metastatic periprostatic LNs (n = 6) included higher tumour volume, Gleason score, stage and a greater propensity for prostate-specific antigen (PSA) recurrence. Conclusions: Despite their infrequent identification, periprostatic LNs if detected in the radical prostatectomy specimen should be evaluated with greater scrutiny (step sections and/or immunohistochemical studies) to evaluate their prognostic potential.