The p14ARF tumor suppressor restrains androgen receptor activity and prevents apoptosis in prostate cancer cells.

Prostate cancer (PCa) is characterized by a unique dependence on optimal androgen receptor (AR) activity where physiological androgen concentrations induce proliferation but castrate and supraphysiological levels suppress growth. This feature has been exploited in bipolar androgen therapy (BAT) for castrate resistant malignancies. Here, we investigated the role of the tumor suppressor protein p14ARF in maintaining optimal AR activity and the function of the AR itself in regulating p14ARF levels. We used a tumor tissue array of differing stages and grades to define the relationships between these components and identified a strong positive correlation between p14ARF and AR expression. Mechanistic studies utilizing CWR22 xenograft and cell culture models revealed that a decrease in AR reduced p14ARF expression and deregulated E2F factors, which are linked to p14ARF and AR regulation. Chromatin immunoprecipitation studies identified AR binding sites upstream of p14ARF. p14ARF depletion enhanced AR-dependent PSA and TMPRSS2 transcription, hence p14ARF constrains AR activity. However, p14ARF depletion ultimately results in apoptosis. In PCa cells, AR co-ops p14ARF as part of a feedback mechanism to ensure optimal AR activity for maximal prostate cancer cell survival and proliferation.

Transcription of Nrdp1 by the androgen receptor is regulated by nuclear filamin A in prostate cancer.

Prostate cancer (PCa) progression is regulated by the androgen receptor (AR); however, patients undergoing androgen-deprivation therapy (ADT) for disseminated PCa eventually develop castration-resistant PCa (CRPC). Results of previous studies indicated that AR, a transcription factor, occupies distinct genomic loci in CRPC compared with hormone-naïve PCa; however, the cause of this distinction was unknown. The E3 ubiquitin ligase Nrdp1 is a model AR target modulated by androgens in hormone-naïve PCa but not in CRPC. Using Nrdp1, we investigated how AR switches transcription programs during CRPC progression. The proximal Nrdp1 promoter contains an androgen response element (ARE); we demonstrated AR binding to this ARE in androgen-sensitive PCa. Analysis of hormone-naive human prostatectomy specimens revealed correlation between Nrdp1 and AR expression, supporting AR regulation of NRDP1 levels in androgen-sensitive tissue. However, despite sustained AR levels, AR binding to the Nrdp1 promoter and Nrdp1 expression were suppressed in CRPC. Elucidation of the suppression mechanism demonstrated correlation of NRDP1 levels with nuclear localization of the scaffolding protein filamin A (FLNA) which, as we previously showed, is itself repressed following ADT in many CRPC tumors. Restoration of nuclear FLNA in CRPC stimulated AR binding to Nrdp1 ARE, increased its transcription, and augmented NRDP1 protein expression and responsiveness to ADT, indicating that nuclear FLNA controls AR-mediated androgen-sensitive Nrdp1 transcription. Expression of other AR-regulated genes lost in CRPC was also re-established by nuclear FLNA. Thus, our results indicate that nuclear FLNA promotes androgen-dependent AR-regulated transcription in PCa, while loss of nuclear FLNA in CRPC alters the AR-regulated transcription program.

Zero positive surgical margins after radical prostatectomy: is the end in sight.

Positive surgical margins represents incomplete resection by the surgeon, and the elimination of positive margins represents the only clinical feature during radical prostatectomy that can lead directly to improved cancer outcomes. The introduction of new robot-assisted technology and technical refinements has led to declines of positive surgical margins. Although margins induced by incomplete cancer resection by the surgeon have been reduced for organ-confined disease, the 'Holy Grail' of zero margins is not yet attainable in prostatectomy, and is more problematic in cancer that has penetrated beyond the prostate. Intraoperative frozen biopsies are imprecise. The union of real-time optical coherence tomography technology of the da Vinci robotic platform for identification of positive margin sites, and technical advances with wider excisions during surgery may provide promise for further reduction of surgical margins to zero.

Docetaxel-induced mitotic arrest in epithelium of gallbladder: a hitherto unreported occurrence.

Chemotherapeutic agents that bind tubulin cause mitotic arrest, which may be seen histologically. Such mitotic arrest has been reported to occur in the skin, alimentary canal, lungs, liver, bone marrow, endometrium, breasts, or in ascites following treatment with paclitaxel, vincristine, colchicine, podophyllotoxin, or maytansine. Mitotic arrest as a result of docetaxel, a taxane that binds tubulin, has yet to be reported. Mitotic arrest in the gallbladder has also yet to be reported. We recently encountered a case of dramatic mitotic arrest as a result of docetaxel, involving the gallbladder of a 66-year-old man with metastatic bronchogenic carcinoma. Strikingly abundant bizarre mitoses initially prompted a diagnosis of primary carcinoma. Carcinoma was eventually excluded based on the absence of dysplasia in all cells at interphase and the history of recent administration of docetaxel. This is the first case of mitotic arrest involving docetaxel or the gallbladder. Awareness of this phenomenon is necessary to avoid misdiagnosing carcinoma.

p16-Positive small cell neuroendocrine carcinoma of the endometrium.

We report herein a small cell neuroendocrine carcinoma of the endometrium that extended to the cervix and showed strong immunohistochemical staining for p16. The p16 staining raised the possibility of a human papillomavirus (HPV)-related tumor, because in the cervix, a positive p16 immunohistochemical stain is presumptive evidence of HPV. However, the current case was HPV negative. We discuss the molecular pathogenesis of non-HPV-related increased p16 expression.