Nuclear factor κB predicts poor outcome in patients with hormone-naive prostate cancer with high nuclear androgen receptor

Despite recent advances in prostate cancer treatments, disease recurrence is common and associated with significant morbidity and mortality. The need for more effective antitumor agents has led researchers to target signaling pathways that drive tumorigenesis by modulating or bypassing androgen receptor signaling--attenuation or blockade of which current treatments aim to effect. The transcription factor nuclear factor κB/p65 has been implicated in prostate cancer progression; however, few studies have examined the involvement of nuclear factor κB in hormone-naive disease. We used immunohistochemistry to investigate expression of p65, androgen receptor, Ki-67, and phosphorylation status of p65 at serine 536, in 154 tumor samples taken from patients before hormone ablation or radical treatment. Nuclear p65 expression was significantly associated with disease-specific mortality: P = .005; hazard ratio, 2.2. When patients were stratified according to androgen receptor status, this relationship was abolished in low androgen receptor-expressing patients and potentiated in high androgen receptor-expressing patients: P = .002; hazard ratio, 3.1. Ki-67 expression was also prognostic of shorter disease-specific mortality: P = .001; hazard ratio, 2.3. When the cohort was stratified according to androgen receptor status, this relationship held for high androgen receptor expressers but not low expressers: P = .0003; hazard ratio, 3.5. Neither androgen receptor nor p65 phosphorylated at S536 were significantly prognostic when considered individually. These data suggest that future prostate cancer treatments that target nuclear factor κB signaling should be assigned primarily to patients with concomitant high nuclear p65 and androgen receptor expression

SPRY2 loss enhances ErbB trafficking and PI3K/AKT signalling to drive human and mouse prostate carcinogenesis

Loss of SPRY2 and activation of receptor tyrosine kinases are common events in prostate cancer (PC). However, the molecular basis of their interaction and clinical impact remains to be fully examined. SPRY2 loss may functionally synergize with aberrant cellular signalling to drive PC and to promote treatment-resistant disease. Here, we report evidence for a positive feedback regulation of the ErbB-PI3K/AKT cascade by SPRY2 loss in in vitro as well as pre-clinical in vivo models and clinical PC. Reduction in SPRY2 expression resulted in hyper-activation of PI3K/AKT signalling to drive proliferation and invasion by enhanced internalization of EGFR/HER2 and their sustained signalling at the early endosome in a PTEN-dependent manner. This involved p38 MAPK activation by PI3K to facilitate clathrin-mediated ErbB receptor endocytosis. Finally, in vitro and in vivo inhibition of PI3K suppressed proliferation and invasion, supporting PI3K/AKT as a target for therapy particularly in patients with PTEN-haploinsufficient-, low SPRY2- and ErbB-expressing tumours. In conclusion, SPRY2 is an important tumour suppressor in PC since its loss drives the PI3K/AKT pathway via functional interaction with the ErbB system

Sprouty2, PTEN, and PP2A interact to regulate prostate cancer progression

Concurrent activation of RAS/ERK and PI3K/AKT pathways is implicated in prostate cancer progression. The negative regulators of these pathways, including sprouty2 (SPRY2), protein phosphatase 2A (PP2A), and phosphatase and tensin homolog (PTEN), are commonly inactivated in prostate cancer. The molecular basis of cooperation between these genetic alterations is unknown. Here, we show that SPRY2 deficiency alone triggers activation of AKT and ERK, but this is insufficient to drive tumorigenesis. In addition to AKT and ERK activation, SPRY2 loss also activates a PP2A-dependent tumor suppressor checkpoint. Mechanistically, the PP2A-mediated growth arrest depends on GSK3β and is ultimately mediated by nuclear PTEN. In murine prostate cancer models, Pten haploinsufficiency synergized with Spry2 deficiency to drive tumorigenesis, including metastasis. Together, these results show that loss of Pten cooperates with Spry2 deficiency by bypassing a novel tumor suppressor checkpoint. Furthermore, loss of SPRY2 expression correlates strongly with loss of PTEN and/or PP2A subunits in human prostate cancer. This underlines the cooperation between SPRY2 deficiency and PTEN or PP2A inactivation in promoting tumorigenesis. Overall, we propose SPRY2, PTEN, and PP2A status as an important determinant of prostate cancer progression. Characterization of this trio may facilitate patient stratification for targeted therapies and chemopreventive interventions

Incidental seminal vesicle amyloidosis observed in diagnostic prostate biopsies—are routine investigations for systemic amyloidosis warranted?

Seminal vesicle (SV) amyloidosis is a well-documented histological entity, but it is observed infrequently. Its incidence is on the rise, which is probably related to the increasing use of prostate biopsies to investigate patients with elevated serum prostate-specific antigen levels. Here, we report seven cases of incidental SV amyloidosis over a 3-year period and consider their relationship to the previously suggested aetiological factors. Based on our series, we conclude that incidental localized SV amyloidosis observed in diagnostic prostate biopsies does not warrant formal investigations for systemic amyloidosis