Androgen deprivation-induced NCoA2 promotes metastatic and castration-resistant prostate cancer

A major clinical hurdle for the management of advanced prostate cancer (PCa) in patients is the resistance of tumors to androgen deprivation therapy (ADT) and their subsequent development into castration-resistant prostate cancer (CRPC). While recent studies have identified potential pathways involved in CRPC development, the drivers of CRPC remain largely undefined. Here we determined that nuclear receptor coactivator 2 (NCoA2, also known as SRC-2), which is frequently amplified or overexpressed in patients with metastatic PCa, mediates development of CRPC. In a murine model, overexpression of NCoA2 in the prostate epithelium resulted in neoplasia and, in combination with Pten deletion, promoted the development of metastasis-prone cancer. Moreover, depletion of NCoA2 in PTEN-deficient mice prevented the development of CRPC. In human androgen-sensitive prostate cancer cells, androgen signaling suppressed NCoA2 expression, and NCoA2 overexpression in murine prostate tumors resulted in hyperactivation of PI3K/AKT and MAPK signaling, promoting tumor malignance. Analysis of PCa patient samples revealed a strong correlation among NCoA2-mediated signaling, disease progression, and PCa recurrence. Taken together, our findings indicate that androgen deprivation induces NCoA2, which in turn mediates activation of PI3K signaling and promotes PCa metastasis and CRPC development. Moreover, these results suggest that the inhibition of NCoA2 has potential for PCa therapy.

Heterogeneous clinicopathological features of intraductal carcinoma of the prostate: a comparison between "precursor-like" and "regular type" lesions

Intraductal carcinoma of the prostate (IDC-P) has been described as a lesion associated with intraductal spread of invasive carcinoma and consequently aggressive disease. However, there are a few reported cases of pure IDC-P without an associated invasive component, strongly suggesting that this subset of IDC-P may represent a precursor lesion. We compared the clinicopathological features between the morphologically "regular type" IDC-P and "precursor-like" IDC-P. IDC-P was defined as follows; 1) solid/dense cribriform lesions or 2) loose cribriform/micropapillary lesions with prominent nuclear pleomorphism and/or non-focal comedonecrosis. We defined precursor-like IDC-P as follows; 1) IDC-P without adjoining invasive adenocarcinoma but carcinoma present distant from the IDC-P or 2) IDC-P having adjoining invasive microcarcinoma (less than 0.05 ml) and showing a morphologic transition from high-grade prostatic intraepithelial neoplasia (HGPIN) to the IDC-P. IDC-P lacking the features of precursor-like IDC-P was categorized as regular type IDC-P. Of 901 radical prostatectomies performed at our hospital, 141 and 14 showed regular type IDC-P and precursor-like IDC-P in whole-mounted specimens, respectively. Regular type IDC-P cases had significantly higher Gleason score, more frequent extraprostatic extension and seminal vesicle invasion, more advanced pathological T stage, and lower 5-year biochemical recurrence-free rate than precursor-like IDC-P cases. Multivariate analysis revealed nodal metastasis and the presence of regular type IDC-P as independent predictors for biochemical recurrence. Our data suggest that IDC-P may be heterogeneous with variable clinicopathological features. We also suggest that not all IDC-P cases represent intraductal spread of pre-existing invasive cancer, and a subset of IDC-P may be a precursor lesion.

The expression level of lysophosphatidylcholine acyltransferase 1 (LPCAT1) correlates to the progression of prostate cancer

BACKGROUND

Lysophosphatidylcholine acyltransferase 1 (LPCAT1), the enzyme catalyzing the reaction in remodeling of phosphatidylcholine (PC) has been reported to express in prostate. However, its diagnostic and prognostic values remain unclear.

METHODS

Immunohistochemistry (IHC) for LPCAT1 was performed on the tissue microarray (TMA) slides containing 251 samples from 148 patients with various prostatic disorders. The association of expression level of LPCAT1 with the progression of prostate cancer was analyzed.

RESULTS

LPCAT1 IHC mean score was the highest in metastatic prostate cancer (8.00±1.28), which was significantly higher than that in primary prostate cancer (4.63±3.00, p=9.73E-07), in high grade prostatic intraepithelial neoplasia (HGPIN, 2.72±2.47, p=1.02E-12), and in benign prostate (2.68, p=6.17E-12). The mean score in primary prostate cancer was significantly higher than that in HGPIN (p=4.09E-04) and in benign prostate (p=2.74E-04). There was no significant difference in the mean score between HGPIN and benign prostate (p=0.951). LPCAT1 IHC score also correlated to the tumor grade and stage of prostate cancer. Patients who underwent prostatectomy for prostate cancer and developed biochemical recurrence or clinical metastasis had higher LPCAT1 IHC score than those who underwent prostatectomy for prostate cancer and did not develop biochemical recurrence and clinical metastasis. The association of LPCAT1 with the progression of prostate cancer was independent of patient race and age, PSA level and positivity of surgical resection margins.

CONCLUSIONS

LPCAT1 correlates with the progression of prostate cancer and could be a new biomarker in diagnosis, prognosis and studying the pathogenesis of prostate cancer.

Stage-specific inhibitory effects and associated mechanisms of silibinin on tumor progression and metastasis in transgenic adenocarcinoma of the mouse prostate model

Herein, using transgenic adenocarcinoma of the mouse prostate (TRAMP) model, we assessed the "stage-specific" efficacy of silibinin feeding against prostate cancer (PCa) initiation, progression, angiogenesis and metastasis, and associated molecular events involved in silibinin effects during these stages. Male TRAMP mice starting at ages 4, 12, 20, and 30 weeks of age were fed with control or 1% silibinin-supplemented diet for 8 to 15 weeks in stage-specific manners. At the end of studies, silibinin-fed mice showed less severe prostatic lesions compared with positive controls. During early stages of prostate tumor development, silibinin mediated its efficacy mostly via antiproliferative mechanisms. Feeding of silibinin to animals burdened with higher stages of prostate tumor significantly decreased tumor grade via antiproliferative effect, and inhibition of angiogenesis as evidenced by decreased expressions of platelet endothelial cell adhesion molecule-1/CD-31, vascular endothelial growth factor, and associated receptor, vascular endothelial growth factor R2, hypoxia-inducible factor-1alpha, and inducible nitric oxide synthase. Metastasis to distant organs was decreased in silibinin-fed mice, which was associated with a decreased expression of matrix metalloproteinases, mesenchymal markers snail-1, and fibronectin in the prostatic tissue and retention of epithelial characteristics. Together, these findings are both novel and highly significant in establishing the dual efficacy of silibinin where it inhibits progression of primary prostatic tumor and also shows protective efficacy against angiogenesis and late stage metastasis. These effects of silibinin could have potential implications to improve the morbidity and survival in PCa patients.

Significance of TWIST and E-cadherin expression in the metastatic progression of prostatic cancer

AIM

Development of metastasis is one of the main causes of prostatic cancer-related death. We have previously found that up-regulation of TWIST, a highly conserved basic helix-loop-helix transcription factor, in prostatic cancer cells can promote epithelial to mesenchymal transition through down-regulation of E-cadherin. The present study aimed to investigate the prognostic significance of TWIST and to correlate TWIST and E-cadherin expression in prostatic cancer specimens.

METHODS AND RESULTS

TWIST and E-cadherin expression was studied in 115 prostatic cancer specimens, eight cases of prostatic intraepithelial neoplasia and 37 cases of benign prostatic hyperplasia by immunohistochemistry. Increased cytoplasmic expression of TWIST was associated with malignant transformation of prostatic epithelium and histological progression of prostatic cancer, while nuclear TWIST expression was significant in predicting the metastatic potential of the primary prostatic cancer. In addition, high levels of TWIST expression were also significantly associated with aberrant E-cadherin expression.

CONCLUSIONS

These results suggest that TWIST may serve as a prognostic marker for high-grade prostatic cancer. In addition, up-regulation of TWIST in combination with aberrant E-cadherin expression in primary prostatic cancer specimens may predict development of distal metastatic disease.

Recurrent prostatic stromal sarcoma with massive high-grade prostatic intraepithelial neoplasia

A unique case of prostatic stromal sarcoma (PSS) that recurred in the pelvic cavity with massive high-grade prostatic intraepithelial neoplasia is described. A 52-year-old man who presented with urinary retention underwent a radical cystoprostatectomy. Tumour tissues of the prostate showed an admixture of hyperplastic glands and markedly cellular stroma of spindle cells arranged in a fascicular pattern, and the tumour was diagnosed as PSS. 66 months after the operation, CT scans revealed three recurrent tumours around the bilateral obturator and left fore iliopsoas. The recurrent tumours were biphasic neoplasms, as before, but the epithelial component had grown prominent and manifested overt atypia in a manner resembling high-grade prostatic intraepithelial neoplasia. Our findings suggest that not only the stromal component but also and the epithelial components of PSS may have malignant potential.

Management of Vertebral Metastases in Prostate Cancer: A Retrospective Analysis in 119 Patients

The objectives of this study were to define clinical problems and treatment strategies in vertebral metastases of prostate cancer. The clinical files of 634 patients with prostate cancer seen in a comprehensive cancer center during a 4-year period were retrospectively reviewed. One hundred nineteen patients (18.8%) had 212 significant episodes of osseous spinal metastases. Pain was nearly universal (93%), and motor and bladder impairment occurred in 25% and 3.1% of patients, respectively. Bone scan and magnetic resonance imaging (MRI) were performed in 197 and 64 episodes, respectively. Fifteen episodes of spinal cord compression were treated surgically. Other treatments included hormonal therapy (163 episodes), chemotherapy (70 episodes), and radiation therapy (103 episodes). Osteolytic lesions were observed alone and in combination with osteoblastic pattern in 18% and 26% of episodes, respectively. Bone scan was the most effective screening procedure of vertebral involvement, and MRI effectively showed epidural involvement. Overall treatment led to improvements in pain and motor impairment in 77% and 50% of patients, respectively. However, clinical episodes were recurrent (1.78 episodes per patient; range, 1-8). Median survival after vertebral metastasis episode was 14 months compared with only 4 months after surgery for spinal cord compression. Vertebral metastases strongly alter quality of life in patients with prostate cancer. Pain and neurologic complications are the major problems. Careful early screening with bone scan and MRI may help to define better treatment strategy. However, further prospective studies of clinical management are needed to determine the optimal timing of radiation therapy, medical treatments, and surgery.

Bcl-2 immunoreactivity in prostate tumorigenesis in relation to prostatic intraepithelial neoplasia, grade, hormonal status, metastatic growth and survival

The Bcl-2 protein prolongs cell survival by overriding apoptosis. To explore the role of Bcl-2 in prostate tumorigenesis, immunoreactivity for Bcl-2 was examined in untreated and androgen-deprived tumours and lymph node metastasis. Following the transurethral resection, 150 untreated patients were maintained under surveillance until death or for a minimum of 11 years, and castration was performed at symptomatic progression. The Bcl-2 index (BI) was defined as the percentage of immunoreactive cells in a tumour. The mean BI was 12 in the untreated tumours, and BI was significantly higher in high-grade tumours, mean BI 17, than in low-grade tumours, mean BI 6. There was no correlation between BI and stage or metastatic disease, nor did BI predict cancer-specific survival. In 16 androgen-deprived, but non-relapsed tumours, the mean BI was 54, at a mean time of 22 months after castration, indicating a permanent increase of Bcl-2 protein expression after androgen withdrawal. In six patients, tissues from the prostate tumour and obturator lymph node metastasis were available. Four primary tumours immunostained for Bcl-2, but only one metastasis stained. Foci of highgrade prostatic intraepithelial neoplasia (PIN) were present in 44 of the 150 untreated tumours. All PIN foci were intensely immunoreactive for Bcl-2, and mean BI was 79, suggesting that Bcl-2 protein expression is associated with early prostate tumorigenesis.