Molecular and genetic prognostic factors of prostate cancer

Increased nuclear factor erythroid 2-related factor 2 expression predicts worse prognosis of prostate cancer patients treated with radical prostatectomy

Reactive oxygen species are known to be linked with cell damage leading to carcinogenesis. Augmented levels of oxidative stress biomarkers, such as nuclear factor erythroid 2-related factor 2 (Nrf-2) and 8-hydroxydeoxyguanosine (8-OHDG), have been shown to associate with more aggressive behavior in many malignancies. The aim of this study was to determine whether Nrf-2 and 8-OHDG expression could predict the outcome in radical prostatectomy patients. Samples of 240 prostate cancer patients were analyzed for Nrf-2 and 8-OHDG expression by immunohistochemistry. The results were compared with clinicopathological data, biochemical recurrence-free survival (BFS), prostate cancer-specific survival, and overall survival (OS). Positive expression of 8-OHDG (P < .0001), Nrf-2 in cytoplasm (c-Nrf-2) (P = .015), and Nrf-2 in nucleus (n-Nrf-2) (P = .016) was more abundant in malignant tissue compared with benign, respectively. Elevated level of c-Nrf-2 expression was associated with positive surgical marginal (P = .005), extraprostatic extension (P = .031), biochemical recurrence (BCR) (P = .030), and OS (P = .002); and n-Nrf-2 expression was associated with pathologic stage class (P = .001), Gleason score (P = .026), extraprostatic extension (P = .027), BCR (P = .037), and OS (P < .0001). The increased c-Nrf-2 expression predicted shortened BFS (P = .034) and worse OS (P = .017). In the multivariate analysis, c-Nrf-2 (P = .028 and P = .019) and Gleason score (P = .001 and P = .033) were independent predictors of BFS and OS, respectively. Expression of the analyzed biomarkers was not linked with prostate cancer-specific survival. Expression of 8-OHDG was not associated with any clinicopathological factors or survival. These results reveal that increased c-Nrf-2 expression is a predictor of BFS and OS in conjunction with Gleason score in prostate cancer patients treated with radical prostatectomy.

Voltage-gated sodium channels were differentially expressed in human normal prostate, benign prostatic hyperplasia and prostate cancer cells

Voltage-gated sodium channels (VGSCs) are expressed not only in excitable cells but also in numerous metastatic cells, particularly in certain types of cancer cells. In some types of cancer, including prostate cancer, the expression of VGSCs is associated with cancer migration, invasion and metastasis in vivo. However, the detailed expression profiles of VGSC α subunits in normal human prostate, in prostatic hyperplasia and prostatic cancer remain controversial. In the present study, quantitative polymerase chain reaction was used to systematically detect all subtypes of VGSC α subunits in normal human prostate, benign prostatic hyperplasia (BPH) and prostate cancer cells. The expression profile of VGSC α subunits was observed to differ between these cell types. Nav1.5 was the major isoform expressed in normal human prostate tissue, while Nav1.5 and Nav1.2 were the predominant isoforms in BPH tissue. However, in PC-3 and LNCaP cells, two typical prostate cancer cell lines, Nav1.6 and Nav1.7 were abundantly expressed. By comparing the relative expression levels of Nav1.5, Nav1.6 and Nav1.7 in these cells, the mRNA levels of Nav1.6 and Nav1.7 were identified to be 6- to 27-fold higher in PC-3 and LNCaP cells than in either normal or BPH samples (P<0.05); however, Nav1.5 mRNA levels were relatively lower compared with those of Nav1.6 or Nav1.7 in all cells analyzed. To confirm whether Nav1.6 and Nav1.7 expression in cancer cells was functional, a patch-clamp technique was used to record whole-cell currents. A tetrodotoxin-sensitive sodium current was successfully recorded in PC-3 cells, but not in LNCaP cells. It was concluded that although all types of VGSC α subunits exhibited low expression levels in normal prostate and BPH cells, both Nav1.6 and Nav1.7 were significantly upregulated in the prostate cancer cell lines, suggesting these subtypes may be potential diagnostic markers and therapeutic targets for certain types of prostate cancer in humans.

Association of the serum vascular endothelial growth factor levels with benign prostate hyperplasia and prostate malignancies

Background:

Recently, the development of new biomarkers as prognostic and predictive markers in prostate cancer has been crucial.

Objectives:

This study was aimed to determine whether serum vascular endothelial growth factor (VEGF) levels would be a prognostic marker or risk assessment factor in patients with prostate cancer and to investigate whether it could differentiate cancerous tissue from benign prostate hyperplasia (BPH).

Patients and Methods:

We enrolled 44 patients with prostate cancer, 57 patients with BPH, and 57 healthy individuals. Serum VEGF levels was measured by ELISA and was compared among all groups; then, its correlation with PSA and Gleason score in cancerous group was assessed. In addition, by using receiver operating characteristic (ROC) curve and area under curve (AUC), we determined the sensitivity and specificity of VEGF as well as combined variable of VEGF and PSA as a diagnostic marker of prostate cancer.

Results:

Serum VEGF level was significantly higher in patients with prostate cancer in comparison to the other groups (P value < 0.001); however, it was not different between BPH and control groups. Only in cancerous group a significant correlation between VEGF and PSA was found (r = 0.425, P = 0.004). Assessing the risk of prostate cancer, we found a powerful correlation between the VEGF alone as well as the combination of VEGF and PSA with prostate cancer.

Conclusions:

VEGF may be a diagnostic biomarker of prostate cancer. In addition, it may differentiate the cancerous tissue from BPH. We suggest that VEGF combined with PSA may be used as a screening test of prostate cancer.

Survivin is a potential mediator of prostate cancer metastasis

PURPOSE

We examined whether Survivin expression is associated with an increased risk of metastasis in prostate cancer.

METHODS AND MATERIALS

A total of 205 patients with T1 (23%) and T2 (77%) prostate cancer were treated with conventional external beam radiation therapy from 1991 to 1993 at the Massachusetts General Hospital. Of the patients, 62 had adequate and suitable-stained tumor material for Survivin analysis. Median follow-up was 102 months (range, 5-127 months). Distant failure was determined on the basis of clinical criteria. In preclinical studies, replication-deficient adenovirus encoding phosphorylation-defective Survivin Thr34→Ala dominant-negative mutant pAd-S(T34A) or short hairpin RNA (shRNA) was used to inhibit Survivin in prostate cancer models, and the cell motility, morphology, and metastasis were investigated.

RESULTS

Our correlative data on men with early-stage (T1/T2) prostate cancers treated at Massachusetts General Hospital by definitive radiotherapy indicated that overexpression of Survivin (positive staining in ≥10% cells) was associated with a significantly increased risk for the subsequent development of distant metastasis (p = 0.016) in the univariate analysis. In the multivariate analysis, overexpression of Survivin remained an independent predictor of distant metastasis (p = 0.008). The inhibition of Survivin dramatically inhibited invasiveness of prostate cancer cells in the in vitro invasion assay and spontaneous metastasis in the Dunning prostate cancer in vivo model. Furthermore, attenuation of Survivin resulted in changes in the microtubule cytoskeleton, loss of cellular polarity, and loss of motility.

CONCLUSIONS

This study suggests that Survivin may be a potentially important prognostic marker and promising therapeutic target in metastatic prostate cancer.

Histone deacetylase inhibitors: the anticancer, antimetastatic and antiangiogenic activities of AN-7 are superior to those of the clinically tested AN-9 (Pivanex)

Histone deacetylase inhibitory prodrugs that are metabolized to butyric acid and formaldehyde possess antineoplastic properties and low toxicity. We sought to characterize the antiangiogenic and antimetastatic activities of two lead prodrugs, pivaloyloxymethyl butyrate (AN-9) and butyroyloxymethyl-diethyl phosphate (AN-7) in murine cancer models. In the sc implanted human colon carcinoma HT-29 xenograft model AN-7, exhibited superior anticancer activity compared to AN-9, as was evident by the significantly greater inhibition of tumor growth and reduction of serum CEA. AN-7 was also more effective in reducing mean vessel density (MVD) by 7-fold, bFGF, Ki-67 (7-fold) and HIF-1alpha in immunohistochemically stained tumor sections. Semi-quantitative evaluation of the levels of bFGF, HDAC1 and HIF-1alpha by Western blot analysis showed a decrease in expression only in the tumors of mice treated with AN-7. The level of bFGF was reduced 3-fold in the tumor and that of TIMP1 was elevated (by 3-fold) in the serum of AN-7 treated mice. In a 4T1 metastatic breast carcinoma model, AN-7 inhibited the formation of lung lesions by 76% and AN-9 by 47%, further demonstrating the greater efficacy of AN-7 compared to AN-9 (P<0.02). Both AN-7 and AN-9 exhibited antimetastatic and antiangiogenic activities by reducing vascularization, bFGF expression and HIF-1alpha. Yet, AN-7 was more potent than AN-9.

The anticancer prodrugs of butyric acid AN-7 and AN-9, possess antiangiogenic properties

The antiangiogenic and antineoplastic activities of the butyric acid prodrugs AN-7 and AN-9 were demonstrated in vitro with HUVEC by inhibition of proliferation and vascular tubes formation, enhanced apoptosis, and inhibition of 22Rv-1 cells migration. In the sc implanted human prostate tumors (22Rv-1) in nude mice, AN-7 significantly inhibited Ki-67, HIF-1alpha, HER-2/neu, bFGF and increased PTEN level. AN-7 and AN-9 reduced hemoglobin accumulation in matrigel plugs implanted sc in Balb-c mice. Herein, we show that the anticancer activity of AN-7 and AN-9 can be attributed in part to their antiangiogenic activities suggesting potential therapeutic benefits for prostate cancer patients.

[Prognostic factors in prostate cancer]

Since several therapeutic options are currently available for clinically organ-confined prostate cancer, morphological parameters have rapidly emerged as prognostic factors to stratify patients into different therapeutic modalities. In addition to the PSA value, pathologic stage, as defined by the TNM system, Gleason grade and the surgical margin status, other markers have prognostic implications. This includes the percent pattern 4/5 cancer, tumor volume, intraductal spread, large volume perineural invasion and molecular markers. This review discusses the methods of sampling and reporting in prostate pathology with an emphasis on well established and new prognostic factors.

A potential novel marker for human prostate cancer: voltage-gated sodium channel expression in vivo

Functional expression of voltage-gated sodium channel alpha-subunits (VGSCalphas), specifically Nav1.7, is associated with strong metastatic potential in prostate cancer (CaP) in vitro. Furthermore, VGSC activity in vitro directly potentiates processes integral to metastasis. To investigate VGSCalpha expression in CaP in vivo, immunohistochemistry and real-time PCR were performed on human prostate biopsies (n>20). VGSCalpha immunostaining was evident in prostatic tissues and markedly stronger in CaP vs non-CaP patients. Importantly, RT-PCRs identified Nav1.7 as the VGSCalpha most strikingly upregulated (approximately 20-fold) in CaP, and the resultant receiver-operating characteristics curve demonstrated high diagnostic efficacy for the disease. It is concluded that VGSCalpha expression increases significantly in CaP in vivo and that Nav1.7 is a potential functional diagnostic marker.

U94 alters FN1 and ANGPTL4 gene expression and inhibits tumorigenesis of prostate cancer cell line PC3

Background

Insensitivity of advanced-stage prostate cancer to androgen ablation therapy is a serious problem in clinical practice because it is associated with aggressive progression and poor prognosis. Targeted therapeutic drug discovery efforts are thwarted by lack of adequate knowledge of gene(s) associated with prostate tumorigenesis. Therefore there is the need for studies to provide leads to targeted intervention measures. Here we propose that stable expression of U94, a tumor suppressor gene encoded by human herpesvirus 6A (HHV-6A), could alter gene expression and thereby inhibit the tumorigenicity of PC3 cell line. Microarray gene expression profiling on U94 recombinant PC3 cell line could reveal genes that would elucidate prostate cancer biology, and hopefully identify potential therapeutic targets.

Results

We have shown that stable expression of U94 gene in PC3 cell line inhibited its focus formation in culture, and tumorigenesis in nude mice. Moreover gene expression profiling revealed dramatic upregulation of FN 1 (fibronectin, 91 ± 16-fold), and profound downregulation of ANGPTL 4 (angiopoietin-like-4, 20 ± 4-fold) in U94 recombinant PC3 cell line. Quantitative real-time polymerase chain reaction (QRT-PCR) analysis showed that the pattern of expression of FN 1 and ANGPTL 4 mRNA were consistent with the microarray data. Based on previous reports, the findings in this study implicate upregulation of FN 1 and downregulation of ANGPTL 4 in the anti tumor activity of U94. Genes with cancer inhibitory activities that were also upregulated include SERPINE 2 (serine/cysteine protease inhibitor 2, 7 ± 1-fold increase) and ADAMTS 1 (a disintegrin-like and metalloprotease with thrombospondin type 1 motif, 7 ± 2-fold increase). Additionally, SPUVE 23 (serine protease 23) that is pro-tumorigenic was significantly downregulated (10 ± 1-fold).

Conclusion

The dramatic upregulation of FN 1 and downregulation of ANGPTL 4 genes in PC3 cell line stably expressing U94 implicate up-regulation of FN 1 and downregulation of ANGPTL 4 in anti tumor activity of U94. Further studies are necessary to determine functional roles of differentially expressed genes in U94 recombinant PC3 cell line, and hopefully provide leads to potential therapeutic targets in prostate cancer.

Transperineal in vivo fluence-rate dosimetry in the canine prostate during SnET2-mediated PDT

Advances in photodynamic therapy (PDT) treatment for prostate cancer can be achieved either by improving selectivity of the photosensitizer towards prostate gland tissue or improving the dosimetry by means of individualized treatment planning using currently available photosensitizers. The latter approach requires the ability to measure, among other parameters, the fluence rate at different positions within the prostate and the ability to derive the tissue optical properties. Here fibre optic probes are presented capable of measuring the fluence rate throughout large tissue volumes and a method to derive the tissue optical properties for different volumes of the prostate. The responsivity of the sensors is sufficient to detect a fluence rate of 0.1 mW cm(-2). The effective attenuation coefficient in the canine prostate at 660 nm is higher at the capsule (2.15+/-0.19 cm(-1)) than in proximity of the urethra (1.84+/-0.36 cm(-1)). Significant spatial and temporal intra- and inter-canine variability in the tissue optical properties was noted, highlighting the need for individualized monitoring of the fluence rate for improved dosimetry.