Cancer of the prostate

Evaluating the Therapeutic Effect of Hispidin on Prostate Cancer Cells

Androgen deprivation therapy (ADT) is the primary treatment for advanced prostate cancer (PCa). However, prolonged ADT inevitably results in therapy resistance with the emergence of the castration-resistant PCa phenotype (CRPC). Hence, there is an urgent need to explore new treatment options capable of delaying PCa progression. Hispidin (HPD) is a natural polyketide primarily derived from plants and fungi. HPD has been shown to have a diverse pharmacological profile, exhibiting anti-inflammatory, antiviral, cardiovascular and neuro-protective activities. However, there is currently no research regarding its properties in the context of PCa treatment. This research article seeks to evaluate the anti-cancer effect of HPD and determine the underlying molecular basis in both androgen-sensitive PCa and CRPC cells. Cell growth, migration, and invasion assays were performed via the MTS method, a wound healing assay and the transwell method. To investigate if HPD affected the expression of proteins, Western blot analysis was conducted. Furthermore, apoptosis was assessed by Annexin V-FITC/PI staining and Western blot analyses. HPD exhibited a favorable pharmaceutical profile to inhibit cell growth; disrupt the cell cycle; attenuate wound healing, migration and invasion; and induce apoptosis in PCa cells in vitro. The mechanistic results demonstrated that HPD reduced AR, MMP-2 and MMP-9 expression and activated the caspase-related pathway, leading to programmed cell death in PCa cells. We showed the anti-cancer effect of HPD on PCa cells and confirmed its feasibility as a novel therapeutic agent. This study provides significant insights into the delineation of the molecular mechanism of HPD in PCa cells and the development of an effective and safe therapy using HPD to eliminate PCa progression.

Natural flavonols: actions, mechanisms, and potential therapeutic utility for various diseases

Background

Flavonols are phytoconstituents of biological and medicinal importance. In addition to functioning as antioxidants, flavonols may play a role in antagonizing diabetes, cancer, cardiovascular disease, and viral and bacterial diseases. Quercetin, myricetin, kaempferol, and fisetin are the major dietary flavonols. Quercetin is a potent scavenger of free radicals, providing protection from free radical damage and oxidation-associated diseases.

Main body of the abstract

An extensive literature review of specific databases (e.g., Pubmed, google scholar, science direct) were conducted using the keywords "flavonol," "quercetin," "antidiabetic," "antiviral," "anticancer," and "myricetin." Some studies concluded that quercetin is a promising antioxidant agent while kaempferol could be effective against human gastric cancer. In addition, kaempferol prevents apoptosis of pancreatic beta-cells via boosting the function and survival rate of the beta-cells, leading to increased insulin secretion. Flavonols also show potential as alternatives to conventional antibiotics, restricting viral infection by antagonizing the envelope proteins to block viral entry.

Short conclusion

There is substantial scientific evidence that high consumption of flavonols is associated with reduced risk of cancer and coronary diseases, free radical damage alleviation, tumor growth prevention, and insulin secretion improvement, among other diverse health benefits. Nevertheless, more studies are required to determine the appropriate dietary concentration, dose, and type of flavonol for a particular condition to prevent any adverse side effects.

Surgical Decompression of High-Grade Spinal Cord Compression from Hormone Refractory Metastatic Prostate Cancer

BACKGROUND

Spine and nonspine skeletal metastases occur in more than 80% of patients with prostate cancer.

OBJECTIVE

To examine the characteristics of the patient population undergoing surgery for the treatment of prostate cancer metastatic to the spine.

METHODS

A retrospective chart review was performed on all patients treated at our institution from June 1993 to August 2014 for surgical management of metastatic spine disease from prostate cancer.

RESULTS

During the study period, 139 patients with 157 surgical lesions underwent surgery for metastatic spine disease. Decompression for high-grade epidural spinal cord compression was required for 126 patients with 143 lesions. Preoperatively, 69% had a motor deficit and 21% were nonambulatory, with 32% due to motor weakness. At surgery, 87% of patients had hormone-refractory prostate cancer (HRPC) and 61% failed prior radiation. Median overall survival for HRPC patients was 6.6 mo (95% confidence interval [CI]: 5.6-8.6) while the median overall survival for hormone-sensitive patients was 16.3 mo (95% CI: 4.0-26.6).

CONCLUSION

The majority of patients undergoing surgery for prostate cancer metastases to the spine were refractory to hormone therapy, indicating that patients with hormone-sensitive prostate cancer are unlikely to develop symptomatic spinal cord compression or spinal instability. A significant number of HRPC patients presented with neurological deficits attributable to spinal cord compression. Vigilant monitoring for the development of signs and symptoms of epidural spinal cord compression and spinal instability in hormone-refractory patients is recommended. Surgical decision making may be affected by the much shorter postoperative survival for HRPC patients as compared to patients with hormone-sensitive cancer.

Glycosylation markers in cancer

Alteration of glycosylation, a hallmark of cancer, results in the production of tumor-associated glycans or glycoproteins. These molecules are subsequently secreted or membrane-shed into the blood stream and thus serve as tumor-associated markers. Increased glycosylation in cancer is triggered by overexpression of glycoproteins that carry certain specific glycans, increase or decrease of nucleotide sugar donors and altered expression of glycosyltransferase and glycosidase enzymes. In this chapter, the biochemistry and function of glycoprotein, glycan and enzyme markers are reviewed. These glycosylation markers, applicable for detection and monitoring of cancer, include CA19-9, CA125, CEA, PSA and AFP. Because of their specific affinity to distinct sugar moieties, lectins are useful for developing assays to detect these tumor associated glycans and glycoproteins in clinical samples. As such, various enzyme-linked lectin assays (ELLA) have been developed for diagnosis, monitoring and prognosis. Because glycosylation changes occur early in cancer, the detection of tumor associated glycosylation markers using lectin based assays is an effective strategy to improve diagnosis and treatment resulting better outcomes clinically.

Roles of p53, NF-κB and the androgen receptor in controlling NGAL expression in prostate cancer cell lines

Neutrophil gelatinase-associated lipocalin (NGAL a.k.a lipocalin 2, lnc2) is a secreted protein which can form a complex with matrix metalloproteinase-9 (MMP9). This MMP9/NGAL complex has been associated with metastasis. MMP9 and NGAL are detected in the urine of patients afflicted with many different types of cancer, including prostate cancer. The effects of p53, NF-κB and the androgen receptor (AR) on the expression of NGAL was examined in four prostate cancer cell lines. Prostate cancer cell lines that are AR negative and expressed either mutant or no p53 (DU145 and PC3) displayed higher levels of NGAL expression compared to the prostate cancer cell lines (LNCaP and 22Rv-1) which are AR positive and express wild type (WT) p53. Introduction of WT-p53 into the PC3 prostate cancer cell line, resulted in reduction of the levels of NGAL expression. Conversely, introduction of dominant negative (DN) p53 or a retroviral construct expressing NF-κB into LNCaP cells increased NGAL expression. NGAL expression had functional effects on the ability of the cells to form colonies in soft agar. Whereas suppression of WT-53 in LNCaP cells increased NGAL expression, the introduction of WT-p53 suppressed NGAL transcription activity in PC3 prostate cells which normally express high level of NGAL. NF-κB and p53 were determined to regulate NGAL expression by positive and negative mechanisms, respectively. Our data indicate that prostate cancer growth, progression and sensitivity to chemotherapeutic drugs are regulated in part by NGAL and may involve complex interactions between NGAL, MMP9, NF-κB and p53.

Combinatorial Effect of Abiraterone Acetate and NVP-BEZ235 on Prostate Tumor Progression in Rats

Use of drug combinations that target different pathways involved in the development and progression of prostate cancer (PCa) has emerged as an alternative to overcome the resistance caused by drug monotherapies. The antiandrogen abiraterone acetate and the PI3K/Akt inhibitor NVP-BEZ235 (BEZ235) may be suitable options for the prevention of drug resistance and the inhibition of PCa progression. The aim of the present study was to evaluate whether abiraterone acetate and BEZ235 achieve superior therapeutic effects to either drug administered as monotherapy, in the early stages of PCa in an androgen-dependent system. Our study showed that each drug might impair tumor growth by reducing proliferation and increasing cell death when administered as monotherapy. However, tumor growth continued to progress with each drug monotherapy and some important side effects were related to BEZ. Conversely, when used in combination, the drugs impaired the inflammatory response, decreased hyperplastic lesions, and blocked tumor progression from premalignant to a malignant stage. Our data showed that the strategy to block the androgenic and PI3K/AKT/mTOR pathway is an effective therapeutic option and should be investigated including distinct PI3K pathway inhibitors.

Biomarkers of Prostatic Cancer: An Attempt to Categorize Patients into Prostatic Carcinoma, Benign Prostatic Hyperplasia, or Prostatitis Based on Serum Prostate Specific Antigen, Prostatic Acid Phosphatase, Calcium, and Phosphorus

Prostatitis, BPH, and P.Ca are the most frequent pathologies of the prostate gland that are responsible for morbidity in men. Raised levels of PSA are seen in different pathological conditions involving the prostate. PAP levels are altered in inflammatory or infectious or abnormal growth of the prostate tissue. Serum calcium and phosphorus levels were also found to be altered in prostate cancer and BPH. The present study was carried out to study the levels of PSA, PAP, calcium, and phosphorus in serum of patients with Prostatitis, BPH, or P.Ca and also to evaluate the relationship between them. Males in the age group of 50–85 years with LUTS disease symptoms and with PSA levels more than 4 ng/mL were included. A total of 114 patients were analyzed including 30 controls. Prostatitis in 35.7% of cases, BPH in 35.7% of the cases, and P.Ca in 28.57% of the cases were observed. Thus, the nonmalignant cases constitute a majority. PSA, a marker specific for prostatic conditions, was significantly high in all the diseases compared to controls. A rise in serum PSA and PAP indicates prostatitis or, in combination with these two tests, decreased serum calcium shows advanced disease.

Recent progress in the development of protein-protein interaction inhibitors targeting androgen receptor-coactivator binding in prostate cancer

The androgen receptor (AR) is a key regulator for the growth, differentiation and survival of prostate cancer cells. Identified as a primary target for the treatment of prostate cancer, many therapeutic strategies have been developed to attenuate AR signaling in prostate cancer cells. While frontline androgen-deprivation therapies targeting either the production or action of androgens usually yield favorable responses in prostate cancer patients, a significant number acquire treatment resistance. Known as the castration-resistant prostate cancer (CRPC), the treatment options are limited for this advanced stage. It has been shown that AR signaling is restored in CRPC due to many aberrant mechanisms such as AR mutations, amplification or expression of constitutively active splice-variants. Coregulator recruitment is a crucial regulatory step in AR signaling and the direct blockade of coactivator binding to AR offers the opportunity to develop therapeutic agents that would remain effective in prostate cancer cells resistant to conventional endocrine therapies. Structural analyses of the AR have identified key surfaces involved in protein-protein interaction with coregulators that have been recently used to design and develop promising AR-coactivator binding inhibitors. In this review we will discuss the design and development of small-molecule inhibitors targeting the AR-coactivator interactions for the treatment of prostate cancer.

The importance of non-nuclear AR signaling in prostate cancer progression and therapeutic resistance

The androgen receptor (AR) remains the major oncogenic driver of prostate cancer, as evidenced by the efficacy of androgen deprivation therapy (ADT) in naïve patients, and the continued effectiveness of second generation ADTs in castration resistant disease. However, current ADTs are limited to interfering with AR ligand binding, either through suppression of androgen production or the use of competitive antagonists. Recent studies demonstrate 1) the expression of constitutively active AR splice variants that no longer depend on androgen, and 2) the ability of AR to signal in the cytoplasm independently of its transcriptional activity (non-genomic); thus highlighting the need to consider other ways to target AR. Herein, we review canonical AR signaling, but focus on AR non-genomic signaling, some of its downstream targets and how these effectors contribute to prostate cancer cell behavior. The goals of this review are to 1) re-highlight the continued importance of AR in prostate cancer as the primary driver, 2) discuss the limitations in continuing to use ligand binding as the sole targeting mechanism, 3) discuss the implications of AR non-genomic signaling in cancer progression and therapeutic resistance, and 4) address the need to consider non-genomic AR signaling mechanisms and pathways as a viable targeting strategy in combination with current therapies.

Exposure of personnel and public due to using 153Sm-labelled EDTMP-Quadramet® in nuclear medicine procedures

The main aim of this study was to highlight the problems of personnel exposure when administering (153)Sm-labelled ethylene diamine tetramethylene phosphonate-Quadramet(®) to patients and especially to evaluate hand exposure of the personnel. The exposure levels of patients' families and the people who takes care of the patients treated by Quadramet(®) were also estimated. Thermoluminescent detectors were used to measure the doses. The doses received during the injection of the Quadramet(®) by the nursing staff have been determined at the level of 1/150 dose limit for the skin. Exposure of members of the patient's family staying 1.5 m away from the patient being treated with Quadramet(®) has been estimated to be 0.40 mGy.

Anti-androgenic effects of flavonols in prostate cancer

Dietary-derived agents, such as the flavonoids, are of particular interest for prostate cancer (PCa) chemoprevention as they may offer a favourable safety and side-effect profile. An agent that demonstrates action on the androgen receptor (AR) axis may have value for preventing or treating castrate-resistant PCa. Four main flavonols - quercetin, myricetin, kaempferol, and fisetin - have been demonstrated in laboratory studies to have chemopreventive action in both castrate-resistant and castrate-sensitive PCa models. Mechanisms of flavonol action on the AR axis in PCa have been proposed to be inhibition of the 5α-reductase enzymes, direct androgen competition, suppression of the AR complex and transactivation by coregulators such as c-Jun, Sp1, and the PI3K/Akt pathway. It is, however, still unclear with current levels of evidence whether AR axis-mediated effects can fully account for the flavonols' chemopreventive action.

Comparative study of trace elements in blood, scalp hair and nails of prostate cancer patients in relation to healthy donors

Prostate cancer is the most common fatal cancers in men, and exposure to toxic elements is the most important factor in the aetiology for prostate cancer. Selected elements (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were analyzed in the blood, scalp hair and nails of prostate cancer patients and counterpart healthy donors by atomic absorption spectrometry. Average concentrations of Cd, Mn, Ni and Pb were found to be significantly higher (p < 0.05) in the blood, scalp hair and nails of the patients compared with those of the healthy subjects who exhibited significantly higher concentrations of Zn. The correlation study revealed significantly diverse relationships of the elements in the blood, scalp hair and nails of the two donor groups. Variations in the elemental concentrations were also noted for various types of prostate cancer (adenocarcinoma, squamous cell carcinoma, transitional cell carcinoma and small cell carcinoma), as well as for different stages of the cancer. Multivariate apportionment of trace elements in the blood, scalp hair and nails of the patients was also significantly different than that in the healthy donors. The study evidenced considerably divergent variations in the elemental concentrations in prostate cancer patients in comparison with healthy subjects.

Pterostilbene-Isothiocyanate Conjugate Suppresses Growth of Prostate Cancer Cells Irrespective of Androgen Receptor Status

Chemotherapy and anti-hormonal therapies are the most common treatments for non-organ-confined prostate cancer (PCa). However, the effectiveness of these therapies is limited, thus necessitating the development of alternative approaches. The present study focused on analyzing the role of pterostilbene (PTER)-isothiocyanate (ITC) conjugate – a novel class of hybrid compound synthesized by appending an ITC moiety on PTER backbone – in regulating the functions of androgen receptor (AR), thereby causing apoptosis of PCa cells. The conjugate molecule caused 50% growth inhibition (IC50) at 40±1.12 and 45±1.50 μM in AR positive (LNCaP) and negative (PC-3) cells, respectively. The reduced proliferation of PC-3 as well as LNCaP cells by conjugate correlated with accumulation of cells in G2/M phase and induction of caspase dependent apoptosis. Both PI3K/Akt and MAPK/ERK pathways played an important and differential role in conjugate-induced apoptosis of these PCa cells. While the inhibitor of Akt (A6730) or Akt-specific small interference RNA (siRNA) greatly sensitized PC-3 cells to conjugate-induced apoptosis, on the contrary, apoptosis was accelerated by inhibition of ERK (by PD98059 or ERK siRNA) in case of LNCaP cells, both ultimately culminating in the expression of cleaved caspase-3 protein. Moreover, anti-androgenic activity of the conjugate was mediated by decreased expression of AR and its co-activators (SRC-1, GRIP-1), thus interfering in their interactions with AR. All these data suggests that conjugate-induced inhibition of cell proliferation and induction of apoptosis are partly mediated by the down regulation of AR, Akt, and ERK signaling. These observations provide a rationale for devising novel therapeutic approaches for treating PCa by using conjugate alone or in combination with other therapeutics.

α-Tocopheryl succinate pre-treatment attenuates quinone toxicity in prostate cancer PC3 cells

α-Tocopheryl succinate is one of the most effective analogues of vitamin E for inhibiting cell proliferation and inducing cell death in a variety of cancerous cell lines while sparing normal cells or tissues. αTocopheryl succinate inhibits oxidative phosphorylation at the level of mitochondrial complexes I and II, thus enhancing reactive oxygen species generation which, in turn, induces the expression of Nrf2-driven antioxidant/detoxifying genes. The cytoprotective role of Nrf2 downstream genes/proteins prompted us to investigate whether and how α-tocopheryl succinate increases resistance of PC3 prostate cancer cells to pro-oxidant damage. A 4h α-tocopheryl succinate pre-treatment increases glutathione intracellular content, indicating that the vitamin E derivative is capable of training the cells to react to an oxidative insult. We found that α-tocopheryl succinate pre-treatment does not enhance paraquat-/hydroquinone-induced cytotoxicity whereas it exhibits an additional/synergistic effect on H₂O₂₋/docetaxel-induced cytotoxicity. While glutathione and heme oxygenase-1 are not involved in α-tocopheryl succinate-induced adaptive response to paraquat,

NAD(P)H

quinone oxidoreductase seems to be responsible, at least in part, for the lack of the additional response. Silencing the gene and/or the inhibition of

NAD(P)H

quinone oxidoreductase activity counteracts the α-tocopheryl succinate-induced adaptive response. In conclusion, the adaptive response to α-tocopheryl succinate shows that the activation of Nrf2 can promote the survival of cancer cells in an unfavourable environment.

Alpha-tomatine synergises with paclitaxel to enhance apoptosis of androgen-independent human prostate cancer PC-3 cells in vitro and in vivo

Alpha (α)-tomatine, a major saponin found in tomato has been shown to inhibit the growth of androgen-independent prostate cancer PC-3 cells. The effects of α-tomatine in combination with the chemotherapeutic agent paclitaxel against PC-3 cells were investigated in the present study. Combined treatment with a sub-toxic dose of α-tomatine and paclitaxel significantly decreased cell viability with concomitant increase in the percentage of apoptotic PC-3 cells. The combined treatment, however, had no cytotoxic effect on the non-neoplastic prostate RWPE-1 cells. Apoptosis of PC-3 cells was accompanied by the inhibition of PI3K/Akt pro-survival signaling, an increase in the expression of the pro-apoptotic protein BAD but a decrease in the expressions of anti-apoptotic proteins, Bcl-2 and Bcl-xL. Results from a mouse xenograft model showed the combined treatment completely suppressed subcutaneous tumor growth without significant side effects. Consistent with its in vitro anti-cancer effects, tumor materials from mice showed increased apoptosis of tumor cells with reduced protein expression of activated PI3K/Akt. These results suggest that the synergistic anti-cancer effects of paclitaxel and α-tomatine may be beneficial for refractory prostate cancer treatment.

Brachytherapy in the therapy of prostate cancer - an interesting choice

Brachytherapy is a curative alternative to radical prostatectomy or external beam radiation [i.e. 3D conformal external beam radiation therapy (CRT), intensity-modulated radiation therapy (IMRT)] with comparable long-term survival and biochemical control and the most favorable toxicity. HDR brachytherapy (HDR-BT) in treatment of prostate cancer is most frequently used together with external beam radiation therapy (EBRT) as a boost (increasing the treatment dose precisely to the tumor). In the early stages of the disease (low, sometimes intermediate risk group), HDR-BT is more often used as monotherapy. There are no significant differences in treatment results (overall survival rate – OS, local recurrence rate – LC) between radical prostatectomy, EBRT and HDR-BT. Low-dose-rate brachytherapy (LDR-BT) is a radiation method that has been known for several years in treatment of localized prostate cancer. The LDR-BT is applied as a monotherapy and also used along with EBRT as a boost. It is used as a sole radical treatment modality, but not as a palliative treatment. The use of brachytherapy as monotherapy in treatment of prostate cancer enables many patients to keep their sexual functions in order and causes a lower rate of urinary incontinence. Due to progress in medical and technical knowledge in brachytherapy (“real-time” computer planning systems, new radioisotopes and remote afterloading systems), it has been possible to make treatment time significantly shorter in comparison with other methods. This also enables better protection of healthy organs in the pelvis. The aim of this publication is to describe both brachytherapy methods.

Prognostication of prostate cancer based on NUCB2 protein assessment: NUCB2 in prostate cancer

BACKGROUND

Nucleobindin 2 (NUCB2) protein, a novel oncoprotein, is overexpressed in breast cancer. To date, there have been no published data regarding the role of NUCB2 protein expression in prostate cancer (PCa). Therefore, this study was performed to investigate the correlations between NUCB2 protein expression and prognosis in patients with PCa.

METHODS

Through immunohistochemistry, NUCB2 protein expression was evaluated in 60 benign prostatic hyperplasia (BPH) specimens and 180 PCa specimens. The correlation of NUCB2 protein expression with clinicopathological parameters was assessed using χ2 analysis. Kaplan-Meier analysis and Cox proportional hazards regression models were used to investigate the correlation between NUCB2 protein expression and prognosis of PCa patients.

RESULTS

The immunohistochemistry results showed that the expression level of NUCB2 in PCa cases was significantly higher than that in BPH tissues (P < 0.001). Moreover, statistical analysis also showed that high NUCB2 protein expression was positively related to seminal vesicle invasion, lymph node metastasis, angiolymphatic invasion, higher Gleason score, biochemical recurrence (BCR), and higher preoperative prostate-specific antigen (PSA). Furthermore, it was also shown that patients with high NUCB2 protein expression had significantly poorer overall survival and BCR- free survival compared with patients with low expression of NUCB2 protein. Multivariate Cox regression analysis revealed that high NUCB2 protein expression level was an independent prognostic factor for overall survival and BCR-free survival of patients with PCa.

CONCLUSIONS

NUCB2 protein expression showed a strong association with the potencies of BCR and progression of PCa, and that may be applied as a novel biomarker for the prediction of BCR, and helpful for improving the diagnosis, prognosis and treatment of PCa.

Polymorphisms in DNA-repair genes in a cohort of prostate cancer patients from different areas in Spain: heterogeneity between populations as a confounding factor in association studies

Background

Differences in the distribution of genotypes between individuals of the same ethnicity are an important confounder factor commonly undervalued in typical association studies conducted in radiogenomics.

Objective

To evaluate the genotypic distribution of SNPs in a wide set of Spanish prostate cancer patients for determine the homogeneity of the population and to disclose potential bias.

Design, Setting, and Participants

A total of 601 prostate cancer patients from Andalusia, Basque Country, Canary and Catalonia were genotyped for 10 SNPs located in 6 different genes associated to DNA repair: XRCC1 (rs25487, rs25489, rs1799782), ERCC2 (rs13181), ERCC1 (rs11615), LIG4 (rs1805388, rs1805386), ATM (rs17503908, rs1800057) and P53 (rs1042522). The SNP genotyping was made in a Biotrove OpenArray® NT Cycler.

Outcome Measurements and Statistical Analysis

Comparisons of genotypic and allelic frequencies among populations, as well as haplotype analyses were determined using the web-based environment SNPator. Principal component analysis was made using the SnpMatrix and XSnpMatrix classes and methods implemented as an R package. Non-supervised hierarchical cluster of SNP was made using MultiExperiment Viewer.

Results and Limitations

We observed that genotype distribution of 4 out 10 SNPs was statistically different among the studied populations, showing the greatest differences between Andalusia and Catalonia. These observations were confirmed in cluster analysis, principal component analysis and in the differential distribution of haplotypes among the populations. Because tumor characteristics have not been taken into account, it is possible that some polymorphisms may influence tumor characteristics in the same way that it may pose a risk factor for other disease characteristics.

Conclusion

Differences in distribution of genotypes within different populations of the same ethnicity could be an important confounding factor responsible for the lack of validation of SNPs associated with radiation-induced toxicity, especially when extensive meta-analysis with subjects from different countries are carried out.

Alpha-tomatine attenuation of in vivo growth of subcutaneous and orthotopic xenograft tumors of human prostate carcinoma PC-3 cells is accompanied by inactivation of nuclear factor-kappa B signaling

Background

Nuclear factor-kappa B (NF-κB) plays a role in prostate cancer and agents that suppress its activation may inhibit development or progression of this malignancy. Alpha (α)-tomatine is the major saponin present in tomato (Lycopersicon esculentum) and we have previously reported that it suppresses tumor necrosis factor-alpha (TNF-α)-induced nuclear translocation of nuclear factor-kappa B (NF-κB) in androgen-independent prostate cancer PC-3 cells and also potently induces apoptosis of these cells. However, the precise mechanism by which α-tomatine suppresses NF-κB nuclear translocation is yet to be elucidated and the anti-tumor activity of this agent in vivo has not been examined.

Methodology/ Principal Findings

In the present study we show that suppression of NF-κB activation by α-tomatine occurs through inhibition of I kappa B alpha (IκBα) kinase activity, leading to sequential suppression of IκBα phosphorylation, IκBα degradation, NF-κB/p65 phosphorylation, and NF-κB p50/p65 nuclear translocation. Consistent with its ability to induce apoptosis, α-tomatine reduced TNF-α induced activation of the pro-survival mediator Akt and its inhibition of NF-κB activation was accompanied by significant reduction in the expression of NF-κB-dependent anti-apoptotic (c-IAP1, c-IAP2, Bcl-2, Bcl-xL, XIAP and survivin) proteins. We also evaluated the antitumor activity of α-tomatine against PC-3 cell tumors grown subcutaneously and orthotopically in mice. Our data indicate that intraperitoneal administration of α-tomatine significantly attenuates the growth of PC-3 cell tumors grown at both sites. Analysis of tumor material indicates that the tumor suppressing effects of α-tomatine were accompanied by increased apoptosis and lower proliferation of tumor cells as well as reduced nuclear translocation of the p50 and p65 components of NF-κB.

Conclusion/ Significance

Our study provides first evidence for in vivo antitumor efficacy of α-tomatine against the human androgen-independent prostate cancer. The potential usefulness of α-tomatine in prostate cancer prevention and therapy requires further investigation.

Impact of applied progressive deep muscle relaxation training on the health related quality of life among prostate cancer patients--a quasi experimental trial

PURPOSE

To determine the impact of applied progressive muscle relaxation training on health related quality of life among prostate cancer patients.

METHOD

A quasi-experimental study was conducted at the University Malaya Medical Centre (UMMC) and Universiti Kebangsaan Malaysia Medical Centre (UKMMC) over six months. Patients from UMMC received the intervention and patients from UKMMC as a comparison group. The general health related quality of life was measured using Short Form-36 (SF-36).

RESULTS

A total of 77 patients from the intervention group and 78 patients from the comparison group participated in the study. At the end of the study, only 90.9% in intervention group and 87.2% in comparison group completed the study. There were significant differences between intervention and comparison groups for mental component summary (MCS) (p=0.032) and overall health related quality of life (p=0.042) scores. However, there was no significant difference between groups for physical component summary (PCS) (p=0.965).

CONCLUSION

The improvement in MCS and overall QOL showed the potential of APMRT in the management of prostate cancer patients. Future studies should be carried out over a longer duration to provide stronger evidence for the introduction of relaxation therapy among prostate cancer patients as a coping strategy to improve their QOL.

A joint effect of new Western diet and retinoid X receptor α prostate-specific knockout with development of high-grade prostatic intraepithelial neoplasia in mice--a preliminary study

BACKGROUND

The "New Western-style Diet" (NWD) characterized by high in fat and low in fiber, vitamin D, calcium, and methyl donors--are considered as a risk factor for prostate cancer. Previous studies have shown that premalignant lesions of human prostate have decreased expression of the Retinoid X Receptor alpha (RXRα). This study was to determine the effect of diet in RXRα knockout mice in developing high-grade prostate intraepithelial neoplasia (mPIN).

METHODS

Male mice (n = 54) with or without the RXRα prostate null mutation were fed either NWD or AIN-76A control diet for 10 months; prostates were harvested at 11 months of age and examined for prostate mPIN.

RESULTS

mPIN was seen in 79% of RXRα prostate null mice fed NWD (n = 19), 30.8% RXRα prostate null mice fed AIN-76A (n = 13), 42.9% RXRα wild-type mice fed NWD (n = 14), and 12.5% RXRα wild-type mice fed AIN-76A (n = 8). Unconditional Logistic analysis showed a significant joint effect of NWD and RXRα status in developing mPIN 26.3 (95% CI: 2.5-280), but interaction was not significant owing to the small sample size 1.6 (0.09-27.7, P = 0.7441).

CONCLUSION

This study provides preliminary data to support a joint RXRα-diet effect in prostate carcinogenesis.

Small interfering RNA targeting HMGN5 induces apoptosis via modulation of a mitochondrial pathway and Bcl-2 family proteins in prostate cancer cells

We investigated the importance of HMGN5, a nuclear protein that binds to nucleosomes, unfolds chromatin, and affects transcription, in the LNCaP prostate cancer cell line. We also examined the molecular mechanisms that promote apoptosis of LNCaP cells after infection with small interfering RNA (siRNA) targeting HMGN5 (siRNA-HMGN5). The androgen-dependent LNCaP human prostate cancer cells were infected with siRNA-HMGN5. Apoptosis was detected using the Annexin V-PE/7-AAD double staining and the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assays. Mitochondrial membrane potential was measured by JC-1 staining. HMGN5 and GAPDH mRNA expression were determined using real-time PCR. Bcl-2 and other apoptosis-related protein levels were determined by Western blot analysis. Caspase activity was measured by cleavage of the caspase substrate. Infection with siRNA targeting HMGN5 efficiently and specifically reduced the HMGN5 expression in LNCaP cells. The downregulation of HMGN5 induced remarkable apoptosis of LNCaP cells and resulted in the reduction of mitochondrial membrane potential. The induction of cell apoptosis was accompanied by the upregulation of Bax, the Bax/Bcl-2 ratio and the activation of caspase3. The HMGN5-targeted siRNA was effective in downregulating the expression of HMGN5 in androgen-dependent prostate cancer cells and inducing cell apoptosis via the regulation of a caspase-related mitochondrial pathway and Bcl-2 family proteins. This study suggests that HMGN5 may be a potential molecular target with therapeutic relevance for the treatment of prostate cancer.

Combination therapy of antiandrogen and XIAP inhibitor for treating advanced prostate cancer

PURPOSE

Overexpression of the androgen receptor (AR) and anti-apoptotic genes including X-linked inhibitor of apoptosis protein (XIAP) provide tumors with a proliferative advantage. Therefore, our objective was to determine whether novel antiandrogen (CBDIV17) and XIAP inhibitor based combination therapy can treat advanced prostate cancer.

METHODS

CBDIV17 and embelin-6g were synthesized and their effect on cell proliferation, apoptosis, cell cycle and AR and XIAP gene silencing determined.

RESULTS

CBDIV17 was more potent than bicalutamide and inhibited proliferation of C4-2 and LNCaP cells, IC(50) for CBDIV17 was ≈ 12 μM and ≈ 21 μM in LNCaP and C4-2 cells, respectively, whereas bicalutamide had IC(50) of ≈ 46 μM in LNCaP cells and minimal effect in C4-2 cells. CBDIV17 induced apoptosis more effectively compared to bicalutamide and significantly inhibited DNA replication. Combination of CBDIV17 and embelin resulted in supra-additive antiproliferative and apoptotic effects. Embelin downregulated AR expression and decreased androgen-mediated AR phosphorylation at Ser(81). These hydrophobic drugs were solubilized using micelles prepared with polyethylene glycol-b-poly (carbonate-co-lactide) (PEG-b-p(CB-co-LA)) copolymer. Combination therapy inhibited prostate tumor growth more effectively compared to control or monotherapy in vivo.

CONCLUSIONS

Our results demonstrated that CBDIV17 in combination with embelin can potentially treat advanced prostate cancer.

Age related changes in selenium and glutathione levels in different lobes of the rat prostate

Aging represents a major risk factor for prostate cancer; however, mechanisms responsible for this relationship remain unclear. Preclinical and some clinical investigations support the protective role of selenium against prostate cancer possibly through the reduction of oxidative stress. While increased levels of oxidative stress together with decreases in selenium and the major cellular antioxidant glutathione (GSH) are common in tissues of old animals, there is little data available on these parameters in the prostate. In the present study we have compared the levels of selenium, GSH and protein-bound GSH (GSSP) in blood and prostate tissues in young (4-month), mature (12-month), old (18 month), and very old (24 month) male F344 rats. Each prostate lobe (dorsolateral, DL; anterior, AL; ventral, VL) was analyzed separately based upon their differing potential for prostate cancer development. At all ages, selenium levels were lowest in DL<VL<AL. After 12 mo, an 85% reduction in selenium in the DL was observed (P<0.05), while levels in other lobes were unchanged. In animals of all ages, levels of GSH were lowest in the VL<DL=AL and no significant changes were observed in GSH levels by 18 mo. However, GSSP, a marker of oxidative stress, was increased 90% after 18 mo in the DL only (P<0.01). These findings of age-related changes in GSSP and selenium in the DL prostate are consistent with the sensitivity of this lobe to carcinogenesis and, thus, may be playing a mechanistic role.

Antiandrogenic and growth inhibitory effects of ring-substituted analogs of 3,3'-diindolylmethane (ring-DIMs) in hormone-responsive LNCaP human prostate cancer cells

BACKGROUND

Cruciferous vegetables protect against prostate cancer. Indole-3-carbinol (I3C) and its major metabolite 3,3'-diindolylmethane (DIM), exhibit antitumor activities in vitro and in vivo. Several synthetic ring-substituted dihaloDIMs (ring-DIMs) appear to have increased anticancer activity.

METHODS

Inhibition of LNCaP prostate cancer cell growth was measured by a WST-1 cell viability assay. Cytoplasmic and nuclear proteins were analyzed by immunoblotting and immunofluorescence. Androgen receptor (AR) activation was assessed by measuring prostate-specific antigen (PSA) expression and using LNCaP cells containing human AR and an AR-dependent probasin promoter-green fluorescent protein (GFP) construct.

RESULTS

Like DIM, several ring-substituted dihaloDIM analogs, namely 4,4'-dibromo-, 4,4'-dichloro-, 7,7'-dibromo-, and 7,7'-dichloroDIM, significantly inhibited DHT-stimulated growth of LNCaP cells at concentrations ≥1 µM. We observed structure-dependent differences for the effects of the ring-DIMs on AR expression, nuclear AR accumulation and PSA levels in LNCaP cells after 24 hr. Both 4,4'- and 7,7'-dibromoDIM decreased AR protein and mRNA levels, whereas 4,4'- and 7,7'-dichloroDIM had minimal effect. All four dihaloDIMs (10 and 30 µM) significantly decreased PSA protein and mRNA levels. Immuofluorescence studies showed that only the dibromoDIMs increased nuclear localization of AR. All ring-DIMs caused a concentration-dependent decrease in fluorescence induced by the synthetic androgen R1881 in LNCaP cells transfected with wild-type human AR and an androgen-responsive probasin promoter-GFP gene construct, with potencies up to 10-fold greater than that of DIM.

CONCLUSION

The antiandrogenic effects of ring-DIMs suggest they may form the basis for the development of novel agents against hormone-sensitive prostate cancer, alone or in combination with other drugs.

Molecular mechanisms of A3 adenosine receptor-induced G1 cell cycle arrest and apoptosis in androgen-dependent and independent prostate cancer cell lines: involvement of intrinsic pathway

PURPOSE

A3 adenosine receptor has shown several physiological and pathological activities, including cell proliferation and apoptosis in various cancer cell lines. This study is designed to investigate molecular mechanism and apoptotic pathway of A3 adenosine receptor in DU-145, PC3 and LNcap-FGC10 human prostate cancer cells.

METHODS

The expression level of A3 adenosine receptor was examined using real-time RT-PCR. cAMP concentration was also measured. MTT viability, cell counting and BrdU incorporation tests were used to study the cell proliferation effect of IB-MECA. Cell cycle analysis, Annexin V-FITC staining, Hoechst 33258 staining, mitochondrial membrane potential (ΔΨM), caspase-3 activity, Bcl-2 and Bax protein expression were used to detect apoptosis.

RESULT

A3 adenosine receptors mRNAs were detected at different levels. IB-MECA inhibited forskolin-stimulated cAMP. IB-MECA at (1 μM) suppressed cell proliferation and induced G1 cell cycle arrest. Indeed, IB-MECA down-regulated the expression of CDK4, cyclin D1 and up-regulated p53 expression. IB-MECA at (10-100 μM) induced apoptosis. The activity of caspase-3 was also increased. Expression of Bcl-2 was decreased in response to IB-MECA, while the expression of Bax protein was increased. The results showed a significant loss of ΔΨM, in a dose-dependent manner.

CONCLUSION

This study introduces a possible mechanism through A3 adenosine receptor activation. IB-MECA inhibited prostate cancer cells proliferation and induced G1 cell cycle arrest through p53, Cdk4/cyclinD1 pathway. Apoptosis determined by characteristic morphological changes and increased in sub-G1 population. Loss of MMP, activation of caspase-3 and down-regulation of Bcl-2 expression indicated mitochondrial signaling pathway that involved in the apoptosis.

d -Limonene sensitizes docetaxel-induced cytotoxicity in human prostate cancer cells: Generation of reactive oxygen species and induction of apoptosis

BACKGROUND

Clinical trials have shown that docetaxel combined with other novel agents can improve the survival of androgen-independent prostate cancer patients. d -Limonene, a non-nutrient dietary component, has been found to inhibit various cancer cell growths without toxicity. We sought to characterize whether a non-toxic dose of d -limonene may enhance tumor response to docetaxel in an in vitro model of metastatic prostate cancer.

MATERIALS AND METHODS

Human prostate carcinoma DU-145 and normal prostate epithelial PZ-HPV-7 cells were treated with various concentrations of d -limonene, docetaxel or a combination of both, and cell viability was determined by MTT assay. Intracellular reactive oxygen species (ROS), reduced glutathione (GSH) and caspase activity were measured. Apoptosis and apoptosis-related proteins were studied by enzyme-linked immunosorbent assay and Western blotting, respectively.

RESULTS

d -Limonene and docetaxel in combination significantly enhanced the cytotoxicity to DU-145 cells than PZ-HPV-7 cells. Exposure of DU-145 cells to a combined d -limonene and docetaxel resulted in higher ROS generation, depletion of GSH, accompanied by increased caspase activity than docetaxel alone. It also triggered a series of effects involving cytochrome c , cleavages of caspase-9, 3 and poly (ADP-ribose) polymerase, and a shift in Bad:Bcl-xL ratio in favor of apoptosis. Apoptotic effect was significantly blocked on pretreatment with N -acetylcystein, indicating that antitumor effect is initiated by ROS generation, and caspase cascades contribute to the cell death.

CONCLUSION

Our results show, for the first time, that d -limonene enhanced the antitumor effect of docetaxel against prostate cancer cells without being toxic to normal prostate epithelial cells. The combined beneficial effect could be through the modulation of proteins involved in mitochondrial pathway of apoptosis. d -Limonene could be used as a potent non-toxic agent to improve the treatment outcome of hormone-refractory prostate cancer with docetaxel.

Pharmacologic disruption of Polycomb Repressive Complex 2 inhibits tumorigenicity and tumor progression in prostate cancer

Background

Polycomb repressive complex 2 (PRC2) mediates gene silencing through histone H3K27 methylation. PRC2 components are over-expressed in metastatic prostate cancer (PC), and are required for cancer stem cell (CSC) self-renewal. 3-Dezaneplanocin-A (DZNeP) is an inhibitor of PRC2 with broad anticancer activity.

Method

we investigated the effects of DZNeP on cell proliferation, tumorigenicity and invasive potential of PC cell lines (LNCaP and DU145).

Results

Exploring GEO and Oncomine databases, we found that specific PRC2 genes (EED, EZH2, SUZ12) predict poor prognosis in PC. Non-toxic DZNeP concentrations completely eradicated LNCaP and DU145 prostatosphere formation, and significantly reduced the expression of CSC markers. At comparable doses, other epigenetic drugs were not able to eradicate CSCs. DZNeP was also able to reduce PC cell invasion. Cells pre-treated with DZNeP were significantly less tumorigenic (LNCaP) and formed smaller tumors (DU145) in immunocompromised mice.

Conclusion

DZNeP is effective both in vitro and in vivo against PC cells. DZNeP antitumor activity is in part mediated by inhibition of CSC tumorigenic potential.

BMI1 silencing enhances docetaxel activity and impairs antioxidant response in prostate cancer

The BMI1 oncogene promotes prostate cancer (PC) progression. High B-cell-specific Moloney murine leukemia virus integration site 1 (BMI1) expression predicts poor prognosis in PC patients. Recent evidence suggests that BMI1 may also play a role in docetaxel chemoresistance. However, mechanisms and clinical significance of BMI1-related chemoresistance have not been investigated. For this purpose, BMI1 was silenced in 2 PC cell lines (LNCaP and DU 145). Cell proliferation and apoptosis after docetaxel treatment were measured. Guanine oxidation was assessed by in-cell western. Global gene expression analysis was performed on BMI1 silenced cells. Oncomine database was used to compare in vitro data with gene expression in PC samples. BMI1 silencing had no effect on cell proliferation but significantly enhanced docetaxel-induced antitumor activity. Gene expression analysis demonstrated that BMI1 silencing downregulates a set of antioxidant genes. Docetaxel treatment increased guanine oxidation, whereas the antioxidant N-acetyl cysteine rescued docetaxel-induced cell death. Examination of clinical datasets revealed a positive correlation of BMI1 and antioxidant gene expression. BMI1-controlled antioxidant genes were predictive of poor prognosis in PC patients. In conclusion, BMI1 enhances antioxidant response, thereby allowing PC survival after docetaxel-based chemotherapy. BMI1-controlled antioxidant genes are overexpressed in aggressive PC and should be tested as predictors of chemotherapy failure.

Zinc status of patients with benign prostatic hyperplasia and prostate carcinoma

OBJECTIVES

The exact cause of benign prostatic hyperplasia (BPH) and prostatic carcinoma is unknown. Changes in the level of the trace element zinc (Zn) are known to be associated with the functioning of different organs (breast, colon, stomach, liver, kidney, prostate, and muscle). This study is aimed at estimating and comparing the zinc levels in the prostate tissue, plasma, and urine obtained from patients diagnosed with BPH or prostatic carcinoma.

MATERIALS AND METHODS

The prostate tissue zinc, plasma zinc, and urine zinc/creatinine ratio in BPH, prostate cancer, and normal subjects were measured by atomic absorption spectrophotometry.

RESULTS

In prostate carcinoma, the mean tissue zinc was decreased by 83% as compared to normal tissue and in BPH, there was a 61% decrease in mean tissue zinc as compared to normal tissues. Both these values were statistically significant. The plasma zinc in prostate cancer patients showed a 27% decrease (P < 0.01) as compared to controls and 18% decrease (P < 0.01) as compared to BPH. The urine zinc/creatinine (ratio) was significantly increased to 53% in prostate cancer patients, and a 20% significant increase was observed in BPH as compared to normal subjects.

CONCLUSIONS

It is evident from this study that BPH or prostate carcinoma may be associated with a reduction in the levels of tissue zinc, plasma zinc, and an increase in urine zinc/creatinine.

Glycan characterization of PSA 2-DE subforms from serum and seminal plasma

Prostate-specific antigen (PSA) two-dimensional electrophoresis (2-DE) subforms (F1-F5) have been described to be altered in prostate cancer (PCa) compared to benign prostatic hyperplasia (BPH). To understand their molecular differences, characterization of these subforms from PCa serum and seminal plasma, namely, at the glycan level, was performed. PSA 2-DE subforms from two serum PCa samples and seminal plasma were analyzed by N-glycan sequencing using high-performance liquid chromatography (HPLC) combined with exoglycosidase array digestions and by mass spectrometry. F1, F2, and F3 subforms showed the same N-glycan pattern, which contained higher levels of sialic acid than the F4 subform, whereas the F5 subform was unglycosylated. When comparing PSA subforms from PCa with seminal plasma, a decrease in sialylation was observed. Furthermore, the analysis of F3, the more abundant PSA subform, showed a higher proportion of alpha 2-3 sialic acid and a decrease in core fucosylated glycans in the PCa sample. These N-glycan changes in PCa PSA subforms highlight the importance of glycosylation as an indicator of PCa disease.

Novel targets for prostate cancer chemoprevention

Among many endocrine-related cancers, prostate cancer (PCa) is the most frequent male malignancy, and it is the second most common cause of cancer-related death in men in the United States. Therefore, this review focuses on summarizing the knowledge of molecular signaling pathways in PCa because, in order to better design new preventive strategies for the fight against PCa, documentation of the knowledge on the pathogenesis of PCa at the molecular level is very important. Cancer cells are known to have alterations in multiple cellular signaling pathways; indeed, the development and the progression of PCa are known to be caused by the deregulation of several selective signaling pathways such as the androgen receptor, Akt, nuclear factor-kappaB, Wnt, Hedgehog, and Notch. Therefore, strategies targeting these important pathways and their upstream and downstream signaling could be promising for the prevention of PCa progression. In this review, we summarize the current knowledge regarding the alterations in cell signaling pathways during the development and progression of PCa, and document compelling evidence showing that these are the targets of several natural agents against PCa progression and its metastases.

Burden of prostate cancer in southwestern Nigeria

OBJECTIVES

To determine the pattern of presentation, prevalent age, hospital incidence, and outcome of management of prostate cancer in our environment.

METHOD

Patients with histopathology evidence of prostate cancer managed between January 1991 and December 2007 were studied. Information entered into a pro-forma sheet and analyzed included the age of patients, clinical features, investigations, histopathology diagnosis, outcome of management, and duration of follow-up.

RESULTS

During the period, 189 patients aged 46-99 years (mean, 68.0; 9.8 SD) confirmed and managed for prostate cancer were studied. The average hospital incidence (2002-2004) was 182.5 per 10(5) male admissions with 15.1-month mean duration of symptoms. Most 178 (94.2%) patients presented with advanced diseases, with 1 or multiple complications in 172 (91.0%), obstructive lower urinary tract symptoms 156 (82.5%), distant metastasis 97 (51.3%), lower back pain 95 (50.3%), weight loss 95 (50.3%), hematuria 86 (45.5%), anemia 77 (40.7%), renal failure 74 (39.2%), and inability to walk 42 (22.2%). Eighty-nine (47.0%) patients were farmers, 111 (58.7%) indulged in alcohol, and 46 (24.3%) smoked cigarettes. Mean prostate-specific antigen results available in 53 patients was 106.0 ng/mL (187.2SD) and digital rectal examination was valuable in diagnosis. Adenocarcinoma (186 [98.4%]) was the main histopathology type and most patients 136 (71.9%) had bilateral orchidectomy with or without antiandrogens. Mean duration of follow-up was 83.7 weeks.

CONCLUSIONS

The burden of prostate cancer in our developing community is worrisome. It is prevalent between 46 and 99 years in our community. Presentation is late, often with urinary retention and other complications. In our setting, treatment is still essentially palliative with orchidectomy, which we found to be beneficial, acceptable, and the most affordable to our patients.

Optoacoustic imaging of the prostate: development toward image-guided biopsy

Optoacoustic (OA) tomography has demonstrated utility in identifying blood-rich malignancies in breast tissue. We describe the development and characterization of a laser OA imaging system for the prostate (LOIS-P). The system consists of a fiber-coupled Q-switched laser operating at 757 nm, a commercial 128-channel ultrasonic probe, a digital signal processor, and software that uses the filtered radial back-projection algorithm for image reconstruction. The system is used to reconstruct OA images of a blood-rich lesion induced in vivo in a canine prostate. OA images obtained in vivo are compared to images acquired using ultrasound, the current gold standard for guiding biopsy of the prostate. Although key structural features such as the urethra could be identified with both imaging techniques, a bloody lesion representing a highly vascularized tumor could only be clearly identified in OA images. The advantages and limitations of both forward and backward illumination modes are also evaluated by collecting OA images of phantoms simulating blood vessels within tissue. System resolution is estimated to be 0.2 mm in the radial direction of the acoustic array. The minimum detectable pressure signal is 1.83 Pa. Our results encourage further development toward a dual-modality OA/ultrasonic system for prostate imaging and image-guided biopsy.

Differential percentage of serum prostate-specific antigen subforms suggests a new way to improve prostate cancer diagnosis

BACKGROUND

Prostate-specific antigen (PSA) is the tumor marker currently used for prostate cancer (PCa) screening and diagnosis. However, its use is controversial as serum PSA levels are also increased in other non-malignant prostatic diseases such as benign prostatic hyperplasia (BPH). PSA sialic acid content is altered in tumor situation and modifies PSA's isoelectric point (pI). Our goal has been to evaluate serum PSA subforms from PCa and BPH patients by two-dimensional electrophoresis (2-DE) and to investigate whether they could be used to improve PCa diagnosis.

METHODS

PSA from 20 PCa and 20 BPH patients' sera was subjected to a four-step method to obtain serum PSA 2-DE subforms from free PSA (fPSA) plus PSA released from the complex with alpha-1-antichymotrypsin. Relative percentages of PSA spots were quantified and subjected to statistical analysis.

RESULTS

Five PSA subforms (F1, F2, F3, F4, and F5) of different pI were obtained. Relative percentages of F3 (%F3) and F4 (%F4) were different between PCa and BPH groups. %F3 decreased in cancers and this decrease correlated with the cancer stage, while F4 behaved oppositely. These observations were also found when only focusing on the patients within the low total PSA (tPSA) range 2-20 ng/ml.

CONCLUSIONS

%F3 showed a tendency of higher sensitivity and specificity than the currently used tPSA and %fPSA tests. Therefore, %F3 measurement should be investigated in a larger cohort of patients to study whether it could be introduced to improve PCa diagnosis.

KG-135, enriched with selected ginsenosides, inhibits the proliferation of human prostate cancer cells in culture and inhibits xenograft growth in athymic mice

Sun ginseng (SG) was recently developed as a heat-processed form of ginseng. The Rg3, Rk1, and Rg5 ginsenosides are its main ginsenoside components. SG has been reported to have more potent pharmacological activities than red ginseng (RG), where these pharmacological activities include vasodilatory, anti-oxidant and anti-tumorigenic effects. In the present study, we investigated KG-135, the ginsenoside-rich fraction of SG and demonstrated that this fraction inhibits proliferation of human prostate cancer cells both in vitro and in vivo. KG-135 caused a significant growth inhibition of DU145 and PC-3 human prostate cancer cells. KG-135 induced cell cycle arrest in the G1 phase and caused an associated increase in the p21(Cip1) protein levels. When KG-135 was fed to mice that had been xenografted with DU145 tumors, a time-dependent inhibition of tumor growth was noted without any observed toxicity. Immunohistochemical analysis of the tumor tissues showed that KG-135 led to a decrease in the expression of proliferating cell nuclear antigen (PCNA). Microarray analysis of the tumors revealed that KG-135 inhibited tumor growth and also caused changes in the expression levels of multiple cancer-related genes. These data suggest that KG-135 effectively inhibits prostate cancer cell proliferation. Its mechanism of action likely involves cyclin inhibition and regulation of the expression of the TNFRSF25 and ADRA2A genes.

Inhibition of prostate cancer cell growth by second-site androgen receptor antagonists

The impact of ligand binding on nuclear receptor (NR) structure and the ability of target cells to distinguish between different receptor-ligand complexes are key determinants of the pharmacological activity of NR ligands. However, until relatively recently, these mechanistic insights have not been used in a prospective manner to develop screens for NR modulators with specific therapeutic activities. Driven by the need for unique androgen receptor (AR) antagonists that retain activity in hormone-refractory prostate cancer, we developed and applied a conformation-based screen to identify AR antagonists that were mechanistically distinct from existing drugs of this class. Two molecules were identified by using this approach, D36 and D80, which interact with AR in a unique manner and allosterically inhibit AR agonist activity. Unlike the clinically important antiandrogens, casodex and hydroxyflutamide, both D36 and D80 block androgen action in cellular models of hormone-refractory prostate cancer. Mechanistically, these compounds further distinguish themselves from classical AR antagonists in that they do not promote AR nuclear translocation and quantitatively inhibit the association of AR with DNA even under conditions of overexpression. Although the therapeutic potential of these antiandrogens is apparent, it is the demonstration that it is possible, to modulate the interaction of cofactors with agonist-activated AR, using second-site modulators, that has the greatest potential with respect to the therapeutic exploitation of AR and other NRs.

Intratumoral delivery of beta-lapachone via polymer implants for prostate cancer therapy

PURPOSE

beta-Lapachone (ARQ 501, a formulation of beta-lapachone complexed with hydroxypropyl-beta-cyclodextrin) is a novel anticancer agent with selectivity against prostate cancer cells overexpressing the NAD(P)H:quinone oxidoreductase-1 enzyme. Lack of solubility and an efficient drug delivery strategy limits this compound in clinical applications. In this study, we aimed to develop beta-lapachone-containing polymer implants (millirods) for direct implantation into prostate tumors to test the hypothesis that the combination of a tumor-specific anticancer agent with site-specific release of the agent will lead to significant antitumor efficacy.

EXPERIMENTAL DESIGN

Survival assays in vitro were used to test the killing effect of beta-lapachone in different prostate cancer cells. beta-Lapachone release kinetics from millirods was determined in vitro and in vivo. PC-3 prostate tumor xenografts in athymic nude mice were used for antitumor efficacy studies in vivo.

RESULTS

beta-Lapachone killed three different prostate cancer cell lines in an NAD(P)H:quinone oxidoreductase-1-dependent manner. Upon incorporation of solid-state inclusion complexes of beta-lapachone with hydroxypropyl-beta-cyclodextrin into poly(D,L-lactide-co-glycolide) millirods, beta-lapachone release kinetics in vivo showed a burst release of approximately 0.5 mg within 12 hours and a subsequently sustained release of the drug ( approximately 0.4 mg/kg/d) comparable with that observed in vitro. Antitumor efficacy studies showed significant tumor growth inhibition by beta-lapachone millirods compared with controls (P < 0.0001; n = 10 per group). Kaplan-Meier survival curves showed that tumor-bearing mice treated with beta-lapachone millirods survived nearly 2-fold longer than controls, without observable systemic toxicity.

CONCLUSIONS

Intratumoral delivery of beta-lapachone using polymer millirods showed the promising therapeutic potential for human prostate tumors.