Prostatic Carcinoma Cell Line LNCaP Research Articles

Overexpression of EGR-1 modulates the activity of NF-κB and AP-1 in prostate carcinoma PC-3 and LNCaP cell lines

To address elements that might uniquely characterize EGR-1 mediated signaling, the expression of two transcription factors, namely, nuclear factor kappa B (NF-κB) and activator protein-1 (AP-1) were studied. PC-3 and LNCaP prostate carcinoma cell lines were transiently transfected with wild-type Egr-1 expression plasmid (pCMV-Egr-1) and treated with cisplatin and TPA. Overexpression of EGR-1 was found to induce nuclear expression of both, NF-κB and AP1. However, the intensity of the induced AP-1 and NF-κB was diminished after cisplatin treatment, but not after TPA. Our findings confirm that the overexpression of wild-type Egr-1 caused a marked increase in cell proliferation in PC-3 and LNCaP proliferation in a 14-day soft agar colony forming assay. In addition, luciferase reporter gene assay showed that the transcriptional activity of AP-1 and NF-κB in PC-3 and LNCaP prostate carcinoma cell lines was also modulated by the overexpression of EGR-1 in these cells using tandem repeated Luc-AP-1 and Luc-NF-κB. The activation of both NF-κB and AP-1 are key steps in the cascade of events following the activation of the EGR-1 gene. It was revealed that overexpression of EGR-1 selectively increased AP-1 and NF-κB activation, and that the activation of these nuclear factors appears to be essential for the induction of proliferation and anchorage independence in activated PC-3 and LNCaP cells. However, the mechanism underlying the modulation of AP-1 and NF-κB by the overexpression of EGR-1 is still unknown.

Snail regulates cell survival and inhibits cellular senescence in human metastatic prostate cancer cell lines

The epithelial-mesenchymal transition (EMT) is regarded as an important step in cancer metastasis. Snail, a master regulator of EMT, has been recently proposed to act additionally as a cell survival factor and inducer of motility. We have investigated the function of Snail (SNAI1) in prostate cancer cells by downregulating its expression via short (21-mer) interfering RNA (siRNA) and measuring the consequences on EMT markers, cell viability, death, cell cycle, senescence, attachment, and invasivity. Of eight carcinoma cell lines, the prostate carcinoma cell lines LNCaP and PC-3 showed the highest and moderate expression of SNAI1 mRNA, respectively, as measured by quantitative RT-PCR. Long-term knockdown of Snail induced a severe decline in cell numbers in LNCaP and PC-3 and caspase activity was accordingly enhanced in both cell lines. In addition, suppression of Snail expression induced senescence in LNCaP cells. SNAI1-siRNA-treated cells did not tolerate detachment from the extracellular matrix, probably due to downregulation of integrin α6. Expression of E-cadherin, vimentin, and fibronectin was also affected. Invasiveness of PC-3 cells was not significantly diminished by Snail knockdown. Our data suggest that Snail acts primarily as a survival factor and inhibitor of cellular senescence in prostate cancer cell lines. We therefore propose that Snail can act as early driver of prostate cancer progression.

Oncolytic Viral Therapy for Prostate Cancer: Efficacy of Reovirus as a Biological Therapeutic

Reovirus is a nonattenuated double-stranded RNA virus that exploits aberrant signaling pathways allowing selective cytotoxicity against multiple cancer histologies. The use of reovirus as a potential treatment modality for prostate cancer has not previously been described, and in this study evidence of in vitro and in vivo activity against prostate cancer was seen both in preclinical models and in six patients. The human prostate carcinoma cell lines PC-3, LN-CaP, and DU-145 exposed to replication-competent reovirus showed evidence of infection as illustrated by viral protein synthesis, cytopathic effect, and release of viral progeny. This oncolytic effect was found to be manifested through apoptosis, as DNA fragmentation, Apo 2.7 expression, Annexin V binding, and poly(ADP-ribose) polymerase cleavage were observed in live reovirus-infected cells, but not in uninfected or dead virus-treated cells. In vivo, hind flank severe combined immunodeficient/nonobese diabetic murine xenograft showed reduction in tumor size when treated with even a single intratumoral injection of reovirus. Finally, intralesional reovirus injections into a cohort of six patients with clinically organ-confined prostate cancer resulted in minimal side effects and evidence of antitumor activity. Histologic analysis after prostatectomy found a significant CD8 T-cell infiltration within the reovirus-injected areas as well as evidence of increased caspase-3 activity. These findings suggest that reovirus therapy may provide a promising novel treatment for prostate cancer and also imply a possible role for viral immune targeting of tumor.

Pioglitazone modulates tumor cell metabolism and proliferation in multicellular tumor spheroids

The anti-diabetic thiazolidinedione compound pioglitazone, a peroxisome proliferator-activated receptor-gamma agonist, and selective cyclooxygenase-2 inhibitors are clinically used in patients with advanced malignancies. Several previously published in vivo and in vitro studies showed growth inhibitory effects on different cancer cell lines. However, the underlying mechanisms are fairly unclear. Here, we analyzed the effects of pioglitazone in combination with other drugs in a three-dimensional multicellular tumor spheroid culture system (MCTS) generated from the two prostate carcinoma cell lines PC3 and LNCaP. As expected, pioglitazone also inhibited tumor cell proliferation in the MCTS system. Further studies revealed that pioglitazone lowered the pH of the culture medium, decreased oxygen consumption and increased lactate secretion in both tumor cell lines. Other glitazones, troglitazone and ciglitazone, had similar effects. The combination of pioglitazone with 2-deoxyglucose, a potent inhibitor of glycolysis, had an additive effect on the inhibition of cell proliferation and led to MCTS disintegration. Our data propose a new mechanism of growth inhibition by pioglitazone through modulation of the tumor cell metabolism.

Culture of Explants from the Sponge Mycale cecilia to Obtain Bioactive Mycalazal-Type Metabolites

Natural products with promising biomedical properties have been described from sponges, but the problem of supply is usually a limiting factor for their pharmacological evaluation. Mycale cecilia produces an array of metabolites containing a pyrrole-2-carbaldehyde moiety (e.g., mycalazals and mycalenitriles) that have shown activity as growth inhibitors of the human prostate carcinoma cell line LNcaP. This study shows that the culture of M. cecilia is a viable method to supply mycalazals while protecting the wild population. Small implants were bound to ceramic tiles, and after 3 to 4days, the tissue samples formed a secure attachment. Subsequently, these explants were simultaneously cultured in their natural environment and in small tanks for 60days. Sponges in the tanks were fed a diet consisting of a mixture of two microalgae (Tetraselmis sp. and Isochrysis sp.) and powdered yeast Saccharomyces cerevisiae. The final survival of the explants differed significantly between the two farming methods: It was higher in the natural environment (95 ± 7.07%; overall mean ± standard error) than in the enclosed system (65 ± 21.21%). Growth was also higher than in the tanks, and after 60days, it increased to 207% in the sea and 65% in the tanks, which represented a daily increase of 3.5% and 1.5%, respectively. At the end of the trial, both the explants cultured in the sea and in the tanks retained the production of bioactive metabolites. The mean concentration of pyrrole-2-carbaldehyde derivatives in wild and cultured sponges was determined by (1)H-NMR. These results demonstrate that in-sea aquaculture of M. cecilia is a viable method for supplying the amounts of mycalazal-type compounds needed to advance the studies on their bioactivity.

Down-regulation of Egr-1 by siRNA inhibits growth of human prostate carcinoma cell line PC-3

The inhibitory effect of a specific small EGR-1 interfering RNA (siRNA) on cell proliferation and the expression of EGR-1 in human prostate carcinoma cell lines PC-3 and LNCaP was investigated. To knockdown Egr-1 expression, a siRNA targeting against Egr-1 was synthesized and transfected into PC-3 and LNCaP cells. The down-regulation of Egr-1 expression at both mRNA and protein levels were detected by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. The transcription activity was determined by luciferase expression. Cell proliferation inhibition rates were determined by soft agar and methyl thiazolyl tetrazolium (MTT) assay. The effect of Egr-1 siRNA on cell cycle distribution and cell apoptosis was determined by flow cytometry (FCM). RNA interference efficiently suppressed the Egr-1 expression in PC-3 and LNCaP cells. At 96 h after transfection, the expression inhibition rate was 44.52% at mRNA level detected by RT-PCR and 40.17% at protein level by Western blot analysis. The cell proliferation inhibition rates at 24, 48, 96 and 120 h after Egr-1 siRNA and non-silencing siRNA transfection, were 5, 25.06, 65.61 and 78.36%, respectively for PC-3 cells and 23, 40.3, 75.9 and 67.4%, respectively for LNCaP cells. The apoptosis rate was similar for both PC-3 and LNCaP and the number of cells was increased in G0/G1 phase from 38.2 to 88.6%, and decreased in S and G2/M phase at 96 h after transfection. Down-regulation of Egr-1 results in significant inhibition of tumor growth in vitro. The inhibition of Egr-1 expression can induce apoptosis of PC-3 cells. The use of Egr-1 siRNA deserves further investigation as a novel approach to cancer therapy.

Image-Based Assessment of Growth and Signaling Changes in Cancer Cells Mediated by Direct Cell-Cell Contact

BackgroundMany important biological processes are controlled through cell-cell interactions, including the colonization of metastatic tumor cells and the control of differentiation of stem cells within their niche. Despite the crucial importance of the cellular environment in regulating cellular signaling, in vitro methods for the study of such interactions are difficult and/or indirect.Methodology/Principal FindingsWe report on the development of an image-based method for distinguishing two cell types grown in coculture. Furthermore, cells of one type that are in direct contact with cells of a second type (adjacent cells) can be analyzed separately from cells that are not within a single well. Changes are evaluated using population statistics, which are useful in detecting subtle changes across two populations. We have used this system to characterize changes in the LNCaP prostate carcinoma cell line when grown in contact with human vascular endothelial cells (HUVECs). We find that the expression and phosphorylation of WWOX is reduced in LNCaP cells when grown in direct contact with HUVECs. Reduced WWOX signaling has been associated with reduced activation or expression of JNK and p73. We find that p73 levels are also reduced in LNCaP cells grown in contact with HUVECs, but we did not observe such a change in JNK levels.Conclusions/SignificanceWe find that the method described is statistically robust and can be adapted to a wide variety of studies where cell function or signaling are affected by heterotypic cell-cell contact. Ironically, a potential challenge to the method is its high level of sensitivity is capable of classifying events as statistically significant (due to the high number cells evaluated individually), when the biological effect may be less clear. The methodology would be best used in conjunction with additional methods to evaluate the biological role of potentially subtle differences between populations. However, many important events, such as the establishment of a metastatic tumor, occur through rare but important changes, and methods such as we describe here can be used to identify and characterize the contribution of the environment to these changes.

Conformationally Constrained Analogues of Diacylglycerol (DAG). 31. Modulation of the Biological Properties of Diacylgycerol Lactones (DAG-lactones) Containing Rigid-Rod Acyl Groups Separated from the Core Lactone by Spacer Units of Different Lengths

Diacylglycerol lactones built with a rigid 4-[(methylphenyl)ethynyl]phenyl rod that is separated from the exocyclic acylcarbonyl of the DAG-lactone core by a spacer unit of variable length were synthesized and studied. Binding affinities for a panel of classical and novel PKC isozymes in two different phospholipid environments, one corresponding to the plasma membrane of cells, were determined. The kinetics and site of translocation for the PKC isozymes α and δ upon treatment with the compounds were also studied as well as the early response of ERK phosphorylation and the late response of induction of apoptosis in the human prostatic carcinoma cell line LNCaP. Finally, the compounds were evaluated in terms of their interaction with biomimetic lipid/polydiacetylene membranes by the associated chromatic response. The different spatial disposition of the rigid structural motif on the DAG-lactones contributes to differential activity.

Expression and Clinical Significance of CD147 in Genitourinary Carcinomas

CD147/extracellular matrix metalloproteinase inducer (EMMPRIN) expressed by tumor cells stimulates peri-tumorous fibroblasts to produce matrix metalloproteinases (MMPs), thus contributing to tumor invasion and metastasis. To assess its suitability as a potential therapeutic target, as well as its association with the clinicopathologic features and the prognosis of patients, the expression of CD147/EMMPRIN in neoplastic tissues of the genitourinary system were analyzed. CD147/EMMPRIN expression in 52 patients with renal carcinoma, 58 patients with bladder carcinoma, 101 patients with prostate carcinoma, 17 patients of penis carcinoma, and 17 patients of testis carcinoma were examined by immunostaining on paraffin-embedded tumor specimens using monoclonal antibodies. Then, the association of its expression with clinicopathologic characteristics to the patients' prognosis was analyzed. The RNA interference approach was used to silence CD147/EMMPRIN expression in the human prostate carcinoma cell line LNCAP and human bladder carcinoma cell line J82. The in vitro proliferative ability of CD147/EMMPRIN-deficient cells was determined by a 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide MTT assay. CD147/EMMPRIN was expressed in neoplastic tissues, but not in normal tissues. Positive expression was shown in 42 of 52 (80.77%) of the patients with renal carcinoma, 41 of 58 (70.69%) of the patients with bladder carcinoma, 67 of 101 (66.34%) of the patients with prostate carcinoma, 16 of 17 (94.12%) of the patients with penis carcinoma and testis carcinoma. Positive CD147/EMMPRIN staining was significantly associated with TNM stages and histological subtypes of patients with various urinary carcinomas (P < 0.05). In all five groups, for different expression levels of CD147/EMMPRIN, the patients with a highly positive expression of CD147/EMMPRIN had the poorest prognosis. The siRNA-treated cells exhibited significantly decreased growth ability compared with control cells in vitro. These results may assist in defining the suitability of CD147/EMMPRIN as a therapeutic target and as a method for predicting a poor outcome in patients with various urinary carcinomas.

An investigation of fludarabine as a potential radiation sensitizer of human prostate cancer cells in vitro

AbstractAim: Patient relapse following radiotherapy for prostate cancer is of major concern to oncologists. As chemotherapeutic agents have shown promise as radiation sensitizers, we investigated the use of fludarabine monophosphate as a radiation enhancement agent in human LNCaP‐LN3, PC3 and LNCaP prostate carcinoma cell lines with different sensitivities to fludarabine and ionizing radiation.Methods: Cells were treated with non‐cytotoxic doses of fludarabine for 16 h pre‐irradiation or 5 days post‐irradiation; survival fractions were determined by clonogenic assay. Cell cycling was also assessed.Results: LNCaP‐LN3 cells incubated with 1 μmol/L fludarabine for 5 days post‐irradiation were slightly sensitized (1.18 times, P = 0.029), whilst 16 h pre‐incubation had no effect on the radiation response. PC3 cells incubated with 10 μmol/L fludarabine for 16 h pre‐irradiation were sensitized to ionizing radiation (1.61 times, P &lt; 0.0001), but treatment for 5 days post‐irradiation with fludarabine had no effect on their radiosensitivity. Neither fludarabine incubation had any effect on the sensitivity of LNCaP cells to ionizing radiation. A characterization of the cell cycle following 16 h exposure to fludarabine demonstrated that enhanced radiosensitivity of PC3 cells is independent of cell cycle.Conclusion: PC3, but not LN3 or LNCaP cells, were sensitized to ionizing radiation by pre‐incubation with 10 μmol/L fludarabine for 16 h (1.61 times, P &lt; 0.0001) but not by post‐irradiation exposure to the drug. The enhanced radiosensitivity of PC3 cells is independent of cell cycle. Further studies are required to elucidate the mechanism of fludarabine mediated sensitization in these cells.

Squalene Synthase, a Determinant of Raft-associated Cholesterol and Modulator of Cancer Cell Proliferation

Several cues for cell proliferation, migration, and survival are transmitted through lipid rafts, membrane microdomains enriched in sphingolipids and cholesterol. Cells obtain cholesterol from the circulation but can also synthesize cholesterol de novo through the mevalonate/isoprenoid pathway. This pathway, however, has several branches and also produces non-sterol isoprenoids. Squalene synthase (SQS) is the enzyme that determines the switch toward sterol biosynthesis. Here we demonstrate that in prostate cancer cells SQS expression is enhanced by androgens, channeling intermediates of the mevalonate/isoprenoid pathway toward cholesterol synthesis. Interestingly, the resulting increase in de novo synthesis of cholesterol mainly affects the cholesterol content of lipid rafts, while leaving non-raft cholesterol levels unaffected. Conversely, RNA interference-mediated SQS inhibition results in a decrease of raft-associated cholesterol. These data show that SQS activity and de novo cholesterol synthesis are determinants of membrane microdomain-associated cholesterol in cancer cells. Remarkably, SQS knock down also attenuates proliferation and induces death of prostate cancer cells. Similar effects are observed when cancer cells are treated with the chemical SQS inhibitor zaragozic acid A. Importantly, although the anti-tumor effect of statins has previously been attributed to inhibition of protein isoprenylation, the present study shows that specific inhibition of the cholesterol biosynthesis branch of the mevalonate/isoprenoid pathway also induces cancer cell death. These findings significantly underscore the importance of de novo cholesterol synthesis for cancer cell biology and suggest that SQS is a potential novel target for antineoplastic intervention.

Inhibition of cyclooxygenase-2 activity by celecoxib does not lead to radiosensitization of human prostate cancer cells in vitro

Purpose To evaluate the potential radiosensitizing effect of the specific COX-2 inhibitor celecoxib (Celebrex ®) on prostate carcinoma cells in vitro. Materials and methods The influence of celecoxib (concentration range 5 to 75 μM) on radiation-induced cellular and clonogenic survival was investigated in prostate carcinoma cell lines PC-3, DU145, LNCaP and normal prostate epithelial cells (PrEC). Western blot analysis and ELISA were used to determine the impact of radiation alone or radiation combined with celecoxib treatment on COX-2 expression and prostaglandin E2 synthesis. To evaluate induction of celecoxib-induced apoptosis cell cycle analysis has been performed. Results Celecoxib (5, 10 and 25 μM) in combination with single-dose irradiation of 2 Gy induced a significant radiosensitization in normal prostate epithelial cells which could not be observed for any of the prostate carcinoma cell lines investigated. Increased COX-2 protein expression in PC-3 cells was obvious only after IR with 15 Gy, while PGE 2 production was elevated following irradiation (2–15 Gy) in a dose-dependent manner. Treatment with celecoxib alone or in combination with IR led to a dose-dependent increase in COX-2 protein expression. Nevertheless pre-treatment with celecoxib caused a marked reduction of radiation-induced enzyme activity as tested at the level of PGE 2 production, both in PC-3 and DU145 cells. Following fractionated irradiation with single doses of 2 Gy, elevated COX-2 protein expression as well as enhanced PGE 2 production was observed already after the second fraction in PC-3 cells. Pre-treatment with celecoxib reduced the amount of PGE 2 significantly, but not of COX-2 protein. Conclusions Our data obtained for the human prostate cancer cell lines do not indicate that a marked inhibition of prostaglandin E2 synthesis by celecoxib leads to enhanced radiosensitization. Thus, in terms of radiosensitization the analysed prostate cancer cells can be classified as non-responders to celecoxib treatment.

Cell-line and tissue-specific signatures of androgen receptor-coregulator transcription

Normal genital skin fibroblasts (GSF) and the human prostate carcinoma cell line LNCaP have been used widely as cell culture models of genital origin to study androgen receptor (AR) signaling. We demonstrate that LNCaP shows a reproducible response to androgens as assessed using cDNA-microarrays representing approximately 32,000 unique human genes, whereas several independent GSF strains are virtually unresponsive. We show that LNCaP cells express markedly higher AR protein levels likely contributing to the observed differences of androgen responsiveness. However, previous data suggested that AR-expression levels alone do not determine androgen responsiveness of human GSF compared to LNCaP. We hypothesized that cell-specific differences in expression levels of AR coregulators might contribute to differences in androgen responsiveness and might be found by comparing LNCaP and GSFs. Using the Canadian McGill-database of AR coregulators ( http://www.mcgill.ca/androgendb ), we identified 61 AR-coregulator genes represented by 282 transcripts on our microarray platform that was used to measure transcript profiles of LNCaP and GSF cells. Baseline expression levels of 48 AR-coregulator transcripts representing 33 distinct genes showed significant differences between GSF and LNCaP, four of which we confirmed by reverse transcriptase polymerase chain reaction. Compared to LNCaP, GSFs displayed significant upregulation of AR coregulators that can function as repressors of AR-transactivation, such as caveolin 1. Analysis of a recently published comprehensive dataset of 115 microarrays representing 35 different human tissues revealed tissue-specific signatures of AR coregulators that segregated with ontogenetically related groups of tissues (e.g., lymphatic system and genital tissues, brain). Our data demonstrate the existence of cell-line and tissue-specific expression patterns of molecules with documented AR coregulatory functions. Therefore, differential expression patterns of AR coregulators could modify tissue-specificity and diversity of androgen actions in development, physiology, and disease.

Prostate tumor CXC-chemokine profile correlates with cell adhesion to endothelium and extracellular matrix

Though chemokines of the CXC family are thought to play key roles in neoplastic transformation and tumor invasion, information about CXC chemokines in prostate cancer is sparse. To evaluate the involvement of CXC chemokines in prostate cancer, we analyzed the CXC coding mRNA of both chemokine ligands (CXCL) and chemokine receptors (CXCR), using the prostate carcinoma cell lines PC-3, DU-145 and LNCaP. CXCR proteins were further evaluated by Western blot, CXCR surface expression by flow cytometry and confocal microscopy. The expression pattern was correlated to adherence of the tumor cells to an endothelial cell monolayer or to extracellular matrix components. Based on growth and adhesion capacity, PC-3 and DU-145 were identified to be highly aggressive tumor cells (PC-3 > DU-145), whereas LNCaP belonged to the low aggressive phenotype. CXCL1, CXCL3, CXCL5 and CXCL6 mRNA, chemokines with pro-angiogenic activity, were strongly expressed in DU-145 and PC-3, but not in LNCaP. CXCR3 and CXCR4 surface level differed in the following order: LNCaP > DU-145 > PC-3. The differentiation factor, fatty acid valproic acid, induced intracellular CXCR accumulation. Therefore, prostate tumor malignancy might be accompanied by enhanced synthesis of angiogenesis stimulating CXC chemokines. Further, shifting CXCR3 and CXCR4 from the cell surface to the cytoplasm might activate pro-tumoral signalling events and indicate progression from a low to a highly aggressive phenotype.

Differential expression of steroid receptors in prostate tissues before and after radiation therapy for prostatic adenocarcinoma

The expression, distribution and the role of steroid receptors in benign and malignant untreated prostate tissues is well recognized, however, the status of steroid receptors in prostate after radiotherapy (RT) for adenocarcinoma has not yet been studied fully. Immunohistochemical evaluation of androgen receptor (AR), estrogen receptor-alpha (ER-alpha), estrogen receptor-beta (ER-beta), and progesterone receptor (PR) was carried out in prostate needle biopsies obtained before and after radiotherapy from 60 patients with adenocarcinoma. The ER-beta transcripts were also studied by RT-PCR in LNCaP prostate carcinoma cell line before and 24 hr after gamma-irradiation at 0.5 Gy and 8.0 Gy. Significantly higher level of ER-beta expression was found in post-radiation samples of prostate adenocarcinoma and benign epithelium. After RT, all steroid receptors were upregulated in prostatic stroma. Tumor AR expression did not change significantly. Although a positive association between AR and ER-beta expression was observed in pre-treatment prostate adenocarcinoma, it was lost after RT suggesting that these 2 steroid receptors respond differently to RT. High levels of pretreatment tumor ER-beta were associated with local recurrence after RT and decreased biochemical recurrence-free survival (p = 0.028). LNCaP cell line that expressed no ER-beta mRNA before gamma-irradiation, clearly expressed ER-beta mRNA 24 hr after 0.5 Gy and 8.0 Gy. Upregulation of all steroid receptors in the prostate stroma and upregulation of ER-beta in the tumor epithelium after RT, may represent a protective tissue response to radiation-induced tissue injury. Although stromal AR was doubled after RT, the tumor and benign epithelium expression of AR seemed resistant to change by RT.

Milk Thistle and Prostate Cancer: Differential Effects of Pure Flavonolignans from Silybum marianum on Antiproliferative End Points in Human Prostate Carcinoma Cells

Extracts from the seeds of milk thistle, Silybum marianum, are known commonly as silibinin and silymarin and possess anticancer actions on human prostate carcinoma in vitro and in vivo. Seven distinct flavonolignan compounds and a flavonoid have been isolated from commercial silymarin extracts. Most notably, two pairs of diastereomers, silybin A and silybin B and isosilybin A and isosilybin B, are among these compounds. In contrast, silibinin is composed only of a 1:1 mixture of silybin A and silybin B. With these isomers now isolated in quantities sufficient for biological studies, each pure compound was assessed for antiproliferative activities against LNCaP, DU145, and PC3 human prostate carcinoma cell lines. Isosilybin B was the most consistently potent suppressor of cell growth relative to either the other pure constituents or the commercial extracts. Isosilybin A and isosilybin B were also the most effective suppressors of prostate-specific antigen secretion by androgen-dependent LNCaP cells. Silymarin and silibinin were shown for the first time to suppress the activity of the DNA topoisomerase IIalpha gene promoter in DU145 cells and, among the pure compounds, isosilybin B was again the most effective. These findings are significant in that isosilybin B composes no more than 5% of silymarin and is absent from silibinin. Whereas several other more abundant flavonolignans do ultimately influence the same end points at higher exposure concentrations, these findings are suggestive that extracts enriched for isosilybin B, or isosilybin B alone, might possess improved potency in prostate cancer prevention and treatment.

D‐TMPP: A novel androgen‐regulated gene preferentially expressed in prostate and prostate cancer that is the first characterized member of an eukaryotic gene family

The understanding of the molecular biology of the prostate and the process of prostate carcinogenesis is brought forward by the identification and characterization of new genes specifically expressed in prostate tissue. The encoded proteins may, in addition, provide novel diagnostic and therapeutic tools in prostate carcinoma (PCa). Here, we identify the novel gene Dresden-transmembrane protein of the prostate (D-TMPP) that is overexpressed in human prostate and prostate cancer. Proceeding from a prostate-specific expressed sequence tag identified with an Affymetrix chip-based expression database, the full-length cDNA of the novel gene was isolated from prostate tissue. The potential protein-coding function of the open reading frame (ORF) was tested by in vitro transcription-coupled translation and recombinant expression in transfected prostate cancer cells. The expression pattern of D-TMPP in malignant and nonmalignant tissues and tumor cell lines was analyzed by hybridization of a radioactively labeled cDNA probe with a multiple tissue expression array and by a quantitative real-time PCR assay. The D-TMPP-mRNA encodes a putative seven-span transmembrane protein of 883 amino acids and is selectively overexpressed in prostate tissue. D-TMPP represents the first cloned and characterized transcript of a family of eukaryotic genes. D-TMPP transcripts were detected in all analyzed pairs (n = 25) of malignant and nonmalignant prostate tissues. In the androgen-dependent PCa cell line LNCaP, D-TMPP was upregulated by methyltrienolone. We describe the novel prostate-restricted molecule D-TMPP widely expressed in prostate cancer tissues.

Role of the phosphatase PP4 in the activation of JNK-1 in prostate carcinoma cell lines PC-3 and LNCaP resulting in increased AP-1 and EGR-1 activity

The specific signaling connections between the mitogen-activated protein kinases (MAPK) such as c-Jun N-terminal kinase (JNK-1) and phosphatases PP4 and M3/6, affecting the family of early nuclear factors, is complex and remains poorly understood. JNK-1 regulates cellular differentiation, apoptosis and stress responsiveness by up-regulating early nuclear factors such as c-Jun, a member of the activating protein (AP-1) family, and the Early Growth Factor (EGR-1). C-Jun, when phosphorylated by c-Jun N-terminal kinase (JNK-1) associates with c-Fos to form the AP-1 transcription factor that activates gene expression. We have investigated the regulation of the JNK-1 kinase by co-transfecting phosphatases PP4 and M3/6 in prostate cancer cell lines PC-3 and LNCaP, which have been previously stimulated with human EGF or cisplatin. Co-transfections of plasmids expressing the JNK-1 and the serine/threonine phosphatases PP4 resulted in a significant increase in JNK-1 activity in both PC3 and LNCaP cells. In contrast, co-transfection of JNK-1 with the dual specific phosphatase serine/threonine M3/6 showed only a marginal effect in JNK-1 activity. The phosphatase M3/6 also failed in blocking the induction of JNK-1 activity observed in presence of PP4. The higher activity of JNK-1 was associated with increased activities of the factors c-Jun/AP-1 and EGR-1. This suggests that JNK-1 activity in PC-3 and LNCaP cells requires not only active PP4 for stable maintenance but also suggests that the relative degree of phosphorylation of multiple cellular components is the determinant of JNK-1 stability.

Induction of anoikis by doxazosin in prostate cancer cells is associated with activation of caspase-3 and a reduction of focal adhesion kinase.

The quinazoline family of alpha1-blockers (prazosin, doxazosin, and terazosin) induce apoptosis of prostate cells through an alpha1-adrenoceptor-independent mechanism. The objective of this study was to gain insight into the non-adrenergic, apoptotic mechanism of action of doxazosin in the prostate and the induction of anoikis by doxazosin. Primary cultures of benign prostate stromal and epithelial cells and the LNCaP (androgen sensitive) and PC-3 (androgen insensitive) prostate carcinoma cell lines were treated with doxazosin (0-50 microM). The effects of doxazosin on cell morphology, caspase-3 activity, and the expression levels of focal adhesion kinase (FAK) and integrin-linked kinase (ILK) were examined. Doxazosin induced changes in morphology consistent with anoikis in both benign and cancerous prostatic cells and increased caspase-3 activity. The effects were similar comparing benign cells (which express alpha1-adrenoceptors) and cancer cells (which do not express alpha1-adrenoceptors), but were more robust in benign cells. Norepinephrine had no effect on doxazosin-induced cell morphology or caspase-3 activity. Treatment of PC-3 cells with doxazosin significantly reduced the protein levels of FAK but did not significantly affect the levels of ILK. These findings suggest that doxazosin induces apoptosis and anoikis of prostate cancer cells by a mechanism of action that is alpha1-adrenoceptor independent. The apoptosis of cancer cells induced by doxazosin counteracts cell proliferation and may have the potential of retarding or reversing prostate cancer cell growth.

Design, synthesis and in vitro antitumor activity of new trans 2-[2-(heteroaryl)vinyl]-1,3-dimethylimidazolium iodides

The design, the synthesis, and the in vitro antitumor activities of trans 2-[2-(heteroaryl)vinyl]-1,3-dimethylimidazolium iodides versus MCF7 (human mammary carcinoma) and LNCap (prostate carcinoma) cell lines are reported. The design indicates trans 2-[2-[5-(2-chlorophenyl)furan-2-yl]vinyl]-1, 3-dimethylimidazolium iodide 5 and trans 2-[2-[5-(4-bromophenyl)furan-2-yl]vinyl]-1, 3-dimethylimidazolium iodide 6 as highly active compounds in the series. The synthesis of the above new derivatives and in vitro antitumor tests, confirm their significant antiproliferative and cytotoxic activities.