μM In PC-3 Cells Research Articles

Thymoquinone Potentially Modulates the Expression of Key Onco- and Tumor Suppressor miRNAs in Prostate and Colon Cancer Cell Lines: Insights from PC3 and HCT-15 Cells.

Prostate cancer (PC) and colon cancer significantly contribute to global cancer-related morbidity and mortality. Thymoquinone (TQ), a naturally occurring phytochemical found in black cumin, has shown potential as an anticancer compound. This study aimed to investigate the effects of TQ on the expression profile of key tumor suppressor and onco-suppressor miRNAs in PC3 prostate cancer cells and HCT-15 colon cancer cells. Cell viability assays revealed that TQ inhibited the growth of both cell lines in a dose-dependent manner, with IC50 values of approximately 82.59 μM for HCT-15 and 55.83 μM for PC3 cells. Following TQ treatment at the IC50 concentrations, miRNA expression analysis demonstrated that TQ significantly downregulated miR-21-5p expression in HCT-15 cells and upregulated miR-34a-5p, miR-221-5p, miR-17-5p, and miR-21-5p expression in PC3 cells. However, no significant changes were observed in the expression levels of miR-34a-5p and miR-200a-5p in HCT-15 cells. The current findings suggest that TQ might exert its antiproliferative effects by modulating specific tumor suppressor and onco-suppressor miRNAs in prostate and colon cancer cells. Further investigations are warranted to elucidate the precise underlying mechanisms and to explore the therapeutic potential of TQ in cancer treatment. To the best of our knowledge, this is the first report regarding the effect of TQ on the miRNA expression profile in colon and prostate cancer cell lines.

Dankasterone A induces prostate cancer cell death by inducing oxidative stress

Oxidative stress plays a dual role in tumor survival, either promoting tumor development or killing tumor cells under different conditions. Dankasterone A is a secondary metabolite derived from the fungus Talaromyces purpurogenu. It showed good potential in a screen for anti-prostate cancer compounds. In this study, MTT results showed dankasterone A was cytotoxic to prostate cancer cells, with an IC50 of 5.10 μM for PC-3 cells and 3.41 μM for 22Rv1 cells. Further studies, plate cloning assays and real-time cell analysis monitoring showed that dankasterone A significantly inhibited clonal colony formation and cell migration in 22Rv1 and PC-3 cells. In addition, flow cytometry results showed that dankasterone A induced apoptosis in prostate cancer cells while having no impact on cell cycle distribution. At the molecular level, Protein microarray experiments and western blot assays revealed that dankasterone A specifically and dramatically upregulated HO-1 protein expression; and the results of cell fluorescence staining showed that dankasterone A induced overexpression of reactive oxygen species in 22Rv1 and PC-3 cells. Taken together, dankasterone A induced prostate cancer cells to undergo intense oxidative stress, which resulted in the production of large amounts of HO-1 and the release of large amounts of reactive oxygen species, leading to apoptosis of prostate cancer cells, ultimately resulting in the inhibition of both cell proliferation and migration. We also validated the anti-prostate cancer effects of dankasterone A in vivo in a zebrafish xenograft tumor model. In conclusion, dankasterone A has the potential to be developed as an anti-prostate cancer drug.

Analysis of regulating activities of 5'-epiequisetin on proliferation, apoptosis, and migration of prostate cancer cells in vitro and in vivo.

Advanced prostate cancer has a poor prognosis, and it is urgent to develop new effective drugs. 5′-Epiequisetin is a tetramic acid derivative which was isolated from a marine sponge-derived fungus Fusarium equiseti in our previous study. In this study, 5′-epiequisetin showed cytotoxicity against four prostate cancer cell lines, namely, LNCaP, 22Rv1, DU145, and PC-3 cells, with the lowest IC50 value of 4.43 ± 0.24 μM in PC-3 cells. Further studies showed that it could dramatically regulate the clonal colony formation, apoptosis, and migration of PC-3 cells. In addition, flow cytometry data showed that 5′-epiequisetin could block the cell cycle at the G1 phase. Proteome profiler array and Western blot revealed that 5′-epiequisetin could regulate the expression of proteins responsible for cell proliferation, apoptosis, and migration. 5′-Epiequisetin regulated the expression of PI3K, Akt, phosphorylated Akt, and proteins which control the cell cycle. Meanwhile, 5′-epiequisetin upregulated expression of DR5 and cleave-caspase 3, which play important roles in the process of apoptosis. Moreover, when DR5 was silenced by small interfering RNA, the proportion of apoptotic cells induced by 5′-epiequisetin remarkably declined. In addition, 5′-epiequisetin downregulated the expression of survivin which plays a key role in the process of survival and apoptosis. 5′-Epiequisetin also impacted beta-catenin and cadherins, which were associated with cell migration. In addition, 5′-Epiequisetin significantly inhibited the progression of prostate cancer in mice, accompanied by regulating the protein expression of DR5, caspase 8, survivin, and cadherins in vivo. Taken together, these findings indicated that 5′-epiequisetin showed an anti–prostate cancer effect by inducing apoptosis and inhibiting cell proliferation and migration both in vitro and in vivo, suggesting a promising lead compound for the pharmacotherapy of prostate cancer.

Chemical Constituents of the Stem Bark of the Hybrid Plant Citrus × paradisi Macfad. (Rutaceae).

The stem bark of Citrus × paradisi Macfad. (Rutaceae) gave (23S)-isolimonexic acid (1), limonin (2), citracridone II (3), citpressine II (4), citpressine I (5), grandisine (6), 2-hydroxynoracronycine (7), citracridone I (8), 5-methoxyseselin (9), umbelliferone (10), scopoletin (11), naringenin (12), apigenin (13), friedelin (14), agrostophyllinone (15) and stigmasterol-3-O-β-D-glucopyranoside (16). The structures of the compounds were determined using NMR and MS spectroscopic data, and by comparison with published data. The relative configuration of 1 was proposed as (23S)-isolimonexic acid using NOE studies. Hydrogenation reaction of compound 3 led to the new derivative 3',4'-dihydrocitracridone II (3a). Cytotoxicity activities against the human adenocarcinoma alveolar basal epithelial cell lines A549 and the Caucasian prostate adenocarcinoma cell lines PC3, using the MTT assays showed that the methanol crude extract was significant with IC50 values of 30.1 and 31.7 μg/mL, respectively, with the positive control, doxorubicin giving an IC50 of 0.9 μM. In addition, compounds 3, 7 and 8 gave moderate cytotoxic activities with IC50 values of 33.1, 31.2 and 32.5 μM for A549 cells and 35.7, 33.8 and 34.9 μM for PC3 cells, respectively. The hydrogenated 3a was less active than 3, suggesting that the presence of the double bond in pyrans is important for structure-activity relationship.

Synthesis and Biological Evaluation of New 1,2,3-Triazole Derivatives of the Chrysin Flavonoid as Anticancer Agents.

Chrysin and its derivatives proved to possess potential anti-tumour activity. A new series of chrysin analogs containing 1,2,3-triazoles with different substituent groups (5a-5l) was designed, synthesized, and evaluated as potential anticancer agents. The synthesized compounds were characterized using FT-IR, 1H NMR 13C NMR spectroscopy and mass spectrometry. The anticancer activities of the synthesized compounds were studied in four cancer cell lines viz. PC3, PC3-PSMA, MCF-7 and UM-UC-3 using doxorubicin as standard. Among all the tested compounds, 5c was found as most active with IC50 value of 10.8 ± 0.04 μM in PC3 cells and 20.53 ± 0.21 μMin MCF-7 cells, respectively. Flow cytometry analyses indicated that synthesized compounds 5a, 5c, and 5h arrested MCF-7 cells at the G2/M phase in a dose-dependent manner. Chyrsin derivatives could be novel anticancer agents.

Dithiocarbamate prodrugs activated by prostate specific antigen to target prostate cancer

Disulfiram in conjunction with copper has been shown to be a potent anticancer agent. However, disulfiram’s therapeutic potential in prostate cancer is hindered by off-target effects due to its reactive and nucleophilic thiol-containing component, diethyldithiocarbamate (DTC). To minimize undesirable reactivity, we have strategically blocked the thiol moiety in DTC with a cleavable p-aminobenzyl (pAB) group linked to peptide substrates recognized by prostate specific antigen (PSA). Here we report the synthesis and evaluation in cancer cell models of two PSA-activatable prodrugs: HPD (Ac-HSSKLQL-pAB-DTC and RPD (RSSYYSL-pAB-DTC). In vitro exposure to PSA was found to trigger activation of HPD and RPD to release diethyldithiocarbamate, and both prodrugs were found to induce toxicity in prostate cancer cells, with HPD showing the most promising selectivity. With copper supplementation, the IC50 of HPD was 1.4 µM in PSA-expressing LNCaP cells, and 11 µM in PC3 cells that do not express PSA. These studies demonstrate the utility of using peptide recognition handles to direct the activity of dithiocarbamate prodrugs for selective cytotoxicity of cancer cells.

Kaempferol Promotes Apoptosis While Inhibiting Cell Proliferation via Androgen-Dependent Pathway and Suppressing Vasculogenic Mimicry and Invasion in Prostate Cancer.

Kaempferol is a well-known natural flavonol reported to be a potential treatment for multiple cancers. In this study, we demonstrated that cell growth of androgen-sensitive LNCaP cells could be inhibited 33% by 5 μM kaempferol, around 60% by 10 μM kaempferol, and almost 100% by 15 μM kaempferol. Also, kaempferol showed relatively limited effect on PC-3 cells and nonmalignant RWPE-1 cells. In the presence of DHT, the IC50 for kaempferol was 28.8 ± 1.5 μM in LNCaP cells, 58.3 ± 3.5 μM in PC-3 cells, and 69.1 ± 1.2 μM in RWPE-1 cells, respectively. Kaempferol promotes apoptosis of LNCaP cells in a dose-dependent manner in the presence of dihydrotestosterone (DHT). Then, luciferase assay data showed that kaempferol could inhibit the activation of androgen receptors induced by DHT significantly. The downstream targets of androgen receptors, such as PSA, TMPRSS2, and TMEPA1, were found decreased in the presence of kaempferol in qPCR data. It was then confirmed that the protein level of PSA was decreased. Kaempferol inhibits AR protein expression and nuclear accumulation. Kaempferol suppressed vasculogenic mimicry of PC-3 cells in an in vitro study. In conclusion, kaempferol is a promising therapeutic candidate for treatment of prostate cancer, where the androgen signaling pathway as well as vasculogenic mimicry are involved.

Docosahexaenoic acid inhibits lipopolysaccharide-induced metastatic activities by decreasing inflammation on prostate cancer cell.

Docosahexaenoic acid (DHA) is rich in fish oil with many pharmacological impacts such as anti-inflammation and anti-cancer activities. In the present study, we aimed to investigate the inhibitory effects of DHA on the invasion and inflammation in prostate cancer cells. The cytotoxicity of DHA with or without lipopolysaccharides (LPS) treatment was evaluated by MTT assay. The invasion and wound healing assays were used to determine the roles of DHA in cell migration and invasion after LPS treatment. The expression levels of IL-6 and IL-8 were detected using ELISA assay. The protein expression was investigated by Western blotting. DHA exhibited significant cytotoxicity at the concentration of 100 μM in PC3 cells. Exposure to DHA (6, 12 and 25 μM) dose-dependently inhibited invasion and wound closure potential in PC3 cells after LPS treatment. DHA dose-dependently downregulated LPS-induced expression levels of IL-6 and IL-8. In addition, the LPS-induced protein levels of p-AKT and COX-2 were suppressed by DHA treatment. Our results indicate that low doses of DHA effectively inhibit metastasis by decreasing IL-6, IL-8, p-AKT and COX-2 expression levels after LPS treatment.

Global and region-specific post-transcriptional and post-translational modifications of bisphenol A in human prostate cancer cells

Bisphenol A (BPA), as synthetic monomer used in the production of polycarbonate plastic and epoxy resins, has endocrine disruptor properties and high risk on human health. Epigenetic alterations could act an important role in BPA-induced toxicity, but its mechanism has not been fully understood. We investigated the effects of BPA on gene expression of chromatin modifying enzymes, promoter methylation of tumor suppressor genes and histone modifications in human prostate carcinoma cells (PC-3). IC50 value of BPA was determined as 217 and 190 μM in PC-3 cells by MTT and NRU tests, respectively. We revealed an increase in global levels of 5-methylcytocine and 5-hydroxymethylcytocine at 10 μM of BPA for 96 h. We observed a significant increase on promoter DNA methylation and decrease on gene expression of p16 gene while no change was observed for Cyclin D2 and Rassf1. Significant changes were observed in global histone modifications (H3K9ac, H3K9me3, H3K27me3, and H4K20me3) in PC-3 cells. According to these results, we investigated wide-range epigenetic modifications using PCR arrays. After 96 h BPA exposure, chromatin modifying enzymes including KDM5B and NSD1 were significantly downregulated. Also, promoter methylation of tumor suppressor genes including BCR, GSTP1, LOX, MGMT, NEUROG1, PDLIM4, PTGS2, PYCARD, TIMP3, TSC2 and ZMYDN10 altered significantly. ChIP results showed that H3K9ac, H3K9me3 and H3K27me3 modifications on p16 gene showed significant increases after 1 and 10 μM of BPA exposure. In conclusion, epigenetic signatures such as DNA methylation and histone modifications could be proposed as molecular biomarkers of BPA-induced prostate cancer progression.

2-Deoxyglycoside Conjugates of Lupane Triterpenoids with High Cytotoxic Activity-Synthesis, Activity, and Pharmacokinetic Profile.

A set of 41 glycosidic conjugates of pentacyclic triterpenes was synthesized in order to improve the solubility of highly cytotoxic parent compounds. Their in vitro cytotoxic activity was evaluated in 25 cancer cell lines and 2 noncancer fibroblasts. Fifteen compounds had high cytotoxicity on the T-lymphoblastic leukemia cell line CCRF-CEM and 6 of them were active in multiple cell lines of various histogenic origin and not toxic in fibroblasts. Compound 11a had IC50 of 0.64 μM in CCRF-CEM cells, 0.60 μM in K-562 cells, and 0.37 μM in PC-3 cells; compound 12a had IC50 of 0.64 μM in CCRF-CEM cells and 0.71 μM in SW620 cells; compound 17b had IC50 of 0.86 μM in HCT116 cells and 0.92 μM in PC-3 cells. Compounds 11b and 12b were slightly less active than the previously mentioned derivatives; however, their solubility was significantly better, and therefore they were selected for the in vivo evaluation of the pharmacokinetic profile in mice. In both compounds, the maximum concentration in plasma was achieved very rapidly-the highest level in plasma was found 1 h after administration (22.2, respectively, 6.4 μM). For compound 12b, the resorption was followed with fast elimination, and 12 h after administration, the compound was not detected in plasma. In contrast, compound 11b was eliminated more slowly; it was still present in plasma after 12 h, but its concentration dropped below the detection limit after 24 h. The elimination half-time determined for compound 11b was 2.4 h and for compound 12b just about 1.4 h. These values are reasonable for further drug development.

Piperine blocks voltage gated K+ current and inhibits proliferation in androgen sensitive and insensitive human prostate cancer cell lines

Piperine is an attractive therapeutic alkaloid from black pepper that exhibits a broad spectrum of pharmacological properties over various pathological disorders including cancer. Voltage gated K+ (KV) channels play an important role in regulating cancer cell proliferation and are considered as potential target for cancer treatment. However, the implication of piperine in KV associated anticancer activities on human prostate cancer cells LNCaP and PC-3 remains unrevealed. The electrophysiological and pharmacological data identifies that both androgen sensitive (LNCaP) and insensitive (PC-3) prostate cancer cells typically expressed voltage gated K+ current (IK). This current was significantly blocked by piperine in a concentration-dependent manner with an IC50 value 39.91 μM in LNCaP and 49.45 μM in PC-3 cells. Analysis of voltage-dependence of activation kinetics showed that piperine induces a positive shift in the relative activation curve in both the cells. Piperine also depolarized the resting membrane potential by an average of 10.2 mV and 8.3 mV in LNCaP and PC-3 cells, respectively. The anticancer studies showed that, treatment with piperine concentration dependently induced G1 phase cell cycle arrest and apoptosis in LNCaP and PC-3 cells. These results unravel that the IK inhibition might be responsible for the anticancer effect of piperine on androgen sensitive and insensitive human prostate cancer cells.

Potential of piperine in modulation of voltage-gated K+ current and its influences on cell cycle arrest and apoptosis in human prostate cancer cells.

Piperine is an attractive therapeutic alkaloid from black pepper that exhibits a broad spectrum of pharmacological properties over various pathological disorders including cancer. Voltage-gated K+ channels (KV) play an important role in regulating cancer cell proliferation and are considered as potential targets for the treatment of cancer. However, there is a paucity of information with regard to the implication of piperine in KV associated anticancer activities on human prostate cancer cells LNCaP and PC-3 cells. Therefore, the primary objective of the present study was to elucidate the anticancer action of piperine that might be mediated via voltage-gated K+ current (IK) blockade. Whole-cell patch clamp was used to record the modulatory effects of piperine on IK expressed in LNCaP and PC-3 cells. Moreover, the anticancer activity of piperine was evaluated by MTT assay, flow cytometry and live/dead assay. Piperine significantly inhibited IK in a dose-dependent manner with an effective IC50 dose 39.91 µM in LNCaP and 49.45 µM in PC-3 cells. Also, piperine induced a positive shift in the relative activation curve in both cells. Blockade of IK by piperine exerted G0/G1 phase cell cycle arrest that led to inhibition of cell proliferation and induced apoptosis in a dose-dependent manner. We showed that the anticancer effects of piperine are directly correlated with the blockade of IK in LNCaP and PC-3 cells. The study also confirmed that IK inhibition by piperine might be responsible for its anticancer activities in prostate cancer cells.

Basic helix-loop-helix transcription factor DEC2 functions as an anti-apoptotic factor during paclitaxel-induced apoptosis in human prostate cancer cells.

The functions of basic helix-loop-helix (bHLH) transcription factor-differentiated embryonic chondrocyte (DEC)1 (BHLHE40) and 2 (BHLHE41) are involved in various fields such as circadian rhythms, immune responses, cell proliferation, hypoxia reaction as well as malignant tumors. Previous findings showed that DEC served as apoptosis regulators of various cancer cell lines. However, little is known regarding the expression of DEC1 and DEC2 in prostate cancer cells. The present study aimed to examine the roles of DEC1 and DEC2 in human prostate cancer DU145 and PC-3 cells that were treated with paclitaxel. The expression of DEC1 and DEC2 was decreased in DU145 cells but was increased in PC-3 cells when treated with paclitaxel. DU145 cells were more sensitive to paclitaxel than PC-3 cells since the amount of cleaved poly(ADP-ribose) polymerase (PARP) reached its peak at 50 μM of paclitaxel in DU145 cells but at 100 μM in PC-3 cells. In addition, the amount of cleaved PARP was decreased by DEC1 siRNA, while it was increased by DEC2 siRNA in the presence of paclitaxel. Although DEC2 overexpression slightly inhibited cleaved PARP in the two cell lines, the effects of DEC1 overexpression on apoptosis remain to be determined. In conclusion, DEC1, at least partly, exerted a pro-apoptotic effect, whereas DEC2 exerted an anti-apoptotic effect in paclitaxel-induced apoptosis of human prostate cancer cells.

Curcumin analog WZ35 induced cell death via ROS-dependent ER stress and G2/M cell cycle arrest in human prostate cancer cells.

BackgroundProstate cancer is the most commonly diagnosed malignancy among men. The Discovery of new agents for the treatment of prostate cancer is urgently needed. Compound WZ35, a novel analog of the natural product curcumin, exhibited good anti-prostate cancer activity, with an IC50 of 2.2 μM in PC-3 cells. However, the underlying mechanism of WZ35 against prostate cancer cells is still unclear.MethodsHuman prostate cancer PC-3 cells and DU145 cells were treated with WZ35 for further proliferation, apoptosis, cell cycle, and mechanism analyses. NAC and CHOP siRNA were used to validate the role of ROS and ER stress, respectively, in the anti-cancer actions of WZ35.ResultsOur results show that WZ35 exhibited much higher cell growth inhibition than curcumin by inducing ER stress-dependent cell apoptosis in human prostate cells. The reduction of CHOP expression by siRNA partially abrogated WZ35-induced cell apoptosis. WZ35 also dose-dependently induced cell cycle arrest in the G2/M phase. Furthermore, we found that WZ35 treatment for 30 min significantly induced reactive oxygen species (ROS) production in PC-3 cells. Co-treatment with the ROS scavenger NAC completely abrogated the induction of WZ35 on cell apoptosis, ER stress activation, and cell cycle arrest, indicating an upstream role of ROS generation in mediating the anti-cancer effect of WZ35.ConclusionsTaken together, this work presents the novel anticancer candidate WZ35 for the treatment of prostate cancer, and importantly, reveals that increased ROS generation might be an effective strategy in human prostate cancer treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1851-3) contains supplementary material, which is available to authorized users.

Assessment of the anticancer mechanism of ferulic acid via cell cycle and apoptotic pathways in human prostate cancer cell lines.

Studies on genetic changes underlying prostate cancer and the possible signaling pathways are getting increased day by day, and new treatment methods are being searched for. The aim of the present study is to investigate the effects of ferulic acid (FA), a phenolic compound, on cell cycle, apoptosis, invasion, and colony formation in the PC-3 and LNCaP prostate cancer cells. The effect of FA on cell viability was determined via a 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) method. Total RNA was isolated with Tri Reagent. Expression of 84 genes for both cell cycle and apoptosis separately was evaluated by reverse transcriptase PCR (RT-PCR). Protein expressions were evaluated by Western blot analysis. Furthermore, apoptotic effects of FA were observed with terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labeling (TUNEL) assay. Effects of FA on cell invasion and colony formation were determined using Matrigel chamber and colony assay, respectively. The half maximal inhibitory concentration (IC50) dose of FA was found to be 300 μM in PC-3 cells and 500 μM in LNCaP cells. According to RT-PCR results, it was observed that FA inhibited cell proliferation by increasing the gene expressions of ATR, ATM, CDKN1A, CDKN1B, E2F4, RB1, and TP53 and decreasing the gene expressions of CCND1, CCND2, CCND3, CDK2, CDK4, and CDK6 in PC-3 cells. On the other hand, it was seen that FA suppressed cell proliferation by increasing in the gene expressions of CASP1, CASP2, CASP8, CYCS, FAS, FASLG, and TRADD and decreasing in the gene expressions of BCL2 and XIAP in LNCaP cells. In this study, protein expression of CDK4 and BCL2 genes significantly decreased in these cells. It could induce apoptosis in PC-3 and LNCaP cells. Also, it was observed that FA suppressed the invasion in PC-3 and LNCaP cells. Moreover, it suppressed the colony formation. In conclusion, it has been observed that FA may lead to cell cycle arrest in PC-3 cells while it may cause apoptosis in LNCaP cells.

Synthesis and anticancer activities of 5,6,7-trimethoxy-N-phenyl(ethyl)-4-aminoquinazoline derivatives

A series of 5,6,7-trimethoxy-N-phenyl(ethyl)-4-aminoquinazoline compounds was prepared by microwave irradiation and conventional heating methods. Compounds 6p, 6q, and 6x strongly inhibited extracellular regulated kinase1/2 (ERK1/2) phosphorylation induced by epidermal growth factor (EGF) at 1.28 μM in PC3 cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that all compounds had certain anticancer activities, and the IC50 values of 6x were 6.2 ± 0.9, 3.2 ± 0.1, and 3.1 ± 0.1 μM against PC3, BGC823, and Bcap37 cells, respectively. Acridine orange/ethidium bromide staining, Hoechst 33258 staining, DNA ladder, and flow cytometry analyses revealed that 6x induced cell apoptosis in PC3 cells, with apoptosis ratios of 11.6% at 1 μM and 31.8% at 10 μM after 72 h.

Activity of gemcitabine-oxalipaltin (GemOx) plus prednisolone in patients with castration-resistant prostate cancer (CRPC) for whom docetaxel-based chemotherapy failed.

108 Background: We assessed the cytotoxic effects of the gemcitabine in combination with oxaliplatin (GemOx) in prostate cancer cell lines and evaluated the efficacy and safety of GemOx in patients with metastatic castration-resistant prostate cancer (CRPC) who failed docetaxel based chemotherapy. Methods: Gemcitabine and oxaliplatin were preclinically tested for their cytotoxic activity in LNCaP, PC3 and DU145 cell lines. The combined drug effects were evaluated using the Chou and Taladay analysis. Clinically, patients with CRPC who failed prior docetaxel chemotherapy were treated with gemcitabine 1,000 mg/m2 at fixed-dose rate (10 mg/m2/min) and oxaliplatin 100 mg/m2 intravenously every 2 weeks and prednisolone 5 mg orally twice daily. Unless disease progression or intolerability develops, treatment could be continued until 12 cycles. Primary endpoint was PSA response rate (PCWG 1.0 criteria). Results: The IC50of gemcitabine and oxaliplatin were, respectively, 1.25 μM and 0.69 μM for LNCaP cells; 50.00+ μM and 12.81 μM for PC3 cells; and 11.23 μM and 11.04 μM for DU145 cells. The GemOx combination displayed synergistic effects in all 3 cell lines. In phase II study, 31 patients were accrued. At the time of this analysis 7 patients were still continuing treatment. The median age was 67 years (range 57 ~ 81) and the median dose of docetaxel exposure was 525 mg/m2. A total of 231 cycles administered with a median of 9 cycles per patient. PSA responses were observed in 52% (95% CI, 34~69) and partial responses were observed in 7 of 10 patients with measurable disease. Out of 23 patients, 10 patients achieved pain response (44%). With a median FU duration of 8.0 months, the median time to PSA progression was 6.4 months (95% CI, 3.5~9.2). Peripheral neuropathy developed in 78% of patients but remained of grade 1 ~2 intensities. Frequently observed grade 3 or 4 toxicities were neutropenia (10%), thrombocytopenia (10%), anemia (3%), and diarrhea (3%). Conclusions: GemOx is active and well tolerated in patients with CPRC after docetaxel failure and deserves further investigation in this setting (NCT 01487720). Clinical trial information: NCT01487720.

Mechanistic study of O-methylcedrelopsin and dehydrogeijerin

Plants that can survive in the harsh environment of South Texas have the potential to produce molecules with activity against diverse biological targets. The Mountain torchwood, Amyris madrensis, was evaluated because the crude lipophilic extract had potent activity against prostate cancer cells. Multiple cytotoxic compounds were isolated using bioassay guided fractionation including 14 previously identified coumarins. Two coumarins, O-methylcedrelopsin and dehydrogeijerin, were evaluated for antiproliferative activities against cancer cell lines. O-methylcedrelopsin has an IC50 of 7.8 and 27.8µM in HeLa and PC-3 cells respectively. Dehydrogeijerin also showed activity in the low micromolar range with an IC50 of 16.0µM in HeLa cells and 43.0µM in PC-3 cells. Both O-methylcedrelopsin and dehydrogeijerin caused a dose dependent accumulation of cells in G2/M as determined by flow cytometry. They have no effects on interphase microtubule structures or on the assembly of purified tubulin, suggesting a mechanism different from microtubule binding compounds. The compounds do however initiate the formation of abnormal mitotic spindles which closely resemble those formed following treatment of cells with mitotic kinase inhibitors. The hypothesis that O-methylcedrelopsin and dehydrogeijerin target mitotic kinases, specifically polo like kinase 1 (PLK1) or cyclin dependent kinase 1 (CDK1) is being tested. Two structurally similar coumarins, 7-O-prenylscopoletin and cedrelopsin, were also identified but they have 10-fold lower antiproliferative potency. These structures will be informative in defining the moieties optimal for inhibiting mitotic progression. Supported by NIDCR (COSTAR) DE14318 and DoD W81XWH-08–1-0395.

The effect of schedule, protein binding and growth factors on the activity of suramin

Suramin has been shown to have antiproliferative activity, either by blocking the binding of growth factors to their receptors or by inhibiting critical cellular enzymes. In 6 different cell lines from 5 tumour types (MCF-7, MCF-7/ADRR, PC3, HT-29, UM-SCC-11B and SW-1573/IR500), we studied the effect of scheduling of suramin, of FCS and of human serum albumin (HSA), of epidermal growth factor (EGF) and of the addition of growth factors in serum-free medium on the activity of suramin. The concentration of suramin which gave 50% growth inhibition (IC50) varied from 45 microM in SW-1573/IR500 to 153 microM in PC3 cells grown in medium supplemented with 5% FCS, after 6 days of continuous exposure. Exposure for more than 4 days did not enhance the sensitivity to suramin, except in PC3. At exposure to suramin for 1 day followed by 5 days recovery, high IC50 values (greater than 0.5 mM) were observed in MCF-7 cells. In medium with 1% and 0.5% FCS these values were 3 to 8 and 14 to 26 times lower respectively. Addition of HSA increased the IC50 in PC3 and MCF-7 cells. Suramin binding to protein was dependent on the concentration of protein and of suramin. Excess of EGF in medium with different FCS concentrations did not change the IC50 values of suramin in PC3 and MCF-7 cells. Addition of EGF, fibroblast growth factor or platelet-derived growth factor in PC3 cells cultured in serum-free medium did not increase the IC50 values. Suramin was active against these 6 cell lines at clinically achievable concentrations. This activity varied depending on the cell line, exposure time and suramin concentration. The most significant factor interfering with sensitivity to suramin was the amount of protein present in the culture medium.