alvocidib and Prostatic-Neoplasms

Despite strategies aimed at early detection and treatment, prostate cancer remains a leading cause of morbidity and mortality among males. Current therapies have limited impact on the natural history of metastatic hormone-refractory prostate cancer (HRPC). With an improved understanding of tumor biology, including apoptosis, differentiation, cell cycling and signaling, and angiogenesis, many potential new targets for therapy have been unveiled. Modulation of these processes may result in cytotoxic or cytostatic effects. The evaluation of therapies based on manipulation of these targets may not be adequately addressed by current study designs and traditional parameters of efficacy. Examples of agents currently in clinical trials that illustrate some of the challenges presented to clinical investigators include monoterpenes such as perillyl alcohol (POH), vitamin D analogs, flavones such as flavopiridol, and angiogenesis inhibitors. Agents such as these are aimed at unique cellular targets and will require novel approaches to determine their clinical utility. Unfortunately, in the United States, only a small proportion of cancer patients, including prostate cancer patients, are enrolled in clinical trials. We must do better to efficiently assess promising new treatment approaches and improve outcome for our patients.

Topics: Angiogenesis Inhibitors; Antineoplastic Agents; Antineoplastic Agents, Hormonal; Apoptosis; Cell Cycle; Cell Differentiation; Clinical Trials as Topic; Cyclin-Dependent Kinases; Drug Resistance, Neoplasm; Flavonoids; Humans; Male; Monoterpenes; Neoplasm Metastasis; Neovascularization, Pathologic; Piperidines; Prostatic Neoplasms; Signal Transduction; Survival Rate; Terpenes; Vitamin D

Flavopiridol is a cyclin-dependent kinase inhibitor with preclinical activity against prostate cancer cell lines. A Phase II trial was conducted to determine the activity of flavopiridol in patients with metastatic hormone-refractory prostate cancer.. A total of 36 patients was enrolled from several institutions and treated with a 72-h continuous infusion of flavopiridol every 14 days at the eventual starting dose of 40 mg/m(2)/day. Dose escalation up to 60 mg/m(2)/day was permitted if no significant toxicity was observed. Responses were assessed every 12 weeks. Only those patients completing four courses of the 72-h infusion were considered evaluable for response because the primary objective was to determine progression-free survival at 6 months given the cytostatic nature of the agent.. This study was conducted in a two-stage fashion. During the first stage, at least 20 evaluable patients needed to be enrolled to assess response. There were 22 of 36 patients evaluable for response. No objective responses were observed. Only 4 patients had stable disease for 16, 26, 29, and 48 weeks, respectively, stopping the trial by design as only 3 of 22 (14%) of the patients met the 6-month progression-free survival end point. The most common toxicities were diarrhea (grade 1 and 2) and nausea, although some grade 3 and 4 diarrhea (11 and 6%, respectively) were evident.. Flavopiridol has disappointing single-agent activity in hormone-refractory prostate cancer when administered at this dose and schedule. Its use in prostate cancer should be reserved for evaluation in combination therapies or alternative schedules.

Topics: Aged; Aged, 80 and over; Androgens; Antineoplastic Agents; Disease-Free Survival; Dose-Response Relationship, Drug; Flavonoids; Humans; Male; Middle Aged; Neoplasm Metastasis; Piperidines; Prostatic Neoplasms; Time Factors; Treatment Outcome

Combining chemotherapeutics to treat malignant tumors has been shown to be effective in preventing drug resistance, tumor recurrence, and reducing tumor size. We modeled combination drug therapy in PC-3 human prostate cancer cells using mixture design response surface methodology (MDRSM), a statistical technique designed to optimize compositions that we applied in a novel manner to design combinations of chemotherapeutics. Conventional chemotherapeutics (mitoxantrone, cabazitaxel, and docetaxel) and natural bioactive compounds (resveratrol, piperlongumine, and flavopiridol) were used in 12 different combinations containing three drugs at varying concentrations. Cell viability and cell cycle data were collected and used to plot response surfaces in MDRSM that identified the most effective concentrations of each drug in combination. MDRSM allows for extrapolation of data from three or more compounds in variable ratio combinations, unlike the Chou-Talalay method. MDRSM combinations were compared with combination index data from the Chou-Talalay method and were found to coincide. We propose MDRSM as an effective tool in devising combination treatments that can improve treatment effectiveness and increase treatment personalization, because MDRSM measures effectiveness rather than synergism, potentiation, or antagonism.

Topics: Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dioxolanes; Docetaxel; Drug Synergism; Flavonoids; Humans; Male; Mitoxantrone; Models, Statistical; Piperidines; Prostatic Neoplasms; Resveratrol; Taxoids

Flavopiridol (FP) is a pan-cyclin dependent kinase inhibitor, which shows strong efficacy in inducing cancer cell apoptosis. Although FP is potent against most cancer cells in vitro, unfortunately it proved less efficacious in clinical trials in various aggressive cancers. To date, the molecular mechanisms of the FP resistance are mostly unknown. Here, we report that a small fraction human prostate cancer DU145 cells can survive long-term FP treatment and emerge as FP-resistant cells (DU145

Topics: Apoptosis; Biomarkers, Tumor; Cell Division; Cell Line, Tumor; Cell Movement; Cisplatin; Docetaxel; Drug Resistance, Neoplasm; Flavonoids; G2 Phase; Gene Expression Regulation, Neoplastic; Humans; Male; Membrane Potential, Mitochondrial; Mitochondria; Neoplastic Stem Cells; Piperidines; Prostatic Neoplasms; Pseudopodia; Up-Regulation

Prostate cancer (PCa) still ranks as the second most frequently diagnosed cancer and metastatic castration resistant prostate cancer (CRPC) is a foremost cause of men cancer death around the world. The aim of this work was to investigate the selectivity and efficacy of new drug combinations for CRPC. We combined three compounds: paclitaxel (PTX: taxane that inhibits microtubule polymerization); 2-(2,4-Difluoro-phenyl)-4,5,6,7-tetrafluoro-1H-isoindole- 1,3(2H)-dione (CPS49; redox-reactive thalidomide analog with anti-angiogenic properties) and flavopiridol (flavo: semisynthetic flavonoid that inhibits cyclin dependent kinases). We assessed CPS49-flavo or -PTX combinations cytotoxicity in a panel of PCa cell lines and PC3 xenografts. We found that CPS49 enhanced flavo or PTX cytotoxicity in human PCa cell lines while showed resistance in a non-tumor cell line. Furthermore, xenografts generated by inoculation of human prostate carcinoma PC3 cells in nu/nu mice showed that CPS49/flavo administration reduced tumor growth both after 2 weeks of co-treatment and after 1 week of pretreatment with a low dose of flavo followed by 2 weeks of co-treatment. PTX and CPS49 combination did not significantly reduce tumor growth in PC3 xenografts. Histological analysis of xenograft PC3 tumor samples from CPS49/flavo combination showed extensive areas of necrosis induced by the treatment. RT-qPCR array containing 23 genes from PC3 cells or PC3 xenografts exposed to CPS49/flavo combination showed that this treatment shut down the expression of several genes involved in adhesion, migration or invasion. In summary, the antitumor activity of CPS49 or flavopiridol was improved by the combination of these compounds and using half dose of that previously reported. Hence, CPS49-flavo combination is a promising new alternative for PCa therapy.

Topics: Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Line, Tumor; Cell Survival; Dose-Response Relationship, Drug; Drug Combinations; Flavonoids; Humans; Male; Mice; Mice, Nude; Piperidines; Prostatic Neoplasms; Thalidomide; Treatment Outcome

Flavopiridol is a flavone that inhibits several cyclin‑dependent kinases and exhibits potent growth‑inhibitory activity, apoptosis and G1‑phase arrest in a number of human tumor cell lines. Flavopiridol is currently undergoing investigation in human clinical trials. The present study focused on the effect of flavopiridol in cell proliferation, cell cycle progression and apoptosis in prostate cancer stem cells (CSCs). Therefore, cluster of differentiation 133 (CD133)(+high)/CD44(+high) prostate CSCs were isolated from the DU145 human prostate cancer cell line. The cells were treated with flavopiridol in a dose‑ and time‑dependent manner to determine the inhibitory effect. Cell viability and proliferation were analyzed and the efficiency of flavopiridol was assessed using the sphere‑forming assay. Flavopiridol was applied to monolayer cultures of CD133(high)/CD44(high) human prostate CSCs at the following final concentrations: 100, 300, 500 and 1000 nM . The cultures were incubated for 24, 48 and 72 h. The half maximal inhibitory concentration (IC(50)) value of the drug was determined as 500 nM for monolayer cells. Dead cells were analyzed prior and subsequent to exposure to increasing flavopiridol doses. Annexin‑V and immunofluorescence analyses were performed for the evaluation of apoptotic pathways. According to the results, flavopiridol treatment caused significant growth inhibition at 500 and 1000 nM when compared to the control at 24 h. G(0)/G(1) analysis showed a statistically significant difference between 100 and 500 nM (P<0.005), 100 and 1000 nM (P<0.001), 300 and 1000 nM (P<0.001), and 500 and 1000 nM (P<0.001). Flavopiridol also significantly influenced the cells in the G(2)/M phase, particularly at high‑dose treatments. Flavopiridol induced growth inhibition and apoptosis at the IC(50) dose (500 nM), resulting in a significant increase in immunofluorescence staining of caspase‑3, caspase‑8 and p53. In conclusion, the present results indicated that flavopiridol could be a useful therapeutic agent for prostate CSCs by inhibiting tumor growth and malignant progression, and inducing apoptosis.

Topics: AC133 Antigen; Antigens, CD; Apoptosis; Caspase 3; Caspase 8; Cell Cycle Checkpoints; Cell Differentiation; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Flavonoids; Glycoproteins; Humans; Inhibitory Concentration 50; Male; Neoplastic Stem Cells; Peptides; Piperidines; Prostate; Prostatic Neoplasms; Tumor Suppressor Protein p53

To evaluate the antiproliferative activity of 3-(2-chlorophenyl)-1-(2-hydroxy-4, 6-dimethoxy-3-((ethyl(methyl) amino) methyl) phenyl) prop-2-en-1-one (DMF) against human androgen-independent prostate cancer PC3 cells in vitro and its underlying mechanisms.. The cytotoxic effect of DMF on PC3 cells was measured by MTT assay. Induction of apoptosis was assessed by propidium iodide staining and flow cytometric analysis. Changes of mitochondrial membrane potential (DeltaPsim) were detected by JC-1 staining. The levels of apoptosis related proteins were analyzed by Western blot.. DMF exhibited high efficiency on cell growth inhibition in PC3 cells with an IC50 value of (9.5 +/- 0.2)micromol/L. Flow cytometric analysis indicated that DMF could induce apoptosis in PC3 cells. A significant decrease of mitochondrial membrane potential was observed in PC3 cells treated with DMF, which was in a time- and dose-dependent manner. The results of Western blot indicated that DMF induced the activation of caspase-3, increased the ratio of Bax/Bcl-2 and downregulated the expression of phosphate-p38.. DMF is a potential compound against PC3 cells and the mitochondrial pathway might be involved in DMF-induced apoptosis in PC3 cells.

Topics: Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Blotting, Western; Caspase 3; Cell Line, Tumor; Cell Proliferation; Chlorobenzenes; Dose-Response Relationship, Drug; Enzyme Activation; Flavonoids; Flow Cytometry; Growth Inhibitors; Humans; Male; Membrane Potential, Mitochondrial; p38 Mitogen-Activated Protein Kinases; Piperidines; Prostatic Neoplasms; Proto-Oncogene Proteins c-bcl-2

Clinical trials have shown that chemotherapy with docetaxel combined with prednisone can improve survival of patients with androgen-independent prostate cancer. It is likely that the combination of docetaxel with other novel chemotherapeutic agents would also improve the survival of androgen-independent prostate cancer patients. We investigated whether the combination of docetaxel and flavopiridol, a broad cyclin-dependent kinase inhibitor, can increase apoptotic cell death in prostate cancer cells. Treatment of DU 145 prostate cancer cells with 500 nmol/L flavopiridol and 10 nmol/L docetaxel inhibited apoptosis probably because of their opposing effects on cyclin B1-dependent kinase activity. In contrast, when LNCaP prostate cancer cells were treated with flavopiridol for 24 hours followed by docetaxel for another 24 hours (FD), there was a maximal induction of apoptosis. However, there was greater induction of apoptosis in DU 145 cells when docetaxel was followed by flavopiridol or docetaxel. These findings indicate a heterogeneous response depending on the type of prostate cancer cell. Substantial decreases in X-linked inhibitor of apoptosis (XIAP) protein but not survivin, both being members of the IAP family, were required for FD enhanced apoptosis in LNCaP cells. Androgen ablation in androgen-independent LNCaP cells increased activated AKT and chemoresistance to apoptosis after treatment with FD. The proteasome inhibitor MG-132 blocked FD-mediated reduction of XIAP and AKT and antagonized apoptosis, suggesting that the activation of the proteasome pathway is one of the mechanisms involved. Overall, our data suggest that the docetaxel and flavopiridol combination requires a maximal effect on cyclin B1-dependent kinase activity and a reduction of XIAP and AKT prosurvival proteins for augmentation of apoptosis in LNCaP cells.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Cycle; Cell Line, Tumor; Cyclin B; Cyclin B1; Docetaxel; Flavonoids; Humans; Inhibitor of Apoptosis Proteins; Male; Microtubule-Associated Proteins; Neoplasm Proteins; Piperidines; Prostatic Neoplasms; Proteasome Endopeptidase Complex; Proto-Oncogene Proteins c-akt; RNA, Messenger; RNA, Small Interfering; Survivin; Taxoids; Up-Regulation; X-Linked Inhibitor of Apoptosis Protein

We investigated whether sequential combinations of flavopiridol and docetaxel can increase apoptotic cell death and inhibit the growth of primary and metastatic prostate tumors in the Ggamma/T-15 transgenic mouse model of prostate cancer.. Transgenic males were treated and the weights of primary and metastatic prostate tumors determined. Immunohistochemistry and Western blot was performed to evaluate the differences in apoptosis, proliferation, and angiogenesis.. Docetaxel was slightly more effective than flavopiridol in inhibiting primary prostate tumors, but neither drug alone inhibited metastases. Single drug treatments decreased angiogenesis but did not increase apoptosis. Both sequential combinations resulted in greater inhibition of primary and metastatic prostate tumors, increased apoptosis, and decreased angiogenesis compared to control mice.. Flavopiridol and docetaxel sequence combinations were effective in inhibiting prostate tumors in the Ggamma/T-15 transgenic mice. An increase in apoptosis and a decrease in angiogenesis resulted in the greatest inhibition of prostate cancers.

Topics: Animals; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Apoptosis; bcl-X Protein; Cell Division; Disease Models, Animal; Docetaxel; Drug Therapy, Combination; Flavonoids; Male; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Mice, Transgenic; Neovascularization, Pathologic; Piperidines; Prostatic Neoplasms; Taxoids; X-Linked Inhibitor of Apoptosis Protein

Flavopiridol (FP) inhibits gene expression and causes apoptosis, and these effects cannot be explained by inhibition of cyclin-dependent kinases that govern cell cycle. The simple and established notion that FP is an inhibitor of transcription predicts its effects. Because Mdm-2 targets p53 for degradation, FP, as predicted, dramatically induced p53 by inhibiting Mdm-2. Once p53 was induced, restoration of transcription (by removal of FP) resulted in superinduction of p21 and Mdm-2. Similarly, low concentrations of FP (50 nm) induced p21 and Mdm-2 because of their initial down-regulation. A sustained decrease of Mdm-2/p21 expression and accumulation of p53 coincided with near-maximal cytotoxicity of FP at concentrations >100 nm. Induction of p53 was a marker, not a cause, of cytotoxicity. FP caused rapid apoptosis (caspase-dependent cell death) in p53-null leukemia cells. In these cells, FP-induced apoptosis was converted to growth arrest by inhibitors of caspases. In apoptosis-reluctant A549 and PC3M cancer cells, FP inhibited cell proliferation but did not cause apoptosis. Like typical inhibitors of transcription, FP sensitized cells to apoptotic stimuli, allowing tumor necrosis factor to cause rapid and massive apoptosis in otherwise apoptosis-reluctant cells. We discuss that, as a reversible inhibitor of transcription, FP can be used clinically in novel rational drug combinations.

Topics: Apoptosis; Cell Line, Tumor; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Dose-Response Relationship, Drug; Drug Synergism; Flavonoids; HCT116 Cells; HL-60 Cells; Humans; Jurkat Cells; Lung Neoplasms; Male; Nuclear Proteins; Piperidines; Prostatic Neoplasms; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-mdm2; Transcription, Genetic; Tumor Necrosis Factor-alpha; Tumor Suppressor Protein p53; U937 Cells

The fraction of noncycling cells found in most tumors represents a major obstacle for conventional chemotherapy. Here, we show that the cyclin-dependent kinase inhibitor p27KIP-1 accumulates to high levels in human tumors grown in immunodeficient mice. We have developed an antisense phosphorothioate oligodeoxynucleotide (ODN) that efficiently inhibits the expression of p27KIP-1 both in vitro and in vivo. Treatment of cultured tumor cells with this ODN sensitized the cells to all chemotherapeutic drugs tested, including the new kinase inhibitor flavopiridol. Furthermore, striking synergistic effects of the p27KIP-1 ODN and flavopiridol were observed in vivo with respect to both the induction of apoptotic cell death and the inhibition of tumor growth. Importantly, p27KIP-1 ODN treatment alone did not provoke any detectable tumor enhancement. A mechanistic explanation for these findings might be derived from the observation that p27 ODN treatment of cultured tumor cells led to a clear increase in the fraction of S-G2 cells in the absence of an efficient progression into M phase. These findings may have direct relevance to the development of new approaches for the treatment of human cancer.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Cell Cycle; Cell Cycle Proteins; Cyclin-Dependent Kinase Inhibitor p27; Cyclin-Dependent Kinases; Drug Synergism; Flavonoids; HeLa Cells; Humans; Lung Neoplasms; Male; Mice; Mice, Nude; Microtubule-Associated Proteins; Mitosis; Oligonucleotides, Antisense; Piperidines; Prostatic Neoplasms; Thionucleotides; Transfection; Tumor Suppressor Proteins; Xenograft Model Antitumor Assays

Flavopiridol is an inhibitor of several cyclin-dependent kinases, and exhibits potent growth-inhibitory activity against a number of human tumor cell lines both in vitro, and when grown as xenografts in mice. It has shown promising antineoplastic activity and is currently undergoing clinical phase II testing. Prostate cancer (PCa) remains a leading cause of morbidity and mortality among males in the United States. There are no effective treatments for hormone and/or radiation refractory PCa, suggesting that novel and newer treatment strategy may be useful in the management of PCa. Our previous study showed that flavopiridol induces cell growth inhibition and apoptosis in breast cancer cells. Here, we investigated whether flavopiridol was effective against prostate cancer cells. Flavopiridol was found to inhibit growth of PC3 prostate cancer cells. Induction of apoptosis was also observed in PC3 cells treated with flavopiridol, as measured by DNA laddering and PARP cleavage. We also found a significant down-regulation of Bcl-2 in flavopiridol-treated cells. These findings suggest that down-regulation of Bcl-2 may be one of the molecular mechanisms through which flavopiridol induces apoptosis and inhibits cell growth, suggesting that flavopiridol may be an effective chemotherapeutic agent against prostate cancer.

Topics: Apoptosis; Cell Division; DNA Fragmentation; Dose-Response Relationship, Drug; Flavonoids; Growth Inhibitors; Humans; Male; Piperidines; Prostatic Neoplasms; Proto-Oncogene Proteins c-bcl-2; Time Factors; Tumor Cells, Cultured

We have selected a panel of human tumor xenografts for in vitro and in vivo studies that allows an indication of selectivity of action of novel chemotherapeutic agents. We report here the antitumor activity of the flavone flavopiridol (previously designated L86-8275), which has been selected for further studies based in part on its behavior in the anticancer drug screening system of the United States National Cancer Institute. Eighteen human tumor and five cell line-derived xenografts established by serial passage in nude mice in our laboratory were used as tumor models for in vitro investigations using a modified double-layer soft agar assay. In vivo investigations were completed in nude mice bearing advanced-stage s.c. growing prostate cancer xenografts. Antitumor activity in vitro (test/control

Topics: Animals; Antineoplastic Agents; Colony-Forming Units Assay; Drug Screening Assays, Antitumor; Flavonoids; Humans; Male; Mice; Mice, Nude; Neoplasm Transplantation; Piperidines; Prostatic Neoplasms; Tumor Cells, Cultured