alvocidib and Carcinoma--Squamous-Cell

Flavopiridol a semisynthetic flavone that inhibits cyclin-dependent kinases (CDKs) and has growth-inhibitory activity and induces a blockade of cell-cycle progression at G1-phase and apoptosis in numerous human tumor cell lines and is currently under investigation in phase II clinical trials. Cancer stem cells (CSCs) are comprised of subpopulation of cells in tumors that have been proposed to be responsible for recurrence and resistance to chemotherapy. The aim of the present study was to investigate the effects of flavopiridol in cancer stem cell cytoskeleton, cell adhesion, and epithelial to mesenchymal transition in CSCs.. The cells were treated with flavopiridol to determine the inhibitory effect. Cell viability and proliferation were determined by using the WST-1 assay. Caspase activity and immunofluorescence analyses were performed for the evaluation of apoptosis, cell cytoskeleton, and epithelial-mesenchymal transition (EMT) markers. The effects of flavopiridol on the cell cycle were also evaluated. Flow cytometric analysis was used to detect the percentages of CSCs subpopulation. We analyzed the gene expression patterns to predict cell cycle and cell cytoskeleton in CSCs by RT-PCR.. Flavopiridol-induced cytotoxicity and apoptosis at the IC50 dose, resulting in a significant increase expression of caspases activity. Cell cycle analyses revealed that flavopiridol induces G1 phase cell cycle arrest. Flavopiridol significantly decreased the mRNA expressions of the genes that regulate the cell cytoskeleton and cell cycle components and cell motility in CSCs.. Our results suggest that Flavopiridol has activity against lung CSCs and may be effective chemotherapeutic molecule for lung cancer treatment.

Topics: AC133 Antigen; Antineoplastic Agents; Carcinoma, Squamous Cell; Caspases; Cell Line, Tumor; Cell Proliferation; DNA, Neoplasm; Flavonoids; Flow Cytometry; Gene Expression Regulation, Neoplastic; Humans; Hyaluronan Receptors; Lung Neoplasms; Neoplastic Stem Cells; Piperidines; Polymerase Chain Reaction

The NUT midline carcinoma (NMC) is a rare but fatal cancer for which systematic testing of therapy options has never been performed.. On the basis of disease biology, we compared the efficacy of the CDK9 inhibitor flavopiridol (FP) with a panel of anticancer agents in NMC cell lines and mouse xenografts.. In vitro anthracyclines, topoisomerase inhibitors, and microtubule poisons were among the most cytotoxic drug classes for NMC cells, while efficacy of the bromodomain inhibitor JQ1 varied considerably between lines carrying different BRD4 (bromodomain-containing protein 4)-NUT (nuclear protein in testis) translocations. Efficacy of FP was comparable to vincristine and doxorubicin, drugs that have been previously used in NMC patients. All three compounds showed significantly better activity than etoposide and vorinostat, agents that have also been used in NMC patients. Statins and antimetabolites demonstrated intermediate single-agent efficacy. In vivo, vincristine significantly inhibited tumour growth in two different NMC xenografts. Flavopiridol in vivo was significantly effective in one of the two NMC xenograft lines, demonstrating the biological heterogeneity of this disease.. These results demonstrate that FP may be of benefit to a subset of patients with NMC, and warrant a continued emphasis on microtubule inhibitors, anthracyclines, and topoisomerase inhibitors as effective drug classes in this disease.

Topics: Animals; Anthracyclines; Antineoplastic Agents; Carcinoma, Squamous Cell; Cell Line, Tumor; Doxorubicin; Drug Screening Assays, Antitumor; Female; Flavonoids; Head and Neck Neoplasms; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Oncogene Proteins; Piperidines; Topoisomerase Inhibitors; Tubulin Modulators; Vincristine; Xenograft Model Antitumor Assays

The cyclin-dependent kinase (cdk) inhibitor p27 preferentially inactivates cdk complexes required for progression through the G1/S transition. Loss of p27 is associated with aggressive behavior in a variety of tumors, including Barrett's associated adenocarcinoma (BAA). We have previously shown that gastroduodenal-esophageal reflux (GDER) together with N-methyl-N-benzylnitrosamine (MBN) induces Barrett's esophagus (BE) and malignant transformation of the esophageal mucosa in mice. This process is enhanced in a p27 null background. Here, we show that chronic flavopiridol administration sharply reduced the prevalence of BE in GDER/MBN-treated p27 knockout mice when compared to animals treated with diluent only (7 vs 26%, P=0.0079). Similarly, flavopiridol reduced the prevalence of BAA (11 vs 32%, P=0.0098) and overall cancer prevalence (15 vs 60%, P<0.0001). In addition, appropriate molecular targeting by flavopiridol in tumor cells was confirmed by downregulation of cyclin D1, a known target of this pan-cdk inhibitor. The results of this study represent the experimental basis for chemoprevention with cdk inhibitors in human BE and BAA.

Topics: Adenocarcinoma; Animals; Anticarcinogenic Agents; Barrett Esophagus; Carcinoma, Squamous Cell; Cell Cycle Proteins; Cell Transformation, Neoplastic; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p27; Esophageal Neoplasms; Flavonoids; Mice; Phosphorylation; Piperidines; Retinoblastoma Protein; Tumor Suppressor Proteins

Tumor hypoxia modifies the efficacy of conventional anticancer therapy and promotes malignant tumor progression. Human chorionic gonadotropin (hCG) is a glycoprotein secreted during pregnancy that has been used to monitor tumor burden in xenografts engineered to express this marker. We adapted this approach to use urinary beta-hCG as a secreted reporter protein for tumor hypoxia. We used a hypoxia-inducible promoter containing five tandem repeats of the hypoxia-response element (HRE) ligated upstream of the beta-hCG gene. This construct was stably integrated into two different cancer cell lines, FaDu, a human head and neck squamous cell carcinoma, and RKO, a human colorectal cancer cell line. In vitro studies showed that tumor cells stably transfected with this plasmid construct secrete beta-hCG in response to hypoxia or hypoxia-inducible factor 1alpha (HIF-1alpha) stabilizing agents. The hypoxia responsiveness of this construct can be blocked by treatment with agents that affect the HIF-1alpha pathways, including topotecan, 1-benzyl-3-(5'-hydroxymethyl-2'-furyl)indazole (YC-1), and flavopiridol. Immunofluorescent analysis of tumor sections and quantitative assessment with flow cytometry indicate colocalization between beta-hCG and 2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide (EF5) and beta-hCG and pimonidazole, two extrinsic markers for tumor hypoxia. Secretion of beta-hCG from xenografts that contain these stable constructs is directly responsive to changes in tumor oxygenation, including exposure of the animals to 10% O2 and tumor bed irradiation. Similarly, urinary beta-hCG levels decline after treatment with flavopiridol, an inhibitor of HIF-1 transactivation. This effect was observed only in tumor cells expressing a HRE-regulated reporter gene and not in tumor cells expressing a cytomegalovirus-regulated reporter gene. The 5HRE beta-hCG reporter system described here enables serial, noninvasive monitoring of tumor hypoxia in a mouse model by measuring a urinary reporter protein.

Topics: Animals; Carcinoma, Squamous Cell; Cell Hypoxia; Cell Line, Tumor; Chorionic Gonadotropin, beta Subunit, Human; Colorectal Neoplasms; DNA-Binding Proteins; Flavonoids; Genes, Reporter; Genetic Vectors; Head and Neck Neoplasms; Humans; Hypoxia-Inducible Factor 1; Hypoxia-Inducible Factor 1, alpha Subunit; Mice; Mice, Inbred BALB C; Mice, Inbred SENCAR; Neoplasm Transplantation; Nuclear Proteins; Piperidines; Topotecan; Transcription Factors; Transfection; Transplantation, Heterologous

Flavopiridol is a synthetic flavone that has shown an antitumor effect against several cancers. Here, we investigated the in vitro effect of flavopiridol alone and the combined effect of low-dose flavopiridol plus radiation on esophageal squamous cell carcinoma cell lines. Esophageal squamous cell carcinoma cell lines (TE8, TE9 and KE4) were exposed to flavopiridol (0.05-400 nmol/L) for 48 h. Growth inhibition was evaluated by MTT assay, cell cycle distribution was determined by flow cytometry, and cyclin D1, Bcl-2 and Rb protein expression was detected by Western blotting. The effect of 0.05 nmol/L flavopiridol as a radio-sensitizer was determined by clonogenic assay. The IC50 was approximately 110-250 nmol/L. Exposure to 0.05 nmol/L flavopiridol for 48 h increased the G2/M population, while 300 nmol/L increased the G1 population. At a concentration of 300 nmol/L, nuclear fragmentation and chromatin condensation were observed in all three cell lines. Exposure to 300 nmol/L flavopiridol decreased the levels of cyclin D1 and Rb protein in all three cell lines and Bcl-2 protein was also decreased in TE8 and KE4 cells. Moreover, exposure to 0.05 nmol/L flavopiridol slightly decreased the levels of cyclin D1, Rb and Bcl-2 protein in KE4 cells. Flavopiridol treatment (0.05 nmol/L) enhanced the radio-sensitivity in all three cell lines. Low-dose flavopiridol augmented the response of esophageal squamous cell carcinoma cell lines to radiation. Administration of a low dose of flavopiridol could be a potent new therapeutic approach for improving the efficacy of radiotherapy against esophageal cancer.

Topics: Antineoplastic Agents; Apoptosis; Blotting, Western; Carcinoma, Squamous Cell; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cyclin D1; Esophageal Neoplasms; Flavonoids; Flow Cytometry; Formazans; Genes, bcl-2; Growth Inhibitors; Humans; Piperidines; Radiation Tolerance; Radiation-Sensitizing Agents; Retinoblastoma Protein; Tetrazolium Salts; Treatment Outcome

Flavopiridol (HMR 1275) has been identified recently as a novel antineoplastic agent in the primary screen conducted by the Developmental Therapeutics Program, National Cancer Institute. Flavopiridol inhibits most cyclin-dependent kinases (cdks) and displays unique anticancer properties. Here, we investigated whether this compound was effective against head and neck squamous cell carcinomas (HNSCC). Exposure of HNSCC cells to flavopiridol diminished cdc2 and cdk2 activity and potently inhibited cell proliferation (IC50 43-83 nM), which was concomitant with the appearance of cells with a sub-G1 DNA content. Moreover, DNA fragmentation and TUNEL (terminal deoxynucleotidyl transferase-mediated nick end labeling) reaction confirmed that flavopiridol induces apoptosis in all cell lines, even on certain HNSCC cells that are insensitive to apoptosis to DNA-damaging agents (gamma-irradiation and bleomycin). A tumorigenic HNSCC cell line was used to assess the effect of flavopiridol in vivo. Treatment (5 mg/kg per day, intraperitoneally) for 5 d led to the appearance of apoptotic cells in the tumor xenografts and caused a 60-70% reduction in tumor size, which was sustained over a period of 10 wk. Flavopiridol treatment also resulted in a remarkable reduction of cyclin D1 expression in HNSCC cells and tumor xenografts. Our data indicate that flavopiridol exerts antitumor activity in HNSCC, and thus it can be considered a suitable candidate drug for testing in the treatment of refractory carcinomas of the head and neck.

Topics: Animals; Antineoplastic Agents; Apoptosis; Carcinoma, Squamous Cell; CDC2 Protein Kinase; CDC2-CDC28 Kinases; Cell Cycle; Cell Division; Cyclin D1; Cyclin D3; Cyclin E; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinases; Cyclins; Enzyme Inhibitors; Female; Flavonoids; Gene Expression; Growth Inhibitors; Head and Neck Neoplasms; Mice; Mice, Nude; Piperidines; Protein Serine-Threonine Kinases; Transplantation, Heterologous; Tumor Cells, Cultured