piperidines and Mesothelioma

Malignant pleural mesothelioma (MPM), arises from the mesothelial cells, is difficult to be diagnosed at an early stage, and is refractory to conventional chemotherapy and radiotherapy. Therefore, the establishment of novel effective therapies is necessary to improve the prognosis for many patients with this disease. Recent studies have demonstrated that angiogenesis plays a significant role in MPM progression, suggesting the importance of tumor vessels as therapeutic targets. To explore molecular pathogenesis and evaluate the efficacy of vascular targeting therapy in MPM, we developed orthotopic implantation SCID mouse models of MPM. We found that selective VEGF inhibitors were effective only in the treatment of high-VEGF-producing MPM models. On the other hand, multiple kinase inhibitor E7080, with inhibitory activity against various angiogenic cytokine receptors, suppressed the progression and prolonged survival of both high-VEGF-producing and low-VEGF-producing MPM models. Further understanding of the functional characteristics of tumor angiogenesis may be essential to improve targeting therapies in MPM. In this review, we introduce current status of clinical strategies and novel therapeutic approaches against angiogenesis in MPM.

Topics: Angiogenesis Inhibitors; Animals; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Bevacizumab; Cell Line, Tumor; Disease Models, Animal; Humans; Mesothelioma; Mice; Mice, SCID; Neoplasm Transplantation; Neovascularization, Pathologic; Phenylurea Compounds; Piperidines; Pleural Effusion, Malignant; Pleural Neoplasms; Quinazolines; Quinolines; Thoracic Cavity; Vascular Endothelial Growth Factors

Although nearly 60% of mesotheliomas contain SV40 early region DNA sequences, the role of T/t antigens in initiating and maintaining the transformed state of mesothelioma cells remains unclear. The majority of mesothelioma cells which contain SV40 early region sequences exhibit extremely low basal expression of SV40 oncoproteins; however, T/t antigen expression can be induced under conditions of cellular stress. Abrogation of SV40 T/t expression by antisense techniques induces apoptosis in part via restoration of p53 function, and enhances chemosensitivity in SV40 (+) MPM cells by mechanisms which have not been fully elucidated. This review briefly summarizes our ongoing efforts to define the role of SV40 oncoproteins in modulating the malignant phenotype of mesothelioma cells, and highlights strategies which may prove efficacious in vivo for circumventing SV40 T/t antigen expression in mesotheliomas.

Topics: Antigens, Polyomavirus Transforming; Antineoplastic Agents; Flavonoids; Gene Expression Regulation, Viral; Humans; Mesothelioma; Oligonucleotides, Antisense; Piperidines; Pleural Neoplasms; Simian virus 40

Malignant pleural mesotheliomas (MPM) are most often surgically unresectable, and they respond poorly to current chemotherapy and radiation therapy. Between 23 and 64% of malignant pleural mesothelioma have somatic inactivating mutations in the BAP1 gene. BAP1 is a homologous recombination (HR) DNA repair component found in the BRCA1/BARD1 complex. Similar to BRCA1/2 deficient cancers, mutation in the BAP1 gene leads to a deficient HR pathway and increases the reliance on other DNA repair pathways. We hypothesized that BAP1-mutant MPM would require PARP1 for survival, similar to the BRCA1/2 mutant breast and ovarian cancers. Therefore, we used the clinical PARP1 inhibitors niraparib and olaparib to assess whether they could induce synthetic lethality in MPM. Surprisingly, we found that all MPM cell lines examined, regardless of BAP1 status, were addicted to PARP1-mediated DNA repair for survival. We found that niraparib and olaparib exposure markedly decreased clonal survival in multiple MPM cell lines, with and without BAP1 mutations. This clonal cell death may be due to the extensive replication fork collapse and genomic instability that PARP1 inhibition induces in MPM cells. The requirement of MPM cells for PARP1 suggests that they may generally arise from defects in HR DNA repair. More importantly, these data demonstrate that the PARP1 inhibitors could be effective in the treatment of MPM, for which little effective therapy exists.

Topics: Cell Line, Tumor; Clone Cells; DNA Repair; Humans; Indazoles; Lung Neoplasms; Mesothelioma; Mesothelioma, Malignant; Mutation; Phthalazines; Piperazines; Piperidines; Pleural Neoplasms; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Synthetic Lethal Mutations; Tumor Suppressor Proteins; Ubiquitin Thiolesterase

Malignant mesothelioma (MM), lung cancers, and asbestosis are hyperproliferative diseases associated with exposures to asbestos. All have a poor prognosis; thus, the need to develop novel and effective therapies is urgent. Vandetanib (Van) (ZD6474, ZACTIMA) is a tyrosine kinase inhibitor that has shown equivocal results in clinical trials for advanced non-small cell lung cancer. However, tyrosine kinase inhibitors alone have shown no significant clinical activity in phase II trials of patients with unresectable MM. Using epithelioid (HMESO) and sarcomatoid (H2373) human MM lines, the efficacy of tumor cell killing and signaling pathways modulated by Van with and without doxorubicin (Dox) was examined. Van alone reduced total cell numbers in HMESO MM and synergistically increased the toxicity of Dox in HMESO and H2373 cells. Most importantly, we identified two novel cell survival/resistance pathways, ERK5 and cyclic AMP response element binding protein (CREB), that were inhibited by Van and Dox. After silencing of either ERK5 or CREB, significant decreases in cell numbers in the Dox-resistant sarcomatoid H2373 line were observed. Results suggest that a plethora of cell signaling pathways associated with cell survival are induced by Dox but inhibited by the addition of Van in MM. Data from our study support the combined efficacy of Van and Dox as a novel approach in the treatment of MM that is further enhanced by blocking ERK5 or CREB signaling cascades.

Topics: Antibiotics, Antineoplastic; Cell Line, Tumor; Cell Survival; Cyclic AMP Response Element-Binding Protein; Doxorubicin; Drug Synergism; Humans; MAP Kinase Signaling System; Mesothelioma; Mitogen-Activated Protein Kinase 7; Neoplasms, Connective Tissue; Phosphorylation; Piperidines; Quinazolines; RNA, Small Interfering; Sarcoma

Although pemetrexed, a potent thymidylate synthase (TS) inhibitor, enhances the cytoytoxic effect of platinum compounds against malignant pleural mesothelioma (MPM), novel combinations with effective targeted therapies are warranted. To this end, the current study evaluates new targeted agents and their pharmacological interaction with carboplatin-pemetrexed in human MPM cell lines.. We treated H2052, H2452, H28 and MSTO-211H cells with carboplatin, pemetrexed and targeted compounds (gefitinib, erlotinib, sorafenib, vandetanib, enzastaurin and ZM447439) and evaluated the modulation of pivotal pathways in drug activity and cancer cell proliferation.. Vandetanib emerged as the compound with the most potent cytotoxic activity, which interacted synergistically with carboplatin and pemetrexed. Drug combinations blocked Akt phosphorylation and increased apoptosis. Vandetanib significantly downregulated epidermal growth factor receptor (EGFR)/Erk/Akt phosphorylation as well as E2F-1 mRNA and TS mRNA/protein levels. Moreover, pemetrexed decreased Akt phosphorylation and expression of DNA repair genes. Finally, most MPM samples displayed detectable levels of EGFR and TS, the variability of which could be used for patients' stratification in future trials with vandetanib-pemetrexed-carboplatin combination.. Vandetanib markedly enhances pemetrexed-carboplatin activity against human MPM cells. Induction of apoptosis, modulation of EGFR/Akt/Erk phosphorylation and expression of key determinants for pemetrexed and carboplatin activity contribute to this synergistic interaction, and, together with the expression of these determinants in MPM samples, warrant further clinical investigation.

Topics: Apoptosis; Blotting, Western; Carboplatin; Cell Cycle; Cell Line, Tumor; Drug Screening Assays, Antitumor; Drug Synergism; Enzyme-Linked Immunosorbent Assay; Glutamates; Guanine; Humans; Immunohistochemistry; Mesothelioma; Pemetrexed; Phosphorylation; Piperidines; Pleural Neoplasms; Polymerase Chain Reaction; Polymorphism, Genetic; Proto-Oncogene Proteins c-akt; Quinazolines

Malignant pleural mesothelioma (MPM) is an aggressive malignancy with a poor prognosis, therefore development of novel effective therapies is urgent. In the present study, we investigated the therapeutic efficacy of vandetanib (ZD6474), an inhibitor of VEGFR-2, EGFR and RET tyrosine kinases, in an orthotopic model of MPM. We found that a human MPM cell line, EHMES-10, expressed RET/PTC3 oncogenic rearrangement and a large amount of VEGF. Vandetanib induced the apoptosis and inhibited the proliferation of EHMES-10 cells in vitro (IC(50)=0.3 microM). Once-daily oral treatment with vandetanib inhibited tumor angiogenesis, and reduced significantly the growth of thoracic tumors and the production of pleural effusions, resulting in the prolonged survival of mice in EHMES-10 orthograft model. In contrast, the selective EGFR tyrosine kinase inhibitor, gefitinib, had no effect against EHMES-10 cells both in vitro and in vivo. Our results suggest that using vandetanib to target RET-dependent tumor cell proliferation and survival and VEGFR-2-dependent tumor angiogenesis may be promising against MPM expressing RET oncogenic rearrangement and VEGF.

Topics: Angiogenesis Inhibitors; Animals; Apoptosis; Base Sequence; Cell Line, Tumor; Cell Proliferation; ErbB Receptors; Gefitinib; Gene Rearrangement; Humans; Male; Mesothelioma; Mice; Mice, SCID; Molecular Sequence Data; Neoplasm Transplantation; Neovascularization, Pathologic; Piperidines; Pleural Neoplasms; Proto-Oncogene Proteins c-ret; Quinazolines; Transplantation, Heterologous; Vascular Endothelial Growth Factor Receptor-2

Recent insights regarding the pathogenesis of malignant pleural mesothelioma (MPM) provide new opportunities for targeted molecular therapies for this highly lethal disease. The present study was undertaken to examine the effects of the histone deacetylase inhibitor, Depsipeptide (DP) FK228, in conjunction with the cyclin-dependent kinase inhibitor, Flavopiridol (FLA), in cultured MPM cells.. Proliferation and apoptosis in drug-treated, virally transduced, or control cells were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Apo-bromodeoxyuridine techniques. Western blot and ELISA techniques were used to examine signal transduction and cell cycle-related protein levels in MPM cells exposed to DP and/or FLA in the presence or absence of calphostin, phorbol-12,13-dibutyrate, 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole, or adenoviral p21 transduction.. DP (1-50 ng/ml x 6 h) or FLA (100-200 nM x 72 h) alone, mediated low-level, dose-dependent growth inhibition in MPM cells. In contrast, sequential DP/FLA treatment mediated marked growth inhibition and apoptosis in these cell lines. The cytotoxic effects of DP/FLA were considerably less pronounced in cultured normal cells. The proapoptotic effects of DP/FLA treatment coincided with inhibition of DP-mediated induction of p21 by FLA. Overexpression of p21 by adenoviral gene transfer techniques rendered MPM cells refractory to the cytotoxic effects of this treatment regimen. In p21 reporter assays, promoter activation by DP was antagonized by FLA. The magnitude of inhibition of DP-mediated p21 induction by FLA exceeded that observed with the pTEFb antagonist 5,6-dichloro-1-beta-D-ribofuranosyl-benzimidazole. Calphostin C abrogated p21 induction mediated by DP and enhanced DP-mediated apoptosis in a manner comparable with FLA in MPM cells; in contrast, phorbol-12,13-dibutyrate blocked FLA-mediated inhibition of p21 induction by DP and markedly protected these cells from the apoptotic effects of sequential DP/FLA.. FLA abrogates DP-mediated induction of p21 expression, in part, via inhibition of protein kinase C signaling and markedly potentiates the cytotoxic effects of DP in MPM cells.

Topics: Apoptosis; Cell Division; Cell Line, Tumor; Cell Survival; Cyclin-Dependent Kinase Inhibitor p21; Cyclins; Enzyme Inhibitors; Flavonoids; Humans; Mesothelioma; Piperidines; Pleural Neoplasms