pyrimidinones and Osteosarcoma

Sarcomas are rare and heterogeneous mesenchymal tumors affecting both pediatric and adult populations with more than 70 recognized histologies. Doxorubicin and ifosfamide have been the main course of therapy for treatment of sarcomas; however, the response rate to these therapies is about 10-20% in metastatic setting. Toxicity with the drug combination is high, response rates remain low, and improvement in overall survival, especially in the metastatic disease, remains negligible and new agents are needed. Wee1 is a critical component of the G2/M cell cycle checkpoint control and mediates cell cycle arrest by regulating the phosphorylation of CDC2. Inhibition of Wee1 by MK1775 has been reported to enhance the cytotoxic effect of DNA damaging agents in different types of carcinomas. In this study we investigated the therapeutic efficacy of MK1775 in various sarcoma cell lines, patient-derived tumor explants ex vivo and in vivo both alone and in combination with gemcitabine, which is frequently used in the treatment of sarcomas. Our data demonstrate that MK1775 treatment as a single agent at clinically relevant concentrations leads to unscheduled entry into mitosis and initiation of apoptotic cell death in all sarcomas tested. Additionally, MK1775 significantly enhances the cytotoxic effect of gemcitabine in sarcoma cells lines with different p53 mutational status. In patient-derived bone and soft tissue sarcoma samples we showed that MK1775 alone and in combination with gemcitabine causes significant apoptotic cell death. Magnetic resonance imaging (MRI) and histopathologic studies showed that MK1775 induces significant cell death and terminal differentiation in a patient-derived xenograft mouse model of osteosarcoma in vivo. Our results together with the high safety profile of MK1775 strongly suggest that this drug can be used as a potential therapeutic agent in the treatment of both adult as well as pediatric sarcoma patients.

Topics: Adolescent; Adult; Animals; Antimetabolites, Antineoplastic; Cell Cycle Proteins; Cell Death; Cell Differentiation; Cell Line, Tumor; Child; Child, Preschool; Deoxycytidine; Drug Synergism; Female; Femoral Neoplasms; Gemcitabine; Humans; Male; Mice; Mice, SCID; Middle Aged; Neoplasm Transplantation; Nuclear Proteins; Osteosarcoma; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones; Transplantation, Heterologous; Xenograft Model Antitumor Assays

Musculoskeletal sarcomas are aggressive malignancies of bone and soft tissues often affecting children and adolescents. Histone deacetylase inhibitors (HDACi) have been proposed to counteract cancer stem cells (CSCs) in solid neoplasms. When tested in human osteosarcoma, rhabdomyosarcoma, and Ewing's sarcoma stem cells, the new HDACi MC1742 (1) and MC2625 (2) increased acetyl-H3 and acetyl-tubulin levels and inhibited CSC growth by apoptosis induction. At nontoxic doses, 1 promoted osteogenic differentiation. Further investigation with 1 will be done in preclinical sarcoma models.

Topics: Aminopyridines; Apoptosis; Bone Neoplasms; Cell Differentiation; Cell Line, Tumor; Cell Proliferation; Drug Screening Assays, Antitumor; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Neoplastic Stem Cells; Osteogenesis; Osteosarcoma; Pyrimidinones; Rhabdomyosarcoma; Sarcoma; Sarcoma, Ewing; Structure-Activity Relationship

Pediatric bone and soft tissue sarcomas often display increased Akt phosphorylation through up regulation of insulin-like growth factor (IGF1) signaling. Additionally, Akt signaling has been linked to resistance to IGF1 receptor (IGF1R) and mTOR (mammalian target of rapamycin) inhibitors in sarcoma, further demonstrating the role of Akt in tumor survival. This suggests targeting components of the PI3K/Akt pathway may be an effective therapeutic strategy. Here, we investigated the in vitro activity of the pan-class I PI3K inhibitor buparlisib (BKM120) in pediatric bone and soft tissue sarcomas. Buparlisib inhibited activation of Akt and signaling molecules downstream of mTORC1 (mTOR complex 1) in Ewing sarcoma, osteosarcoma, and rhabdomyosarcoma cell lines. Anti-proliferative effects were observed in both anchorage dependent and independent conditions and apoptosis was induced within 24 hours of drug treatment. Buparlisib demonstrated cytotoxicity as a single agent, but was found to be more effective when used in combination. Synergy was observed when buparlisib was combined with the IGF1R inhibitor NVP-AEW541 and the mTORC1 inhibitor rapamycin. The addition of NVP-AEW541 also further reduced phospho-Akt levels and more potently induced apoptosis compared to buparlisib treatment alone. Additionally, the combination of buparlisib with the MEK1/2 inhibitor trametinib resulted in synergy in sarcoma cell lines possessing MAPK pathway mutations. Taken together, these data indicate buparlisib could be a novel therapy for the treatment of pediatric bone and soft tissue sarcomas.

Topics: Aminopyridines; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Cells, Cultured; Class I Phosphatidylinositol 3-Kinases; Drug Synergism; Extracellular Signal-Regulated MAP Kinases; Humans; Mechanistic Target of Rapamycin Complex 1; Morpholines; Multiprotein Complexes; Mutation; Osteosarcoma; Phosphorylation; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; Pyridones; Pyrimidines; Pyrimidinones; Pyrroles; Sarcoma; Signal Transduction; TOR Serine-Threonine Kinases

Systemic therapy has improved osteosarcoma event-free and overall survival, but 30-50% of patients originally diagnosed will have progressive or recurrent disease, which is difficult to cure. Osteosarcoma has a complex karyotype, with loss of p53 in the vast majority of cases and an absence of recurrent, targetable pathways. In this study, we explored 54 agents that are clinically approved for other oncologic indications, agents in active clinical development, and others with promising preclinical data in osteosarcoma at clinically achievable concentrations in 5 osteosarcoma cell lines. We found significant single-agent activity of multiple agents and tested 10 drugs in all permutations of two-drug combinations to define synergistic combinations by Chou and Talalay analysis. We then evaluated order of addition to choose the combinations that may be best to translate to the clinic. We conclude that the repurposing of chemotherapeutics in osteosarcoma by using an in vitro system may define novel drug combinations with significant in vivo activity. In particular, combinations of proteasome inhibitors with histone deacetylase inhibitors and ixabepilone and MK1775 demonstrated excellent activity in our assays.

Topics: Animals; Apoptosis; Bone Neoplasms; Cell Survival; Drug Synergism; Drug Therapy, Combination; Epothilones; Female; Histone Deacetylase Inhibitors; Humans; Mice; Mice, Inbred C57BL; Mice, Nude; Middle Aged; Osteosarcoma; Proteasome Inhibitors; Pyrazoles; Pyrimidines; Pyrimidinones; Transplantation, Heterologous; Tumor Cells, Cultured

Combinations of targeted drugs have been employed to treat sarcomas, however, response rates have not improved notably, therefore emphasizing the need for novel treatments. In addition, imaging approaches to assess therapeutic response is lacking, as currently measurable indices, such as volume and/or diameter, do not accurately correlate with changes in tumor biology. In this study, quantitative and profound analyses of magnetic resonance imaging (MRI) were developed to evaluate these as imaging biomarkers for MK1775 and Gem in an osteosarcoma xenotransplant model at early time-points following treatment. Notably, we showed that Gem and Gem+MK1775 groups had significantly inhibited tumor growth by day 4, which was presaged by elevations in mean ADC by 24 hours post treatment. Significant differences were also observed at later time points for the Gem+MK1775 combination and MK1775 therapy. ADC distribution and entropy (randomness of ADC values) were also elevated by 24 hours following therapy. Immunohistochemistry demonstrated that these treatment-related increases in ADC correlated with apoptosis and observed cell condensations (dense- and exploded bodies). These findings underline the role of ADC as a quantitative imaging biomarker for therapy-induced response and show promising clinical relevance in the sarcoma patient population.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Bone Neoplasms; Cell Cycle Checkpoints; Deoxycytidine; Diffusion Magnetic Resonance Imaging; Female; Gemcitabine; Humans; Mice; Mice, SCID; Middle Aged; Molecular Targeted Therapy; Osteosarcoma; Prognosis; Pyrazoles; Pyrimidines; Pyrimidinones; Treatment Outcome; Xenograft Model Antitumor Assays

The Chk1 kinase is required for the arrest of cell cycle progression when DNA is damaged, and for stabilizing stalled replication forks. As a consequence, many Chk1 inhibitors have been developed and tested for their potential to enhance DNA damage-induced tumor cell killing. However, inhibition of Chk1 alone, without any additional exogenous agent, can be cytotoxic. Understanding the underlying mechanisms of this sensitivity is critical for defining which patients might respond best to therapy with Chk1 inhibitors. We have investigated the mechanism of sensitivity in U2OS osteosarcoma cells. Upon incubation with the Chk1 inhibitor MK-8776, single-stranded DNA regions (ssDNA) and double-strand breaks (DSB) begin to appear within 6 h. These DSB have been attributed to the structure-specific DNA endonuclease, Mus81. The Mre11/Rad50/Nbs1 complex is known to be responsible for the resection of DSB to ssDNA. However, we show that inhibition of the Mre11 nuclease activity leads, not only to a decrease in the amount of ssDNA following Chk1 inhibition, but also inhibits the formation of DSB, suggesting that DSB are a consequence of ssDNA formation. These findings were corroborated by the discovery that Mre11-deficient ATLD1 cells are highly resistant to MK-8776 and form neither ssDNA nor DSB following treatment. However, once complimented with exogenous Mre11, the cells accumulate both ssDNA and DSB when incubated with MK-8776. Our findings suggest that Mre11 provides the link between aberrant activation of Cdc25A/Cdk2 and Mus81. The results highlight a novel role for Mre11 in the production of DSB and may help define which tumors are more sensitive to MK-8776 alone or in combination with DNA damaging agents.

Topics: Cell Line, Tumor; Checkpoint Kinase 1; DNA Breaks, Double-Stranded; DNA Damage; DNA-Binding Proteins; Humans; MRE11 Homologue Protein; Osteosarcoma; Phosphorylation; Protein Kinases; Pyrazoles; Pyrimidines; Pyrimidinones; Thiones

Aberrant activation of the Wnt/β-catenin signaling pathway promotes osteosarcoma tumorigenesis and metastasis. In this study, we tested the hypothesis that osteosarcoma progression may be delayed by disrupting the Wnt/β-catenin pathway using small molecule inhibitors such as curcumin and PKF118-310. Effective inhibitions of the Wnt/β-catenin pathway by curcumin and PKF118-310 in osteosarcoma cells were shown by the suppression of both intrinsic and activated β-catenin/Tcf transcriptional activities using luciferase reporter assays. Western blot analysis revealed that there was no change in the amount of cytosolic β-catenin, although nuclear β-catenin was markedly reduced by treatment with either compounds. We next performed wound healing and Matrigel invasion assays and observed a dose-dependent decrease in osteosarcoma cell migration and invasion with curcumin and PKF118-310 treatment. Overexpression of the wild-type β-catenin plasmid in osteosarcoma cells resulted in enhanced cell invasiveness but this effect was significantly overcome by curcumin. Gelatin zymography and Western blotting showed that reduced cell invasion with curcumin and PKF118-310 treatment correlated with the activity and protein level of matrix metalloproteinase-9 under conditions of intrinsic or extrinsic Wnt/β-catenin activation. Using cell apoptosis assay and cell cycle analysis, we further showed that the anti-proliferative effect of PKF118-310 is attributed to PKF118-310-induced apoptosis and G2/M phase arrest. Lastly, we observed that these anti-cancer effects correlated with the decreased expression of cyclin D1, c-Myc and survivin. Our findings strongly suggest that curcumin and PKF118-310 have great therapeutic potential for the treatment of osteosarcoma.

Topics: Antineoplastic Agents; beta Catenin; Biological Products; Cell Cycle; Cell Death; Cell Line, Tumor; Cell Movement; Cell Nucleus; Cell Proliferation; Cell Survival; Curcumin; Drug Screening Assays, Antitumor; Gene Expression Regulation, Neoplastic; Humans; Matrix Metalloproteinase 9; Neoplasm Invasiveness; Osteosarcoma; Pyrimidinones; Signal Transduction; Triazines; Wnt Proteins

Metastasis continues to be the leading cause of mortality for patients with cancer. Several years ago, it became clear that chemokines and their receptors could control the tumor progress. CXCR3 has now been identified in many cancers including osteosarcoma and CXCR3 ligands were expressed by lungs that are the primary sites to which this tumor metastasize. This study tested the hypothesis that disruption of the CXCR3/CXCR3 ligands complexes could lead to a decrease in lungs metastasis. The experimental design involved the use of the CXCR3 antagonist, AMG487 and 2 murine models of osteosarcoma lung metastases. After tail vein injection of osteosarcoma cells, mice that were systematically treated with AMG487 according to preventive or curative protocols had a significant reduction in metastatic disease. Treatment of osteosarcoma cells in vitro with AMG487 led to decreased migration, decreased matrix metalloproteinase activity, decreased proliferation/survival and increased caspase-independent death. Taken together, our results support the hypothesis that CXCR3 and their ligands intervene in the initial dissemination of the osteosarcoma cells to the lungs and stimulate the growth and expansion of the metastatic foci in later stages. Moreover, these studies indicate that targeting CXCR3 may specifically inhibit tumor metastasis without adversely affecting antitumoral host response.

Topics: Acetamides; Animals; Apoptosis; Blotting, Western; Calcium; Caspases; Cell Movement; Female; Humans; Lung Neoplasms; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Invasiveness; Osteosarcoma; Pyrimidinones; Receptors, CXCR3; Signal Transduction; Tumor Cells, Cultured; Xenograft Model Antitumor Assays

Paediatric solid tumours exhibit steep dose-response curves to alkylating agents and are therefore considered candidates for high-dose chemotherapy and autologous stem cell support. There is growing evidence that autologous stem cell grafts from patients with solid tumours are frequently contaminated with live tumour cells. The objective of this study was to perform, in a preclinical purging model, an initial assessment of the safety and efficacy of a two-step purging procedure that combined Merocyanine 540-mediated photodynamic therapy (MC540-PDT) with a brief exposure to the alkyl-lysophospholipid, Edelfosine. Human and murine bone marrow cells and Neuro-2a murine neuroblastoma, SK-N-SH human neuroblastoma, SK-ES-1 and U-2 OS human osteosarcoma, G-401 and SK-NEP-1 human Wilms' tumour, and A-204 human rhabdomyosarcoma cells were exposed to a fixed dose of MC540-PDT followed by a brief incubation with graded concentrations of Edelfosine. Survival was subsequently assessed by in vitro clonal assay or, in the case of CD34-positive haematopoietic stem cells, by an immunohistochemical method. Combination purging with MC540-PDT and Edelfosine depleted all tumour cells by >4 log while preserving at least 15% of murine granulocyte/macrophage progenitors (CFU-GM), 34% of human CFU-GM, and 31% of human CD34-positive cells. The data suggest that combination purging with MC540-PDT and Edelfosine may be useful for the ex vivo purging of autologous stem cell grafts from patients with paediatric solid tumours.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Survival; Dose-Response Relationship, Drug; Hematopoietic Stem Cell Transplantation; Humans; Mice; Neuroblastoma; Osteosarcoma; Phospholipid Ethers; Photochemotherapy; Photosensitizing Agents; Pyrimidinones; Rhabdomyosarcoma; Tumor Cells, Cultured; Wilms Tumor