pyrimidinones and Nasopharyngeal-Neoplasms

The development of chemoresistance is the major cause of treatment failure in nasopharyngeal carcinoma (NPC). Although 'paradoxical' activation of extracellular signal-regulated kinase (ERK) has been shown to contribute resistance to anticancer treatment, the role of ERK in NPC chemoresistance has not been yet revealed. In this work, we report that trametinib, a clinically available mitogen-activated protein kinase inhibitor for melanoma treatment, overcomes NPC chemoresistance via suppressing ERK activation induced by chemotherapy. We first showed that trametinib at nanomolar concentrations was active against NPC cells and acted synergistically with cisplatin. Trametinib remarkably decreased phosphorylation of ERK and its downstream effector in NPC cells. We next showed that cisplatin treatment stimulates ERK signaling, and furthermore that this can be abolished by trametinib. We finally generated cisplatin-resistant NPC models and demonstrated that trametinib was effective in inhibiting cisplatin-resistant NPC growth, colony formation and survival via suppressing ERK signaling in vitro and in vivo. Our work demonstrates the potential of trametinib in overcoming chemoresistance in preclinical NPC models and provides evidence of initializing clinical trials of using trametinib for NPC treatment.

Topics: Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Cisplatin; Drug Resistance, Neoplasm; Drug Synergism; Extracellular Signal-Regulated MAP Kinases; Humans; MAP Kinase Signaling System; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Pyridones; Pyrimidinones; Signal Transduction

Nasopharyngeal carcinoma (NPC) is an EBV-associated epithelial malignancy prevalent in southern China. Presence of treatment-resistant cancer stem cells (CSC) may associate with tumor relapse and metastasis in NPC. ICG-001 is a specific CBP/β-catenin antagonist that can block CBP/β-catenin-mediated transcription of stem cell associated genes and enhance p300/β-catenin-mediated transcription, thereby reducing the CSC-like population via forced differentiation. In this study, we aimed to evaluate the effect of ICG-001 on the CSC-like population, and the combination effect of ICG-001 with cisplatin in the C666-1 EBV-positive NPC cells. Results showed that ICG-001 inhibited C666-1 cell growth and reduced expression of CSC-associated proteins with altered expression of epithelial-mesenchymal transition (EMT) markers. ICG-001 also inhibited C666-1 tumor sphere formation, accompanied with reduced SOX2(hi)/CD44(hi) CSC-like population. ICG-001 was also found to restore the expression of a tumor suppressive microRNA-145 (miR-145). Ectopic expression of miR-145 effectively repressed SOX2 protein expression and inhibited tumor sphere formation. Combination of ICG-001 with cisplatin synergistically suppressed in vitro growth of C666-1 cells and significantly suppressed growth of NPC xenografts. These results suggested that therapeutically targeting of the CBP/β-catenin signaling pathway with ICG-001 can effectively reduce the CSC-like population and combination with cisplatin can effectively suppress the growth of NPC.

Topics: Animals; Antineoplastic Agents; beta Catenin; Bridged Bicyclo Compounds, Heterocyclic; Carcinoma; Cell Line, Tumor; Cell Proliferation; Cisplatin; Drug Synergism; Epithelial-Mesenchymal Transition; Herpesvirus 4, Human; Humans; Hyaluronan Receptors; Mice; Mice, Nude; MicroRNAs; Microscopy, Confocal; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Neoplastic Stem Cells; p300-CBP Transcription Factors; Pyrimidinones; RNA Interference; RNA, Small Interfering; Signal Transduction; SOXB1 Transcription Factors; Transplantation, Heterologous

Nasopharyngeal carcinoma (NPC) is a rare but highly invasive cancer. As radiotherapy is the primary treatment for NPC, this offers a rationale to investigate if uncoupling the DNA damage responses can sensitize this cancer type. The G2 DNA damage checkpoint is controlled by a cascade of protein kinases: ATM/ATR, which phosphorylates CHK1/CHK2, which in turn phosphorylates WEE1. A number of small molecule inhibitors have been developed against these kinases as potential therapeutic agents. Here we demonstrated that compare to that in immortalized nasopharyngeal epithelial cells, ATR, CHK1, and WEE1 were overexpressed in NPC cell lines. Inhibitors of these kinases were unable to promote extensive mitotic catastrophe in ionizing radiation-treated NPC cells, indicating that they are not very effective radiosensitizer for this cancer. In the absence of prior irradiation, however, mitotic catastrophe could be induced with inhibitors against CHK1 (AZD7762) or WEE1 (MK-1775). NPC cells were more sensitive to WEE1 inactivation than nasopharyngeal epithelial cells. Targeting CHK1 and WEE1 together induced more extensive mitotic catastrophe than the individual components alone. Taken together, our results show that NPC cells depend on CHK1 and WEE1 activity for growth and that inhibitors of these kinases may serve as potential therapeutics for NPC.

Topics: Animals; Ataxia Telangiectasia Mutated Proteins; Carcinoma; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Checkpoint Kinase 1; DNA Damage; Flow Cytometry; G2 Phase; Gene Expression Regulation, Neoplastic; Green Fluorescent Proteins; HeLa Cells; Humans; Mice; Mice, Inbred BALB C; Mitosis; Nasopharyngeal Carcinoma; Nasopharyngeal Neoplasms; Neoplasm Invasiveness; Neoplasm Transplantation; Nuclear Proteins; Phosphorylation; Protein Kinase Inhibitors; Protein Kinases; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrimidinones; RNA Interference; Thiophenes; Urea

c-Met represents an important emerging therapeutic target in cancer. In this study, we demonstrate the mechanism by which c-Met tyrosine kinase inhibition inhibits tumor growth in a highly invasive Asian-prevalent head and neck cancer, nasopharyngeal cancer (NPC). c-Met tyrosine kinase inhibitors (TKIs; AM7 and c-Met TKI tool compound SU11274) downregulated c-Met phosphorylation, resulting in marked inhibition of NPC cell growth and invasion. Strikingly, inhibition of c-Met resulted in significant downregulation of TP53-induced Glycolysis and Apoptosis Regulator (TIGAR) and subsequent depletion of intracellular NADPH. Importantly, overexpression of TIGAR ameliorated the effects of c-Met kinase inhibition, confirming the importance of TIGAR downregulation in the growth inhibitory activity of c-Met TKI. The effects of c-Met inhibition on TIGAR and NADPH levels were observed with two different c-Met TKIs (AM7 and SU11274) and with multiple cell lines. As NADPH provides a crucial reducing power required for cell survival and proliferation, our findings reveal a novel mechanistic action of c-Met TKI, which may represent a key effect of c-Met kinase inhibition. Our data provide the first evidence linking c-Met, TIGAR and NADPH regulation in human cancer cells suggesting that inhibition of a tyrosine kinase/TIGAR/NADPH cascade may have therapeutic applicability in human cancers.

Topics: Apoptosis; Apoptosis Regulatory Proteins; Cell Line, Tumor; Cell Proliferation; Cell Survival; Down-Regulation; Humans; Indoles; Intracellular Signaling Peptides and Proteins; NADP; Nasopharyngeal Neoplasms; Phosphoric Monoester Hydrolases; Phosphorylation; Piperazines; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-met; Pyrimidinones; Quinolines; Signal Transduction; Sulfonamides

Topics: Anti-HIV Agents; CD4 Lymphocyte Count; Humans; Lamivudine; Lopinavir; Lymphoma, AIDS-Related; Lymphoma, B-Cell, Marginal Zone; Male; Middle Aged; Nasopharyngeal Neoplasms; Pyrimidinones; Radiotherapy, Adjuvant; Remission Induction; Ritonavir; Viral Load; Zidovudine

Photodynamic therapy (PDT) is a new approach to cancer treatment for a variety of malignant tumors. In this study, two clinical photosensitizers, Temoporfin (meta-tetra-hydroxyl-phenyl-chlorin; mTHPC) and merocyanine 540 (MC540), were selected to explore for their photocytotoxic and genotoxic effects on nasopharyngeal carcinoma cells (NPC/HK1 and CNE2). Results of tetrazolium reduction assay showed that 80% cell killing were achieved for both cell lines at 0.4 microg/ml mTHPC for 24 h incubation and then with 40 kJ/m2 light irradiation, whereas 40 microg/ml MC540 with 50 kJ/m2 light dosage was required to attain the same level of phototoxicity for NPC/HK1. On the contrary, NPC/CNE2 was quite resistant to MC540. Hence, mTHPC-mediated PDT exerted a more potent effect than MC540-mediated PDT, even though the molar extinction coefficient of the main absorption peak for MC540 is much higher than that of mTHPC. Dark cytotoxicity remained negligible for both sensitizers. Comet assay was used to evaluate the DNA strand break and potential genotoxic effect induced by mTHPC and MC540 on the NPC cells. No DNA strand break was detected in the absence of light, and under sublethal treatment (LD25) for either sensitizer-loaded cells. Confocal laser scanning microscopy showed that mTHPC and MC540 localized in the cytoplasm but not in the nucleus of the tumor cells, which provided evidence for undetectable DNA damage under dark and low photodynamic dose.

Topics: Aged; Analysis of Variance; Antineoplastic Agents; Comet Assay; DNA; DNA Damage; Humans; Male; Mesoporphyrins; Nasopharyngeal Neoplasms; Photosensitizing Agents; Pyrimidinones; Tumor Cells, Cultured