homoharringtonine and Neuroblastoma

High-risk neuroblastoma (NB) is a heterogeneous and malignant childhood cancer that is frequently characterized by MYCN proto-oncogene amplification or elevated N-Myc protein (N-Myc) expression. An N-Myc downstream target gene, insulinoma associated-1 (INSM1) has emerged as a biomarker that plays a critical role in facilitating NB tumor cell growth and transformation. N-Myc activates endogenous INSM1 gene expression through binding to the E2-box of the INSM1 proximal promoter in NB. We identified a plant alkaloid, homoharringtonine (HHT), from a chemical library screening showing potent inhibition of INSM1 promoter activity. This positive-hit plant alkaloid exemplifies an effective screening approach for repurposed compound targeting INSM1 expression in NB cancer therapy. The elevated N-Myc and INSM1 expression in NB constitutes a positive-loop through INSM1 activation that promotes N-Myc stability. In the present study, the biological effects and anti-tumor properties of HHT against NB were examined. HHT either down regulates and/or interferes with the binding of N-Myc to the E2-box of the INSM1 promoter and the inhibition of PI3K/AKT-mediated N-Myc stability could lead to the NB cell apoptosis. HHT inhibition of NB cell proliferation is consistent with the INSM1 expression as higher level of INSM1 exhibits a more sensitive IC

Topics: Cell Line, Tumor; Child; Drug Repositioning; Gene Expression Regulation, Neoplastic; Homoharringtonine; Humans; Insulinoma; Neuroblastoma; Pancreatic Neoplasms; Phosphatidylinositol 3-Kinases; Repressor Proteins

Neuroblastoma, a childhood cancer affecting the sympathetic nervous system, continues to challenge the development of potent treatments due to the limited availability of druggable targets for this aggressive illness. Recent investigations have uncovered that phosphoglycerate dehydrogenase (PHGDH), an essential enzyme for de novo serine synthesis, serves as a non-oncogene dependency in high-risk neuroblastoma. In this study, we show that homoharringtonine (HHT) acts as a PHGDH inhibitor, inducing intricate alterations in cellular metabolism, and thus providing an efficient treatment for neuroblastoma. We have experimentally verified the reliance of neuroblastoma on PHGDH and employed molecular docking, thermodynamic evaluations, and X-ray crystallography techniques to determine the bond interactions between HHT and PHGDH. Administering HHT to treat neuroblastoma resulted in effective cell elimination in vitro and tumor reduction in vivo. Metabolite and functional assessments additionally disclosed that HHT treatment suppressed de novo serine synthesis, initiating intricate metabolic reconfiguration and oxidative stress in neuroblastoma. Collectively, these discoveries highlight the potential of targeting PHGDH using HHT as a potent approach for managing high-risk neuroblastoma.

Topics: Child; Enzyme Inhibitors; Homoharringtonine; Humans; Molecular Docking Simulation; Neuroblastoma; Phosphoglycerate Dehydrogenase; Serine

We previously developed a homoharringtonine resistant C-1300 neuroblastoma cell line with cross-resistance to adriamycin and increased levels of p-glycoprotein, and showed that drug resistance could be reversed in this cell line by cyclosporin A. The present study shows that cremophor EL, a parenteral vehicle for cyclosporin A, can also completely reverse this multidrug resistance in a clonogenic assay system. Cremophor EL incubated with resistant cells for up to six days did not reduce levels of p-glycoprotein. Intracellular homoharringtonine analysis using HPLC revealed increased drug accumulation in resistant cells treated with cremophor EL. The increased drug level was not due to blocking of drug efflux commonly seen in other multidrug resistant models. The data suggest that resistance modulation with cyclosporin A should be interpreted with caution when cremophor EL is a solvent. Our work suggests cremophor EL, a relatively nontoxic lipophylic solvent, may have a direct effect on membrane permeability, although other mechanisms cannot be ruled out.

Topics: Animals; ATP Binding Cassette Transporter, Subfamily B, Member 1; Cell Division; Chromatography, High Pressure Liquid; Clone Cells; Cyclosporine; Doxorubicin; Drug Interactions; Drug Resistance, Multiple; Glycerol; Harringtonines; Homoharringtonine; Intracellular Fluid; Mice; Neuroblastoma; Pharmaceutical Vehicles; Solvents; Tumor Cells, Cultured

The development of resistance accounts for therapy failure in the majority of advanced cases of neuroblastoma in children. A new transplantable murine C-1300 neuroblastoma cell line was developed in vitro, by repeated exposure of a sensitive cell line to increasing, but sublethal, doses of Homoharringtonine (HHT). The ED50 of the highly resistant cells for HHT, using a standard agar colony assay, is 480 ng/ml, compared with 13 ng/ml for the sensitive parental line. The resistant cells have cross-resistance to a number of other agents, including adriamycin, vinca alkaloids, melphalan, and CCNU. Western blot analysis revealed progressive increases in P-glycoprotein, parallel to the graded development of resistance with a 29-fold elevation in the highest resistant cells. High-performance liquid chromatography (HPLC) indicated that resistant cells have a significantly lower uptake of HHT than parental sensitive cells. cyclosporine A (CsA) and dipyridamole (DPM) could modulate the acquired resistance and completely restore the cytotoxic effects of HHT and adriamycin as determined by the clonogenic assay. The reversal of resistance by CsA and DPM was dose dependent. With the relative low toxicity of dipyridamole and CsA in doses required for modulation of resistance, these agents may be candidates for clinical utilization in chemotherapy of resistant neuroblastoma.

Topics: Animals; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; ATP Binding Cassette Transporter, Subfamily B, Member 1; Biological Transport; Blotting, Western; Cyclosporine; Dipyridamole; Drug Interactions; Drug Resistance; Drug Screening Assays, Antitumor; Harringtonines; Homoharringtonine; Kinetics; Membrane Glycoproteins; Neoplasm Proteins; Neuroblastoma