sincalide and Retinoblastoma

Retinoblastoma is the most common primary intraocular malignant tumor in children. Although intra-arterial chemotherapy and conventional chemotherapy have become promising therapeutic approaches for advanced intraocular retinoblastoma, the side effects threaten health and are unavoidable, making the development of targeted therapy an urgent need. Therefore, we intended to find a potential drug for human retinoblastoma by screening an in-house compound library that included 89 purified and well-characterized natural products.. We screened a panel of 89 natural products in retinoblastoma cell lines to find the inhibitor. The inhibition of the identified inhibitor xanthatin on cell growth was detected through half-maximal inhibitory concentration (IC50), flow cytometry assay, and zebrafish model system. RNA-seq further selected the target gene PLK1.. We reported the discovery of xanthatin as an effective inhibitor of retinoblastoma. Mechanistically, xanthatin selectively inhibited the proliferation of retinoblastoma cells by inducing cell cycle arrest and promoting apoptosis. Interestingly, xanthatin targeted PLK1-mediated cell cycle progression. The efficacy of xanthatin was further confirmed in zebrafish models.. Collectively, our data suggested that xanthatin significantly inhibited tumor growth in vitro and in vivo, and xanthatin could be a potential drug treatment for retinoblastoma.

Topics: Antineoplastic Agents, Phytogenic; Apoptosis; Blotting, Western; Cell Cycle; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Cell Survival; Drug Screening Assays, Antitumor; Furans; Humans; Polo-Like Kinase 1; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Real-Time Polymerase Chain Reaction; Retinal Neoplasms; Retinoblastoma; RNA, Messenger; RNA, Small Interfering; Signal Transduction; Sincalide

To study the inhibition of retinoblastoma cell viability by two commonly used autophagy inhibitors, chloroquine (CQ) and 3-methyladenine (3-MA), alone or in combination with the conventional chemotherapeutic drug vincristine (VCR), and to investigate whether the mechanisms of these drugs are related to inhibition of autophagy.. On retinoblastoma cell line HXO-Rb44, VCR, CQ and 3-MA were used individually or combined. The cell viability was determined by CCK8 method, and the cellular autophagic activity was determined by Western blotting of LC3 and p62. Caspase 3 fragmentation and Akt activation was also determined by Western blotting.. VCR induced cell cycle arrest and apoptosis in HXO-Rb44 cells, but only inhibited autophagy at relatively high doses. Both CQ and 3-MA were synergistic with VCR to inhibit the growth of retinoblastoma cells and the combinational use significantly reduced the dosage of each drug. The lowest effective dose of CQ and 3-MA was most efficient to add on VCR; however, such dose was not sufficient to suppress autophagy in these cells. CQ could directly induce caspase activation, while 3-MA significantly inhibited Akt phosphorylation.. CQ and 3-MA were synergistic with VCR to inhibit retinoblastoma cells. Our result suggested a novel strategy to combine CQ or 3-MA with VCR to reduce the side effects of each drug. However, lack of change in the autophagic activity when using the two drugs at lower doses suggests multiple mechanisms of action of the same drug at different doses. At higher doses, the drugs could inhibit autophagy, while at lower doses, they suppress tumor growth via autophagy-independent mechanisms.

Topics: Adenine; Antineoplastic Agents, Phytogenic; Antirheumatic Agents; Apoptosis; Autophagy; Blotting, Western; Cell Cycle Checkpoints; Cell Survival; Chloroquine; Drug Synergism; Drug Therapy, Combination; Enzyme Inhibitors; Humans; Microtubule-Associated Proteins; Retinal Neoplasms; Retinoblastoma; RNA-Binding Proteins; Sincalide; Tumor Cells, Cultured; Vincristine