Dataset Information

A Potent Autophagy Inhibitor (Lys05) Enhances the Impact of Ionizing Radiation on Human Lung Cancer Cells H1299.

ABSTRACT: Autophagy inhibition through small-molecule inhibitors is one of the approaches to increase the efficiency of radiotherapy in oncological patients. A new inhibitor-Lys05-with the potential to accumulate within lysosomes and to block autophagy was discovered a few years ago. Several studies have addressed its chemosensitizing effects but nothing is known about its impact in the context of ionizing radiation (IR). To describe its role in radiosensitization, we employed radioresistant human non-small cell lung carcinoma cells (H1299, p53-negative). Combined treatment of H1299 cells by Lys05 together with IR decreased cell survival in the clonogenic assay and real-time monitoring of cell growth more than either Lys05 or IR alone. Immunodetection of LC3 and p62/SQSTM1 indicated that autophagy was inhibited, which correlated with increased SQSTM1 and decreased BNIP3 gene expression determined by qRT-PCR. Fluorescence microscopy and flow cytometry uncovered an accumulation of lysosomes. Similarly, transmission electron microscopy demonstrated the accumulation of autophagosomes confirming the ability of Lys05 to potentiate autophagy inhibition in H1299 cells. We report here for the first time that Lys05 could be utilized in combination with IR as a promising future strategy in the eradication of lung cancer cells.

SUBMITTER: Cechakova L

PROVIDER: S-EPMC6928878 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature

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A Potent Autophagy Inhibitor (Lys05) Enhances the Impact of Ionizing Radiation on Human Lung Cancer Cells H1299.

Cechakova Lucie L Ondrej Martin M Pavlik Vojtech V Jost Petr P Cizkova Dana D Bezrouk Ales A Pejchal Jaroslav J Amaravadi Ravi K RK Winkler Jeffrey D JD Tichy Ales A

International journal of molecular sciences 20191123 23

Autophagy inhibition through small-molecule inhibitors is one of the approaches to increase the efficiency of radiotherapy in oncological patients. A new inhibitor-Lys05-with the potential to accumulate within lysosomes and to block autophagy was discovered a few years ago. Several studies have addressed its chemosensitizing effects but nothing is known about its impact in the context of ionizing radiation (IR). To describe its role in radiosensitization, we employed radioresistant human non-sma ...[more]

PMID: 31771188

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Project description:The resistance of cancer cells to radiation-based treatment is a major clinical challenge confounding standard of care in cancer. This problem is particularly notable in many solid tumors where cancer cells are only partially responsive to radiation therapy. Combination of radiation with radiosensitizers is able to enhance tumor cell killing. However, currently available radiosensitizers are associated with significant normal tissue toxicity. Accordingly, there is an unmet need to develop safer and more effective radiosensitizers to improve tumor control. Here, we evaluated the radiosensitizing effect of the FDA-approved drug esomeprazole in normal and radioresistant human head and neck squamous cell carcinoma (HNSCC) cells in vitro, and in a mouse model of HNSCC. For the in vitro studies, we used cancer cell colony formation (clonogenicity) assay to compare cancer cell growth in the absence or presence of esomeprazole. To determine mechanism(s) of action, we assessed cell proliferation and profiled cell cycle regulatory proteins. In addition, we performed reverse phase protein array (RPPA) study to understand the global effect of esomeprazole on over 200 cancer-related proteins. For the in vivo study, we engrafted HNSCC in a mouse model and compared tumor growth in animals treated with radiation, esomeprazole, and combination of radiation with esomeprazole. We found that esomeprazole inhibits tumor growth and dose-dependently enhances the cell killing effect of ionizing radiation in wildtype and p53-mutant radioresistant cancer cells. Mechanistic studies demonstrate that esomeprazole arrests cancer cells in the G1 phase of the cell cycle through upregulation of p21 protein and inhibition of cyclin-dependent kinases (Cdks) type 1 (Cdk1) and type 2 (Cdk2). In vivo data showed greater tumor control in animals treated with combination of radiation and esomeprazole compared to either treatment alone, and that this was associated with inhibition of cell proliferation in vivo. In addition, combination of esomeprazole with radiation significantly impaired repair following radiation-induced DNA damage. Our studies indicate that esomeprazole sensitizes cancer cells to ionizing radiation, and is associated with upregulation of p21 to arrest cells in the G1 phase of the cell cycle. Our findings have significant therapeutic implications for the repurposing of esomeprazole as a radiosensitizer in HNSCC and other solid tumors.

Dataset Information

A Potent Autophagy Inhibitor (Lys05) Enhances the Impact of Ionizing Radiation on Human Lung Cancer Cells H1299.

Publications

A Potent Autophagy Inhibitor (Lys05) Enhances the Impact of Ionizing Radiation on Human Lung Cancer Cells H1299.

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