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Rath EM, Cheng YY, Pinese M, Sarun KH, Hudson AL, Weir C, Wang YD, Håkansson AP, Howell VM, Liu GJ, Reid G, Knott RB, Duff AP, Church WB. BAMLET kills chemotherapy-resistant mesothelioma cells, holding oleic acid in an activated cytotoxic state. PLoS One 2018; 13:e0203003. [PMID: 30157247 PMCID: PMC6114908 DOI: 10.1371/journal.pone.0203003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 08/13/2018] [Indexed: 12/29/2022] Open
Abstract
Malignant pleural mesothelioma is an aggressive cancer with poor prognosis. Here we have investigated in vitro efficacy of BAMLET and BLAGLET complexes (anti-cancer complexes consisting of oleic acid and bovine α-lactalbumin or β-lactoglobulin respectively) in killing mesothelioma cells, determined BAMLET and BLAGLET structures, and investigated possible biological mechanisms. We performed cell viability assays on 16 mesothelioma cell lines. BAMLET and BLAGLET having increasing oleic acid content inhibited human and rat mesothelioma cell line proliferation at decreasing doses. Most of the non-cancer primary human fibroblasts were more resistant to BAMLET than were human mesothelioma cells. BAMLET showed similar cytotoxicity to cisplatin-resistant, pemetrexed-resistant, vinorelbine-resistant, and parental rat mesothelioma cells, indicating the BAMLET anti-cancer mechanism may be different to drugs currently used to treat mesothelioma. Cisplatin, pemetrexed, gemcitabine, vinorelbine, and BAMLET, did not demonstrate a therapeutic window for mesothelioma compared with immortalised non-cancer mesothelial cells. We demonstrated by quantitative PCR that ATP synthase is downregulated in mesothelioma cells in response to regular dosing with BAMLET. We sought structural insight for BAMLET and BLAGLET activity by performing small angle X-ray scattering, circular dichroism, and scanning electron microscopy. Our results indicate the structural mechanism by which BAMLET and BLAGLET achieve increased cytotoxicity by holding increasing amounts of oleic acid in an active cytotoxic state encapsulated in increasingly unfolded protein. Our structural studies revealed similarity in the molecular structure of the protein components of these two complexes and in their encapsulation of the fatty acid, and differences in the microscopic structure and structural stability. BAMLET forms rounded aggregates and BLAGLET forms long fibre-like aggregates whose aggregation is more stable than that of BAMLET due to intermolecular disulphide bonds. The results reported here indicate that BAMLET and BLAGLET may be effective second-line treatment options for mesothelioma.
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Affiliation(s)
- Emma M. Rath
- Faculty of Pharmacy, University of Sydney, Sydney, NSW, Australia
| | - Yuen Yee Cheng
- Asbestos Diseases Research Institute (ADRI), Concord, NSW, Australia
- University of Sydney, Sydney, NSW, Australia
| | - Mark Pinese
- Kinghorn Cancer Centre and Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Kadir H. Sarun
- Asbestos Diseases Research Institute (ADRI), Concord, NSW, Australia
| | - Amanda L. Hudson
- Bill Walsh Translational Cancer Research Laboratory, Kolling Institute, University of Sydney, Sydney, NSW, Australia
| | - Christopher Weir
- Northern Blood Research Centre, Kolling Institute, University of Sydney, Sydney, NSW, Australia
| | - Yiwei D. Wang
- Burns Research, ANZAC Research Institute, Concord Hospital, University of Sydney, Concord, NSW, Australia
| | | | - Viive M. Howell
- Bill Walsh Translational Cancer Research Laboratory, Kolling Institute, University of Sydney, Sydney, NSW, Australia
| | - Guo Jun Liu
- Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Rd, Lucas Heights, NSW, Australia
- Brain and Mind Centre and Faculty of Health Sciences, University of Sydney, Sydney, NSW, Australia
| | - Glen Reid
- Asbestos Diseases Research Institute (ADRI), Concord, NSW, Australia
- University of Sydney, Sydney, NSW, Australia
| | - Robert B. Knott
- Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Rd, Lucas Heights, NSW, Australia
| | - Anthony P. Duff
- Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Rd, Lucas Heights, NSW, Australia
| | - W. Bret Church
- Faculty of Pharmacy, University of Sydney, Sydney, NSW, Australia
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