Fluorescence based autophagy imaging and in vitro study of possible antitumor effect after Rhamnolipid treatment
Severina Semkova1, Georgi Antov1,2, Ivan Iliev1,3, Iana Tsoneva1, Pavel Lefterov1, Galya Staneva1 and Biliana Nikolova1*1
1 Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, “Acad. G. Bonchev” Str., Bl. 21, 1113 Sofia, Bulgaria
2 Institute of Plant Physiology and Genetics Bulgarian Academy of Sciences, “Acad. G. Bonchev” Str., Bl. 21, 1113 Sofia, Bulgaria
3 Institute of Experimental Morphology, Pathology and Anthropology with Museum, Bulgarian Academy of Sciences, “Acad, G. Bonchev” Str., Bl. 25, 1113 Sofia, Bulgaria
Abstract
Background/Aim: A number of biologically active substances were proved as an alternative to conventional anticancer medicines. In this regard, the group of Rhamnolipid biosurfactants represents great interest, but it is still poorly studied. The aim of the study is in vitro investigation of the anticancer activity of mono- and di-Rhamnolipids (RL-1 and RL-2), isolated from Pseudomonas aeruginosa strain, against human breast cancer cell lines against human breast cancer. Moreover, we try to explain the mechanism of action of tested biosurfactants in relation to development of autophagy process and cell death of cancer cells. Additionally, the combination with Cisplatin was analyzed.
Materials and Methods: Breast cell lines (MCF-10A, MCF-7 and MDA-MB-231) were treated with RLs alone or and in combination with Cis-platin. The viability was analyzed using MTT assay, and investigation of autophagy was performed via acridine orange staining.
Results: In contrast to the healthy cells, both tested cancer lines exhibited sensitivity to RLs treatment. This effect was accompanied by an influence on the autophagy-related acidic formation process. Only for the triple-negative breast cancer cell line (MDA-MB-231) the synergistic effect of the combined treatment (10 µM Cisplatin and 1 µg/mL RL-2) was observed. Conclusion: Based on studies on the reorganization of membrane models in the presence of RL and the data about a higher amount of lipid rafts in cancer cell membranes than in non-tumorigenic, we suggest a possible mechanism of membrane remodelling by formation of endosomes. Shortly, in order to have a synergistic effect, it is necessary to have Cisplatin andRL-2 as RL2 is a molecule inducing positive membrane curvature.
Acknowledgments: The authors acknowledged COST Action 17 121: Correlated Multimodal Imaging in Life Sciences-COMULIS. The authors thank the Bulgarian Ministry of Education and Science for support (Scientific Infrastructure on Cell Technologies in Biomedicine (SICTB) DO1-154/28/08/2018).