Aluminium phthalocyanine–mediated photodynamic therapy promotes antitumour activity in oesophageal cancer stem cells.

person Onyisi Christiana Didamson University of Johannesburg, Johannesburg, South Africa info_outline Onyisi Christiana Didamson, Rahul Chandran, Heidi Abrahamse

Authors person Onyisi Christiana Didamson University of Johannesburg, Johannesburg, South Africa info_outline Onyisi Christiana Didamson, Rahul Chandran, Heidi Abrahamse Organizations University of Johannesburg, Johannesburg, South Africa Abstract Disclosures Research Funding Institutional Funding University of Johannesburg Global Excellence and Stature, Fourth Industrial Revolution (GES 4.0) Doctoral Scholarship, South African Research Chairs Initiative of the Department of Science and Technology and National Research Foundation of South Africa (SARChI/NRF-DST) (Grant no: 98337) Background: Photodynamic therapy (PDT), a non-invasive treatment modality, has emerged as an effective treatment measure for various cancers, including oesophageal cancer. PDT has attracted much attention in the field of oncology due to its low toxicity profile and the selective accumulation of the photoactivated agent in the tumour cells. However, the therapeutic effect of Aluminium (III) Phthalocyanine Chloride Tetra sulfonic Acid (AlPcS 4 Cl) mediated PDT on oesophageal CSCs is limited. In this study, we evaluated the cellular localization of AlPcS 4 Cl and its PDT anticancer effects on oesophageal CSCs. Methods: An in vitro experimental design was employed in this study. Oesophageal cancer (HKESC-1 cells) was grown, and the CSCs were isolated using the magnetic-activated cell sorting (MACS). The isolated CSCs were characterised using a flow cytometry, Hoechst efflux side population test, and immunofluorescence. The CSCs were maintained in a serum-free culture medium and incubated at 37° C, 5% CO 2 and 85% humidity. The cells were grouped into control and experimental groups. The CSCs received two-fold increasing concentrations of AlPcS 4 Cl and were exposed to irradiation at 673.2nm wavelength using a diode laser. After 24 hours post-PDT, the anticancer activities of AlPcS 4 Cl on oesophageal CSCs were examined. The MTT cell viability assay was used to determine the 50% inhibitory concentration (IC50), light microscopy for morphological changes, and adenosine triphosphate (ATP) assay for cell proliferation, lactate dehydrogenase (LDH) assay for cellular toxicity. While cellular localization of AlPcS 4 Cl was examined using fluorescent microscopy. All experimental and control cells were conducted in six biological replicates (n = 6). Results: Results were compiled, and statistical analysis was performed using GraphPad Prism (v5). The mean values of experimental groups were compared with the mean value of the control cells. One-way ANOVA was employed, and a p-value of less than 0.05 was considered statistically significant. Findings from cellular localization showed that the AlPcS 4 Cl is localized in the mitochondria and lysosomes, indicating a probable cellular death pathway. The dose-response of AlPcS 4 Cl on oesophageal CSCs showed an IC50 value of 4µM, suggesting the photosensitizer is efficient for the treatment of CSCs at low concentrations. The CSCs exposed to PDT showed remarkable morphological distortion, high cytotoxic activity, decreased viable cells and significant antiproliferative potential. Conclusions: This study showed that AlPcS 4 Cl promote PDT anticancer effects on oesophageal CSCs and could serve as an efficient therapeutic option for eradicating oesophageal CSCs.

Pre-clinical