Introduction: Oesophageal cancer is the eleventh most diagnosed malignancy and the seventh most common cause of cancer-associated mortality globally. Studies have shown that cancer stem cells (CSCs) are the main drivers for resistance in oesophageal cancer. Photodynamic therapy (PDT), a light-based treatment strategy, has demonstrated efficiency against several cancers. However, the therapeutic effect of aluminium phthalocyanine chloride tetra sulfonate (AlPcS4Cl)-mediated PDT in inducing oxidative stress and potentiating apoptotic activity in oesophageal CSCs is limited. This study examined the effects of AlPcS4Cl in promoting oxidative stress and apoptotic cell death in HKESC-1 human oesophageal CSCs.
Method: The CSCs were isolated from HKESC-1 cells and grouped into control and treatment groups. The CSC treatment group was exposed to AlPcS4Cl-PDT at 5J/cm2. Twenty-four hours after PDT, the anticarcinogenic actions of AlPcS4Cl on oesophageal CSCs in inhibiting cell growth and promoting oxidative stress and cell death were evaluated. Cell viability was assessed using a viability assay; a cellular ROS assay was used to determine the induction of oxidative stress, rhodamine-123 flow cytometry analysis was used for mitochondria membrane potential, Annexin V-FITC/PI double-staining flow cytometry analysis for cell death mechanism, and Caspase-Glo 3/7 fluorometric assay for caspase activities. All treatment and control cells were conducted in biological and technical replicates. GraphPad Prism (v5) was used to collate the results and perform statistical analysis. The treatment groups were compared relative to the control cells. One-way ANOVA was used, and a p-value of 0.05 indicated statistical significance.
Results: Findings from our study showed that AlPcS4Cl-PDT with 5 J/cm2 irradiation significantly inhibited cell growth, induced oxidative stress via increased intracellular ROS production, altered the integrity of mitochondria membrane potential, and induced caspase 3/7-mediated apoptosis in oesophageal CSCs.
Conclusion: This study demonstrates the promising use of AlPcS4Cl-PDT in eradicating oesophageal CSCs and improving prognosis.
