Investigation the effect of autophagy inhibition on the efficiency of photothermal therapy using gold nanorod in SH-SY5Y cancer stem sells

Abstract

Background: Different photothermal modalities have shown encouraging results in targeted cancer therapy. However, the underlying tumoricidal mechanisms of photothermal therapy (PTT) are the subject of debate. Here, we investigated the tumoricidal effects of GNRs on human neuroblastoma CD133+ CSCs. Methods: GNRs were synthesized using CTAB and then covered with BSA, following which they were characterized using TEM imaging, DLS, and UV-Vis spectrophotometry. CD133+ CSCs were derived from human neuroblastoma using the MACS technique. Cells were incubated with BSA-GNRs and exposed to near-infrared laser irradiation to yield 43, 46 and 49°C temperatures. The CSCs survival rate was assessed using an MTT assay. Flowcytometry was performed to measure the percent of apoptotic and necrotic CSCs. The expression of different autophagy-related genes was measured using PCR array analysis. Protein levels of P62 and LC3 were detected using ELISA. Results: MTT assay revealed a reduction of CSCs viability compared to the control group. At higher temperature, the percent of apoptotic CSCs, but not necrotic cells, increased compared to the lower temperature. We found a significant intracellular reduction of LC3 and an increase of P62 when temperature was increased to 49°C. CSCs clonogenic capacity was suppressed after PTT. PCR array showed that the photothermal modulation of CSCs led to the alteration of autophagy-related genes and promotion of co-regulator of apoptosis and autophagy signaling pathways. Conclusion These data exhibited tumoricidal effects of GNRs and laser irradiation through the alteration of autophagic response and apoptosis.