Antitumor effects and mechanisms of pyropheophorbide‑α methyl ester‑mediated photodynamic therapy on the human osteosarcoma cell line MG‑63

Photodynamic therapy (PDT) is a promising treatment for osteosarcoma, and pyropheophorbidealpha methyl ester (MPPa) is a secondgeneration photosensitizer for tumor treatment. The present study aimed to determine the efficacy and possible mechanisms of MPPaPDT in the treatment of osteosarcoma MG63 cells. Flow cytometry and western blotting were used to detect cell cyclerelated indicators Cyclin D1, Cyclin E, Cyclin A and Cyclin B1. Cell migration and invasion abilities were detected using woundhealing and Transwell chamber assays. Cellular endoplasmic reticulum stress (ERS), autophagy and apoptosisrelated indicators were detected by flow cytometry and western blotting. The results demonstrated that MPPaPDT blocked the MG63 cell cycle and inhibited cell migration and invasion. Additionally, MPPaPDT inhibited the activation of the Akt/mammalian target of rapamycin (mTOR) pathway. MG63 cells underwent ERSinduced apoptosis following MPPaPDT treatment. Pretreatment with the mTOR phosphorylation inhibitor rapamycin affected the autophagy of MPPaPDTinduced osteosarcoma MG63 cells and enhanced apoptosis through targeting mTOR.