Antitumor effects and mechanisms of pyropheophorbide­α methyl ester­mediated photodynamic therapy on the human osteosarcoma cell line MG­63.

ABSTRACT

Photodynamic therapy (PDT) is a promising treatment for osteosarcoma, and pyropheophorbide­α 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.