Related Experiment Video
Updated: Jul 4, 2025
Cytotoxic Efficacy of Photodynamic Therapy in Osteosarcoma Cells In Vitro
Published on: March 18, 2014
Targeting PERK-ATF4-P21 axis enhances the sensitivity of osteosarcoma HOS cells to Mppα-PDT
Shenxi Zhong1,2, Ye Zhang1,2, Hai Mou1,2
1Department of Orthopedics, The First Affiliated Hospital of Chongqing Medical University, Yuzhong, Chongqing 400016, China.
Abstract:
Osteosarcoma (OS) is the most prevalent type of malignant bone tumor in adolescents. The overall survival of OS patients has reached a plateau recently. Thus, there is an urgent need to develop approaches to improve the sensitivity of OS to therapies. Pyropheophorbide-α methyl ester-mediated photodynamic therapy (MPPα-PDT) is a new type of tumor therapy, and elucidating its mechanism is helpful to improve its anti-tumor efficacy. Here, we investigated how PERK signaling promotes the human OS (HOS) cell survival induced by MPPα-PDT, as overcoming this may enhance sensitivity to MPPα-PDT. We found that MPPα-PDT combined with PERK inhibitor GSK2656157 enhanced HOS cell apoptosis by suppressing autophagy and p21. Autophagy inhibition and p21 depletion enhanced cell death, indicating pro-survival effects in MPPα-PDT. Notably, p21 was found to be an effector of the PERK-Atf4 pathway, which could positively regulate autophagy mediated by MPPα-PDT. In conclusion, we found that the combination of MPPα-PDT and GSK2656157 enhanced apoptosis in HOS cells by inhibiting autophagy. Mechanistically, this autophagy is p21-dependent and can be suppressed by GSK2656157, thereby enhancing sensitivity to MPPα-PDT.
Insights
Combining photodynamic therapy with a PERK inhibitor enhances osteosarcoma cell death by blocking survival pathways. This approach targets autophagy and p21, improving cancer treatment sensitivity.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Osteosarcoma (OS) is a prevalent bone cancer in adolescents with stagnant survival rates.
- Novel therapeutic strategies are crucial to improve osteosarcoma treatment efficacy.
- Pyropheophorbide-α methyl ester-mediated photodynamic therapy (MPPα-PDT) is an emerging anti-cancer modality.
Purpose of the Study:
- To investigate the role of PERK signaling in human osteosarcoma (HOS) cell survival following MPPα-PDT.
- To determine if inhibiting PERK signaling can enhance sensitivity to MPPα-PDT.
- To elucidate the molecular mechanisms underlying PERK-mediated pro-survival effects in MPPα-PDT treated HOS cells.
Main Methods:
- Treatment of HOS cells with MPPα-PDT and the PERK inhibitor GSK2656157.
- Assessment of apoptosis, autophagy, and p21 expression levels.
- Investigation of the PERK-Atf4 pathway and its downstream effectors.
Main Results:
- MPPα-PDT combined with GSK2656157 significantly enhanced HOS cell apoptosis.
- This combination therapy suppressed autophagy and reduced p21 levels.
- p21 was identified as a downstream effector of the PERK-Atf4 pathway, positively regulating MPPα-PDT-induced autophagy.
Conclusions:
- The combination of MPPα-PDT and GSK2656157 promotes HOS cell apoptosis by inhibiting autophagy.
- p21-dependent autophagy plays a pro-survival role during MPPα-PDT treatment.
- Inhibiting the PERK pathway enhances osteosarcoma sensitivity to MPPα-PDT by modulating autophagy and p21.
