Mitophagy Effects of Protodioscin on Human Osteosarcoma Cells by Inhibition of p38MAPK Targeting NIX/LC3 Axis

Area of Science:

• Biochemistry
• Molecular Biology
• Oncology

Background:

• Protodioscin (PD) exhibits diverse pharmacological effects, but its impact on human osteosarcoma (OS) remains largely uncharacterized.
• Osteosarcoma is a primary bone malignancy with limited effective therapeutic options.

Purpose of the Study:

• To investigate the effects of Protodioscin (PD) on human osteosarcoma cell growth and elucidate the underlying molecular mechanisms.
• To explore the potential of PD as a novel therapeutic agent for osteosarcoma.

Main Methods:

• Cell viability assays were performed on human HOS and 143B osteosarcoma cell lines treated with PD.
• Western blotting was used to analyze the expression of apoptosis-related proteins (caspase-3, caspase-9, PARP) and mitophagy-related proteins (LC3B, NIX).
• Mitochondrial membrane potential (MMP) was assessed, and siRNA-mediated knockdown of p38MAPK, LC3, or NIX was employed.
• Binding affinity analysis (KD values) was conducted for PD-NIX and PD-LC3 complexes.

Main Results:

• PD significantly inhibited the proliferation of HOS and 143B osteosarcoma cells.
• PD upregulated cleaved caspase-3, cleaved caspase-9, and cleaved PARP, indicating apoptosis induction.
• PD promoted mitophagy by upregulating LC3B and NIX, leading to mitochondrial membrane potential dysfunction.
• Inhibition of LC3 or NIX, or knockdown of p38MAPK, attenuated PD-induced apoptosis, mitophagy, and mitochondrial dysfunction.
• High binding affinity was observed between PD and NIX (-7.6 Kcal/mol) and PD and LC3B (-8.9 Kcal/mol).

Conclusions:

• Protodioscin effectively inhibits human osteosarcoma cell growth by inducing apoptosis and mitophagy.
• The NIX/LC3B pathway plays a crucial role in PD-mediated mitophagy and apoptosis in osteosarcoma cells.
• Targeting the NIX/LC3B pathway with PD presents a promising novel therapeutic strategy for osteosarcoma treatment.