Water extract of sporoderm-broken spores of ganoderma lucidum induces osteosarcoma apoptosis and restricts autophagic flux

Abstract

Purpose: Osteosarcoma (OS) is a malignant bone tumor with easy metastasis and poor prognosis. Ganoderma lucidum (G. lucidum), a traditional Chinese medicine, was reported playing a critical role in suppressing multiple tumor progress. So we wanted to investigate the effects and molecular mechanisms of water extract of sporoderm-broken spores of G. lucidum (BSGLWE) on osteosarcoma. Methods: In vitro, the effects on cell proliferation of BSGLWE in osteosarcoma cells were detected by CCK-8, colony formation assay and flow cytometry; migration ability of osteosarcoma cells was evaluated by cell scratch and transwell assays. Cell apoptosis and autophagy were tested by transmission electron microscopy (TEM). Potential signaling pathways were detected by Western blotting and immunofluorescence. In xenograft orthotopic model, the luminescence intensity measured by an in vivo bioluminescence imaging system, and the expression of related proteins in tumor cells were assessed by IHC analysis. Results: BSGLWE suppressed the proliferation and migration of osteosarcoma cells in a dose-dependent manner, and osteosarcoma cell cycle progression at the G2/M phase was arrested by the BSGLWE. In addition, increased apoptosis-related protein expression meant BSFLWE induced caspase-dependent apoptosis of osteosarcoma cells. TEM results indicated that BSGLWE promoted the formation of apoptotic bodies and autophagosomes in HOS and U2 cells. Western blotting or immunofluorescence and rescue assay revealed that BSGLWE blocked autophagic flux by inducing initiation of autophagy and increasing autophagosome accumulation of osteosarcoma cells. BSGLWE not only repressed the angiogenesis in the mouse model, but also induced apoptosis and blocked autophagy in vivo. Conclusion: BSGLWE inhibits osteosarcoma progression.