Water extract of sporoderm-broken spores of Ganoderma lucidum enhanced pd-l1 antibody efficiency through downregulation and relieved complications of pd-l1 monoclonal antibody

PURPOSE

Osteosarcoma is a malignant musculoskeletal tumor with early metastasis and a poor prognosis, especially in adolescents. Ganoderma lucidum (Leyss. Ex Fr.) Karst (G. lucidum), a traditional East Asian medicine, has been reported to play a critical role in antitumor and immunomodulatory activity. The aim of this study was to investigate the effects and molecular mechanisms of water extract of sporoderm-broken spores of G. lucidum (BSGWE) on osteosarcoma PD-L1 (programmed cell death-ligand 1) transcriptional regulation, efficacy enhancement, and side effect remission.

METHODS

The antitumor effects on cell proliferation of BSGWE in osteosarcoma cells were detected by apoptosis flow cytometry, and the migration ability of HOS and K7M2 cells were evaluated by cell scratch assay. Potential signaling regulation of PD-L1 was detected by western blotting. To confirm the signaling pathway of BSGWE-related PD-L1 downregulation, a pho-STAT3 turnover experiment was carried out. Colivelin was administered as a pho-STAT3 activator to rescue the BSGWE-induced PD-L1 inhibition. To further study in vivo signaling, in a Balb/c osteosarcoma allograft model, tumor volume was measured using an in vivo bioluminescence imaging system. The body weight curve and tumor volume curve were analyzed to reveal the remission effects of BSGWE on PD-L1 antibody-related body weight loss and its immunomodulatory effects on the osteosarcoma and spleen. The PD-L1 expression level and expression of related transcription-factor pho-STAT3 in tumor cells and spleens were assessed by IHC analysis.

RESULTS

BSGWE suppressed the proliferation and migration of osteosarcoma cells in vitro via induction of apoptosis. In addition, BSGWE downregulated PD-L1 expression and related STAT3 (signal transducers and activators of transcription) phosphorylation levels in a dose-dependent manner. Western blotting and qRT-PCR assay revealed that BSGWE downregulated PD-L1 expression by inhibiting STAT3 phosphorylation. A turnover experiment showed that colivelin administration could rescue PD-L1 inhibition via pho-STAT3 activation. BSGWE not only downregulated PD-L1 expression via the STAT3 pathway in an allograft Balb/c mouse model, but also relieved complications including weight loss and spleen atrophy in a mouse monoclonal antibody therapy model on the basis of its traditional advantages in immune enhancement.

CONCLUSION

BSGWE downregulated PD-L1 expression via pho-STAT3 inhibition of protein and RNA levels. BSGWE enhanced PD-L1 antibody efficacy via phosphorylated STAT3 downregulation in vitro and in vivo. BSGWE also relieved complications of weight loss and spleen atrophy in a murine allograft osteosarcoma immune checkpoint blockade therapy model.

Water Extract of Sporoderm-Broken Spores of Ganoderma lucidum Induces Osteosarcoma Apoptosis and Restricts Autophagic Flux

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.