Aqueous extract of Fritillariae cirrhosae induces cellular apoptosis through activation of STATs-mediated immunomodulation.

Abstract

ETHNOPHARMACOLOGICAL RELEVANCE\nFritillariae cirrhosae (FC), referred to Chuan beimu in China. As an important edible and medicinal plant, the bulbs of F.cirrhosae is used traditionally in the treatment of pulmonary diseases associated with lung heat, inflammation and tumors. In the study, we investigated the effect of aqueous extract of FC (FC-AE) and elucidated its mechanism in non-small cell lung cancer A549\u202fcells and a xenograft model of nude mice.\n\n\nMATERIALS AND METHODS\nCCK-8 and plate colony formation assay were used to evaluate the effect of FC-AE in A549\u202fcells in vitro, and the gene expression profile of FC-AE on A549\u202fcells was assessed by RNA sequencing system. Then, the effects of FC-AE on cell cycle and apoptosis of A549\u202fcells were analyzed by flow cytometry. In combination with RNA-seq data, RT-PCR and western blot were used to evaluate the expression of proteins related to apoptosis and immune regulation. A xenograft model of nude mice was used to assess the effect of FC-AE in vivo.\n\n\nRESULTS\nCCK-8 and plate cloning assays showed that FC-AE inhibited the proliferation and colony formation of A549\u202fcells. A549 cells treated with FC-AE can triggered apoptosis. GO and KEGG pathway enrichment analysis of RNA-seq data showed that most of the differentially expressed genes (DEGs) were related to immune response, apoptosis and cell cycle process. Several immune and apoptotic DEGs were identified by qRT-PCR which were consistented with RNA-seq data. In nude mice, FC-AE reduced the tumor size and promoted the secretion of cytokines IL12 and IFNγ. FC-AE up-regulated the two members (STAT1 and STAT4) of STATs and their target genes (IFNγ and IL-12, respectively) protein expressions, and actively regulates Bcl-2/Bax family proteins which resulted in cellular apoptosis in A549\u202fcells.\n\n\nCONCLUSION\nOur finding suggests that FC-AE mediates apoptosis through a STAT1 and STAT4-mediated co-regulatory network, which may be the key novel mechanism for its antitumor activity. The F. cirrhosa may be a promising antitumor drug for modulating immune responses to improve cancer therapy.