The immunogenic cell death (ICD) has aroused great interest in cancer immunotherapy. Doxorubicin (DOX), which can induce ICD, is a widely used chemotherapeutic drug in liver cancer. However, DOX‑induced ICD is not potent enough to initiate a satisfactory immune response. Cucurbitacin IIa (CUIIa), a tetracyclic triterpene, is a biologically active compound present in the Cucurbitaceae family. The present study assessed the effects of the combination of DOX and CUIIa on the viability, colony formation, apoptosis and cell cycle of HepG2 cells. In vivo anticancer effect was performed in mice bearing H22 tumor xenografts. The hallmark expression of ICD was tested using immunofluorescence and an ATP assay kit. The immune microenvironment was analyzed using flow cytometry. The combination of CUIIa and DOX displayed potent apoptosis inducing, cell cycle arresting and in vivo anticancer effects, along with attenuated cardiotoxicity in H22 mice. The combination of DOX and CUIIa also facilitated ICD as manifested by elevated high‑mobility group box 1, calreticulin and ATP secretion. This combination provoked a stronger immune response in H22 mice, including dendritic cell activation, increment of cytotoxic T cells and T helper 1 cells. Moreover, the proportion of immunosuppressive cells including myeloid‑derived suppressor cells, T regulatory cells and M2‑polarized macrophages, decreased. These data suggested that CUIIa is a promising combination partner with DOX for liver cancer treatment, probably via triggering ICD and remolding the immune microenvironment.
Purpose Cucurbitacins have demonstrated anti-inflammatory effects and show promise for inflammatory bowel diseases. However, the underlying mechanisms by which cucurbitacins affect colitis remain largely unknown.Methods In this study, we investigated the impact of cucurbitacin IIa on dextran sulfate sodium (DSS)-induced colitis in rats and the alterations in intestinal extracellular vesicles (EVs). EVs were isolated and characterized, followed by analysis of the small RNAs and proteins encapsulated within them using small RNA sequencing and proteomics, respectively.Results Our results revealed that cucurbitacin IIa alleviated colitis symptoms in DSS-treated rats, along with changes in the morphology and composition of intestinal EVs. Notably, EVs from cucurbitacin IIa-treated rats also mitigated colitis symptoms in DSS-treated rats. Further analysis showed that cucurbitacin IIa modified the protein profiles and microRNA composition of EVs extracted from the feces of colitis rats. Specifically, microRNA-30b-5p, significantly increased by cucurbitacin IIa, was found to alleviate colitis symptoms in DSS-treated rats. In conclusion, cucurbitacin IIa appears to alleviate colitis by promoting the release of microRNA-30b-5p from host-derived extracellular vesicles.Conclusion These findings enhance our understanding of cucurbitacin IIa’s effects on intestinal health and offer potential new therapeutic targets for inflammatory bowel disease treatment.
Cucurbitacin IIa (CuIIa), a tetracyclic triterpenoid harboring anticancer activity, was investigated in A549 cells to reveal its mechanism of targeting on epidermal growth factor receptor (EGFR) signaling pathway. Results showed that CuIIa was capable of inducing apoptosis and cell cycle arrest at G2/M phase. The transcription of EGFR pathway genes and their proteins accumulation was inconsistently influenced by CuIIa. Notably, transcription of Raf1 was significantly upregulated, nevertheless, MEK1 and ERK1 were significantly downregulated. On the other hand, the accumulation of the total and phosphorylated proteins of the most members in EGFR-mitogen-activated protein kinase (MAPK) pathway, as well as CylclinB1 and survivin were also shifted by CuIIa treatment. Remarkably, total MEK remained constant but survivin completely degraded. Moreover, phosphorylated BRAF continuously increased while Raf1 and MEK decreased continuously. CuIIa was further confirmed to be a tyrosine kinase inhibitor (TKI) of EGFR by kinase inhibition assay. The results of molecular simulation showed that the long side chain of CuIIa occupied the binding pocket of EGFR and the ligand was stabilized at the active site of EGFR. In view of the results above, it is suggested that CuIIa inhibits cell proliferation by interfering the EGFR-MAPK signaling pathway.
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