Hepatocellular carcinoma (HCC) is well-known to be a highly prevalent malignant tumor, but the treatment of this pathological state has been still challenging. Solamargine (SM), a traditional Chinese herb-derived compound, has been widely reported to possess multiple antitumor properties. However, whether SM plays a vital role in HCC therapy and how it exerts an antitumor effect remains unclear. Thus, in this study, we demonstrated that SM inhibited the proliferation of HCC and effectively induced HCC cell apoptosis and autophagy in vitro and in vivo. Mechanistically, the oncogenic factor LIF was aberrantly elevated in HCC tissues and down-regulated by SM in HCC cells, as well as subsequently the overexpression of LIF could restore the anti-HCC effects of SM via miR-192-5p/CYR61/Akt signaling pathways. Additionally, SM could repolarize tumor associated macrophages by LIF/p-Stat3 to inhibit the growth and epithelial-mesenchymal transition of HCC, and simultaneously affected other immune cell populations in the immune (tumor) microenvironment by regulating macrophages, such as MDSCs, DCs and T cell populations. Together, these findings exploit the potential use of SM against HCC and shed light on exploring SM as a potent candidate drug for the future HCC therapeutics.
Objectives
Autophagy, a highly conserved lysosomal degradation process in eukaryotic cells, has been widely reported closely related to the progression of many types of human cancers, including LGG; however, the intricate relationship between autophagy and LGG remains to be clarified.
Materials and methods
Multi‐omics methods were used to integrate omics data to determine potential autophagy regulators in LGG. The expression of ZFP36L2 and RAB13 in SW1088 cells was experimentally manipulated using cDNAs and small interfering RNAs (siRNA). RT‐qPCR detects RNAi gene knockout and cDNA overexpression efficiency. The expression levels of proteins in SW1088 cells were evaluated using Western blot analysis and immunofluorescence analysis. Homology modelling and molecular docking were used to identify compounds from Multi‐Traditional Chinese Medicine (TCM) Databases. The apoptosis ratios were determined by flow cytometry analysis of Annexin‐V/PI double staining. We detect the number of autophagosomes by GFP‐MRFP‐LC3 plasmid transfection to verify the process of autophagy flow.
Results
We integrated various omics data from LGG, including EXP, MET and CNA data, with the SNF method and the LASSO algorithm, and identified ZFP36L2 and RAB13 as positive regulators of autophagy, which are closely related to the core autophagy regulators. Both transcription level and protein expression level of the four autophagy regulators, including ULK1, FIP200, ATG16L1 and ATG2B, and LC3 puncta were increased by ZFP36L2 and RAB13 overexpression. In addition, RAB13 participates in autophagy through ATG2B, FIP200, ULK1, ATG16L1 and Beclin‐1. Finally, we screened multi‐TCM databases and identified gallic acid as a novel potential RAB13 inhibitor, which was confirmed to negatively regulate autophagy as well as to induce cell death in SW1088 cells.
Conclusion
Our study identified the key autophagic regulators ZFP36L2 and Rab13 in LGG progression, and demonstrated that gallic acid is a small molecular inhibitor of RAB13, which negatively regulates autophagy and provides a possible small molecular medicine for the subsequent treatment of LGG.
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