23-hydroxybetulinic-acid and Lung-Neoplasms

Hepatocellular carcinoma (HCC) shows recurrence and lung metastasis even after treatment. 23-hydroxybetulinic acid (23-HBA), a major active constituent of Pulsatilla chinensis, exhibits potent antitumor activities. We herein investigate the biological effect of 23-HBA on metastasis and immunosuppression in a mouse model of HCC. Microarray-based gene expression profiling was employed to identify the target genes of 23-HBA in the treatment of HCC. The effect of 23-HBA on the progression of HCC was evaluated by in-vitro cell function measurements along with in-vivo xenograft implantation, lung metastasis and CD11b+Gr1+ staining experiments. The potential mechanism involving target signaling pathway was investigated by western blot analysis. Bioinformatics analysis revealed that matrix metalloproteinase 2 (MMP2) was a key target gene mediated by 23-HBA in HCC, whereas Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis demonstrated that MMP2 mainly affects the development and metastasis of HCC. 23-HBA significantly reduced cell malignant functions in vitro while delaying the HCC growth and metastasis in vivo. In addition, the number of myeloid-derived suppressor cells was shown to be reduced following administration of 23-HBA in mice. Mechanistic analysis indicated that these effects of 23-HBA during HCC were involved with the mitogen-activated protein kinase (MAPK) signaling pathway inactivation and resulted in decreased phosphorylation of both mitogen-activated protein kinases 1/2 and extracellular signal-regulated kinase 1/2. Our study reveals that 23-HBA acts as a tumor suppressor agent and suppresses HCC tumorigenesis, metastasis and immunosuppression via blockade of the MAPK signaling pathway, suggesting that 23-HBA may serve as a promising drug target to treat HCC.

Topics: Animals; Carcinogenesis; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Gene Expression Regulation, Neoplastic; Humans; Immunosuppression Therapy; Liver Neoplasms; Lung Neoplasms; Matrix Metalloproteinase 2; Mice; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases; Piperidines; Signal Transduction; Triterpenes

Epidermal growth factor receptor (EGFR) activation plays a pivotal role in EGFR-driven non-small cell lung cancer (NSCLC) and is considered as a key target of molecular targeted therapy. EGFR tyrosine kinase inhibitors (TKIs) have been canonically used in NSCLC treatment. However, prevalent innate and acquired resistances and EGFR kinase-independent pro-survival properties limit the clinical efficacy of EGFR TKIs. Therefore, the discovery of novel EGFR degraders is a promising approach towards improving therapeutic efficacy and overcoming drug resistance. Here, we identified a 23-hydroxybetulinic acid derivative, namely DPBA, as a novel EGFR small-molecule ligand. It exerted potent in vitro and in vivo anticancer activity in both EGFR wild type and mutant NSCLC by degrading EGFR. Mechanistic studies disclosed that DPBA binds to the EGFR extracellular domain at sites differing from those of EGF and EGFR. DPBA did not induce EGFR dimerization, phosphorylation, and ubiquitination, but it significantly promoted EGFR degradation and repressed downstream survival pathways. Further analyses showed that DPBA induced clathrin-independent EGFR endocytosis mediated by flotillin-dependent lipid rafts and unaffected by EGFR TKIs. Activation of the early and late endosome markers rab5 and rab7 but not the recycling endosome marker rab11 was involved in DPBA-induced EGFR lysosomal degradation. The present study offers a new EGFR ligand for EGFR pharmacological degradation and proposes it as a potential treatment for EGFR-positive NSCLC, particularly NSCLC with innate or acquired EGFR TKI resistance. DPBA can also serve as a chemical probe in the studies on EGFR trafficking and degradation.

Topics: A549 Cells; Animals; Carcinoma, Non-Small-Cell Lung; Drug Discovery; ErbB Receptors; HCT116 Cells; HEK293 Cells; Hep G2 Cells; HT29 Cells; Humans; Ligands; Lung Neoplasms; Male; MCF-7 Cells; Mice; Mice, Inbred NOD; Mice, Nude; Mice, SCID; Neoplasm Proteins; Proteolysis; Triterpenes