Inhibitory effect and mechanism of alkaloids derived from Gelsemium elegans Benth on lung cancer

To determine the anti-lung cancer effect of koumine (KOU) and total alkaloids of Gelsemium elegans Benth (TAG) and investigate the underlying mechanism.

After low, medium and high concentrations (100, 150, 200 μg/mL) of KOU were used to treat human lung adenocarcinoma cell lines A549 and SPCA1, Live Cell Imaging and Analysis by Sartorius colony formation assay was employed to detect the cell proliferation. The transplanted tumor model of lung cancer cells in mice was constructed and divided into model group (model group), cyclophosphamide group (CTX group, 20 mg/kg), KOU group (2 mg/kg) and TAG group (0.5 mg/kg). After the mice of the CTX, KOU and TAG groups were intraperitoneally injected with 0.1 mL/10 g corresponding agents every other day for 10 d, the growth of lung cancer solid tumors was observed grossly and with HE staining, immunohistochemical (IHC) assay and TUNEL staining to and calculate the tumor size and growth inhibitory rate. RNA sequencing analysis was performed on A549 cells treated with TAG for 48 h to screen the differentially expressed genes (DEGs) between the treatment group and the control group, and the obtained DEGs were further analyzed with Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) functional enrichment analyses. RT-qPCR was applied to further analyze and verify the expression of related genes.

Live Cell Imaging and Analysis fitted that the confluence of A549 and SPCA1 cells was decreased and the number of cells in the treated groups was observed to decrease, with poor growth. The results of colony formation assay confirmed that KOU reduced the number of cell clones, especially at a dose of 200 μg/mL (P < 0.01). Animal experiments showed that KOU and TAG treatment inhibited the tumor growth by 24.55% and 36.08%, respectively. TAG treatment resulted in significantly decreased tumor size when compared with the model group (P < 0.05). RNA sequencing analysis revealed that there were totally 2793 DEGs, including 1433 up-regulated genes and 1360 down-regulated ones. Enrichment analysis displayed that the DEGs were mainly enriched in IL-17 signaling pathway, tumor necrosis factor signaling pathway and P53 signaling pathway. The results of RT-qPCR were consistent with the results of RNA sequencing analysis. The expression levels of GADD34, ZFP36, GADD45 A, GADD45 B and TP53INP2 genes were significantly increased in the TAG group (P < 0.01).

Alkaloids of Gelsemium elegans Benth inhibits the proliferation of lung cancer in vivo and in vitro. Transcriptomics find that KOU and TAG inhibit multiple DEGs and pathways of lung cancer.