BACKGROUND: Gracillin, a steroidal saponin isolated from Reineckia carnea, exhibits broad anti-tumor activity. However, current studies on its mechanisms of action against lung cancer remain scarce, necessitating further investigation to elucidate the specific targets of its anti-tumor activity. This study aims to preliminarily elucidate the effects of Gracillin against human non-small cell lung cancer (NSCLC) cells and its potential mechanisms. METHODS: NCI-H1299 cells were selected for in vitro cell experiments. Gracillin's cytotoxic, pro-apoptotic and anti-metastatic effects were assessed by CCK-8, flow cytometry, wound healing, Transwell assays and Western Blot. Potential target STC1 was identified through RNA-sequencing and validated via RT-qPCR, ELISA, and immunofluorescence. Interaction between Gracillin and STC1 was confirmed by molecular docking and SPR. STC1 knockdown and pathway inhibitors were applied to explore the role of STC1 and MAPK/ERK signaling in Gracillin's actions. RESULTS: Gracillin inhibited proliferation, migration, invasion and induced apoptosis in NCI-H1299 cells. RNA-sequencing and validation assays identified that STC1's expression and secretion were upregulated by Gracillin. Direct binding between Gracillin and STC1 was confirmed by the values of molecular docking and SPR. Then, knockdown of STC1 attenuated Gracillin's anti-tumor effects and suppressed its activation of the ERK pathway. Furthermore, the inhibition of ERK pathway reversed Gracillin-mediated suppression of proliferation, migration and invasion. CONCLUSIONS: Gracillin exerts its inhibitory effects on the proliferation, migration, and invasion of NCI-H1299 cells by targeting STC1 protein, upregulating STC1 protein level, and subsequently activating the ERK signaling pathway. Gracillin holds promise as a targeted therapeutic agent for NSCLC.
Cui et al. (Thu,) studied this question.