Swertiamarin inhibits the proliferation of hepatocellular carcinoma cells by promoting the expression of CDKN1A/p21

This study aims to systematically examine the potential inhibitory effects of Swertiamarin on human hepatocellular carcinoma (HCC) cells and elucidate its underlying molecular mechanisms. The anti-proliferative effect of Swertiamarin was evaluated on human HCC cells (HepG2, Huh7, SK-Hep-1) and normal hepatocytes (HL-7702) using CCK-8 assay, with apoptosis assessed by flow cytometry. To investigate the functional role of p21, the p21 knockdown and overexpression vectors were constructed and transfected into HepG2 cells. Mechanistically, the effect of Swertiamarin on the expression of p21, AKT and TNF-α was verified by RT-qPCR and Western blot (WB) at gene and protein level, respectively, and the results were further verified by immunofluorescence (IF). Finally, the anti-tumor efficacy of Swertiamarin was validated in a SK-Hep-1 xenograft mouse model. Swertiamarin demonstrated significant growth inhibition against HCC cells (P < 0.05), with IC 50 values of 88 μg/mL, 63 μg/mL, and 55 μg/mL for HepG2, Huh7, and SK-Hep-1 cells, respectively. After the treatment of Swertiamarin on HCC cells, the expression of p21 and TNF-α increased, while the expression of AKT decreased at both mRNA and protein levels (P < 0.05). siRNA-mediated p21 knockdown attenuated Swertiamarin-induced proliferation inhibition (cell viability increased from ∼66 % to ∼80 %) and apoptosis (apoptosis rate decreased from ∼51 % to ∼33 %), and reduced its regulatory effects on TNF-α and AKT. Conversely, p21 overexpression enhanced the anti-cancer effects of Swertiamarin (P < 0.05). The results of animal experiments in vivo were consistent with those of the above in vitro cell experiments. The anti-tumor mechanism of Swertiamarin is at least partially mediated through p21-dependent regulation of both PI3K/AKT and TNF-α signaling pathways, leading to proliferation inhibition and apoptosis induction in HCC cells. These results indicate that Swertiamarin, as a novel natural product-derived agent targeting p21, is expected to become a therapeutic or adjunctive strategy for HCC.