Saikosaponin-b2 Inhibits Primary Liver Cancer by Regulating the STK4/IRAK1/NF-κB Pathway

The development of primary liver cancer (PLC) is associated with chronic liver inflammation and the loss of associated tumor suppressor genes, which characterizes inflammation-related tumors. In this study, we aimed to explore the effect of saikosaponin-b2 (SS-b2) on the development of PLC and its effect of the STK4 expression and IRAK1/NF-κB signaling axis. In vitro and in vivo experiments showed that SS-b2 exerted potent anti-inflammatory and antitumor effects. A PLC model was induced in vivo by treating male BALB/c mice with diethylnitrosamine, while an inflammatory model was induced in vitro by exposing RAW 264.7 macrophages to lipopolysaccharides (LPS). After treating cancer mice with SS-b2, the serum levels of alpha-fetoprotein, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase significantly reduced. Ki67 expression also decreased. The carcinomatous lesions of the liver were attenuated. Similar results were observed in liver tissue and RAW 264.7 macrophages, where SS-b2 significantly elevated serine/threonine protein kinase 4 (STK4) expression and decreased the expression of interleukin-1 receptor-associated kinase 1 (IRAK1), nuclear factor-kappaB (NF-κB), and downstream inflammatory cytokines, thus exerting anti-cancer and anti-inflammatory effects. Moreover, we employed siRNA to silence the STK4 expression in HepG2 to investigate the anti-tumor effect of SS-b2 in vitro. The STK4 knockdown would upregulate IRAK1 and thus the activation of NF-κB activity revealed by the increase in the levels of proinflammatory cytokines, consequently impairing SS-b2-induced inhibition of liver cancer development. Consequently, SS-b2 effectively inhibited PLC by upregulating STK4 to suppress the IRAK1/NF-κB signaling axis and is a promising agent for treating this disease.