Inhibition of nuclear factor κB transcription activity drives a synergistic effect of cisplatin and oridonin on HepG2 human hepatocellular carcinoma cells

Abstract

Activation of nuclear factor κB (NF-κB) by cisplatin and other chemotherapeutics is responsible, at least in part, for the development of drug resistance in the treatment of hepatocellular carcinoma. Therefore, a combination of chemotherapeutics with NF-κB inhibitors could overcome resistance of cancer cells. Oridonin is a diterpenoid isolated from Rabdosia rubescens that can block the NF-κB signaling cascades. In this study, we investigated the synergistic effect of oridonin and cisplatin on human hepatocellular carcinoma HepG2 cells. Cell apoptosis and mitochondrial membrane potential loss were examined using Hoechst 33258 and rhodamine-123 staining, followed by flow cytometry, respectively. The expression of apoptosis-related proteins and NF-κB subunits was detected by real-time PCR and western blot. The activity of caspase 3 and 9 was measured using the Caspase Activity Kit. Electrophoretic mobility shift assay and the enzyme-linked immunosorbent assay-based kit were used to assess the DNA-binding activity of NF-κB. We found a synergistic antitumor effect between cisplatin and oridonin on HepG2 cells both in vitro and in vivo. In addition, the combination of cisplatin and oridonin synergistically induces apoptosis and regulates the expression and activity of several key apoptosis-related proteins. Furthermore, the combination treatment not only downregulates nuclear translocation of p50 and p65, but more significantly, decreases the transcription activity of all NF-κB subunits to a greater degree than either agent alone. Our results suggest that the synergistic effect between both agents is likely to be driven by the inhibition of transcription activity of NF-κB and the resulting increased apoptosis.

Therapeutic Potential of Oridonin and Its Analogs: From Anticancer and Antiinflammation to Neuroprotection

“…Oridonin ( 1 , Figure 1 ), an ent -kaurane diterpenoid isolated from Rabdosia rubenscens , was first identified as an antitumor compound in 1967 [ 7 , 8 ]. It has since attracted considerable attention due to its various pharmacological and physiological properties including antitumor [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ], anti-inflammatory [ 18 , 19 , 20 ], antimicrobial [ 21 ], and hepatic fibrosis prevention actions [ 22 , 23 , 24 , 25 ], and its effects in the central nervous system (CNS) [ 26 , 27 , 28 ]. Over the past decade, significant progress has been made in structural optimization and mechanism of action studies of oridonin for the treatment of cancer and other diseases [ 29 , 30 , 31 ].…”

<p>Oridonin Sensitizes Hepatocellular Carcinoma to the Anticancer Effect of Sorafenib by Targeting the Akt Pathway</p>

“… 9 In addition, oridonin shows synergistic anticancer effects when combined with other treatments. For example, cotreatment with oridonin and cisplatin inhibited the transcriptional activity of NF-κB and induced apoptosis in HCC, 10 oridonin enhanced radiation-induced cell death in lung cancer, 11 and oridonin intensified the toxicity of 5-FU in renal carcinoma. 12 However, the synergistic effect of oridonin and sorafenib remains unclear, although both drugs are effective in treating HCC.…”

Oridonin ameliorates carbon tetrachloride‐induced liver fibrosis in mice through inhibition of the NLRP3 inflammasome

“…Furthermore, the ability of oridonin to increase the expression and activity level of a hepatic drug‐metabolizing enzyme (CYP450) was verified. Oridonin might thus work in synergy with other hepatoprotective drugs (X. Dong, Liu, & Li, ; T. Xu, Jin, Wu, Ye, & Li, ; Y. W. Zhang, Bao, Hu, Qu, & Zhou, ).…”