COX-2与C/EBP β在人肝细胞肝癌中的表达及其临床意义

Saikosaponin-d Suppresses COX2 Through p-STAT3/C/EBPβ Signaling Pathway in Liver Cancer: A Novel Mechanism of Action

Saikosaponin-d (SSd) is an active extract from Radix Bupleuri, the dried root from the plant Bupleurum falcatum used in China for thousands of years to treat liver diseases. The SSd extract possesses valuable pharmacological activities including anti-cancer and anti-inflammatory effects; however, the mechanism underlying the anti-cancer activity of SSd is largely unknown. Here, we explored the mechanism of action of SSd as an anti-cancer agent for liver cancer in two human hepatocellular carcinoma cell lines. Using MTT and annexin-V-FITC/PI assays, Western blots, immunohistochemistry, qRT-PCR, luciferase reporter assay, and a JAK2-specific inhibitor (AG490), we demonstrated that the anti-tumorigenic effects of SSd act through the intermediatory p-STAT3/C/EBPβ signaling pathway to suppress cyclooxygenase (COX)-2. SSd effectively inhibited cell proliferation in a dose-dependent manner. Apoptosis was significantly increased in cells treated with SSd (2.5–15 µg/ml) with concurrent increase and decrease in pro- and anti-apoptosis proteins, respectively. COX-2, C/EBPβ, and p-STAT3 were significantly decreased, at both the translational and transcriptional levels, by SSd treatment. AG490 produced similar inhibitory effects on STAT3, p-STAT3, C/EBPβ, and COX-2. In conclusion, our data suggest that SSd controls liver cancer proliferation through suppression of the p-STAT3/C/EBPβ signaling pathway inhibiting COX2 expression. These findings further our understanding of the pharmacological action of SSd, providing new information on SSd mechanism of action and showing potential for SSd as a novel therapy for liver cancer.

EGCG enhances 5-fluorouracil-induced cell growth inhibition in human hepatocellular carcinoma cell line BEL-7402

AIM: To investigate whether epigallocatechin-3-gallate (EGCG) enhances 5-fluorouracil (5-FU)-induced cell growth inhibition in human hepatocellular carcinoma cell line BEL-7402 and to explore potential mechanisms involved.

METHODS: MTT assay was used to evaluate cell viability. Western blotting analysis was performed to detect protein expression, and small interfering RNA was used to suppress COX-2 expression. ELISA assay was applied to test the release of prostaglandin E2 (PGE2).

RESULTS: Treatment with different concentrations of EGCG (5, 10, 25, or 50 mmol/L) significantly inhibited the growth of BEL-7402 cells compared with control cells (treated with 0.1% DMSO, all P < 0.05). When cells were treated with 10 mmol/L 5-FU in combination with either 5, 10, 25, or 50 mmol/L EGCG, the percentages of viable cell significantly decreased when compared with cells treated with each drug alone, suggesting a synergistic effect between the two drugs. Moreover, EGCG down-regulated the expression of COX-2 and reduced the release of PGE2 in BEL-7402 cells.

CONCLUSION: EGCG enhances 5-FU-induced cell growth inhibition in human hepatocellular carcinoma cell line BEL-7402 possibly by down-regulating COX-2 expression and inhibiting PGE2 release.