Anticancer activity of Scutellaria baicalensis and its potential mechanism

Objective: Scutellaria baicalensis is a widely used Chinese herbal medicine that historically is used in anti-inflammatory and anticancer therapy. The aim of the study is to determine its ability to inhibit human cancer cells in vitro and to determine whether its anticancer activity is because of the inhibition of prostaglandin E-2 (PGE(2)) production that is derived from arachidonic acid through cyclooxygenase-2 (COX-2) pathway. Methods: Cell lines from the most common human cancers, including squamous cell carcinoma (SCC-25, KB), breast cancer (MCF-7), hepatocellular carcinoma (HepG2), prostate carcinoma (PC-3 and LNCaP), and colon cancer (KM-12 and HCT-15) were tested. The cells were treated with various concentrations of Scutellaria baicalensis (0.1-100 mg/mL) for 72 hours. Percentage of viable cells after treatment was assessed using a trypan blue dye exclusion assay and the level of PGE2 production was determined by enzyme immunoassay (EIA). Results: Scutellaria baicalensis demonstrated a strong dose-dependent growth inhibition in all cell lines. Inhibition concentration at 50% (IC50) for HepG2, MCF-7, PC-3, LNCaP, KM-12, HCT-15, KB and SCC-25 cells was 1.1, 0.9, 0.52, 0.82, 1.1, 1.5, 1.0, and 1.2 mg/mL, respectively. Three cell lines (KB, SCC-25, and HepG2) were assessed for the production of PGE2 and a high level of extracellular (KB and SCC-25) and intracellular PGE2 (HepG2) was noted. In the presence of Scutellaria baicalensis extract, there was a significant decrease of PGE2 in a dose-dependent fashion. Conclusions: Scutellaria baicalensis strongly inhibits cell growth in all cancer cell lines tested. However, prostate and breast cancer cells (PC-3, LNCaP, and MCF-7) are slightly more sensitive than other type of cancer cells. It also inhibits PGE2 production, indicating that suppression of tumor cell growth may be due to its ability to inhibit COX-2 activity. This study supports the notion of using Scutellaria baicalensis as a novel anticancer agent to treat various cancers.