Scutellaria Baicalensis, a Herbal Medicine: Antitumor Activity Against Acute Lymphocytic Leukemia, Lymphoma and Myeloma in Vitro.

Scutellaria baicalensis is a widely used Chinese herbal medicine for anti-inflammatory and anti-cancer therapy. The anticancer activity of Scutellaria baicalensis against prostate, breast, hepatocellular, colon and squamous cell carcinomas in vitro has been reported. In this study, we initially investigated its in vitro antitumor activities against 29 cancer cell lines including prostate, breast, ovarian, endometrial and pancreatic cancers as well as myeloid and lymphocytic leukemias, lymphomas, myelomas. The cells were cultured with Scutellaria baicalensis at a dose of 50 μg/ml for 4 days. The herb showed strong anti-proliferative activities against Blin-1 and Nalm-6 acute lymphocytic leukemia cells, Daudi Burkitt′s lymphoma cells and NCI-H929 myeloma cells as measured by MTT assays. Dose-response studies showed an ED50 of 8.32 μg/ml (Blin-1), 12.3 μg/ml (Nalm-6), 4.57 μg/ml (Daudi) and 5.01 μg/ml (NCI-H929) as measured by soft agar colony assay. Treatment with Scutellaria bacalensis at 50 μg/ml for 2 days induced apoptosis of 30% of Blin-1, 17% of Nalm-6, 20% of Daudi and 39% of NCI-H929 cells as measured by Annexin V assay. It also induced G₂/M cell cycle arrest of Daudi cells. Scutellaria baicalensis also induced mitchondrial damage in 4 cell lines as measured by fluorescent emissions using the JC-1 assay. Protein expressions were examined by western blot using Blin-1 cells that were most sensitive to Scutellaria baicalensis. After treatment with 50 μg/ml of Scutellaria baicalensis for 2 days, levels of p27^KIP1 increased by 152 % independently of p53, expression of the pro-apoptotic gene Bax increased by 208 %, and the anti-apoptotic proteins Bcl-2 and Bcl-X_L decreased by 64 % and 38 %, respectively. Notably Scutellaria baicalensis decreased the expression of c-myc oncogene in a dose-dependent manner (80 % decrease at 50 μg/ml). Scutellaria baicalensis contains 21% of baicalin as measured by HPLC. The antiproliferative dose-response assays were repeated using baicalin and calculating the percent baicalin in the herb showed that the results nearly mirrored those of Scutellaria baicalensis, suggesting baicalin is the major anticancer component of this herb. We conclude that Scutellaria baicalensis inhibited the cell growth of B cell hematological malignancies including ALL, lymphoma, and myeloma in vitro by induction of apoptosis associated with mitchondrial damage and modulation of the Bcl family of genes. Thus, Scutellaria baicalensis and its major component, baicalin, should be tested in clinical trials for these hematological malignancies.