Abstract
A135
Scutellaria barbata (SB) and Oldenlandia diffusa (OD) have long been used in Chinese medicine for treating various cancers. Prostate cancer is the second leading cause of deaths due to cancer among men in America. LNCaP is a cell line established from a metastatic lesion of prostatic adenocarcinoma in a 50-year-old male. Our previous data demonstrated that SB and OD could delay in vivo tumor development in TRAMP mice. In vitro positive TUNEL assay results were also detected in LNCaP cells indicating significant apoptosis induction via DNA fragmentation. In this study, we investigated the extent of caspases (C) 3, 8, and 9 activation and necrosis of living LNCaP cells on chamber slides with 50 μl of distilled water as controls and the experimental groups with 50 μl of aqueous extract (1 mg/ml) of SB or OD for 2 and 8 hours separately, using a specific carboxyfluorescein (FAM) labeled peptide fluoromethyl ketone (FMK) caspase inhibitor (FAM-Peptide-FMK). Caspase positive (+) cells appeared green whereas necrotic cells were stained red by propidium iodide as revealed by fluorescence microscopy. Significant time-dependent induction of caspases and necrosis were observed. Both 2 hr and 8 hr treatments of SB and OD showed elevated activation of all three caspases in most cells in the chamber slides relative to the controls which had a few caspase activated cells and significantly more necrotic cells. After 2hr incubation, the extent of caspases activation of both herbs were: C9 >C3 >C8. In 8 hr treatments using both herbs, there were many more observable necrotic cells. These data show that 2 hr is the optimum incubation time for both herbs to activate these caspases in LNCaP cells. Our data indicated SB and OD might exert this function via up-regulating the apoptotic pathway of the cancer cells by the induction and activation of caspases 3, 8, and 9 cascades, thus suggesting their chemopreventive and treatment potential. Combination effects of the two herbs warrant further investigation.
Sixth AACR International Conference on Frontiers in Cancer Prevention Research-- Dec 5-8, 2007; Philadelphia, PA