Abstract 3656: Chinese herbal mixture Tien-Hsien Liquid and its active fraction EAS5 mediated multiple molecular targeting and radiosensitizing effects in human breast cancer MCF-7 cells

Abstract

Purpose: Apoptosis induction by Tien-Hsien Liquid (THL) had been reported in various types of human cancer cells. Although our previous report had demonstrated its multiple molecular targeting effects on acute promyelocytic leukemia (APL) cells, whether THL may also exert the similar anticancer effects and play radiosensitizing role in solid tumor have not yet been well elucidated. In this study, we explored the effects of THL on MCF-7 human breast cancer cells in the aspects of cell cycle regulation, signaling pathways inhibition as well as enhancement of radiosensitivity. Materials and Methods: THL was provided by Feida Union Pharmaceutical Manufactory and its active fraction EAS5 was obtained by ethyl acetate extraction followed by silica gel chromatography. The cell viability was determined by sulforhodamine B assay. Cell-cycle distribution was analyzed by flow cytometry. Western blot and antibodies against specific phosphorylated proteins were employed to analyze the activities of affected signaling pathways. Irradiation was performed by a Cesium-137 source. Amido black staining was used to examine the colony formation ability. Results: THL and the active fraction EAS5 could inhibit MCF-7 cells growth dose-dependently, the IC50 were 1.6 mg/ml and 10μg/ml, respectively. The DNA methyltransferase 1 (DNMT1) were down regulated dose-dependently by THL/EAS5. Cell cycle arrest in G2/M phase by THL/EAS5 were shown in flow cytometry, in accompany with the down regulation of cyclin A and cyclin B1 and increase of p15 and p21. The phosphorylatd Akt protein was down-regulated dose-dependently by THL, and the inhibition of MAPK/ERK could be observed at higher dose of THL. On the other hand, THL/EAS5 could down-regulate the level of Rad51 dose-dependently. Compared to other radiation inducible repair enzymes, such as Ku70 and Ku86, Rad51 is more sensitive to THL. The inhibition of colony formation by irradiation was further enhanced in the presence of THL at dose of 0.375 and 0.75 mg/ml. The dose of irradiation required for inhibition of 50% colonies at THL doses of 0, 0.375 and 0.75 mg/ml were 7.5, 4.5 and 3.5 Gy, respectively. The enhanced ratio was 1.7 and 2.1 folds, respectively. In the presence of EAS5 at dose of 1.875μg/ml, the Gy required for 50% inhibition of colonies was down from 5.6 to 2.7; the enhanced ratio was 2.1 folds. Conclusion: Our results indicated the multi-molecular targeting anticancer effects of THL on MCF-7 cells. The EAS5 seems to be one hundred times more potent than THL and conserve most of the anticancer activities of THL, similar to the phenomena we observed in APL cells. In addition to G2/M arrest, THL and its active fraction are able to inhibit the DNA repair and then enhance radiosensitivity in breast cancer cells. Therefore, THL could be considered as a potential radiosensitizers for future clinical use. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3656.