Sweet Wormwood and Tortoise Shell Decoction (Thanh Hao Miet Giap Thang) Induces DNA Damage, S-Phase Arrest, and Apoptosis in MCF-7 Cells via ATR-CHK1 Signaling Pathway

INTRODUCTION: Sweet wormwood and tortoise shell decoction, Thanh Hao Miet Giap Thang (THMGT) in Vietnamese, a traditional formula composed of five ingredients, is used in complementary care in Vietnam for patients who underwent conventional cancer treatment. To expand the clinical use and explore novel functions of THMGT, this study was conducted to investigate the effect of THMGT in terms of antiproliferative activity and selective cytotoxicity toward human breast cancer cells MCF-7. METHODS: Cytotoxicity of THMGT against human breast cancer cells MCF-7 and primary fibroblasts from a heathy donor were studied using sulforhodamine B (SRB) assay. Flow cytometry analysis, immunofluorescence, and western blotting were also performed to elucidate underlying mechanisms of THMGT action. RESULTS: The SRB assay on treated MCF-7 cells and primary fibroblasts from a heathy donor indicated selective cytotoxicity of THMGT with a selective index of 3.92. Annexin V/PI staining and flow cytometric analysis on stained MCF-7 cells showed that the THMGT-treated cells were arrested at the S phase and subsequently underwent apoptosis. Western blot analysis showed an upregulation of γ-H2AX, increased protein levels of phosphorylated CHK1, TP53, and phosphorylated TP53 in a time-dependent manner, and a downregulated expression of ATR and MDM2. CONCLUSION: These results suggested DNA damaging effect and ATR-CHK1-mediated cell cycle arrest of THMGT on MCF-7 cells resulting in apoptosis induction.