Ethanol extract of Kilkyung-baeksan, a traditional herbal formula, induces G0/G1 cell cycle arrest in human lung cancer cell lines

BACKGROUND Despite current advances in diagnostics and medicines, the incidence of lung cancer is increasing and effective treatment is very challenging. Traditional herbal formulae as well as many herbal plant extracts have been recognized as attractive sources for novel multi-targeted therapy of cancer with minimal side effects. METHODS The ethanol extract of Kilkyung-baeksan (EE-KKBS) and its component herbs were tested for their ability to inhibit cancer growth in several lung cancer cell lines. The effects of EE-KKBS and ethanol extract of Croton tiglium Linné seed (EE-CT) on cell cycle progression were measured by flow cytometric analysis using propidium iodide staining. Western blot analyses were performed to measure the expression profiles of proteins regulating cell cycle checkpoints. RESULTS EE-KKBS inhibited the growth of lung cancer cells after 24-72 hours treatment. Lung cancer cells treated with either EE-KKBS or EE-CT showed strong G0/G1 cell cycle arrest. The expressions of p21 and p27, two key regulators of G1 cell cycle checkpoint, were significantly upregulated upon treatment with EE-KKBS and EE-CT. CONCLUSION EE-KKBS exerted its cytostatic activity through regulating G1 cell cycle checkpoint in lung cancer cells, and this activity is mainly mediated by one of its component herbs, seeds of Croton tiglium. Collectively, our data suggest that EE-KKBS could be a novel candidate for adjuvant therapy for lung cancer.