Study On Liquiritigenin (lq)-induced Apoptosis And Its Molecular Mechanisms In Human Cervical Carcinoma (hela) Cells

Cervical cancer is one of the most common cancers in women in the world, and is the first most frequent cause of cancer death in Chinese women and the serious damage to health. So it has theoretical and practical significance to prevent and therapy cervical cancer.Abundant studies have demonstrated many flavonoids possess antitumor effects by cell growth inhibitory, induction of cell apoptosis and regulation of signal transduction pathway. It has been a hot spot to research the antitumor effects of flavonoids at home and abroad. Glycyrrhizae, has extensive medical medicinal value, and is used as blindly ideal antitumor drugs in Chinese medicine. LQ, a kind of flavonoids existed in Glycyrrhizae with the polyphenolic structure, has extensive effects including anti-inflammatory, hepatoprotection, and selective estrogenic properties. Our former research indicates LQ can suppress the growth of human hepatocarcinoma SMMC-7721 cells. LQ has a significant inhibitory effect in H22 tumor-bearing mice in vivo. Then we found that LQ was more effective to exhibit an antiproliferative effect. This study was aimed to elucidate the effects of LQ on apoptosis induction and its molecular mechanisms in human cervical carcinoma (HeLa) cells. To further clarify the mechanism of antitumor effects induced by LQ to explore the regulation of mitochondrial pathway. Objective: This study was aimed to elucidate the effects of LQ on cell viability and induction of apoptosis in human cervical carcinoma (HeLa) cells. Methods: The effect of LQ on HeLa cell viability was examined by the MTT assay. The morphological alterations were observed by Hoechst 33258 staining, and the pattern of cell apoptosis was analyzed by flow cytometry with annexin V-FITC/PI staining.Results: HeLa cells were treated with LQ (0.05-0.4 mM) for 24, 48 and 72 hrs. The exposure of HeLa cells to LQ resulted in significant decrease of cell viability as compared with controls. The vaibility rates were 93.4%, 90.6% and 78.9% respectively with 0.05 mM LQ treatment for 24 h, 48 and 72 h, and were 57.8%, 30.9% and 22.3% at the same time with 0.4 mM LQ treatment. IC50 for LQ was 0.247 mM at 48 h and 0.137 mM at 72 h in HeLa cells. Cells exhibited characteristic features of apoptosis including chromatin condensation and nuclear fragmentation in 0.05-0.2 mM LQ treatment cells in contrast to control cells. The percentage of apoptotic cells increased with the increased concentration of LQ, and the total apoptotic rates was 46.46% with the corresponding concentrations of 0.2 mM LQ for 48 h, whereas the apoptotic rate was only at 5.81% for the control.Conclusion: LQ can inhibit cell viability and induce apoptosis in HeLa cells. Objective: The aim of our study was to explore the molecular mechanisms of LQ-induced apoptosis in human cervical carcinoma (HeLa) cells.Methods: The apoptosis-associated proteins of p53, Bax, Bcl-2, Survivin, cytochrome c, caspase-9, caspase-3 and PARP were examined using Western blot analysis. The effect of caspase inhibtor against LQ on HeLa cell viability was examined by the MTT assay, and on the cell apoptosis was analyzed by flow cytometry with annexin V-FITC/PI staining.Results: LQ up-regulated p53 and Bax, and the ratios respectively reached 7.6 and 2.64-fold compared with the control group at 0.2mM treated group. It decreased Bcl-2 and Survivin, and the level of Bcl-2 was 0.66 fold at 0.2 mM LQ treatment whereas Survivin was 0.5 fold at 0.1mM LQ treatment. Remarkable cytochrome c was released from mitochondria to cytoso, and the mitochondrial fraction was 0.3-fold at 0.1 mM LQ and cytosolic fraction added to 3.3-fold compared to control. Caspase-9 and -3 was activated and poly (ADP-ribose) polymerase (PARP) was cleaved in a dose manner. Pan caspase inhibitor Z-VAD-FMK and caspase-9 inhibitor Z-LEHD-FMK both blocked LQ-induced apoptosis.Conclusion: LQ induces apoptosis via the mitochondrial pathway, which is associated with the up-regulation of p53 and Bax, and down-regulation of Bcl-2, release of cytochrome c and elevated activity of caspase-9 and -3 in HeLa cells.