Intrinsic apoptotic pathway and G2/M cell cycle arrest involved in tubeimoside I-induced EC109 cell death

Objective： Squamous esophageal carcinoma is highly prevalent in developing countries, especially in China. Tu Bei Mu （TBM）, a traditional folk medicine, has been used to treat esophageal squamous cell carcinoma （ESCC） for a long term. tubeimoside I （TBMS1） is the main component of TBM, exhibiting great anticancer potential. In this study, we investigated the mechanism of TBMS1 cytotoxic effect on EC109 cells. Methods： Comparative nuclear proteomic approach was applied in the current study and we identified several altered protein spots. Further biochemical studies were carried out to detect the mitochondrial membrane potential, cell cycle and corresponding proteins＇ expression and location. Results： Subcellular proteomic study in the nucleus from EC109 cells revealed that altered proteins were associated with mitochondrial function and cell proliferation. Further biochemical studies showed that TBMSl-induced molecular events were related to mitochondria-induced intrinsic apoptosis and P21-cyclin B 1/cdc2 complex-related G2/M cell cycle arrest. Conclusions： Considering the conventional application of TBM in esophageal cancer, TBMS1 therefore may have a great potential as a chemotherapeutic drug candidate for ESCC.

Ent-11α-Hydroxy-15-oxo-kaur-16-en-19-oic-acid Inhibits Growth of Human Lung Cancer A549 Cells by Arresting Cell Cycle and Triggering Apoptosis

Objective： To examine the apoptotic effect of ent-llα-hydroxy-15-oxo-kaur-16-en-19-oic-acid （5F）, a compound isolated from Pteris semipinnata L （PsL）, in human lung cancer A549 cells. Methods： A549 cells were treated with 5F （0-80 lag/ml） for different time periods. Cytotoxicity was examined using a Ml-I- method. Cell cycle was examined using propidium iodide staining. Apoptosis was examined using Hoechst 33258 staining, enzyme-linked immunosorbent assay （ELISA） and caspase-3 activity analysis. Expression of representative apoptosis-related proteins was evaluated by Western blot analysis. Reactive oxygen species （ROS） level was measured using standard protocols. Potential interaction of 5F with cisplatin was also examined. Results： 5F inhibited the proliferation of A549 cells in a concentration- and time-dependent manner. 5F increased the accumulation of cells in sub-G1 phase and arrested the cells in the G2 phase. Exposure to 5F induced morphological changes and DNA fragmentation that are characteristic of apoptosis. The expression of p21 was increased. 5F exposure also increased Bax expression, release of cytochrome c and apoptosis inducing factor （AIF）, and activation of caspase-3. 5F significantly sensitized the cells to cisplatin toxicity. Interestingly, treatment with 5F did not increase ROS, but reduced ROS production induced by cisplatin. Conclusion： 5F could inhibit the proliferation of A549 cells by arresting the cells in G2 phase and by inducing mitochondrial-mediated apoptosis.

Arsenic Trioxide Inhibits Proliferation in K562 Cells by Changing Cell Cycle and Survivin Expression

To study the mechanisms involved in the inhibition of chronic myeloid leukemic cells (K562) proliferation induced by arsenic trioxide (As 2O 3) and to explore the potential role of Survivin, an inhibitor of apoptosis protein, in the regulation of As 2O 3 induced cell apoptosis, K562 cells were cultured with As 2O 3 of different concentrations. Cells were collected for proliferation analysis by MTT assay. Cell cycle distribution and cell apoptosis were analyzed by flow cytometry. Expression of Survivin protein and mRNA were detected by flow cytometry and RT-PCR, respectively. Our results showed that As 2O 3 (2-10 μmol/L) inhibited K562 cells growth effectively, but it did not induce cells apoptosis significantly. The percentage of K562 cells at G 2/M phase increased in proportion to As 2O 3 concentrations, and the expression of Survivin mRNA and content of Survivin protein was up-regulated accordingly. It is concluded that As 2O 3 inhibited K562 cells growth by inducing cell cycle arrest mainly at G 2/M phase. Over-expression of Survivin gene and protein might be one of the possible mechanisms contributing to K562 cells' resistance to As 2O 3-induced apoptosis.

Genistein-induced Anticancer Effects on Acute Leukemia Cells Involve the Regulation of Wnt Signaling Pathway Through H4K20mel Rather Than DNA Demethylation

Objective:To investigate the effects and mechanisms of genistein on the gene expression in the Wnt pathway in acute leukemia(AL)cells.Methods:The expression of Wnt pathway genes and cell cycle-related genes were analyzed in two AL cell lines.Pyrophosphate sequencing was performed to determine the methylation degree.Then,the enrichment of H4K20mel and H3K9ac was determined using ChIP-qPCR.Flow cytometry was used to analyze the cell cycle.Results:The IC_(50) of genistein in the two AL cell lines was lower than that for the bone marrow mesenchymal stem cell line.Genistein upregulated H4K20mel,KMT5A and Wnt suppressor genes,including Wnt5a,and downregulated the downstream target genes of Wnt,such as c-myc and β-catenin.The methylation degree and H3K9ac enrichment in the Wnt5a promoter region remained unchanged.However,the enrichment of H4K20mel in the Wnt5a promoter and coding regions increased.In addition,genistein upregulated Phospho-cdc2,Mytl,Cyclin A,Cyclin E2,p21 and Phospho-histone H3,but downregulated Phospho-weel.Cell cycle arrest was induced in the G2/M phase.Conclusion:Genistein inhibits the activation of the Wnt pathway by promoting the expression of Wnt5a through the activation of KMT5A and enrichment of H4K20mel in the Wnt5a gene promoter and coding regions,rather than demethylation.Genistein also blocks the cell cycle in the G2/M phase.Therefore,genistein is a potential anti-leukemia drug.

Role of reactive oxygen species in the antiproliferative effects of metavanadate on human prostate cancer DU145 cells

In the present study, the effects of metavanadate on the human prostate cancer cell line DU145 and the underlying mechanism were investigated. The results showed that metavanadate can cause cell cycle arrest at G2/M phase which was evidenced by cell cycle analysis and the increased phosphorylation of Cdc2 at its inactive Tyr-15 site. In addition, the results showed that metavanadate can induce reactive oxygen species （ROS） elevation and decrease the level of Cdc25C. This process can be rescued by an antioxidant, N-acetyl cysteine. In conclusion, the results demonstrate that metavanadate can inhibit cell proliferation via cell cycle arrest at G2/M phase in DU145 ceils. Metavanadate-induced ROS formation may play an important role in this process by mediating the degradation of Cdc25C.

Substituent-regulated highly X-ray sensitive Os(Ⅵ)nitrido complex for low-toxicity radiotherapy

A high efficiency and low toxicity radiosensitizer,OsN(PhenOH)Cl_3,was designed and synthesized through substituent regulation.To the best of our knowledge,this is the first osmium-based coordination complex radiosensitizer.The experimental results shown that this radiosensitizer induced G2/M cell cycle arrest mainly through induction of intracellular ROS overproduction.