Magnolol inhibits growth of gallbladder cancer cells through the p53 pathway.

Magnolol, the major active compound found in Magnolia officinalis has a wide range of clinical applications due to its anti-inflammation and anti-oxidation effects. This study investigated the effects of magnolol on the growth of human gallbladder carcinoma (GBC) cell lines. The results indicated that magnolol could significantly inhibit the growth of GBC cell lines in a dose- and time-dependent manner. Magnolol also blocked cell cycle progression at G0 /G1 phase and induced mitochondrial-related apoptosis by upregulating p53 and p21 protein levels and by downregulating cyclin D1, CDC25A, and Cdk2 protein levels. When cells were pretreated with a p53 inhibitor (pifithrin-a), followed by magnolol treatment, pifithrin-a blocked magnolol-induced apoptosis and G0 /G1 arrest. In vivo, magnolol suppressed tumor growth and activated the same mechanisms as were activated in vitro. In conclusion, our study is the first to report that magnolol has an inhibitory effect on the growth of GBC cells and that this compound may have potential as a novel therapeutic agent for the treatment of GBC.

Antineoplastic effects of deoxypodophyllotoxin, a potent cytotoxic agent of plant origin, on glioblastoma U-87 MG and SF126 cells.

BACKGROUND: Deoxypodophyllotoxin (DPT) is a semi-synthetic compound derived from the extract of Dysosma versipellis (Hance) M. Cheng, one of the most popular Chinese herbal medicines. The present study evaluates the in vitro cytotoxicity of DPT on a wide panel of human cancer cell lines and investigates its molecular mechanism of action on high grade glioma U-87 MG and SF126 cells. METHODS: The growth inhibitory effect of DPT on different types of human cancer cells was measured by the Cell Counting Kit-8 (CCK-8) assay. For the elucidation of the nature of the cellular response to DPT-treatment; flow cytometry-based assays, light and fluorescent microscopy, caspase colorimetric and inhibition assays, and Western blot analysis were performed. RESULTS: Our data show that DPT possesses a potent growth-inhibitory action, with IC50 values in nanomolar ranges. Cell cycle analysis revealed G2/M phase arrest in a dose- and time-dependent manner before cell death occurred. Additional studies indicated that DPT induced G2 arrest in U-87 MG cells by decreasing the expression of Cdc2, cyclin B1, and Cdc25C proteins. In contrast, DPT failed to down-regulate these cell cycle regulatory molecules in SF126 glioblastoma cells and stopped the cell cycle at M phase. Interestingly, morphological changes and biochemical markers such as phosphatydylserine externalization, DNA fragmentation, and caspase activation, confirmed that DPT-treatment resulted in an induction of apoptosis in both examined cell lines via caspase-dependent pathways. CONCLUSIONS: Taken together, our data demonstrated that DPT possesses a potent in vitro cytotoxic activity and exerts its effect via G2/M arrest and apoptosis.

Inhibitory effects of α-pinene on hepatoma carcinoma cell proliferation.

BACKGROUND: Pine needle oil from crude extract of pine needles has anti-tumor effects, but the effective component is not known. METHODS: In the present study, compounds from a steam distillation extract of pine needles were isolated and characterized. Alpha-pinene was identified as an active anti-proliferative compound on hepatoma carcinoma BEL-7402 cells using the MTT assay. RESULTS: Further experiments showed that α-pinene inhibited BEL-7402 cells by arresting cell growth in the G2/M phase of the cell cycle, downregulating Cdc25C mRNA and protein expression, and reducing cycle dependence on kinase 1(CDK1) activity. CONCLUSION: Taken together, these findings indicate that α-pinene may be useful as a potential anti-tumor drug.

The natural anticancer compound rocaglamide selectively inhibits the G1-S-phase transition in cancer cells through the ATM/ATR-mediated Chk1/2 cell cycle checkpoints.

Targeting the cancer cell cycle machinery is an important strategy for cancer treatment. Cdc25A is an essential regulator of cycle progression and checkpoint response. Over-expression of Cdc25A occurs often in human cancers. In this study, we show that Rocaglamide-A (Roc-A), a natural anticancer compound isolated from the medicinal plant Aglaia, induces a rapid phosphorylation of Cdc25A and its subsequent degradation and, thereby, blocks cell cycle progression of tumor cells at the G1-S phase. Roc-A has previously been shown to inhibit tumor proliferation by blocking protein synthesis. In this study, we demonstrate that besides the translation inhibition Roc-A can induce a rapid degradation of Cdc25A by activation of the ATM/ATR-Chk1/Chk2 checkpoint pathway. However, Roc-A has no influence on cell cycle progression in proliferating normal T lymphocytes. Investigation of the molecular basis of tumor selectivity of Roc-A by a time-resolved microarray analysis of leukemic vs. proliferating normal T lymphocytes revealed that Roc-A activates different sets of genes in tumor cells compared with normal cells. In particular, Roc-A selectively stimulates a set of genes responsive to DNA replication stress in leukemic but not in normal T lymphocytes. These findings further support the development of Rocaglamide for antitumor therapy.

Induction of G2/M Arrest by Berberine via Activation of PI3K/Akt and p38 in Human Chondrosarcoma Cell Line.

Berberine is a clinically important natural isoquinoline alkaloid found in many medicinal herbs. Berberine has been shown to have many pharmacological effects including antimicrobial, antitumor, and anti-inflammatory activities. However, the effects and mechanism of action of berberine have not been studied in chondrosarcoma. Therefore, the effects of berberine on proliferation in a human chondrosarcoma cell line (HTB-94) were investigated. Berberine inhibited cell proliferation in a concentration-dependent manner. We also determined that inhibition of cell proliferation by berberine occurred via G2/M phase arrest in HTB-94 cells. Berberine induced cell cycle arrest at the G2/M phase by upregulation of p53 and p21 expression and suppressed cyclin B1, cyclin-dependent kinase 1 (cdc2), cdc25c, and phosphorylated retinoblastoma tumor-suppressor protein (pRb) expression. In addition, berberine stimulated phosphorylation of protein kinase B (Akt) and p38 kinase. Inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt with LY294002 (LY) and p38 kinase with SB203580 (SB), respectively, decreased berberine-induced p53 and p21 expression and restored cell proliferation and expression of cyclin B1, cdc2, cdc25c, and pRb cell cycle progression proteins. These results suggest that berberine-induced inhibition of cell proliferation by cell cycle arrest at the G2/M phases was regulated through PI3K/Akt and p38 kinase pathways in HTB-94 chondrosarcoma cells.

Physalis angulata induced G2/M phase arrest in human breast cancer cells.

Physalis angulata (PA) is employed in herbal medicine around the world. It is used to treat diabetes, hepatitis, asthma and malaria in Taiwan. We have evaluated PA as a cancer chemopreventive agent in vitro by studying the role of PA in regulation of proliferation, cell cycle and apoptosis in human breast cancer cell lines. PA inhibited cell proliferation and induced G2/M arrest and apoptosis in human breast cancer MAD-MB 231 and MCF-7 cell lines. In this study, under treatment with various concentrations of PA in MDA-MB 231 cell line, we checked mRNA levels for cyclin A and cyclin B1 and the protein levels of cyclin A and cyclin B1, Cdc2 (cyclin-dependent kinases), p21(waf1/cip1) and P27(Kip1) (cyclin-dependent kinase inhibitors), Cdc25C, Chk2 and Wee1 kinase (cyclin-dependent kinase relative factors) in cell cycle G2/M phase. From those results, we determined that PA arrests MDA-MB 231 cells at the G2/M phase by (i) inhibiting synthesis or stability of mRNA and their downstream protein levels of cyclin A and cyclin B1, (ii) increasing p21(waf1/cip1) and P27(kip1) levels, (iii) increasing Chk2, thus causing an increase in Cdc25C phosphorylation/inactivation and inducing a decrease in Cdc2 levels and an increase in Wee1 level. According to the results obtained, PA appears to possess anticarcinogenic properties; these results suggest that the effect of PA on the levels of phosphorylated/inactivated Cdc25C are mediated by Chk2 activation, at least in part, via p21(waf1/cip1) and P27(kip1) cyclin-dependent kinase inhibitors pathway to arrest cells at G2/M phase in breast cancer carcinoma cells.

Expression of fission yeast cdc25 driven by the wheat ADP-glucose pyrophosphorylase large subunit promoter reduces pollen viability and prevents transmission of the transgene in wheat.

Cell number was to be measured in wheat (Triticum aestivum) endosperm expressing Spcdc25 (a fission yeast cell-cycle regulator) controlled by a supposedly endosperm-specific promoter, AGP2 (from the large subunit of ADP glucose pyrophosphorylase). Wheat was transformed by biolistics either with AGP2::GUS or AGP2::Spcdc25. PCR and RT-PCR checked integration and expression of the transgene, respectively. In cv. Chinese Spring, AGP2::GUS was unexpectedly expressed in carpels and pollen, as well as endosperm. In cv. Cadenza, three AGP2::Spcdc25 plants, AGP2::Spcdc25.1, .2 and .3, were generated. Spcdc25 expression was detected in mature leaves of AGP2::Spcdc25.1/.3 which exhibited abnormal spikes, 50% pollen viability and low seed set per plant; both were small compared with the nonexpressing and normal AGP2::Spcdc25.2. Spcdc25 was not transmitted to the T(1) in AGP2::Spcdc25.1 or .3, which developed normally. Spcdc25 was PCR-positive in AGP2::Spcdc25.2, using primers for a central portion, but not with primers for the 5' end, of the ORF, indicating a rearrangement; Spcdc25 was not expressed in either T(0) or T(1). The AGP2 promoter is not tissue-specific and Spcdc25 expression disrupted reproduction.