Ellipticine induces apoptosis through p53-dependent pathway in human hepatocellular carcinoma HepG2 cells

Norsolorinic acid inhibits proliferation of T24 human bladder cancer cells by arresting the cell cycle at the G0/G1 phase and inducing a Fas/membrane-bound Fas ligand-mediated apoptotic pathway

1. Norsolorinic acid, isolated from Aspergillus nidulans, has been shown to have antiproliferative activity in T24 human bladder cancer cells by arresting the cell cycle at the G(0)/G(1) phase and inducing apoptosis. The aim of the present study was to investigate the antiproliferative activity of norsolorinic acid in T24 human bladder cancer cells. 2. The effects of norsolorinic acid (1, 5, 10 and 20 micromol/L) on the proliferation of T24 cells and on the distribution of cells within different phases of the cell cycle were investigated indirectly using an XTT assay and a flow cytometer, respectively. Factors affecting the cell cycle and apoptosis, including p53, p21, Fas receptor, Fas ligand (FasL) and caspase 8 activity, were examined using ELISA. 3. The results showed that norsolorinic acid inhibited proliferation of T24 cells in a dose-dependent manner, with an IC(50) of 10.5 micromol/L. The effect involved the induction of cell cycle arrest at the G(0)/G(1) phase and apoptosis. 4. These results demonstrate that G(0)/G(1) phase arrest is due to increased expression of p21 in cells treated with norsolorinic acid (10 and 20 micromol/L) for 24 h. Moreover, enhanced Fas and membrane-bound Fas ligand (mFasL) may be responsible for the apoptotic effect of norsolorinic acid. Thus, the present study reports, for the first time, that induction of p21 and the Fas/mFas ligand apoptotic system may participate in the antiproliferative action of norsolorinic acid in T24 human bladder cancer cells.

A high-content chemical screen identifies ellipticine as a modulator of p53 nuclear localization

p53 regulates apoptosis and the cell cycle through actions in the nucleus and cytoplasm. Altering the subcellular localization of p53 can alter its biological function. Therefore, small molecules that change the localization of p53 would be useful chemical probes to understand the influence of subcellular localization on the function of p53. To identify such molecules, a high-content screen for compounds that increased the localization of p53 to the nucleus or cytoplasm was developed, automated, and conducted. With this image-based assay, we identified ellipticine that increased the nuclear localization of GFP-mutant p53 protein but not GFP alone in Saos-2 osteosarcoma cells. In addition, ellipticine increased the nuclear localization of endogenous p53 in HCT116 colon cancer cells with a resultant increase in the transactivation of the p21 promoter. Increased nuclear p53 after ellipticine treatment was not associated with an increase in DNA double stranded breaks, indicating that ellipticine shifts p53 to the nucleus through a mechanism independent of DNA damage. Thus, a chemical biology approach has identified a molecule that shifts the localization of p53 and enhances its nuclear activity.

Chalcone arrests cell cycle progression and induces apoptosis through induction of mitochondrial pathway and inhibition of nuclear factor kappa B signalling in human bladder cancer cells

Chalcones (1,3-diphenyl-2-propenone) are cancer preventive food components found in a human diet rich in fruits and vegetables. In this study, we first report the chemopreventive effect of chalcone in two human bladder cancer cell lines: T24 and HT-1376. The results show that chalcone inhibits the proliferation of T24 and HT-1376 cells by inducing apoptosis and blocking cell cycle progression in the G2/M phase. Western blot assay showed that chalcone significantly increases the expression of p21 and p27 proteins, and decreases the levels of cyclin B1, cyclin A and Cdc2, thereby contributing to cell cycle arrest. In addition, chalcone increased the expression of Bax and Bak, but decreased the levels of Bcl-2 and Bcl-X(L) and subsequently triggered mitochondrial apoptotic pathway (release of cytochrome c and activation of caspase-9 and caspase-3). Our study suggests that the induction of mitochondrial pathway and inhibition of the nuclear factor kappa B survival system may play important roles in the antiproliferative activity of chalcone in T24 and HT-1376 cells.

Proliferative effects of excretory/secretory products from Clonorchis sinensis on the human epithelial cell line HEK293 via regulation of the transcription factor E2F1

Clonorchis sinensis is one of the most prevalent parasitic helminths of humans in East Asia. Although several complications in bile duct epithelial cells are caused by C. sinensis infection, the mechanism is not clearly understood. To clarify the effects of C. sinensis excretory-secretory products (ES products) on bile duct epithelial cells, we investigated their effects on the human embryonic kidney epithelial cell line HEK293 in vitro. Our results show that ES products alter the proportion of cells in each stage of the cell cycle and induce HEK293 cell proliferation. Among cell cycle-related proteins, the expression of cyclin E increased markedly after treatment with ES products, indicating that the G1/S transition occurred. In addition, the expression of the transcription factor E2F1 was up-regulated by the addition of ES products. Small interfering RNA (siRNA) was used to demonstrate that the transcription factor E2F1 is a key factor in the control of cell proliferation in HEK293 cells. The present results demonstrate that ES products from C. sinensis stimulate cell proliferation by inducing E2F1 expression. We suggest that the ES products released from C. sinensis during infection may play an important role in the development of cholangiocarcinoma via the overgrowth of the bile duct epithelium.

Antiproliferative activity of paeoniflorin is through cell cycle arrest and the Fas/Fas ligand-mediated apoptotic pathway in human non-small cell lung cancer A549 cells

1. Paeoniflorin (PF), isolated from the paeony root, is reported to have immunoregulatory, neuromuscular blocking, anticonvulsant, antihyperglycaemic and antihypotensive effects. 2. The present study investigated the antiproliferative activity of PF. The results showed that PF inhibited the proliferation of A549 by blocking cell cycle progression in the G(0)/G(1) phase and inducing apoptosis. 3. An ELISA showed that G(0)/G(1) phase arrest may be due to p53-independent induction of p21/wild-type p53-activated fragment 1 (WAF1). Increased protein expression of Fas/apoptosis-1 (APO-1) and its two ligands, membrane-bound Fas ligand and soluble Fas ligand, may be responsible for the PF-induced apoptosis. 4. This is the first study to show that the induction of p21/WAF1 and the activity of the Fas/Fas ligand apoptotic system may participate in the antiproliferative activity of PF in A549 cells.