Barbigerone, a natural isoflavone, induces apoptosis in murine lung-cancer cells via the mitochondrial apoptotic pathway.

Barbigerone is a naturally occurring isoflavone with antioxidant activity. In present study, we investigated the antitumor activity of barbigerone against murine lung cancer cells LL/2 and the possible mechanism in vitro. Our results showed that barbigerone inhibited LL/2 cells proliferation in a concentration- and time-dependent manner and caused apoptotic death of LL/2 cells. Barbigerone-induced apoptosis was characterized by enhanced mitochondrial cytochrome c release, activation of caspase-3,-9, but not caspase-8. Exposure of LL/2 cells to barbigerone resulted in upregulation of Bcl-2-associated protein (Bax) and down-regulation of Bcl-2. In addition, proliferation inhibitory effect of barbigerone was associated with decreased level of phosphorylated p42/44 mitogen-activated protein kinase (p42/44 MAPK) and phosphorylated Akt. Moreover, barbigerone exhibit less toxicity to non-cancer cells than tumor cells. In conclusion, our results indicated that barbigerone can inhibit murine lung cancer cell proliferation by inducing apoptosis via mitochondrial apoptotic pathway and by decreasing phosphorylated p42/44 MAPK and Akt. Its potential to be a candidate of anti-cancer agent is worth being further investigated.

Cell growth inhibition, G2/M cell cycle arrest, and apoptosis induced by chloroquine in human breast cancer cell line Bcap-37.

Chloroquine is an antimalarial drug that has been used in the treatment and prophylaxis of malaria since the 1950s. The present study was undertaken to examine the effects of chloroquine on Bcap-37 human breast cancer cells' growth, cell cycle modulation, apoptosis induction, and associated molecular alterations in vitro. The chloroquine treatment decreased the viability of Bcap-37 cells in a concentration- and time-dependent manner, which correlated with G(2)/M phase cell cycle arrest. The chloroquine-mediated cell cycle arrest was associated with a decrease in protein levels/activity of polo-like kinase 1 (Plk1), phosphorylated cell division cycle 25C (Cdc25C), phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2), phosphorylated Akt. The chloroquine-treated Bcap-37 cells exhibited a marked decrease in the level of mitochondrial transmembrane potential (DeltaPsim), which was accompanied by the activation of caspase-3 and cleaved poly(ADP-ribose) polymerase (PARP). Exposure of Bcap-37 cells to chloroquine also resulted in the induction of spindle abnormalities. In conclusion, the findings in this study suggested that chloroquine might have potential anticancer efficacy, which could be attributed, in part, to its proliferation inhibition and apoptosis induction of cancer cells through modulation of apoptosis and cell cycle-related proteins expressions, down-regulation of mitochondrial transmembrane potential (DeltaPsim), and induction of spindle abnormalities.

Pharmacophore modeling and virtual screening for designing potential PLK1 inhibitors.

Pharmacophore models of Polo-like kinase-1 (PLK1) inhibitors have been established by using the HipHop and HypoGen algorithms implemented in the Catalyst software package. The best quantitative pharmacophore model, Hypo1, which has the highest correlation coefficient (0.9895), consists of one hydrogen bond acceptor, one hydrogen bond donor, one hydrophobic feature, and one hydrophobic aliphatic feature. Hypo1 was further validated by test set and cross validation method. Then Hypo1 was used as a 3D query to screen several databases including Specs, NCI, Maybridge, and Chinese Nature Product Database (CNPD). The hit compounds were subsequently subjected to filtering by Lipinski's rule of five and docking study to refine the retrieved hits and as a result to reduce the rate of false positive. Finally, a total of 20 compounds were selected and have been shifted to in vitro and in vivo studies. As far as we know, this is the first report on the pharmacophore modeling even the first publicly reported virtual screening study of PLK1 inhibitors.

Antitumor and antimetastatic activities of chloroquine diphosphate in a murine model of breast cancer.

Metastatic breast cancers are hard to treat and almost always fatal. Chloroquine diphosphate, a derivative of quinine, has long been used as a potent and commonly used medicine against different human diseases. We therefore investigated the effects of chloroquine diphosphate on a highly metastatic mouse mammary carcinoma cell line. In vitro treatment of 4T1 mouse breast cancer cells with chloroquine diphosphate resulted in significant inhibition of cellular proliferation and viability, and induction of apoptosis in 4T1 cells in a time- and dose-dependent manner. Further analysis indicated that induction of apoptosis was associated with the loss of mitochondrial membrane potential, release of cytochrome c, and activation of caspase-9 and caspase-3, and cleavage of poly(ADP-ribose) polymerase. The effect of chloroquine diphosphate was then examined using a mice model in which 4T1 cells were implanted subcutaneously. Chloroquine diphosphate (25mg/kg and 50mg/kg, respectively) significantly inhibited the growth of the implanted 4T1 tumor cells and induced apoptosis in the tumor microenvironment. Moreover, the metastasis of tumor cells to the lungs was inhibited significantly and the survival of the mice enhanced. These data suggested that chloroquine diphosphate might have chemotherapeutic efficacy against breast cancer including inhibition of metastasis.

[Effects of chloroquine diphosphate on proliferation and apoptosis of human leukemic K562 cells].

The purpose of this study was to investigate the effects of chloroquine diphosphate on the proliferation and apoptosis of human leukemic K562 cells, and to elucidate its possible mechanism of activity. The inhibitory effect of chloroquine diphosphate with different concentrations on K562 cell proliferation was detected by MTT method. Apoptosis was measured by flow cytometry (FCM); morphological analysis of apoptosis was performed after staining with propidium iodide (PI) under fluorescence microscope; cell apoptosis was assessed by the DNA ladder shown agarose gel electrophoresis. After treatment with chloroquine diphosphate, K562 cells were stained by Rhodamine 123 to detect changes in mitochondrial transmembrane potential (DeltaPsim) by FCM. The results showed that the cell viability decreased in dose-dependent manner, following chloroquine diphosphate treatment at different concentrations (1.5625, 3.125, 6.25, 12.5, 25, 50 and 100 micromol/L) for 24, 48 and 72 hours. By FCM analysis, the significant increases of sub-G(1) were observed. DNA ladder was detected and apoptotic nuclei were observed. DeltaPsim decreased in K562 cells after chloroquine diphosphate treatment. It is concluded that the chloroquine diphosphate can inhibit the proliferation of K562 cells and induce cell apoptosis, which may relate to down-regulation of mitochondrial transmembrane potential (DeltaPsim).

Pharmacophore modelling and virtual screening for identification of new Aurora-A kinase inhibitors.

Aurora-A has been identified as one of the most attractive targets for cancer therapy and a considerable number of Aurora-A inhibitors have been reported recently. In order to clarify the essential structure-activity relationship for the known Aurora-A inhibitors as well as identify new lead compounds against Aurora-A, 3D pharmacophore models were developed based on the known inhibitors. The best hypothesis, Hypo1, was used to screen molecular structural databases, including Specs and China Natural Products Database for potential lead compounds. The hit compounds were subsequently subjected to filtering by Lipinski's rules and docking study to refine the retrieved hits and as a result to reduce the rate of false positive. Finally, 39 compounds were purchased for further in vitro assay against several human tumour cell lines including A549, MCF-7, HepG2 and PC-3, in which Aurora-A is overexpressed. Two compounds show very low micromolar inhibition potency against some of these tumour cells. And they have been selected for further investigation.