Zhenhua Xie

Pro-oncogene Pokemon promotes breast cancer progression by upregulating survivin expression

IntroductionPokemon is an oncogenic transcription factor involved in cell growth, differentiation and oncogenesis, but little is known about its role in human breast cancer. In this study, we aimed to reveal the role of Pokemon in breast cancer progression and patient survival and to understand its underlying mechanisms.MethodsTissue microarray analysis of breast cancer tissues from patients with complete clinicopathological data and more than 20 years of follow-up were used to evaluate Pokemon expression and its correlation with the progression and prognosis of the disease. DNA microarray analysis of MCF-7 cells that overexpress Pokemon was used to identify Pokemon target genes. Chromatin immunoprecipitation (ChIP) and site-directed mutagenesis were utilized to determine how Pokemon regulates survivin expression, a target gene.ResultsPokemon was found to be overexpressed in 158 (86.8%) of 182 breast cancer tissues, and its expression was correlated with tumor size (P = 0.0148) and lymph node metastasis (P = 0.0014). Pokemon expression led to worse overall (n = 175, P = 0.01) and disease-related (n = 79, P = 0.0134) patient survival. DNA microarray analyses revealed that in MCF-7 breast cancer cells, Pokemon regulates the expression of at least 121 genes involved in several signaling and metabolic pathways, including anti-apoptotic survivin. In clinical specimens, Pokemon and survivin expression were highly correlated (n = 49, r = 0.6799, P < 0.0001). ChIP and site-directed mutagenesis indicated that Pokemon induces survivin expression by binding to the GT boxes in its promoter.ConclusionsPokemon promotes breast cancer progression by upregulating survivin expression and thus may be a potential target for the treatment of this malignancy.

New synthetic flavone derivatives induce apoptosis of hepatocarcinoma cells

Natural flavonoids have broad biological activity, including anticancer. In this study, a series of novel flavone derivatives were synthesized with the substitutions of chlorine, isopropyl, methoxy, and nitro groups on the benzene ring of flavone skeleton to develop effective anticancer agents. Antiproliferative assays showed that the synthesized chemicals possess notable activity against hepatocarcinoma cells (HepG-2); in particular, the compound 6f with chlorine and dimethoxy modifications at the two benzene rings showed an IC(50) at 1.1 microM to HepG-2. The 6f also displayed marked anticancer activity towards a panel of cancer cells, including nasopharyngeal carcinoma cells (CNE-2 and CNE-1), breast adenocarcinoma cell (MCF-7), and epithelial carcinoma cells (Hela). Exposing HepG-2 cells to compound 6f at 10 microM induced chromatin condensation, nuclear disassembly, and DNA fragmentation. In 6f-treated HepG-2 cells, the sub-G(0) population was remarkably increased; and in these cells, both caspase-8 and caspase-9 activity was significantly increased, which in turn activated caspase-3. In addition, proapoptotic Bax was upregulated by compound 6f while the antiapoptotic Bcl-2 was downregulated. Taken together, our data suggest that the new flavonoid derivative 6f triggers apoptosis through both death-receptor and mitochondria-dependent intrinsic pathways, being a potent therapeutic agent against hepatocarcinoma.

P-Glycoprotein/MDR1 Regulates Pokemon Gene Transcription Through p53 Expression in Human Breast Cancer Cells

P-glycoprotein (Pgp), encoded by the multidrug resistance 1 (MDR1) gene, is an efflux transporter and plays an important role in pharmacokinetics. In this study, we demonstrated that the pokemon promoter activity, the pokemon mRNA and protein expression can be significantly inhibited by Pgp. Chromatin immunoprecipitation assay showed that Pgp can bind the pokemon prompter to repress pokemon transcription activity. Furthermore, Pgp regulated pokemon transcription activity through expression of p53 as seen by use of p53 siRNA transfected MCF-7 cells or p53 mutated MDA-MB-231 cells. Moreover, p53 was detected to bind with Pgp in vivo using immunoprecipitation assay. Taken together, we conclude that Pgp can regulate the expression of pokemon through the presence of p53, suggesting that Pgp is a potent regulator and may offer an effective novel target for cancer therapy.

Antitumor effect of F-PBFβ-TrCP-induced targeted PTTG1 degradation in HeLa cells

Pituitary tumor-transforming gene 1 (PTTG1), a proto-oncogene, is associated with tumor formation, proliferation and invasiveness. F-PBF(beta-TrCP), a fusion protein, was produced by replacing the WD40-repeat of F-box protein beta-TrCP with the PTTG1-binding factor (PBF) for targeted degradation of PTTG1. To evaluate the function of F-PBF(beta-TrCP), PTTG1-EGFP fusion protein was constructed. Our results showed that F-PBF(beta-TrCP) can both degrade exogenous PTTG1-EGFP fusion protein in COS-7 cells and endogenous PTTG1 protein in HeLa cells and the targeted PTTG1 knock down resulted in bFGF mRNA level down-regulation and inhibition of proliferation and clonogenicity in HeLa cells. In conclusion, targeted degradation of PTTG1 by F-PBF(beta-TrCP) has antitumor activity in vitro in HeLa cells. These results suggest that F-PBF(beta-TrCP) could be used for cancer treatment by targeted degradation of PTTG1.

Apoptosis induced by (di-isopropyloxyphoryl-Trp) 2 -Lys-OCH 3 in K562 and HeLa cells

According to the method used in our laboratory, our group synthesized (DIPP-Trp)2-Lys-OCH3. It inhibited the proliferation of K562 and HeLa cells in a dose-and time-dependent manner with an IC50 of 15.12 and 42.23 µM, respectively. (DIPP-Trp)2-Lys-OCH3 induced a dose-dependent increase of the G2/M cell population in K562 cells, and S cell population in HeLa cells; the sub-G0 population increased dramatically in both cell lines as seen by PI staining experiments using a FACS Calibur Flow cytometer (BeckmanCoulter, USA). Phosphatidylserine could significantly translocate to the surface of the membrane in (DIPP-Trp)2-Lys-OCH3-treated K562 and HeLa cells. The increase of an early apoptotic population was observed in a dose-dependent manner by both annexin-FITC and PI staining. It was concluded that (DIPP-Trp)2-Lys-OCH3 not only induced cells to enter into apoptosis, but also affected the progress of the cell cycle. It may have arrested the K562 and HeLa cells in the G2/M, S phases, respectively. The apoptotic pathway was pulsed at this point, resulting in the treated cells entering into programmed cell death. (DIPP-Trp)2-Lys-OCH3 is a potential anticancer drug that intervenes in the signalling pathway.

The Pharmacokinetics Analysis of the Phosphoryl Peptides in MCF-7/ADR Cells

We have developed and validated a practical high-performance liquid chromatography method to determine the concentration of N-diisopropyloxyphosphoryl-valine-phenylalanine-3, 4, 5-trimethoxy aniline (DIPP-Val-Phe-TMOA) in Adriamycin-resistant human breast adenocarcinoma (MCF-7/ADR) cells. First, DIPP-Val-Phe-TMOA was extracted from MCF-7 cells with perchloric acid, followed by a cleanup procedure with centrifugal separation, and then determinated by HPLC using a Waters C18 column with a gradient elution (solvent A: 10 mM ammonium acetate at pH 7.0, B: acetonitrile). The flow rate was maintained at 1.0 ml/min at room temperature. The detection wavelength was at 254 nm. Meanwhile, this validated method was successfully applied to analyze the concentration levels and the pharmacokinetics parameters of DIPP-Val-Phe-TMOA in MCF-7/ADR cells.