Pien Tze Huang Inhibits Proliferation of Colorectal Cancer Cells through Suppressing PNO1 Expression and Activating p53/p21 Signaling Pathway.

OBJECTIVE: To explore the regulatory effect of Pien Tze Huang (PZH) on targeting partner of NOB1 (PNO1) and it's down-stream mediators in colorectal cancer (CRC) cells. METHODS: Quantitative polymerase chain reaction was performed to determine mRNA levels of PNO1, TP53, and CDKN1A. Western blotting was performed to determine protein levels of PNO1, p53, and p21. HCT-8 cells were transduced with a lentivirus over-expressing PNO1. Colony formation assay was used to detect cell survival in PNO1 overexpression of HCT-8 cells after PZH treatment. Cell-cycle distribution, cell viability and cell apoptosis were performed to identify the effect of PNO1 overexpression on cell proliferation and apoptosis of HCT-8 cells after PZH treatment. Xenograft BALB/c nude mice bearing HCT116 cells transduced with sh-PNO1 or sh-Ctrl lentivirus were evaluated. Western blot assay was performed to detect PNO1, p53, p21 and PCNA expression in tumor sections. Terminal deoxynucleotidyl transferase dUTP nick end labling (TUNEL) assay was used to determine the apoptotic cells in tissues. RESULTS: PZH treatment decreased cell viability, down-regulated PNO1 expression, and up-regulated p53 and p21 expressions in HCT-8 cells (P<0.05). PNO1 overexpression attenuated the effects of PZH treatment, including the expression of p53 and p21, cell growth, cell viability, cell cycle arrest and cell apoptosis in vitro (P<0.05). PNO1 knockdown eliminated the effects of PZH treatment on tumor growth, inhibiting cell proliferation inhibition and apoptosis induction in vivo (P<0.05). Similarly, PNO1 knockdown attenuated the effects of PZH treatment on the down-regulation of PNO1 and up-regulation of p53 and p21 in vivo (P<0.05). CONCLUSION: The mechanism by which PZH induces its CRC anti-proliferative effect is at least in part by regulating the expression of PNO1 and its downstream targets p53 and p21.

[Effects of CeO2 nanoparticles on the viabilities of neural PC12 and SH-SY5Y cells].

OBJECTIVE: To investigate the effects of cerium oxide (CeO2) nanoparticles on the viabilities of nerve cells PC12 and SH-SY5Y. METHODS: CeO2 nanoparticles were synthesized, structures were characterized and properties were evaluated. PC12 cells and SH-SY5Y cells were treated with CeO2 nanoparticles at different concentrations (1, 2.5, 5, 10, 25, 50, 75, 100, 150 µg/ml) for 24 h and the cell viability was measured by MTT assay. Then PC12 cells and SH-SY5Y cells were co-treated with CeO2 and active oxygen scavenger NAC and the cells were stained with DCFH-DA probe for ROS. The number of cells and the fluorescence intensity were observed under a fluorescent inverted microscope. Differences were assessed by one-way ANOVA. RESULTS: After treatment with CeO2 nanoparticles, the viabilities of both PC12 cells (P＜0.01) and SH-SY5Y cells (P＜0.01) were decreased comparing with the control group. After staining with DCFH-DA probe, the fluorescence intensity of the nerve cells was enhanced depending on the concentration of CeO2 nanoparticles suggesting that CeO2 induced the generation of reactive oxygen species (ROS). The fluorescence intensity of PC12 cells was decreased after CeO2 nanoparticles (100 µg/ml) co-treatment with active oxygen scavenger NAC. Compared with CeO2 nanoparticles alone at 25 µg/ml (P＜0.01), 50 µg/ml (P＜0.01), 75 µg/ml (P＜0.01), 100 µg/ml (P＜0.01), the cell viability was significantly increased after co-treatment with NAC. CONCLUSION: CeO2 nanoparticles has a negative effect on the viabilities of nerve cells PC12 and SH-SY5Y, and the effect might be depend on ROS.

Oleanolic acid and ursolic acid inhibit proliferation in transformed rat hepatic oval cells.

AIM: To investigate H2O2-induced promotion proliferation and malignant transformation in WB-F344 cells and anti-tumor effects of ursolic acid (UA) and oleanolic acid (OA). METHODS: WB-F344 cells were continuously exposed to 7 x 10(-7) mol/L H2O2 for 21 d. Observations of cell morphology, colony formation rates, flow cytometric analysis of cell cycle changes and aneuploidy formation indicated that H2O2 was able to induce malignant transformation of WB-F344 cells. We treated malignantly transformed WB-F344 cells with 4 µmol/L OA or 8 µmol/L UA for 72 h and analyzed the cell cycle distribution by flow cytometry. RESULTS: MTT assay showed that 7 x 10(-7) mol/L H2O2 decreased G1 phase subpopulation from 73.8% to 49.6% compared with the control group, and increased S phase subpopulation from 14.5% to 31.8% (P < 0.05 vs control group). Cell morphology showed that nucleus to cytoplasm ratio increased, many mitotic cells, prokaryotes and even tumor giant cells were shown in H2O2-induced WB-F344 cells. Fluorescence activated cell sorting analysis showed that WB-F344 cell aneuploidy increased to 12% following H2O2 treatment. Flow cytometric analysis of the transformed WB-F344 cells following treatment with OA (4 µmol/L) and UA (8 µmol/L) showed that OA increased G1 subpopulation to 68.6%, compared to 49.7% in unexposed cells. UA increased G1 subpopulation to 67.4% compared to 49.7% in unexposed cells (P < 0.05 vs H2O2 model group). CONCLUSION: H2O2 causes the malignant transformation of WB-F344 cells. OA and UA exert anti-tumor effects by inhibiting the proliferation in malignantly transformed WB-F344 cells.

E2F1-mediated DNA damage is implicated in 8-Cl-adenosine-induced chromosome missegregation and apoptosis in human lung cancer H1299 cells.

Although E2F1-mediated DNA double-stranded breaks (DSBs) and tetraploid have been extensively studied, the role of E2F1 in mitotic catastrophe is still unknown. We have previously shown that 8-chloro-adenosine (8-Cl-Ado) induces DNA DSBs and aberrant mitosis in human lung cancer cells, followed by delayed apoptosis. Here, we demonstrate that E2F1-mediated DNA damage is implicated in 8-Cl-Ado-induced chromosome missegregation and apoptosis in lung cancer H1299 cells. We showed that E2F1 was accumulated upon 8-Cl-Ado-induced DNA DSBs. Induction of E2F1 by 8-Cl-Ado caused DNA damage in cycling cells including M cells. In contrast, silencing of E2F1 expression decreased 8-Cl-Ado-induced DNA DSBs, particularly eliminated E2F1-mediated mitotic DNA damage. Over-expression of E2F1 and/or 8-Cl-Ado exposure resulted in aberrant mitotic spindles and chromosome segregation errors. Furthermore, over-expression of E2F1 expression enhanced 8-Cl-Ado-induced apoptosis. Together, our data indicate that E2F1-mediated DNA damage, in particular mitotic DNA damage, is an important fraction of 8-Cl-Ado-induced DNA damage, which is implicated in 8-Cl-Ado-induced mitotic catastrophe and delayed apoptosis. Induction of E2F1 by 8-Cl-Ado may contribute at least partly to the drug-inhibited proliferation of cancer cells.