Ubiquitin-specific protease 7 accelerates p14(ARF) degradation by deubiquitinating thyroid hormone receptor-interacting protein 12 and promotes hepatocellular carcinoma progression.

UNLABELLED: The prognosis for hepatocellular carcinoma (HCC) remains dismal in terms of overall survival (OS), and its molecular pathogenesis has not been completely defined. Here, we report that expression of deubiquitylase ubiquitin-specific protease 7 (USP7) is higher in human HCC tissues than in matched peritumoral tissues. Ectopic USP7 expression promotes growth of HCC cells in vivo and in vitro. Mechanistically, USP7 overexpression fosters HCC cell growth by forming a complex with and stabilizing thyroid hormone receptor-interacting protein 12 (TRIP12), which induces constitutive p14(ARF) ubiquitination. Clinically, USP7 overexpression is significantly correlated with a malignant phenotype, including larger tumor size, multiple tumor, poor differentiation, elevated alpha-fetoprotein, and microvascular invasion. Moreover, overexpression of USP7 and/or TRIP12 correlates with shorter OS and higher cumulative recurrence rates of HCC. CONCLUSION: USP7 stabilizes TRIP12 by deubiquitination, thus constitutively inactivating p14(ARF) and promoting HCC progression. This represents a novel marker for predicting prognosis and a potential therapeutic target for HCC.

[Inhibitory effect of agarohexaose on antimycin A induced generation of reactive oxygen species].

AIM: To evaluate the hepatocyte protective effect of agarohexaose against indirect oxidative stress injury induced by antimycin A. METHODS: Antimycin A was used to induce oxidative injury of human hepatocyte L-02. The oxidative degree in cells was detected by dichlorofluorescin diacetate (DCFH-DA) and the fluorescence generation was recorded by flow cytometer and fluorescent microscope. The apoptosis of L-02 cells induced by oxidation was identified by TUNEL test, and the morphologic features of cells were also observed. RESULTS: Agarohexaose at concentration of 1 mg x mL(-1) inhibited the oxidation of DCFH into DCF significantly. The fluorescence intensity and oxidized cell number decreased after the incubation with agarohexaose. The photomicrographs of antimycin A and agarohexaose treated cells revealed that agarohexaose could reduce the apoptotic morphologic features. The TUNEL results also indicated that the number of apoptotic cells decreased significantly after the treatment of agarohexaose. CONCLUSION: Agarohexaose could inhibit the sudden increase reactive oxygen species (ROS) in cells significantly, and it also protected cells against oxidative stress injury in vitro.

Effects of daidzein on estrogen-receptor-positive and negative pancreatic cancer cells in vitro.

AIM: To study the effects of daidzein on human pancreatic cancer cells in vitro. METHODS: Human estrogen-receptor (ER)-positive pancreatic cancer cells MiaPaCa-2 and ER-negative pancreatic cancer cells PANC-1 were treated by 0.1 micromol/L, 1 micromol/L, 10 microL, 25 microL, 50 microL, 75 microL and 100 microL of daidzein, respectively. Its antiproliferative effect was studied by MTT assay. RESULTS: Daidzein inhibited the growth of MiaPaCa-2 and PANC-1 cells at the concentrations from 0.1 microL to 100 microL. A dose- and time-dependent manner was found. The IC(50) of daidzein on MiaPaCa-2 and PANC-1 cells was 45 microL and 75 micro, respectively. After MiaPaCa-2 cells were treated by daidzein for 3 d and at the concentrations more than IC(50), the inhibitory manner was identical and the inhibition appeared a saturation phenomenon, but the inhibitory manner of daidzein on PANC-1 cells was different from that of MiaPaCa-2 cells. CONCLUSION: Daidzein has antiproliferative effects on human estrogen-receptor-positive and negative pancreatic cancer cells, but their mechanisms may be different.

[Effects of Bt corn straw insecticidal proteins on enzyme activities of Eisenia fetida].

Bacillus thuringiensis (Bt) proteins released from Bt corn can enter soil ecosystem via returning straw into field, root exudation, and pollen fluttering-down. In this study, the straws of Bt corn and its near-isogenic non-Bt line were added into soil with an application rate of 5% and 7.5% to breed Eisenia fetida, and the total protein content and the activities of acetylcholine esterase (AchE), glutathione peroxidase (GSH-PX), catalase (CAT), and superoxide dismutase (SOD) in E. fetida were determined after 7 and 14 days. Under the same application rate of the straws, the total protein content and GSH-PX activity of E. fetida decreased while the AchE, CAT, and SOD activities increased on the 14th day, compared with those on the 7th day. The Bt corn straw increased the SOD activity and decreased the AchE and GSH-PX activities, but had less effects on the total protein content and CAT activity, compared with non-Bt corn straw. All the results suggested that Bt corn straw had no inhibitory effect on E. fetida total protein but could inhibit the AchE and GSH-PX activities, and could not induce CAT activity but induce SOD activity within a short time.