The biphasic redox sensing of SENP3 accounts for the HIF-1 transcriptional activity shift by oxidative stress.

AIM: To investigate the mechanisms underlying the biphasic redox regulation of hypoxia-inducible factor-1 (HIF-1) transcriptional activity under different levels of oxidative stress caused by reactive oxidative species (ROS). METHODS: HeLa cells were exposed to different concentrations of H(2)O(2) as a simple model for mild and severe oxidative stress. Luciferase reporter assay and/or quantitative real-time PCR were used to investigate the transcriptional activity. Immunoblot was used to detect protein expression. Chromatin immunoprecipitation assay was used to detect HIF-1/DNA binding. The interaction of p300 with HIF-1α or with SENP3, and the SUMO2/3 conjugation states of p300 were examined by coimmunoprecipitation. RESULTS: HIF-1 transcriptional activity in HeLa cells was enhanced by low doses (0.05-0.5 mmol/L) of H(2)O(2), but suppressed by high doses (0.75-8.0 mmol/L) of H(2)O(2). The amount of co-activator p300 bound to HIF-1α in HeLa cells was increased under mild oxidative stress, but decreased under severe oxidative stress. The ROS levels differentially modified cysteines 243 and 532 in the cysteine protease SENP3, regulating the interaction of SENP3 with p300 to cause different SUMOylation of p300, thus shifting HIF-1 transcriptional activity. CONCLUSION: The shift of HIF-1 transactivation by ROS is correlated with and dependent on the biphasic redox sensing of SENP3 that leads to the differential SENP3/p300 interaction and the consequent fluctuation in the p300 SUMOylation status.

Emodin enhances sensitivity of gallbladder cancer cells to platinum drugs via glutathion depletion and MRP1 downregulation.

Glutathione conjugation and transportation of glutathione conjugates of anticancer drugs out of cells are important for detoxification of many anticancer drugs. Inhibition of this detoxification system has recently been proposed as a strategy to treat drug-resistant solid tumors. Gallbladder carcinoma is resistant to many anticancer drugs, therefore, it is needed to develop a novel strategy for cancer therapy. In the present study, we tested the effect of emodin (1,3,8-trihydroxy-6-methylanthraquinone), a reactive oxygen species (ROS) generator reported by our group previously, in combination with cisplatin (CDDP), carboplatin (CBP) or oxaliplatin in treating the gallbladder carcinoma cell line SGC996. Our results showed that co-treatment with emodin could remarkably enhance chemosensitivity of SGC996 cells in comparison with cisplatin, carboplatin or oxaliplatin treatment alone. We found that the mechanisms may be attributed to reduction of glutathione level, and downregulation of multidrug resistance-related protein 1 (MRP1) expression in SGC996 cells. The experiments on tumor-bearing mice showed that emodin/cisplatin co-treatment inhibited the tumor growth in vivo via increasing tumor cell apoptosis and downregulating MRP1 expression. In conclusion, emodin can work as an adjunct to enhance the anticancer effect of platinum drugs in gallbladder cancer cells via ROS-related mechanisms.

[The influence of elective course of emergency treatment for medical students on the cultivation of first aid knowledge and skill of cardio-pulmonary resuscitation].

OBJECTIVE: To investigate the influence of elective course of emergency treatment for medical students on the cultivation of first aid knowledge and skills of cardio-pulmonary resuscitation. METHODS: Senior students major in medicine of our university were randomly divided into observation group and contrast group with 30 students in each group according to whether an elective course of emergency treatment was given or not. All of them then received a test of first aid knowledge and cardio-pulmonary resuscitation skills. RESULTS: The theoretical exam scores in observation group and contrast group were respectively 78.5+/-9.1 and 46.7+/-15.6. The scores in observation group were significantly higher than that in contrast group (P < 0.01). Cardio-pulmonary resuscitation skills scores in observation group and contrast group were respectively 7.32+/-0.83 and 6.63+/-0.91. The scores in observation group were significantly higher than that in contrast group (P < 0.01). The number of failure for closed cardiac massage in 60 times in observation group and contrast group was respectively 5.06+/-0.58 and 5.77+/-0.63. The number of mouth to mouth artificial respiration in 4 times in observation group and contrast group was 0.92+/-0.16 and 1.10+/-0.17, respectively. There were notable differences in the number of failure in resuscitation maneuvers between two groups (both P < 0.01), observation group being obviously poorer than contrast group. CONCLUSION: An elective course of emergency treatment given to medical students plays an important role in the cultivation of first aid knowledge and skills in cardio-pulmonary resuscitation. It is therefore necessary that emergency medicine is included as a required course in medical college.

[Effects of rosiglitazone on inflammatory reaction and insulin resistance in obese patients with newly diagnosed type 2 diabetes].

OBJECTIVE: To study the effect of rosiglitazone on serum high-sensitivity C-reactive protein (hs-CRP), interleukin-1beta (IL-1beta), IL-6, tumor necrosis factor-alpha (TNF-alpha) and insulin resistance in obese patients with newly diagnosed type 2 diabetes. METHODS: This study involved 118 patients with newly diagnosed type 2 diabetes and obesity, who were randomly assigned into two groups for a 12-week treatment with rosiglitazone (4 mg/day, group A) or sulfonylureas (group B). Serum hs-CRP, IL-1beta, IL-6, TNF-alpha, fasting plasma glucose (FPG) and fasting insulin (FINS) were measured before and after the treatment. Insulin resistance index was calculated according to the HOMA Model. RESULTS: In group A, rosiglitazone treatment resulted in significantly reduced serum hs-CRP, IL-1beta, IL-6, TNF-alpha, FPG and insulin resistance index (P<0.01). No difference in FPG was found between the two groups after the treatment (P>0.05), but serum hs-CRP, IL-1beta, IL-6, TNF-alpha and insulin resistance index were significantly lower in group A than in group B (P<0.05). CONCLUSION: Rosiglitazone can decrease FPG, reduce the inflammation reaction and improve insulin resistance in obese patients with type 2 diabetes.

Emodin enhances cytotoxicity of chemotherapeutic drugs in prostate cancer cells: the mechanisms involve ROS-mediated suppression of multidrug resistance and hypoxia inducible factor-1.

The intrinsic or acquired resistance to multiple drugs (MDR) of cancer cells remains one of the main obstacles for chemotherapy. Development of small molecule targeting to hypoxia inducible factor-1 (HIF-1) has been recently proposed as strategy for treatments of drug-resistant solid tumors. In the present study, emodin, proven as a reactive oxygen species (ROS) generator by our previous work, was applied in combination with cisplatin and other chemotherapeutic drugs in the multidrug resistant prostate carcinoma cell line DU-145 and normal human dermal fibroblasts. Results showed that emodin/cisplatin co-treatment remarkably elevated ROS level and enhanced chemosensitivity in DU-145 cells, compared with cisplatin-only treatment, but exerted little effect on non-tumor cells. The effect of co-treatment on MDR1 gene and its upstream regulator HIF-1 was then investigated in DU-145. Co-treatment downregulated MDR1 expression and promoted drug retention, and meanwhile suppressed transactivation of HIF-1 in response to hypoxia without changing expression of HIF-1 alpha. The experiments on tumor-bearing mice showed that co-treatment inhibited the tumor growth in vivo, owing to oxidative stress and MDR1 down-regulation within tumors. HIF-1 transactivation and clonegenesis were suppressed in cells isolated from the tumors. Finally, examinations for the body weight, the organ histology and the antioxidant capacity of serum suggested that no systemic toxicity related to co-treatment was discernable. In conclusions, emodin, as a novel small inhibitor of HIF-1, may be recognized an effective adjunctive to improve efficacy of cytotoxic drugs in prostate cancer cells with over-activated HIF-1 and potent MDR.

[Allogenic transplantation studies on human fetal pancreatic nestin positive cells].

Human fetal pancreatic nestin positive cells cultured in vitro could self assemble to form islet-like cell clusters(ICC). They are multipotential and are capable of generating insulin-producing cells. To investigate their biological character and physiological function in vivo, ICCs were implanted into NOD-Scid mice subcapsularly. The results showed that: (1) Neovascularizations were observed in implant sites. (2) Blood glucose levels of diabetic mice were reduced markedly after implantation of ICCs. (3) ICCs in non-diabetic mice proliferated abnormally and infiltrated into renal parenchyma with many cell structures formed.