Downregulation of mitochondrial cyclooxygenase-2 inhibits the stemness of nasopharyngeal carcinoma by decreasing the activity of dynamin-related protein 1.

Cancer stem cells (CSCs) are a small subset of malignant cells, possessing stemness, with strong tumorigenic capability, conferring resistance to therapy and leading to the relapse of nasopharyngeal carcinoma (NPC). Our previous study suggested that cyclooxygenase-2 (COX-2) would be a novel target for the CSCs-like side population (SP) cells in NPC. In the present study, we further found that COX-2 maintained the stemness of NPC by enhancing the activity of mitochondrial dynamin-related protein 1 (Drp1), a mitochondrial fission mediator, by studying both sorted SP cells from NPC cell lines and gene expression analyses in NPC tissues. Using both overexpression and knockdown of COX-2, we demonstrated that the localization of COX-2 at mitochondria promotes the stemness of NPC by recruiting the mitochondrial translocation of p53, increasing the activity of Drp1 and inducing mitochondrial fisson. Inhibition of the expression or the activity of Drp1 by siRNA or Mdivi-1 downregulates the stemness of NPC. The present study also found that inhibition of mitochondrial COX-2 with resveratrol (RSV), a natural phytochemical, increased the sensitivity of NPC to 5-fluorouracil (5-FU), a classical chemotherapy drug for NPC. The underlying mechanism is that RSV suppresses mitochondrial COX-2, thereby reducing NPC stemness by inhibiting Drp1 activity as demonstrated in both the in vitro and the in vivo studies. Taken together, the results of this study suggest that mitochondrial COX-2 is a potential theranostic target for the CSCs in NPC. Inhibition of mitochondrial COX-2 could be an attractive therapeutic option for the effective clinical treatment of therapy-resistant NPC.

Protein phosphatase 2A-B55δ enhances chemotherapy sensitivity of human hepatocellular carcinoma under the regulation of microRNA-133b.

BACKGROUND: Hepatocellular carcinoma (HCC) remains a major public health problem worldwide. The identification of effective chemotherapeutic targets for advanced HCC patients is urgently required. In this study, we investigated the role of protein phosphatase 2A-B55δ subunit (PP2A-B55δ, encoded by the PPP2R2D gene) and related mechanisms affecting chemotherapy sensitivity of HCC. METHODS: Experimental approaches for measuring the levels of PPP2R2D mRNA and B55δ protein in HCC included bioinformatics analyses, quantitative real-time polymerase chain reaction (qRT-PCR), western blotting (WB), immunofluorescence and immunohistochemistry assays. Cell cycle, migration, colony formation, apoptosis, and cell proliferation assays in stable PPP2R2D-knockdown and -overexpression cell lines in vitro, and tumorigenicity assays in vivo, were performed to explore the function of B55δ in cisplatin (cDDP) chemotherapy of HCC. Bioinformatics prediction, luciferase reporter assays, qRT-PCR, WB, and cell cycle analyses were used to reveal the regulatory relationship between microRNA-133b (miR-133b) and PPP2R2D expression. miR-133b mimic and inhibitor were used to elucidate the regulatory mechanism. RESULTS: Our studies showed that PPP2R2D expression was down-regulated in both HCC tumors and HCC cell lines. Treatment with cDDP increased the amount of B55δ protein. Artificially increasing the expression of B55δ counteracted cyclin-dependent kinase 1 activation, modulated transitions of the cell cycle, and increased the suppressive effect of cDDP on cell migration, colony formation, apoptosis, and proliferation in vitro and tumor growth in vivo, thus enhancing therapeutic efficiency. In contrast, knockdown of B55δ partially inhibited the effect of cDDP chemotherapy. miR-133b was shown to regulate PPP2R2D expression by binding to the 3'-untranslated region of PPP2R2D mRNA. The miR-133b/PPP2R2D signaling pathway affects the effectiveness of cDDP chemotherapy. CONCLUSIONS: PP2A-B55δ, regulated by miR-133b, enhances the sensitivity of HCC to cDDP chemotherapy. Our data indicate that PP2A-B55δ might be a novel and attractive target for increasing chemotherapy sensitivity of HCC.

Parthenolide inhibits cancer stem-like side population of nasopharyngeal carcinoma cells via suppression of the NF-κB/COX-2 pathway.

Cancer stem cells play a central role in the pathogenesis of nasopharyngeal carcinoma and contribute to both disease initiation and relapse. In this study, cyclooxygenase-2 (COX-2) was found to regulate cancer stem-like side population cells of nasopharyngeal carcinoma cells and enhance cancer stem-like cells' characteristics such as higher colony formation efficiency and overexpression of stemness-associated genes. The regulatory effect of COX-2 on cancer stem-like characteristics may be mediated by ABCG2. COX-2 overexpression by a gain-of-function experiment increased the proportion of side population cells and their cancer stemness properties. The present study also demonstrated that in contrast to the classical chemotherapy drug 5-fluorouracil, which increased the proportion of side population cells and upregulated the expression of COX-2, parthenolide, a naturally occurring small molecule, preferentially targeted the side population cells of nasopharyngeal carcinoma cells and downregulated COX-2. Moreover, we found that the cancer stem-like cells' phenotype was suppressed by using COX-2 inhibitors NS-398 and CAY10404 or knocking down COX-2 with siRNA and shRNA. These findings suggest that COX-2 inhibition is the mechanism by which parthenolide induces cell death in the cancer stem-like cells of nasopharyngeal carcinoma. In addition, parthenolide exhibited an inhibitory effect on nuclear factor-kappa B (NF-κB) nucler translocation by suppressing both the phosphorylation of IκB kinase complex and IκBα degradation. Taken together, these results suggest that parthenolide may exert its cancer stem cell-targeted chemotherapy through the NF-κB/COX-2 pathway.

[Exposure risk assessment of plasticizer in dietary food in Xiamen].

OBJECTIVE: To understand the dietary consumption of residents in Xiamen and the content of phthalic acid esters (PAEs) in food, and to assess the plasticizer exposure risk of diet in Xiamen. METHODS: The survey was conducted by stratified cluster random sampling method in Xiamen from September to October in 2010. According to the Xiamen administrative division, six neighborhood communities were selected as sampling units, then 25 families were randomly chosen from each sampling units.From the above 150 families, the permanent residents over the age of six were permitted to our study. The survey included 495 residents totally. These participants' information, such as basic personal information, physical activity levels, meal frequency and the average consumption of 33 kinds of food in 13 categories were collected using questionnaires. Thirteen categories included cereal and tubers, beans, vegetables, fungi and algae, fruits, dairy products, meat, seafood, eggs, snacks, beverages, cooking oil and spices. The height and weight of residents were measured and the average daily dietary intake was calculated. Thirty-three kinds of food in 13 categories were collected in supermarkets in Xiamen. According to the annual sales ranking, the top three-five brands of each kinds of food were selected and numbered, then two or three brands were chosen by random number table method from them; three completely individual packed samples in the same batch of each brand were detected; 243 samples were included in our study.100-500 g solid samples or 100-500 ml liquid samples were collected. The content of diethyl phthalate (DEP), dibutyl phthalate (DBP), di (2-ethylhexyl) phthalate (DEHP) in food were detected by liquid chromatography mass spectrometry, which expressed by median (minimum-maximum). The exposure dose, contribution rate and risk index of PAEs were calculated by point estimation method. RESULTS: According to the average daily dietary intake of residents in Xiamen, the top three ones in 13 categories of food were cereal and tubers (337.16 g/d, 18.21%), vegetables (309.12 g/d, 16.69%) and fruits (213.20 g/d, 11.51%). The content of DEP, DBP or DEHP among different categories of food was significantly different (χ² values were 58.05, 50.19 and 102.10, P < 0.01). Among 13 categories of food, seafood contained the most DEP (0.090 (0.000-0.324)mg/kg); cooking oil had the most DBP (0.700(0.000-2.980) mg/kg) and DEHP (5.115(0.000-24.160) mg/kg). DEP, DBP and DEHP exposure(0.19, 4.20, 18.10 µg × kg⁻¹ ×d ⁻¹)in dietary food in Xiamen were less than the reference dose(RfD) (800, 100, 20 µg × kg⁻¹ × d⁻¹) proposed by the United States Environmental Protection Agency (EPA), and the risk indexes were 0.02%, 4.20% and 90.50%, respectively. Among 13 categories of foods, seafood was the main source of DEP dietary exposure. The exposure dose and contribution rate of DEP in seafood were 0.18 µg × kg⁻¹ × d⁻¹ and 94.74%, respectively.Vegetables were the main source of DBP and DEHP dietary exposure. The exposure dose and contribution rate of DBP and DEHP were 1.48 µg × kg⁻¹ × d⁻¹, 35.24% and 6.07 µg × kg⁻¹ × d⁻¹, 33.54%, respectively. CONCLUSION: The food consumed by residents in Xiamen was overall in a safe state, but to some extent, there still exists DEHP exposure risk in foods.

[Risk factors analysis of nonalcoholic fatty liver disease in Chinese men].

OBJECTIVE: To explore risk factors of nonalcoholic fatty liver disease (NAFLD) in men in order to provide a theoretical basis for developing more effective NAFLD prevention and control strategies. METHODS: One-hundred-and-two male patients (37.3+/-11.4 years old) hospitalized with NAFLD at the Dongnan Affiliated Hospital of Xiamen University between January 2009 and December 2010 were enrolled in the study, along with 23 age-matched healthy men (34.4+/-16.7 years old) to serve as the control group. The correlation(s) of body mass index (BMI; overweight defined as more than or equal to 22.717 kg/m2), waist circumference (WC), waist-to-hip ratio (WHR; central obesity defined as more than or equal to 0.866), fasting plasma glucose (FPG), triglyceride (TG), and total cholesterol (TC) with NAFLD was analyzed by univariate and multivariate logistic regression analyses. Receiver operating characteristic (ROC) curves were used to select proper thresholds for classification. RESULTS: BMI, WC, WHR, FPG, TG, and TC were significantly different between the cases and controls (P less than 0.01). BMI, WC, WHR, TG and TC were identified as risk factors of NAFLD in these male cases (P less than 0.01). Relative to WC, TG and TC, both BMI and WHR had significant predictive value for NAFLD (odds ratio (OR) = 10.819 and 10.588, respectively). In addition, BMI had the highest diagnostic value for the prediction of NAFLD (area under the curve (AUC) = 0.931) followed by WHR (AUC = 0.879). CONCLUSION: BMI, WC, WHR, TG, and TC are risk factors of NAFLD in Chinese men. BMI and WHR are effective anthroposomatology indices of NAFLD and may be useful factors on which to base future prevention and early diagnosis strategies for NAFLD in males.

Clinical and virological characteristics of chronic hepatitis B patients with hepatic steatosis.

OBJECTIVE: This study aimed to explore clinical and virological characteristics of chronic hepatitis B (CHB) patients with hepatic steatosis in order to provide a theoretical basis for the prevention and control of hepatic steatosis. METHODS: A total of 360 CHB inpatients were recruited from Affiliated Dongnan Hospital of Xiamen University and divided into hepatic steatosis group and non-hepatic steatosis group. The body mass index (BMI), waist-to-hip ratio (WHR), fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyl transpeptidase (GGT), hepatitis B e antigen (HBeAg), hepatitis B virus DNA (HBV DNA) and hepatic histological changes were detected and compared between the two groups. The association of these factors with hepatic steatosis was evaluated in CHB patients. RESULTS: BMI, FPG, TG, TC, GGT, AST and HBV DNA showed statistically significant differences between two groups (P<0.01). The patients with hepatic steatosis had markedly higher BMI, FBG, TG and TC than those without steatosis did. No significant differences were found in ALT and HBeAg between two groups (P>0.05). In male patients, there was marked difference in the WHR between two groups (P < 0.01), which was not found in female patients (P > 0.05). The severity of hepatic steatosis increased in patients with hepatic steatosis, compared to those without steatosis (P < 0.01), but the severities of inflammation and fibrosis in the non-hepatic steatosis group were dramatically higher than those in the hepatic steatosis group (P < 0.01). CONCLUSIONS: BMI, WHR, FBG, TG and TC appeared to be influencing factors of CHB combined with hepatic steatosis. Hepatic steatosis in CHB patients was closely related to changes in anthropometric indices and metabolic factors but not HBV. It is necessary to improve these factors to effectively prevent hepatic steatosis in CHB patients.

[Relationship between mannose-binding protein gene polymorphisms and disease progression and HBV DNA in patients with chronic HBV infection].

OBJECTIVE: To determine the influences of Mannose binding protein (MBP) gene polymorphisms on HBV DNA loads and on the progression of liver disease in patients with chronic HBV infection. METHOD: The Codons on 54 MBP gene polymorphisms and HBV DNA loads in a cohort of 395 patients with chronic HBV infection, including 244 with chronic hepatitis B (CHB), 151 with liver cirrhosis (LC) and 88 normal controls were examined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and fluorescent quantitative PCR (FQ-PCR). RESULT: The MBP genotype frequencies of GGC/GAC and alleles genetic frequencies of GAC in CHB group showed no significant differences comparing to the normal control group (P > 0.05). The MBP genotype frequencies of GGC/GAC and alleles genetic frequencies of GAC on CHB group (severe), compensation phase of LC group and decompensation phase of LC group were higher than those in the normal control group (P < 0.05), the genetic polymorphism of decompensation of LC was 36.5%, highest of all. The MBP genotype frequencies of GGC/GAC and alleles genetic frequencies of GAC of patients with chronic HBV infection were not changed with the differences of HBV-DNA loads. CONCLUSION: The codes on 54 MBP gene polymorphisms is not closely related to HBV DNA loads, but was associated with the progression of hepatitis B infection.