[Show abstract][Hide abstract] ABSTRACT: Previous studies have shown that selenite exerts pro-apoptosis and pro-autophagy effects and is associated with the activation of ER stress in T-cell acute lymphoblastic leukemia (T-ALL). Herein we demonstrate the underlying mechanisms by which the activation of p38MAPK plays essential roles in apoptosis and autophagy and the coordination of cellular metabolic processes during leukemia therapy. MKK3/6-dependent activation of p38MAPK is required for the phosphorylation of eIF4E, thus initiating the translation of ER stress-related transcription factor ATF4. Upregulated ATF4 results in the transcriptional initiation of the apoptosis-related chop gene and autophagy-related map1lc3b gene, through which selenite links ER stress to apoptosis and autophagy during leukemia treatment. Moreover, autophagy induction enhances cell apoptosis under this condition.
[Show abstract][Hide abstract] ABSTRACT: Background
Previous studies demonstrated that selenite induced cancer-cell apoptosis through multiple mechanisms; however, effects of selenite on microtubules in leukemic cells have not been demonstrated.
The toxic effect of selenite on leukemic HL60 cells was performed with cell counting kit 8. Selenite effects on cell cycle distribution and apoptosis induction were determined by flow cytometry. The contents of cyclin B1, Mcl-1, AIF, cytochrome C, insoluble and soluble tubulins were detected with western blotting. Microtubules were visualized with indirect immunofluorescence microscopy. The interaction between CDK1 and Mcl-1 was assessed with immunoprecipitation. Decreasing Mcl-1 and cyclin B1 expression were carried out through siRNA interference. The alterations of Mcl-1 and cyclin B1 in animal model were detected with either immunohistochemical staining or western blotting. In situ detection of apoptotic ratio was performed with TUNEL assay.
Our current results showed that selenite inhibited the growth of HL60 cells and induced mitochondrial-related apoptosis. Furthermore, we found that microtubule assembly in HL60 cells was altered, those cells were arrested at G2/M phase, and Cyclin B1 was up-regulated and interacted with CDK1, which led to down-regulation of the anti-apoptotic protein Mcl-1. Finally, in vivo experiments confirmed the in vitro microtubule disruption effect and alterations in Cyclin B1 and Mcl-1 levels by selenite.
Taken together, the results from our study indicate that microtubules are novel targets of selenite in leukemic HL60 cells.
Preview · Article · Jan 2013 · Journal of Hematology & Oncology
[Show abstract][Hide abstract] ABSTRACT: Autophagy has been suggested as a possible mechanism for non-apoptotic death despite evidence from many species that autophagy represents a survival strategy of cells under stress. From our previous findings that supranutritional doses of sodium selenite induced apoptosis in human leukemia cells, now we show autophagic cell death occurred after selenite exposure in HL60, suggested an alternative mechanism for the potential therapeutic properties of selenite. Additionally, Death-associated Protein Kinase (DAPK) performed a significantly increased expression during this process, concomitantly with gradually decreased phosphorylation at Ser(308). We further reveal that the up-regulation of DAPK which depends on selenite-activated ERK had no effect on autophagy. However, activation of DAPK via PP2A-mediated dephosphorylation at Ser(308) serves as a new strategy for autophagy induction. In conclusion, these results indicate that PP2A-mediated activated DAPK sensitizes HL60 cells to selenite, ultimately triggers autophagic cell death pathway to commit cell demise. [BMB reports 2012; 45(3): 194-199].
[Show abstract][Hide abstract] ABSTRACT: Mounting evidence reveals that selenium possesses chemotherapeutic potential against cancer cells. However, the molecular mechanisms underlying the anti-cancer effect of selenium remain elusive. In this study, with the aim to explore the detailed mechanisms how selenite induces apoptosis in colorectal cancer cells, we investigated the role of AKT/β-catenin signaling, a critical regulator of cell proliferation, survival and tumorigenesis, in selenite-induced apoptosis of colorectal cancer cells and xenograft tumors. We showed that selenite exerted a remarkable inhibitory effect on activation of AKT, leading to suppression of β-catenin activity and expression of its targets: cyclin D1 and survivin. Further experiments by transient expression of AKT and β-catenin revealed that inhibition of AKT/β-catenin was closely correlated with selenite-triggered apoptosis. Importantly, MnTMPyP pretreatment implied reactive oxygen species (ROS) was a crucial upstream signal for selenite-triggered inhibition of AKT/β-catenin. Overall, these observations demonstrate that selenite could induce apoptosis through ROS-dependent inhibition of AKT/β-catenin signaling in colorectal cancer cells in vitro and in vivo, and our findings yield novel insights into elucidating the mechanisms involved in the anti-cancer effect of selenium.
[Show abstract][Hide abstract] ABSTRACT: Autophagy can protect cells while also contributing to cell damage, but the precise interplay between apoptosis and autophagy and the contribution of autophagy to cell death are still not clear. Previous studies have shown that supranutritional doses of sodium selenite promote apoptosis in human leukemia NB4 cells. Here, we report that selenite treatment triggers opposite patterns of autophagy in the NB4, HL60, and Jurkat leukemia cell lines during apoptosis and provide evidence that the suppressive effect of selenite on autophagy in NB4 cells is due to the decreased expression of the chaperone protein Hsp90 (heat shock protein 90), suggesting a novel regulatory function of Hsp90 in apoptosis and autophagy. Excessive or insufficient expression indicates that Hsp90 protects NB4 cells from selenite-induced apoptosis, and selenite-induced decreases in the expression of Hsp90, especially in NB4 cells, inhibit the activities of the IκB kinase/nuclear factor-κB (IKK/NF-κB) signaling pathway, leading to less nuclear translocation and inactivation of NF-κB and the subsequent weak binding of the becn1 promoter, which facilitates the transition from autophagy to apoptosis. Taken together, our observations provide novel insights into the mechanisms underlying the balance between apoptosis and autophagy, and we also identified Hsp90-NF-κB-Beclin1 as a potential biological pathway for signaling the switch from autophagy to apoptosis in selenite-treated NB4 cells.
Preview · Article · Feb 2011 · Molecular biology of the cell
[Show abstract][Hide abstract] ABSTRACT: Microtubule associated protein tau is considered to play roles in some types of human transmissible spongiform encephalopathies (TSE). In this study, the full-length and several truncated human tau proteins were expressed from E. coli and purified. Using GST pull down, co-immunoprecipitation assay and tau-coated ELISA, the molecular interaction between tau protein and PrP was confirmed in the context of the full-length human tau. The N terminus (amino acids 1-91) and tandem repeats region (amino acids 186-283) of tau protein were responsible for the interaction with PrP. The octapeptide repeats within PrP directly affected the binding activity of PrP with tau. GSS-related mutant PrP102L and fCJD- related mutants with two and seven extra octarepeats showed more active binding capacity with tau than wild-type PrP. The molecular interactions between PrP and tau protein highlight a potential role of tau in the biological function of PrP and the pathogenesis of TSE.
No preview · Article · Apr 2008 · Molecular and Cellular Biochemistry
[Show abstract][Hide abstract] ABSTRACT: Although the function of cellular prion protein (PrPc) and the pathogenesis of prion diseases have been widely described, the mechanisms are not fully clarified. In this study, increases of the portion of non-glycosylated prion protein deposited in the hamster brains infected with scrapie strain 263K were described. To elucidate the pathological role of glycosylation profile of PrP, wild type human PrP (HuPrP) and two genetic engineering generated non-glycosylated PrP mutants (N181Q/N197Q and T183A/T199A) were transiently expressed in human astrocytoma cell line SF126. The results revealed that expressions of non-glycosylated PrP induced significantly more apoptosis cells than that of wild type PrP. It illustrated that Bcl-2 proteins might be involved in the apoptosis pathway of non-glycosylated PrPs. Our data highlights that removal of glycosylation of prion protein provokes cells apoptosis.
Preview · Article · Oct 2007 · Journal of biochemistry and molecular biology
[Show abstract][Hide abstract] ABSTRACT: To evaluate changes in the prevalence rates of ultrasonographic fatty liver (FL) in a specific population.
An analysis of the medical records of BaoSteel Group (Shanghai, China) employees was done to evaluate the prevalence of FL in this population, in which health examinations were performed biennially between 1995 and 2002.
The study reviewed a database of 59 131 employees, of which 27.1% received medical check-ups four times within the study period, 26.6% three times, and 24.0% twice. The prevalence rates of obesity and metabolic disorders were high at baseline and increased significantly with time. The prevalence of ultrasonographic FL increased from 3.87% to 14.04% in the overall population, while there was an increase from 4.44% to 14.64% in men and 1.56% to 11.37% in women over the 6-year study period. Increased rates of FL were also noted, from 25.88% to 51.39%, among patients with elevated serum alanine aminotransferase (ALT) levels (> 40 U/L). The highest overall prevalence rates of FL were found in individuals aged 50-60 years, with all age-associated prevalence significantly higher in males than females.
The prevalence of FL increased rapidly over the study period with increased rates of obesity and metabolic disorders; FL is becoming a major cause of abnormal ALT levels in the specific population.
No preview · Article · May 2007 · Journal of Gastroenterology and Hepatology
[Show abstract][Hide abstract] ABSTRACT: To explore the change of the prevalence rates of overweight and obesity in Shanghai Bao-Steel Company population.
We retrospectively analyzed the medical records of all employees undergoing health examination biennially from 1995 to 2002. Overweight and obesity were respectively diagnosed when body mass index (BMI) > or = 24 kg/m2 but still less than 28 kg/m2 and > or = 28 kg/ m2. SPSS 11.5 and SAS of statistical software were used for data analysis.
During the period studied, in 59 131 times of medical check-up, 27.1% participants received four times check-up, 26.6% thrice and 24.0% twice. After adjusted by sex and age, the total prevalence rates of overweight and obesity increased from 26.50% and 4.10% to 34.60% and 7.70% between 1995 to 1996 and 2001 to 2002, respectively. After adjusted by age, the prevalence rates of overweight and obesity in men increased from 28.20% and 4.20% to 37.90% and 8.40%; less significantly in women from 19.60% and 3.70% to 21.10% and 5.20%. Among men, the prevalence rates of overweight and obesity in men younger than 60 years old increased along with time. While in women, only the overweight prevalence in women younger than 30 years old and the obesity prevalence in women between 50 years old and 60 years old increased along with time, with unchanged prevalence in other age sub-group.
The prevalence rates of overweight and obesity have been growing rapidly in Bao-Steel Company employees, primarily in middle-aged and young men, who should be paid more attention.
No preview · Article · Feb 2007 · Zhonghua yu fang yi xue za zhi [Chinese journal of preventive medicine]
[Show abstract][Hide abstract] ABSTRACT: Microtubule-associated protein tau is considered to play roles in many neurodegenerative diseases including some transmissible spongiform encephalopathies. To address the possible molecular linkage of prion protein (PrP) and tau, a GST-fusion segment of human tau covering the three-repeat region and various PrP segments was used in the tests of GST pull-down and immunoprecipitation. We found tau protein interacted with various style prion proteins such as native prion protein (PrPc) or protease-resistant isoform (PrPSc). Co-localization signals of tau and PrP were found in the CHO cell tranfected with both PrP and tau gene. The domain of interaction with tau was located at N-terminal of PrP (residues 23 to 91). The evidence of molecular interactions between PrP and tau protein highlights a potential role of tau in the biological function of PrP and the pathogenesis of TSEs.
No preview · Article · Nov 2006 · Science in China Series C Life Sciences
[Show abstract][Hide abstract] ABSTRACT: To report a protocol using biotin-labelled PrP protein in cell free conversion assay instead of isotope.
A hamster PrP protein (HaPrP) was expressed in E. coli and purified with HIS-tag affinity chromatograph. After being labelled with biotin, HaPrP was mixed with PrPSc preparation from scrapie strain 263K.
Protease-resistant bands were detected after four-day incubation.
The new conversion model provides a reliable, easily handling, and environment-friendly method for studies of prion and transmissible spongiform encephalopathies.
No preview · Article · Jul 2006 · Biomedical and Environmental Sciences
[Show abstract][Hide abstract] ABSTRACT: To explore the relationship between fatty liver and the metabolic syndrome in the adults of Shanghai and evaluate the value of fatty liver as a marker for risk factor clustering.
Questionnaires, physical examinations, laboratory tests (blood lipid and glucose) and real-time liver ultrasonographies were performed in Shanghai adults and analyzed using randomized, multistage, stratified cluster sampling. Prevalence of the metabolic syndrome was defined by the National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATPIII) criteria with the exception of abdominal obesity (waist circumference > 90 cm in men and > 80 cm in women); fatty liver was diagnosed in accordance with the presence of an ultrasonographic pattern consistent with 'bright' liver (brightness and posterior attenuation of liver).
The study population consisted of 3175 subjects (1218 men) with a mean (+/- SD) age of 52.4 +/- 15.1 years. Metabolic syndrome and fatty liver were found in 726 (22.87%) and 661 (20.82%) of sampled cases, respectively. After adjustment by age and sex, the prevalence of the metabolic syndrome and fatty liver in the general population of Shanghai were 15.30 and 17.29%, respectively. The risk for fatty liver in subjects with abdominal obesity, diabetes, dyslipidemia and hypertension increased 32.78-fold (95% confidence interval (CI) 14.85-72.35), 31.58-fold (95% CI 14.18-70.35), 22.64-fold (95% CI 10.26-49.99) and 23.25-fold (95% CI 10.54-51.30), respectively, compared with controls, whereas the risk for fatty liver in subjects with metabolic syndrome was increased by 39.33-fold (95% CI 17.77-87.05). After the 661 patients with fatty liver had been stratified by body mass index (BMI), the prevalence of abdominal obesity, hypertension and the metabolic syndrome were increased from 25.0, 47.2 and 36.1%, respectively, in people with normal BMI to 81.0, 73.8 and 55.4%, respectively, in obese persons. However, the prevalence of hypertriglyceridemia, high fasting glucose and low high-density lipoprotein-cholesterol showed no significant changes with increased BMI. Moreover, among fatty liver patients with normal BMI, the detection rate for one or more features of metabolic disorders was as high as 83.3% and that for five features was 2.8%. Compared with obesity (BMI > or = 25 kg/m2) and abdominal obesity, fatty liver had the highest clustering rate, specificity, positive predictive value and attributable risk percentage in detecting risk factor clustering in both sexes.
There is a high prevalence of metabolic syndrome and fatty liver among Shanghai adults. Metabolic disorders are closely related to fatty liver; moreover, fatty liver appears to be a good predictor for the clustering of risk factors for metabolic syndrome.
No preview · Article · Jan 2006 · Journal of Gastroenterology and Hepatology
[Show abstract][Hide abstract] ABSTRACT: To determine the prevalence and risk factors of fatty liver (FL) among Shanghai adults.
A cross-sectional ultrasonographic survey with randomized multistage stratified cluster sampling was used.
The study included 3175 subjects (1218 men) with a mean age of 52 years. FL was found in 661 (20.82%) subjects. After adjustment by age and sex, FL prevalence was found to be 17.29%, and the prevalences of alcoholic, suspected alcoholic and nonalcoholic FL were determined to be 0.79, 1.15 and 15.35%, respectively. Generally, age, body mass index (BMI), waist circumference, blood pressure, and the prevalences of obesity, diabetes, hypertension and dyslipidemia were all significantly higher in FL patients than in controls; In contrast, the levels of high-density-lipoprotein cholesterol (HDL-C), education and physical activity were markedly lower. Multiple regression analyses showed that only nine factors (male, educational level, waist circumference, BMI, HDL-C, triglyceride, fasting plasma glucose, diabetes and hypertension) were closely related to FL. In excessive drinkers, obesity increased the risk for FL by 4.8-fold, but excessive drinking was associated with only a 1.5-fold increased risk in obese subjects.
FL in Shanghai is highly prevalent and mainly related to multiple metabolic disorders.
No preview · Article · Oct 2005 · Journal of Hepatology
[Show abstract][Hide abstract] ABSTRACT: To investigate the prevalence and major risk factors of fatty liver among adult residents in Shanghai.
A cross-sectional survey with multiple-stage stratified cluster and random sampling was performed. All residents aged 16 and above were invited to participate in the survey; they came from four communities of Yangpu District and Pudong New District. Questionnaire, physical examination, serum lipid-profile, and 75 gram oral glucose tolerance test and ultrasonographic examination of liver were undertaken. Analysis of data was performed through SPSS 11.0 for Windows statistical package.
A total of 3175 residents took part in the survey, which was 75% of adult residents of the investigated communities and 2.26/10 000 of Shanghai municipal residents. Of the 3175, 1218 were males and 1957 were females. The mean age of the participants was 52.4+/-15.1 years and ranged from 16 to 88 years. Fatty liver was detected with ultrasound examination in 661 participants (20.82%), among which 3.48% had alcoholic fatty liver, 4.08% had suspected alcoholic fatty liver, and 92.43% had nonalcoholic fatty liver. The age-adjusted, sex-adjusted prevalence of fatty liver in Shanghai adult residents was 17.29%, the prevalence of alcoholic fatty liver, suspicious alcoholic fatty liver, and nonalcoholic fatty liver in Shanghai adult residents were 0.79%, 1.15%, and 15.35%, respectively. The prevalence of fatty liver was increased with aging in males and in females. Among participants younger than 50 years old, the prevalence of fatty liver in males was significantly higher than that in females, but in participants older than 50 years the case was just the opposite, higher in females. The mean age (years), body mass index (BMI), waist circumference, blood pressure, fasting and two hour serum glucose level, triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and the presence of obesity, diabetes mellitus, hypertension, dyslipidemia, and gallstones in the fatty liver group was significantly higher than those in the group without fatty liver, but the high-density lipoprotein cholesterol (HDL-C) level and the educational level were both lower in the fatty liver group. Logistic regression analysis demonstrated that the prevalence of fatty liver was only positively correlated to nine risk factors, including male sex, educational level, waist circumference, BMI, fasting glucose level, HDL-C, TG, hypertension and diabetes mellitus. In heavy drinkers, obesity increased the risk for fatty liver by 4.8-fold, but heavy drinking only increased the risk for fatty liver 1.5-fold (95% CI 0.9-2.6, P=0.1685).
There is a high prevalence of fatty liver among adult residents in Shanghai, and nonalcoholic fatty liver is the major type. Metabolic disorders such as obesity and diabetes mellitus, hypertension and hyperlipidemia are more closely associated with fatty liver than heavy drinking in Shanghai.
No preview · Article · Mar 2005 · Zhonghua gan zang bing za zhi = Zhonghua ganzangbing zazhi = Chinese journal of hepatology