Glycyrrhizin attenuates HMGB1-induced hepatocyte apoptosis by inhibiting the p38-dependent mitochondrial pathway

AIM: To examine how high-mobility group box 1 (HMGB1) regulates hepatocyte apoptosis and, furthermore, to determine whether glycyrrhizin (GL), a known HMGB1 inhibitor, prevents HMGB1-induced hepatocyte apoptosis.METHODS: A human hepatocellular carcinoma cell line stably transfected with a bile acid transporter (Huh-BAT cells), were used in this study. Apoptosis was quantified using 4’,6-diamidino-2-phenylindole dihydrochloride staining and the APO Percentage apoptosis assay, and its signaling cascades were explored by immunoblot analysis. Kinase signaling was evaluated by immunoblotting and by using selective inhibitors. It is also tried to identify hepatocyte apoptosis affected by the HMGB1 inhibitor, GL.RESULTS: HMGB1 increased cellular apoptosis in Huh-BAT cells. HMGB1 led to increased cytochrome c release from mitochondria into the cytosol, and induced the cleavage of procaspase 3. However, it did not affect the activation of caspase 8. HMGB1-induced caspase 3 activation was significantly attenuated by the p38 inhibitor SB203580. GL significantly attenuated HMGB1-induced hepatocyte apoptosis. GL also prevented HMGB1-induced cytochrome c release and p38 activation in Huh-BAT cells.CONCLUSION: The present study demonstrated that HMGB1 promoted hepatocyte apoptosis through a p38-dependent mitochondrial pathway. In addition, GL had an anti-apoptotic effect on HMGB1-treated hepatocytes.     

Glycyrrhizic acid inhibits apoptosis and fibrosis in carbontetrachloride-induced rat liver injury

AIM:To investigate anti-apoptotic effects of glycyrrhizic acid(GA) against fibrosis in carbon tetrachloride(CCl4)-induced liver injury and its contributing factors.METHODS:Liver fibrosis was induced by administration of CCl4 for 8 wk.Pathological changes in the liver of rats were examined by hematoxylin-eosin staining.Collagen fibers were detected by Sirius red staining.Hepatocyte apoptosis was determined by TUNEL assay and the expression levels of cleaved caspase-3,Bax,α-SMA,connective tissue growth factor(CTGF),matrix metalloproteinase(MMP) 2 and MMP9 proteins were evaluated by western blot analysis,and α-SMA m RNA,collagen type Ⅰ and Ⅲ m RNA were estimated by real-time PCR.RESULTS:Treatment with GA significantly improved the pathological changes in the liver and markedly decreased the positive area of Sirius red compared with rats in the CCl4-treated group.TUNEL assay showed that GA significantly reduced the number of TUNEL-positive cells compared with the CCl4-treated group.The expression levels of cleaved caspase-3,Bax,α-SMA,CTGF,MMP2 and MMP9 proteins,and α-SMA m RNA,collagen type Ⅰ and Ⅲ m RNA were also significantly reduced by GA compared with the CCl4-treated group(P 0.05).CONCLUSION:GA treatment can ameliorate CCl4-induced liver fibrosis by inhibiting hepatocyte apoptosis and hepatic stellate cell activation.     

甘草酸对四氯化碳诱导大鼠肝纤维化肝组织p53蛋白表达的影响

目的：探讨甘草酸对四氯化碳诱导大鼠肝纤维化肝组织p53蛋白表达的影响。方法45只雄性SD大鼠随机均分为对照组、肝纤维化组和甘草酸干预组3组,每组各15只。肝纤维化组和甘草酸干预组构建四氯化碳诱导大鼠肝纤维化模型,对照组大鼠注射等量的橄榄油。甘草酸干预组大鼠以0．2％甘草酸溶液予腹腔注射,3 ml／只,3次／周;对照组大鼠予等量双蒸水替代。3组于实验第1、4、8周各处死5只大鼠,取肝组织行HE染色检测纤维化情况,采用免疫组织化学和Western印迹定量分析检测p53蛋白在大鼠肝组织内的表达情况。采用单因素方差分析比较各组大鼠实验第1、4、8周p53蛋白表达量差异,进一步组间两两比较采用LSD-t检验。结果实验第1周,3组大鼠肝组织p53蛋白表达量差异无统计学意义;实验第4、8周,肝纤维化组大鼠肝组织中p53蛋白表达量均较对照组大鼠升高,而甘草酸干预组大鼠肝组织中p53蛋白表达量均较肝纤维化组大鼠降低,且差异均有统计学意义（实验第4周：t值分别为2．39、2．74;实验第8周：t值分别为1．58、7．79;P值均为0．000）。结论甘草酸可减缓肝纤维化进程,其分子机制可能与p53蛋白的表达下调有关。     

SGK1 inhibits cellular apoptosis and promotes proliferation via the MEK/ERK/p53 pathway in colitis

AIM: To investigate the role of serum-and-glucocorticoid-inducible-kinase-1(SGK1) in colitis and its potential pathological mechanisms.METHODS: SGK1 expression in mucosal biopsies from patients with active Crohn's disease(CD) and normal controls was detected by immunohistochemistry. We established an acute colitis model in mice induced by 2,4,6-trinitrobenzene sulfonicacid, and demonstrated the presence of colitis using the disease activity index, the histologic activity index and hematoxylin and eosin staining. The cellular events and potential mechanisms were implemented with small interference RNA and an inhibitor of signaling molecule(i.e., U0126) in intestinal epithelial cells(IECs). The interaction between SGK1 and the signaling molecule was assessed by coimmunoprecipitation.RESULTS: SGK1 expression was significantly increased in the inflamed epithelia of patients with active CD and TNBS-induced colitis model(0.58 ± 0.055 vs 0.85 ± 0.06, P 0.01). At the cellular level, silencing of SGK1 by small interference RNA(si SGK1) significantly inhibited the phosphorylation of mitogen-activated protein kinase kinase 1(MEK1) and the downstream molecule extracellular signal regulated protein kinase(ERK) 1/2, which induced the upregulation of p53 and Bcl-2-associated X protein, mediating the subsequent cellular apoptosis and proliferation in IECs. Cells treated with MEK1 inhibitor(i.e., U0126) before si SGK1 transfection showed a reversal of the si SGK1-induced cellular apoptosis. CONCLUSION: Our data suggested that SGK1 may protect IECs in colitis from tumor necrosis factor-α-induced apoptosis partly by triggering MEK/ERK activation.     

Ursolic acid causes DNA-damage, p53-mediated, mitochondria- and caspase-dependent human endothelial cell apoptosis, and accelerates atherosclerotic plaque formation in vivo

Objective

The plant derived triterpene ursolic acid (UA) has been intensively studied in the past; mainly as an anti-cancer compound and for its cardiovascular protective properties. Based on the controversy of reports suggesting anti-angiogenic and cytotoxic effects of UA on one side and cardiovascular and endothelial protective effects on the other side, we decided to assess UA effects on primary human endothelial cells in vitro and atherosclerotic plaque formation in vivo.

Methods and results

Our in vitro analyses clearly show that UA inhibits endothelial proliferation and is a potent inducer of endothelial cell death. UA causes DNA-damage, followed by the activation of a P53-, BAK-, and caspase-dependent cell-death pathway. Oral application of UA in APO E knockout mice potently stimulated atherosclerotic plaque formation in vivo, which was correlated with decreased serum levels of the athero-protective cytokine IL-5.

Conclusions

Due the potent endothelial cell death inducing activity of UA, a systemic application of UA in the treatment of cardiovascular diseases seems unfavourable. UA as an anti-angiogenesis, anti-cancer and – locally applied – cardiovascular drug may be helpful. The DNA damaging activity of UA may however constitute a serious problem.     

三氧化二砷对人体胃肠癌细胞凋亡及p53、survivin表达的影响

目的研究三氧化二砷（arsenic trioxide,As2O3）在人体内诱导胃肠癌细胞凋亡作用及对凋亡相关基因p53、survivin表达的影响,探讨其抗肿瘤作用及发生机制。方法采用原位末端转移酶标记技术（TUNEL）和免疫组化法分别检测As2O3用药前后胃肠癌细胞凋亡指数和凋亡相关基因蛋白P53、Survivin的表达变化情况。结果 As2O3用药后胃肠癌细胞凋亡指数为（17.04±3.67）%,与用药前（6.07±2.21）%相比差异有统计学意义（P〈0.01）;用药后胃肠癌细胞P53蛋白阳性表达率为（35.05±19.64）%,与用药前（34.80±16.48）%相比差异无统计学意义（P〉0.05）;用药后胃肠癌细胞Survivin蛋白阳性表达率为（15.59±3.94）%,与用药前（36.74±20.5）%相比明显下调,差异有统计学意义（P〈0.01）;As2O3作用后胃肠癌细胞Survivin蛋白表达下调时凋亡率升高,二者之间具有相关性（r=-0.47,P=0.04）。结论 As2O3在人体内可诱导胃肠癌细胞凋亡而发挥抗肿瘤作用,其机制可能与下调survivin基因的表达有关。     

Early apoptosis and cell death induced by ATX-S10Na ( Ⅱ)-mediated photodynamic therapy are Bax- and p53-dependent in human colon cancer cells

AIM: To investigate the roles of Bax and p53 proteins in photosensitivity of human colon cancer cells by using lysosome-localizing photosensitizer, ATX-S10Na (Ⅱ).METHODS: HCT116 human colon cancer cells and Bax-null or p53-null isogenic derivatives were irradiated with a diode laser. Early apoptosis and cell death in response to photodynamic therapy were determined by MTT assays, annexin V assays, transmission electron microscopy assays, caspase assays and western blotting.RESULTS: Induction of early apoptosis and cell death was Bax- and p53-dependent. Bax and p53 were required for caspase-dependent apoptosis. The levels of anti-apoptotic Bcl-2 family proteins, Bcl-2 and Bcl-XL,were decreased in Bax- and p53-independent manner.CONCLUSION: Our results indicate that early apoptosis and cell death of human colon cancer cells induced by photodynamic therapy with lysosome-localizingphotosensitizer ATX-S10Na (Ⅱ) are mediated by p53-Bax network and Iow levels of Bcl-2 and Bcl-XL proteins.Our results might help in formulating new therapeutic approaches in photedynamic therapy.     

Inhibitor of growth 4 induces apoptosis in human lung adenocarcinoma cell line A549 via Bcl-2 family proteins and mitochondria apoptosis pathway

Objective  Inhibitor of growth 4 (ING4) is considered to be a tumor suppressor implicated in several human malignancies by tumor growth inhibition and apoptosis enhancement. In present study, the effects of ING4 on apoptosis and its mechanisms were investigated through the transduction of ING4 cDNA into lung adenocarcinoma cell line A549. Methods  The effects of ING4 on A549 apoptosis were observed by FCM analysis, TUNEL assay, and electron microscopy. Simultaneously, the effects of ING4 on the expression of several apoptosis-related proteins in cell line A549 were evaluated by Western blot analysis. Results  Both Annexin-V FITC analysis by FCM and TUNEL assay revealed more apoptotic cells in A549 cells with exogenous ING4 gene. For electron microscopy, A549 cells with exogenous ING4 gene showed typical morphological changes of apoptosis. The deregulation of Bcl-2 family proteins (Bcl-2, Bcl-xl, Bax, Bak, Bid) and the major apoptotic executioners of mitochondria pathway (Cyt-c, caspase3, PARP) were also observed. Conclusion  Our findings suggest that exogenous ING4 can enhance A549 apoptosis via regulating the expression of Bcl-2 family proteins and the activation of mitochondrial apoptotic pathway. Xiaomei Li, Qingyuan Zhang, and Limin Cai contributed equally to this work.     

The harmful effect of exercise on reducing taurine concentration in the tissues of rats treated with CCl<Subscript>4</Subscript> administration

Background We have previously reported that oral taurine administration reduced the frequency of painful muscle cramps in patients with liver cirrhosis, and that skeletal muscle taurine concentration was significantly decreased after exercise. The aim of this study was to examine taurine concentration in various tissues of a liver damaged with fibrosis (LD) in a rat model before and after exercise.Methods Rats were divided into normal (NML) and LD groups. The LD group received CCl₄ injection for 10 weeks. Thereafter, both groups were divided into control (NML/CTL, LD/CTL) and exercise (NML/EX, LD/EX) groups, respectively. The rats in the EX groups were subjected to treadmill running. Plasma, liver, brain, heart, and skeletal muscle taurine concentration, as well as plasma and liver lipid peroxidase (LPO) concentration, were measured.Results The liver, brain, and skeletal muscle taurine concentration in the LD groups was significantly decreased compared to that in the respective NML groups. Furthermore, the taurine concentration in the heart and skeletal muscles in the LD/CTL group was significantly decreased post exercise. The respective plasma and liver LPO concentration in the LD groups was significantly increased compared to that in the corresponding NML group. Moreover, plasma LPO concentration in the LD/EX group was significantly higher than in the LD/CTL group.Conclusions Tissue taurine concentration, particularly in skeletal muscle, was significantly decreased in the LD model rats induced by CCl₄ administration, and furthermore, the significantly decreased concentration, except for liver, was aggravated by exercise, even though at lower intensity.     

p21<Superscript>WAF1/CIP1</Superscript> is more effective than p53 in growth suppression of mouse renal carcinoma cell line Renca in vitro and in vivo

Purpose Although there are many controversial reports about the effect of p53 and p21^WAF1/CIP1 overexpression in different human tumor cells, the p53 gene is shown to be a more effective candidate for cancer gene therapy because of its more pronounced ability to induce apoptosis. In the present study, we present the effect of p53 and p21^WAF1/CIP1 overexpression on mouse renal carcinoma cells in vitro and in vivo.Methods p53 and p21^WAF1/CIP1 genes were introduced into Renca cells using adenoviral vectors (Ad5CMV-p53 and Ad5CMV-p21). The induction of apoptosis was measured using Annexin V assay and DNA fragmentation analysis. The expression of proteins was examined using immunocytochemistry and Western blot methods. The ability of adenoviral vectors to inhibit tumorigenicity of Renca cells, as well as the growth of pre-established tumors was measured.Results In vitro growth assays revealed higher growth suppression after Ad5CMV-p21 infection. Although both vectors induced apoptosis, Ad5CMV-p53 was slightly more efficient. In vivo studies in Balb/c mice, demonstrated that tumorigenicity was completely suppressed by Ad5CMV-p21. Besides this, Ad5CMV-p21 significantly inhibited the growth of established tumors, while Ad5CMV-p53 did not.Conclusions These data suggest that p21^WAF1/CIP1 is a more potent growth suppressor than p53 of mouse tumor cells Renca. The divergent responses of tumor cells to p21^WAF1/CIP1 overexpression could be due to various networks that differ between species.     

Effects of folic acid on epithelial apoptosis and expression of Bcl-2 and p53 in premalignant gastric lesions

AIM: To evaluate the effects of folic acid on epithelial apoptosis and expression of Bcl-2 and p53 in the tissues of premalignant gastric lesions. METHODS: Thirty-eight patients, with premalignant gastric lesions including 18 colonic-type intestinal metaplasia (IM) and 20 mild or moderate dysplasia, were randomly divided into a treatment group (n = 19) receiving folic acid 10 mg thrice daily and a control group (n = 19) receiving sucralfate 1 000 mg thrice daily for 3 mo. All patients underwent endoscopies and four biopsies were taken prior to treatment and repeated after concluding therapy. Folate concentrations in gastric mucosa were measured with chemiluminescent enzyme immunoassay. Epithelial apoptosis and the expression of Bcl-2 and p53 protein in gastric mucosa were detected with flow cytometric assay. RESULTS: The mean of folate concentration in gastric mucosa was 9.03±3.37 μg/g wet wt in the folic acid treatment group, which was significantly higher than 6.83±3.02 μg/g wet wt in the control group. Both the epithelial apoptosis rate and the tumor suppressor p53 expression in gastric mucosa significantly increased after folic acid treatment. In contrast, the expression of Bcl-2 oncogene protein decreased after folic acid therapy. CONCLUSION: These data indicate that folic acid may play an important role in the chemoprevention of gastric carcinogenesis by enhancing gastric epithelial apoptosis in the patients with premalignant lesions.     

Effects of low-dose hydroxychloroquine on expression of phosphorylated Akt and p53 proteins and cardiomyocyte apoptosis in peri-infarct myocardium in rats

BACKGROUND:

Low-dose hydroxychloroquine (HCQ) and ataxia-telangiectasia-mutated (ATM) protein kinase have recently been postulated to be beneficial for the prevention of the age-associated metabolic syndrome including hypertension, hypercholesterolemia and glucose intolerance; however, the effects of low-dose HCQ on the expression of ATM downstream phosphorylated Akt (protein kinase B) and p53 proteins and cardiomyocyte apoptosis in the peri-infarct myocardium remain unclear.

OBJECTIVE:

To explore the effects of low-dose HCQ on the expression of phosphorylated Akt and p53 proteins and cardiomyocyte apoptosis in the peri-infarct myocardium in a rat model.

METHODS:

Myocardial infarction (MI) was induced experimentally in a subset of rats, while others underwent sham operation (sham). Three days after operation, surviving Sprague-Dawley male rats were divided into MI+HCQ, MI, sham+HCQ and sham groups. MI+HCQ and sham + HCQ groups were treated with HCQ (3.4 mg/kg); and MI and sham groups were treated with phosphate buffered (ie, physiological) saline (10 mL/kg) by gavage every day for 12 weeks. The expression of phosphorylated Akt and p53 proteins and cardiomyocyte apoptosis in the peri-infarct myocardium was detected by Western blot and terminal deoxynucleotidyl transferase dUTP nick end labelling, respectively.

RESULTS:

Twelve weeks after treatment, the expression of phosphorylated Akt protein was significantly increased (P<0.05). Expression of phosphorylated p53 protein was not significantly different (P>0.05) in the peri-infarct myocardium of the MI+HCQ group from that in the MI group. The cardiomyocyte apoptosis rate in the peri-infarct myocardium was significantly decreased in the MI+HCQ group compared with the MI group (P<0.05).

CONCLUSION:

Low-dose HCQ can significantly increase the expression of phosphorylated Akt protein without significantly impacting expression of phosphorylated p53 protein in the peri-infarct myocardium. Accordingly, it can inhibit cardiomyocyte apoptosis in the peri-infarct myocardium.     

Alteration of the <Emphasis Type="Italic">p14</Emphasis><Superscript><Emphasis Type="Italic">ARF</Emphasis></Superscript> gene and p53 status in human hepatocellular carcinomas

Background The INK4a/ARF locus encodes p16^INK4a and p14^ARF, both of which are crucial for two tumor suppressor pathways, retinoblastoma (RB)/p16^INK4a and p53/ARF. Inactivation of RB/p16^INK4a was frequently reported, but alterations of the p14^ARF gene in hepatocellular carcinoma (HCC) in the Japanese population have been insufficiently analyzed.Methods To determine the role of p53/ARF alteration in hepatocarcinogenesis, we examined 44 HCCs for mRNA expression, deletion, mutation, and promoter hypermethylation of the p14^ARF gene; alterations of p53 were also analyzed in the same series of HCCs.Results Homozygous deletion, spanning from exon 1 to exon 2, was found in 1 HCC mutations within exon 2 were found in 2 HCCs, but no promoter hypermethylation was detected. All 3 HCCs with p14^ARF alteration were well differentiated. Twelve of the 44 HCCs (27.2%) showed immunohistochemical evidence of p53 alteration; however, only 1 of the tumors with p53 alteration was well differentiated. TaqMan polymarase chain reaction (PCR) indicated that the expression of p14^ARF in HCCs was higher than in that in all but three of the corresponding non-tumorous tissues (P < 0.0001), and increased expression of p14^ARF seemed to be associated with poorly differentiated phenotype. Absence of p14^ARF expression was seen in only one HCC, with homozygous deletion of the p14^ARF gene.Conclusions Compared with p53 alteration, p14^ARF alteration does not occur frequently, but may play a role in a subset of Japanese HCCs in the early stage of hepatocarcinogenesis. On the other hand, overexpression of p14^ARF was frequently observed in HCC, especially in poorly differentiated tumors, probably reflecting oncogenic stimuli in these tumors.     

Early apoptosis and cell death induced by ATX-S10Na （ Ⅱ ）-mediated photodynamic therapy are Bax- and p53-dependent in human colon cancer cells

AIM： To investigate the roles of Bax and p53 proteins in photosensitivity of human colon cancer cells by using lysosome-localizing photosensitizer, ATX-S10Na （Ⅱ）. METHODS： HCT116 human colon cancer cells and Bax-null or p53-null isogenic derivatives were irradiated with a diode laser. Early apoptosis and cell death in response to photodynamic therapy were determined by MTT assays, annexin Ⅴ assays, transmission electron microscopy assays, caspase assays and western blotting. RESULTS： Induction of early apoptosis and cell death was Bax- and p53-dependent. Bax and p53 were required for caspase-dependent apoptosis. The levels of anti-apoptotic Bcl-2 family proteins, Bcl-2 and Bcl-xL, were decreased in Bax- and p53-independent manner. CONCLUSION： Our results indicate that eady apoptosis and cell death of human colon cancer cells induced by photodynamic therapy with lysosome-localizing photosensitizer ATX-S10Na （Ⅱ） are mediated by p53- Bax network and low levels of Bcl-2 and Bcl-xL proteins. Our results might help in formulating new therapeutic approaches in photodynamic therapy.     

白黎芦醇对肝纤维化大鼠肝组织E-钙粘附素表达的干预作用

目的研究E-钙粘附素在不同肝纤维化阶段的表达情况以及在抗肝纤维化中药单体白黎芦醇干预下表达的变化。方法制备大鼠肝纤维化模型,分别给予小（40mg·kg^-1）、中（120mg·kg^-1）和大剂量（200mg·kg^-1）白黎芦醇处理,取肝组织检测E-钙粘附素、转化生长因子β（TGF-β）、基质金属蛋白酶抑制因子（TIMP-1）1mRNA水平;采用放射免疫法检测血清HA和pcⅢ水平。结果正常组大鼠肝组织E-钙粘附素呈低水平（0．515±0．02）表达,而随着肝纤维化的进展,其水平增加,其中在12周时,肝组织E-钙粘附素mRNA水平（0．878±0．03）明显高于中剂量（0．755±0．24）和大剂量白黎芦醇处理组（0．763±0．21,P〈0．01）;在大鼠肝纤维化进展过程中,肝组织TIMP-1和TGF-β mRNA水平不断增加。结论E-钙粘附素在不同阶段肝纤维化大鼠肝组织均有表达,且随着纤维化程度的加重而表达增强。白黎芦醇可以明显改善大鼠肝纤维化程度,并减少E-钙粘附素mRNA水平。     

Low presence of <Emphasis Type="Italic">p53</Emphasis> abnormalities in <Emphasis Type="Italic">H. pylori</Emphasis>-infected gastric mucosa and in gastric adenocarcinoma

Background: Alterations of the p53 gene and/or its abnormal protein accumulation have been observed in gastric cancer and preneoplastic lesions. Our aim was to assess possible associations between different H. pylori strains and p53 abnormalities in patients with dyspepsia and with gastric cancer. Methods: Seventy-five dyspeptic patients and 40 patients with gastric adenocarcinoma entered the study. H. pylori status was determined by the rapid urease test, histology, and polymerase chain reaction (PCR) analysis. Overexpression of the p53 protein was evaluated by immunohistochemistry. Detection of p53 mutations was done by direct DNA sequencing. Results: Fifty-four of the 75 (72.0%) dyspeptic patients and 27 of the 40 (67.5%) gastric cancer patients showed H. pylori infection. Cytotoxin-associated gene (cagA)-positive strains were found in 31 of the 54 (58%) dyspeptic patients and in 25 of the 27 (92.6%) neoplastic patients. As regards vacA, s2 strains showed the highest prevalence among dyspeptic patients (24 of 54 patients; 44.4%), whereas s1 strains were more expressed among cancer patients (23 of 27; 85.2%). Among the dyspeptic patients, 1 patient with duodenal ulcer showed p53 overexpression. Three mutations were identified by DNA sequencing: one in a patient with normal endoscopic findings and two in patients suffering from gastritis. Among the neoplastic patients, 16 subjects (40%) showed p53 overexpression (9 had diffuse-type and 7 intestinal-type cancer). Four mutations (10%) occurred in patients with intestinal-type gastric cancer. No association between p53 abnormalities (overexpression/mutation) and H. pylori infection was found in either group of patients. Conclusions: These results lead us to hypothesize that H. pylori infection does not affect the p53 pattern in gastric mucosa. Moreover, mutations of the p53 gene do not seem to be a predominant event in gastric carcinogenesis, at least in our populations. Received: December 14, 2001 / Accepted: May 17, 2002 RID="*" ID="*"  These authors contributed equally to the work RID="*" ID="*"  These authors contributed equally to the work Acknowledgments. The authors would like to thank Mrs B. D'Attoma and Mrs P. Fiorente for their valuable technical assistance, and Mrs M.V.C. Pragnell, B.A., for her help in revising the English. Reprint requests to: A. Di Leo     

Nucleostemin knocking-down causes cell cycle arrest and apoptosis in human T-cell acute lymphoblastic leukemia MOLT-4 cells via p53 and p21Waf1/Cip1 up-regulation

Objectives

Nucleostemin (NS), a recently discovered nucleolar protein, is essential for maintaining self-renewal and proliferation of embryonic and adult stem cells as well as cancerous cells. The aim of this study was to determine biological function of NS in MOLT-4 cells as a human T-cell acute lymphocytic leukemia (T-ALL) model.

Methods

Efficacy of a specific small interference RNA on NS depletion was studied by quantitative polymerase chain reaction and western blotting. The growth rate and viability were analyzed by trypan blue exclusion test. Fluorescent microscopy was used for detecting apoptosis. Cell cycle and apoptosis were mechanistically studied by flow cytometry and western blotting.

Results

Knockdown of NS inhibited proliferation, arrested the cell cycle, and induced apoptosis through p53 and p21^Waf1/Cip1 pathways in MOLT-4 cells.

Discussion

These findings demonstrate critical roles of NS in MOLT-4 cells and may implicate on its therapeutic potential in this human T-ALL model.