OBJECTIVE: To investigate the effect of 5-Aza-dC and TSA to tumor suppressor gene RASSF1A expression and methylation level in Hep-2 cell line. METHOD: Hep-2 cell line were cultured in vitro and handled with 5-Aza-dC and TSA. Detected RASSF1A expression and methylation level were detected before and after drug intervention using Realtime PCR and MSP. RESULT: (1) Before intervention with drug, tumor suppressor gene RASSF1A was weakly expressed and methylated in Hep-2 cell line. (2) With the effect of 5-Aza-dC and TSA, the methylation of RASSF1A gene was reversed. And the effect of combination of 5-Aza-dC and TSA was similar with 5-Aza-dC alone. There was no obvious effect using TSA alone. (3) With the effect of 5-Aza-dC and TSA, the expression of RASSF1A was improved. And the effect of 5-Aza-dC was stronger than TSA. Synergetic effect was found when using 5-Aza-dC and TSA simultaneously. CONCLUSION In Hep-2 cell line, Promoter methylation of tumor suppressor RASSF1A may play a very important role in loss of gene expression, but it is not the only cause. 5-Aza-dC and TSA can improve RASSF1A expression by reversing DNA methylation and histone deacetylation.
Antimetabolites, Antineoplastic ; pharmacology ; Azacitidine ; analogs & derivatives ; pharmacology ; Cell Line, Tumor ; DNA Methylation ; Gene Expression ; Gene Silencing ; Genes, Tumor Suppressor ; Humans ; Hydroxamic Acids ; pharmacology ; Promoter Regions, Genetic ; Tumor Suppressor Proteins ; genetics

OBJECTIVETo construct a tumor-targeting recombinant adenovirus vector containing hepatocellular carcinoma suppressor gene HCCS1 to enhance the safety of tumor treatment.

METHODSCCK-8 assay was used to observe different inhibitory effects on normal and malignant liver cells with high expressions of HCCS1 protein. The relative transcriptional activity of PEG-3p was quantified by luciferase assay. Recombinant adenovirus Ad-PEG-3p-HCCS1 was packaged with AdEasy system and confirmed by PCR. The tumor-targeted expression of HCCS1 protein in cells infected with Ad-PEG-3p-HCCS1 was determined by Western blot. Crystal violet assay and MTT assay were applied to observe the selective anti-tumor effects of the newly constructed virus in vitro.

RESULTSA higher inhibitory rate of about 60% was found in BEL-7404 and SW-620 than that in L02 and NHLF 96 h after the high expression of HCCS1. Luciferase assay showed 3.9-, 4.7-, and 1.5-fold transcriptional activity in BEL-7404, BEL-7405 and QGY-7703 respectively, in comparison with that in L02. Ad-PEG-3p-HCCS1 was constructed successfully and was verified by PCR. Western blot indicated that high expression of HCCS1 could be induced in BEL-7404 and QGY-7703 but not in L02. Crystal violet assay and MTT assay showed that it remarkably reduced the toxicity to L02 but still had enough antitumoral effect on Ad-CMV-HCCS1.

CONCLUSIONSWith high expression of HCCS1 the tumor cells we used are being inhibited more. PEG-3p has the tumor-selective driving function in malignant liver cells. Our recombinant adenovirus Ad-PEG-3p-HCCS1 can tumor-targeting induce HCCS1 expression in tumor cells, which can improve the safety of gene therapy with HCCS1.

Carcinoma, Hepatocellular ; therapy ; Cell Line ; Cell Line, Tumor ; Gene Expression ; Genetic Therapy ; Genetic Vectors ; Humans ; Liver Neoplasms ; therapy ; Tumor Suppressor Proteins ; genetics ; pharmacology ; Vesicular Transport Proteins

OBJECTIVETo investigate the inhibitory effect and mechanism against the growth of human gastric carcinoma cell line HS-746T by the combination of the survivin antisense oligonucleotide (ASODN) and P53 gene and its mechanism.

METHODSGastric carcinoma cell line HS-746T was treated by P53 gene and survivin antisense oligonucleotide was designed. There were four regimen groups treated by different agents:ASODN alone, P53 gene alone and the combination of ASODN and P53 gene, blank control. Cell proliferative ability and cell growth were determined by cells counting and MTT. The expression of survivin mRNA and protein was detected by RT-PCR and Western blot respectively. Cell apoptotic index was detected by TUNEL.

RESULTSASODN alone, P53 alone and the combination of ASODN and P53 could inhibit not only the growth of gastric carcinoma cell, but also down-regulate the survivin mRNA and protein expression. The inhibitory effect was stronger, and the apoptosis index was higher in the combined transfection group than those in the other two single transfection groups.

CONCLUSIONThe combination of survivin ASODN and P53 gene is more efficient to inhibit cell growth and induce apoptosis than that of agent alone.

Apoptosis ; Cell Line, Tumor ; Cell Proliferation ; Humans ; Inhibitor of Apoptosis Proteins ; Microtubule-Associated Proteins ; genetics ; Oligonucleotides, Antisense ; genetics ; pharmacology ; Stomach Neoplasms ; genetics ; pathology ; Transfection ; Tumor Suppressor Protein p53 ; genetics

Platycodon grandiflorum (Jacq.) A. DC. is a famous medicinal plant commonly used in East Asia. Triterpene saponins isolated from P. grandiflorum are the main biologically active compounds, among which polygalacin D (PGD) has been reported to be an anti-tumor agent. However, its anti-tumor mechanism against hepatocellular carcinoma is unknown. This study aimed to explore the inhibitory effect of PGD in hepatocellular carcinoma cells and related mechanisms of action. We found that PGD exerted significant inhibitory effect on hepatocellular carcinoma cells through apoptosis and autophagy. Analysis of the expression of apoptosis-related proteins and autophagy-related proteins revealed that this phenomenon was attributed to the mitochondrial apoptosis and mitophagy pathways. Subsequently, using specific inhibitors, we found that apoptosis and autophagy had mutually reinforcing effects. In addition, further analysis of autophagy showed that PGD induced mitophagy by increasing BCL2 interacting protein 3 like (BNIP3L) levels.In vivo experiments demonstrated that PGD significantly inhibited tumor growth and increased the levels of apoptosis and autophagy in tumors. Overall, our findings showed that PGD induced cell death of hepatocellular carcinoma cells primarily through mitochondrial apoptosis and mitophagy pathways. Therefore, PGD can be used as an apoptosis and autophagy agonist in the research and development of antitumor agents.
Humans ; Mitophagy ; Carcinoma, Hepatocellular/pathology* ; Liver Neoplasms/pathology* ; Cell Line ; Autophagy ; Apoptosis ; Membrane Proteins ; Proto-Oncogene Proteins/genetics* ; Tumor Suppressor Proteins/pharmacology*

OBJECTIVETo investigate arsenic trioxide (As(2)O(3))-induced apoptosis and the effects on cell nuclear matrix related protein promyelocytic leukaemia (PML).

METHODSHepG2 cells were cultured in MEM medium and treated with 0.5, 2, 5 and 10 micro mol/L As(2)O(3) for either 24 h or 96 h at each concentration. In situ terminal deoxynucleotidyl transferase (TdT) labeling (TUNEL) and DNA ladders were used to detect apoptosis. Confocal microscopy and Western blotting were used to observe the expression of PML.

RESULTSThe growth rates of HepG2 cells were slower in the As(2)O(3) treated than the untreated control group. DNA ladder and TUNEL positive apoptotic cells could be detected in As(2)O(3) treated groups. The expression of PML decreased in HepG2 cells with 2 micro mol/L As(2)O(3) treatment. Confocal images demonstrated that the expression of PML protein in HepG2 cell nuclei decreased after treatment with 2 micro mol/L As(2)O(3), and micropunctates characteristic of PML protein in HepG2 cell nuclei disappeared after treatment with 5 micro mol/L As(2)O(3).

CONCLUSIONSOur results show that arsenic trioxide can significantly inhibit the growth of HepG2 cells in vitro. As(2)O(3) induces apoptosis in HepG2 tumor cells in a time and concentration dependent manner. As(2)O(3) may degrade the PML protein in HepG2 cell nuclei. The decreased expression of PML in As(2)O(3) treated tumor cells is most likely to be caused by apoptosis. Nuclear matrix associated protein PML could be the target of As(2)O(3) therapy.

Antineoplastic Agents ; pharmacology ; Arsenicals ; pharmacology ; Humans ; Neoplasm Proteins ; metabolism ; Nuclear Matrix ; drug effects ; metabolism ; Nuclear Proteins ; Oxides ; pharmacology ; Promyelocytic Leukemia Protein ; Transcription Factors ; metabolism ; Tumor Cells, Cultured ; Tumor Suppressor Proteins

OBJECTIVETo investigate the effect of quercetin on apoptosis and feedback regulation of MDM2-p53 in multiform glioblastoma U87 cells in vitro.

METHODSU87 cells exposed to different concentrations of quercetin (50, 100, and 150 µmol/L) were examined with flow cytometry, RT-PCR and Western blotting for detecting the cell apoptosis, MDM2 mRNA expression, and p53 and caspase-3 expressions.

RESULTSQuercetin induced obvious apoptosis in U87 cells in a concentration-dependent manner, with apoptosis rates of (12.40∓0.70)% at Q0, (22.53∓0.72)% at Q50, (29.06∓0.81)% at Q100, and (31.5∓0.45)% at Q150. Quercetin significantly increased the expressions of MDM2 mRNA and active caspase-3 protein but decreased the expression of p53 in the cells.

CONCLUSIONQuercetin promotes the apoptosis of multiform glioblastoma U87 cells mediated by caspase-3 and influences the feedback balance of MDM2-p53.

Apoptosis ; Caspase 3 ; metabolism ; Cell Line, Tumor ; drug effects ; Glioma ; metabolism ; pathology ; Humans ; Proto-Oncogene Proteins c-mdm2 ; metabolism ; Quercetin ; pharmacology ; Tumor Suppressor Protein p53 ; metabolism

OBJECTIVETo investigate the effect of demethylating agent 5-Aza-CdR (5-aza-2'- deoxycytidine) on demethylation and transcription-regulating of RASSF1A gene in gastric cancer cell SGC7901 in vitro, as well as on the growth inhibition of cells.

METHODSAfter SGC7901 cells were treated with 5-Aza-CdR, MTT assay, flow cytometry, and Annexin V-FITC staining were performed to analyze the cell proliferation, cell cycle and apoptotic rate respectively. Methylation- specific PCP (MSP), RT-PCR and Western blotting were used to detect methylation state, expression of mRNA and protein of RASSF1A gene.

RESULTSAfter SGC7901 cells were treated with different concentrations of 5-Aza-CdR, the cell growth was inhibited(P<0.05), the cell cycle was blocked at G(1) phase, and the apoptotic rate increased significantly(P<0.05). Hypermethylation was detected in the promoter region of RASSF1A gene in SGC7901 cells, and no expression of RASSF1A mRNA and protein was found. After treated with 5-Aza-CdR, demethylation occurred in RASSF1A gene,which subsequently induced re-expression of this gene at both mRNA and protein level.

CONCLUSIONDemethylating agent 5-Aza-CdR can regulate demethylation and re-expression of RASSF1A gene in gastric cancer cell SGC7901,and inhibit its growth.

Azacitidine ; analogs & derivatives ; pharmacology ; Cell Line, Tumor ; DNA Methylation ; Gene Expression Regulation, Neoplastic ; drug effects ; Humans ; Stomach Neoplasms ; genetics ; metabolism ; Tumor Suppressor Proteins ; metabolism

OBJECTIVETo explore hepatitis C virus (HCV) non-structural protein 5A (NS5A)'s influence on inhibition of AFP expression executed by p53 protein and its possible molecular mechanism.

METHODSPlasmid transfection and MEIA were employed to observe p53's inhibitive effect on AFP expression of Huh7 cells and the HCV NS5A's influence on p53 function. Western blot was employed to find out if HCV NS5A affects p53 protein expression and GST pull down assay was applied to examine the interaction between HCV NS5A and p53.

RESULTSThe AFP concentration in the supernatant of the culture of the Huh7 cells transfected with pRc/CMV was (14322+/-2412) ng/ml, and that of the Huh7 cells transfected with pCNS5A was (13843+/-3218) ng/ml; no significant difference existed between these two groups (t = 1.42, P > 0.05). After transfection with pC53-NS3, the AFP level was decreased to (10 241+/-1326) ng/ml, and in comparison to the above two groups it had a statistically significant difference (t values were 2.41 and 2.38, P < 0.05). When co-transfected with pCNS5A and pC53-NS3, the AFP expression (14582+/-1238) ng/ml returned to the level of pRc/CMV transfected, and there was a remarkably significant difference between this and that of the pC53-NS3 transfected cells (t = 3.12, P < 0.01). HCV NS5A had no function on the p53 protein expression with Western blot experiment. In the GST pull down assay, an HCV NS5A protein band was found after GST-p53 was added, but not detected with GST only.

CONCLUSIONWe found that p53 has an inhibitive function on the AFP expression in Huh7 cells and HCV NS5A minimized this p53 function. HCV NS5A did not affect p53 protein expression, but was able to form a complex with p53, by which HCV NS5A inactivated this p53 function.

Carcinoma, Hepatocellular ; metabolism ; virology ; Hepacivirus ; genetics ; Humans ; Liver Neoplasms ; metabolism ; virology ; Tumor Cells, Cultured ; Tumor Suppressor Protein p53 ; genetics ; pharmacology ; Viral Nonstructural Proteins ; genetics ; alpha-Fetoproteins ; biosynthesis ; genetics

The aim of this study was to evaluate the changes in the expression of Bax, Bcl-2 and P53 when HeLa cells were induced by free cytokines or co-immobilized cytokines. The cells were induced for 24 hrs,72 hrs, 120 hrs and 168 hrs. Then, the expression of Bax, Bcl-2 and P53 was observed by immunohistochemistry. The average optic density of reaction products was tested by image analysis. Lastly, data were analyzed statistically. After the HeLa cells were induced for 120 hrs, the average optic denisity of Bcl-2 was much decreased. However, the average optic Bax was much increased. The average optic density of P53 also increased with the increase of time. The results suggest that HeLa apoptosis was induced by tumor necrosis factor-a and interferon -gamma, and the increasing expression of P53 may induce the expression of Bax and prevent the expression of Bcl-2, via the mitochondrial induction of cell apoptosis.
Apoptosis ; drug effects ; HeLa Cells ; Humans ; Immobilized Proteins ; pharmacology ; Interferon-gamma ; pharmacology ; Photochemistry ; methods ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Tumor Necrosis Factor-alpha ; pharmacology ; Tumor Suppressor Protein p53 ; metabolism ; bcl-2-Associated X Protein ; genetics ; metabolism

OBJECTIVETo study the inhibition effect of HCV NS5A on p53 protein transactivity and its possible mechanism.

METHODSLuciferase reporter gene system was used for the study of p53 transactivity on p21 promoter and electrophorectic mobility-shift assay (EMSA) was applied to observe whether HCV NS5A could suppress the binding ability of p53 protein to its specific DNA sequence.

RESULTSEndogenous p53 protein could stimulate p21 promoter activity, and the relative luciferase activity increased significantly (3.49 x 10(5) vs 0.60 x 10(5), t = 5.92, P<0.01). Exogenous p53 protein also up-regulated p21 promoter driving luciferase expression, comparing to the control group (0.47 x 10(5)), the relative luciferase activity increased (5.63 x 10(5)) obviously (t = 10.12, P<0.01). HCV NS5A protein inhibited both endogenous and exogenous p53 transactivity on p21 promoter in a dose-dependent manner (F > or = 20.71, P<0.01). In the experiment of EMSA, p53 could bind to its specific DNA sequence, but when co-transfected with HCV NS5A expressing vector, the p53 binding affinity to its DNA decreased.

CONCLUSIONHCV NS5A can inhibit p53 protein transactivity on p21 promoter through its inhibiting of p53 binding ability to the specific DNA sequence.

Hepacivirus ; genetics ; Humans ; Promoter Regions, Genetic ; Transcriptional Activation ; drug effects ; Tumor Suppressor Protein p53 ; drug effects ; genetics ; metabolism ; physiology ; Viral Core Proteins ; genetics ; Viral Nonstructural Proteins ; genetics ; pharmacology