Multiple genetic alterations and behavior of cellular biology in gastric cancer and other gastric mucosal lesions: H. pylori infection, histological types and staging

The Role of Immunoglobulin G (IgG), IgA and IgE-Antibodies against Helicobacter pylori in the Development of Oxidative Stress in Patients with Chronic Gastritis

Aim: To study the predominant serum responses (antibodies IgG, IgA, IgE) against H. pylori in relation to the indicators of the system “lipid peroxidation−antioxidant system” in various pathogenetic variants of chronic gastritis (CG). Materials and Methods: Sixty patients with CG, 33 patients with chronic atrophic gastritis (CAG) and 31 patients with chronic allergic gastritis (CALG) were examined. The values of the system of lipid peroxidation and antioxidant protection in plasma were determined in the serum of patients using a spectrophotometric method. Statistical data processing was carried out using the Statistica 7.0 software package (StatSoft, Tulsa, OK, USA). Results: With serum responses “antibodies IgG > IgA” and “high concentrations of IgE antibodies”, we found unidirectional changes in the form of an increase in the amount of diene conjugates, malondialdehyde and an increase in the activity of all enzymes: superoxide dismutase, catalase, glutathione-S-transferase and glutathione peroxidase. With a serum response with low concentrations of IgG, IgA antibodies, multidirectional changes were found in the form of an increase in the amount of diene conjugates, malondialdehyde and a decrease in the activity of all enzymes: superoxide dismutase, catalase, glutathione-S-transferase and glutathione peroxidase relative to the control group. Conclusions: The obtained data testify to the balance of lipid peroxidation and antioxidant system processes and depend on the characteristics of the immune response to H. pylori infection.

Pathways of Gastric Carcinogenesis, Helicobacter pylori Virulence and Interactions with Antioxidant Systems, Vitamin C and Phytochemicals

Helicobacter pylori is a class one carcinogen which causes chronic atrophic gastritis, gastric intestinal metaplasia, dysplasia and adenocarcinoma. The mechanisms by which H. pylori interacts with other risk and protective factors, particularly vitamin C in gastric carcinogenesis are complex. Gastric carcinogenesis includes metabolic, environmental, epigenetic, genomic, infective, inflammatory and oncogenic pathways. The molecular classification of gastric cancer subtypes has revolutionized the understanding of gastric carcinogenesis. This includes the tumour microenvironment, germline mutations, and the role of Helicobacter pylori bacteria, Epstein Barr virus and epigenetics in somatic mutations. There is evidence that ascorbic acid, phytochemicals and endogenous antioxidant systems can modify the risk of gastric cancer. Gastric juice ascorbate levels depend on dietary intake of ascorbic acid but can also be decreased by H. pylori infection, H. pylori CagA secretion, tobacco smoking, achlorhydria and chronic atrophic gastritis. Ascorbic acid may be protective against gastric cancer by its antioxidant effect in gastric cytoprotection, regenerating active vitamin E and glutathione, inhibiting endogenous N-nitrosation, reducing toxic effects of ingested nitrosodimethylamines and heterocyclic amines, and preventing H. pylori infection. The effectiveness of such cytoprotection is related to H. pylori strain virulence, particularly CagA expression. The role of vitamin C in epigenetic reprogramming in gastric cancer is still evolving. Other factors in conjunction with vitamin C also play a role in gastric carcinogenesis. Eradication of H. pylori may lead to recovery of vitamin C secretion by gastric epithelium and enable regression of premalignant gastric lesions, thereby interrupting the Correa cascade of gastric carcinogenesis.

Synthesis, characterization and anti proliferative effect of [Au(en)2]Cl3 and [Au(N-propyl-en)2]Cl3 on human cancer cell lines

Two Au(III) complexes of the type [Au(en)2]Cl3 (2a) and [Au(N-pr-en)2]Cl3 (3a) were synthesized by reacting Auric acid (HAuCl(4)·3H2O) with 2 equiv. ethylenediamine (en) or N-alkyl substituted ethylenediamine ligands. This metallodrug was characterized by various analytical and spectroscopic techniques such as elemental analysis, UV-Vis, Far-IR, 1H NMR and solution 13C as well as solid 13C and 15N NMR. Potentiality of [Au(en)2]Cl3 and [Au(N-pr-en)2]Cl3 as an anti-cancer agent were investigated by measuring some relevant physicochemical and biochemical properties such as stability of Au-N bonds by vibrational stretching from Far IR as well as cytotoxicity and stomach cancer cell inhibiting effect, respectively. The solid-state 15N NMR chemical shift shows that the ligand is strongly bound to gold(III) centre via N atoms. The computational study of 2a shows that the gold coordination sphere adopts distorted square planar geometry with bidentate ethylenediamine ligands acting as a tetradentate chelate. While stable in the solution state, the in vitro biological studies performed with these compounds 2a in solution showed higher activity towards the inhibitory effects of the human cancer cell lines such as prostate cancer (PC-3) and gastric carcinoma (SGC-7901) than that of the N-substituted gold(III) complex (3a). Cytotoxicity of the new compounds has also been estimated in PC-3 and SGC-7901 cells.

DNA repair Ku proteins in gastric cancer cells and pancreatic acinar cells

The DNA repair protein Ku acts as a heterodimer of Ku70 and Ku80 that binds to the DNA ends, nicks, or single-to-double-strand transition. It has a crucial role for DNA double-strand-break repair. Either Ku70 or Ku80 itself may have a unique function that is independent of the other Ku subunit. In this review, the role of Ku on cell proliferation and apoptosis will be discussed. Ku acts as a regulator of transcription by interacting with the recombination signal binding protein Jkappa and the NF-kappaB p50 homodimer to up-regulate p50 expression, which may regulate the proliferation of gastric cancer cells. Both Ku70 and Ku80 expressions are mediated by constitutively activated NF-kappaB and constitutively expressed cyclooxygenase-2 in gastric cancer cells, which may be related to gastric cell proliferation and carcinogenesis. In addition, nuclear loss of Ku may underlie the mechanism of apoptosis in pancreatic acinar cells after oxidative stress.

Bax and Bcl-2 protein expression in gastric precancerous lesions: immunohistochemical study

BACKGROUND AND AIMS

Bcl-2 protein prolongs cell survival in the face of classical apoptotic stimuli, and is considered to be a suppressor of apoptosis. Bax plays a key role in apoptosis by accelerating cell death after an apoptotic stimulus. The aim of our study was to determine the roles of the Bax proapoptotic gene and the Bcl-2 antiapoptotic gene in the carcinogenesis of gastric cancer.

METHODS

One hundred and forty-five gastric biopsy specimens of chronic gastritis, atrophic gastritis, intestinal metaplasia and gastric dysplasia were studied. Using immunohistochemical methods, Bax and Bcl-2 protein expression was observed.

RESULTS

Bax was expressed in epithelial cells in all cases of chronic gastritis. Bax was not detected in 26% of specimens of atrophic gastritis. As intestinal metaplasia develops, Bax is further suppressed. In biopsy samples with dysplasia, Bax expression was demonstrated only in 12% of biopsy samples. Although Bcl-2 protein was not detected in chronic gastritis, aberrant expression was found in gastric epithelial intestinal metaplasia and dysplasia.

CONCLUSIONS

The suppression of Bax and overexpression of Bcl-2 protein is an early event in gastric tumorigenesis, before gastric dysplastic changes occur.

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Detection of Helicobacter pylori cagA gene in patients with digestive diseases in Guangxi and its clinical significance

AIM: To study the positive rate of Helicobacter pylori (H. pylori) cagA gene of strains and the virulence of H. pylori infecting patients in Guangxi, China.

METHODS: H. pylori strains were isolated in gastric biopsy specimens from the patients with chronic gastritis and peptic ulcer in Nanning area of Guangxi. The sequence of D008/R008 primers were used to amplify 297 bp fragment of cagA gene and PCR were used to detect the frequency of cagA gene in the 45 H. pylori isolates.

RESULTS: The positive rate of cagA gene in H. pylori strains was 84.4% (38/45). The positive rate of cagA gene in peptic ulcer (PU) patients was 76.0% (19/25), which was lower than that in chronic gastritis (CG) patients (95.0%,19/20), but there was no significant difference (P > 0.05). The positive rate of cagA gene was higher in female patients than that in male patients (100.0% vs 73.1%, P < 0.01). The positive rate of cagA gene in different age groups was no significant difference (P > 0.05).

CONCLUSION: The positive rate of cagA gene in H. pylori strains among patients in Guangxi is high, and the positive rate is lower in PU patients than that in CG patients, and higher in male than female patients. But there is no significant difference in different age groups.

Sequence diversity analysis of CagA gene and corresponding protein in Helicobacter pylori

AIM: To find the structural characteristics and correlation with region and the clinical outcomes by analyzing nucleotide and amino acid sequences of CagA, our research results and data of CagA sequences deposited in NCBI database.

METHODS: The characteristics of CagA sequences were analyzed, and a phylogenetic tree was constructed by using Vector NTI Suite 9.0, ClastalX (version 1.8), Phylip (version 3.5) and Treeview (version 1.61).

RESULTS: Through searching NCBI nucleotide and protein database, we obtained 44 complete and 560 partial CagA sequences. Aligning these sequences, analyzing similarity and constructing phylogenetic tree, we found CagA seqenceses could be classified into two types: western type and eastern type. Analyzing the CagA C terminal of 44 complete and 266 partial sequences, we classified the repeat sequence of CagA C terminal into two types: type I was discontinuous repeat sequence, common among all the strains, and type II was continuous repeat sequence, found in some individual strains. The type II repeat sequence was found in 31% (12/39) of strains from gastric cancer patients, compared with 13% (9/71) of strains from non-cancer patients (P = 0.021 < 0.05). Strains with the type II repeat sequence were associated with gastric cancer.

CONCLUSION: There is a high diversity of CagA nucleotide and amino acid sequences among H. pylori strains, showing a distinct geographic character as western and eastern region collection. The repeat sequence of CagA C terminal can be classified into two types, and strains with the type II repeat sequence containing EPIYA motif exhibits a stronger pathogenecity.

Effects of COX-2 inhibitor with cisplatin on proliferation and apoptosis of pancreatic cancer cells

AIM: To investigate the effects of proliferation and apoptosis induced by cyclooxygenase-2 (COX-2) inhibitor celecoxib in combination with cisplatin.

METHODS: The human pancreatic cancer cell line BxPC-3 cells were treated with COX-2 inhibitors celecoxib and cisplatin. The cell relative viability was examined using 3 (4, 5-dimethylethiazoly 1-2-) 2, 5-diphonyl tetrazolium bromide (MTT) assays. the expression of COX-2 mRNA was detected by RT-PCR, flow cytometry and Hoechst-33258 were used to demonstrate apoptotic changes in celecoxib and cisplatin treated cells.

RESULTS: After treatment of BxPC-3 cells with celecoxib, as measured by MTT, cell viability was inhibited in a dose-dependent and time-dependent manner with an IC50 of 100 nM at the time of 24h. The expression of COX-2 mRNA could be significantly decreased by celecoxib. Furthermore, we demonstrated that the combination of celecoxib with cisplatin inhibited cell growth and induced cell apoptosis to a greater degree than either compound alone. The apoptotic morphologies were demonstrated by Hoechst-33 258.

CONCLUSION: Combination of celecoxib with cisplatin inhibits cell proliferation and induces cell apoptosis, and the potent effectiveness of celecoxib in combination with gemcitabine may hold a promise in the clinical treatment of pancreatic cancer.

Relationship between expression of VEGF, Flt1, bFGF and P53and outcome in patients with gastric carcinoma

AIM: To investigate the relationship between the expression of VEGF, Flt1, bFGF and P⁵³, the clinicopathological characteristics and outcome in patients with gastric carcinoma.

METHODS: The relationship between VEGF, Flt1, bFGF, P⁵³ expression and clinicopathological characteristics and outcome in the patient was assessed by streptoavidin-biotin method of immunohistochemistry with polyclonal antibodies against VEGF, Flt1, bFGF, and P⁵³ protein. The survival curves were formulated using Kaplan-Meier method and analyzed by the log-rank test, and the influence of each variable on suvival was assessed by the Cox' s proportional hazard model.

RESULTS: VEGF expression was closely correlated with serosal invasion (Se, Sei invasion vs Pm, SS and M, SM invasion, P < 0.01). Expression of P⁵³ was obviously higher in the patients with lymph node metastasis than those without (lymph node metastasis vs non-lymph node metastasis, P < 0.05). There was a positive correlation between VEGF and Flt1 expression (VEGF expression in Flt1 positive group vs Flt1 negative group, P < 0.01). The factors that affected the prognosis in patients with gastric carcinoma were PTNM stage, VEGF expression, serosal invasion, and surgical curability. Flt1, bFGF, and P⁵³ expression had no influence on the prognosis of patients with gastric carcinoma (P > 0.05).

CONCLUSION: P⁵³ expression has significant relationship with lymph node metastasis in gastric carcinoma. VEGF expression is correlated with serosal invasion and the prognosis and may be a good prognostic indicator in gastric carcinoma.

Influence of H. pylori on cyclinD1 and PCNA mRNA expression in HepG2 cell line

AIM: To observe the effects of Helicobacter pylori (H. pylori) on cyclinD1 and PCNA mRNA expression in a human hepatoma cell line HepG2.

METHODS: H. pylori was co-cultured with HepG2 for 1, 3,6, 12 and 24 h. The cyclinD1 and PCNA mRNA expression was detected by semi-quantitative RT-PCR.

RESULTS: When HepG2 cells were cocultured with H. pylori CagA⁺ strain, the amount of cyclinD1 mRNA was increased 4.0-fold by 3 h and PCNA mRNA was increased 2.0-fold by 6 h, compared with that of uninfected control. Neither cyclinD1 mRNA nor PCNA mRNA of the HepG2 cells was increased after incubation with H. pylori CagA^- strain.

CONCLUSION: H. pylori can induce increasing expression of cyclinD1 and PCNA mRNA in HepG2, which may play some roles in the development of hepatocellular carcinoma.

Endoscopic patterns of gastric mucosa and its clinicopathological significance

AIM

To explore the correlation of magnifying endoscopic patterns and histopathology, Helicobacter pylori (H pylori) infection of the gastric mucosa.

METHODS

Gastric mucosal patterns in 140 patients with chronic gastritis were studied using Olympus GIF-Q240Z magnifying endoscope. Histopathological examination, rapid urease test and Warrthin-Starry staining were taken with biopsy samples from the magnified sites of stomach. The magnifying endoscopic patterns were compared with histopathological results and H pylori detection.

RESULTS

The pit patterns of gastric mucosa were classified as types A (round spot), B (short rod), C (branched), D (reticular) and E (villus). The detection rate of chronic atrophic gastritis (CAG) by magnifying endoscopy was 94.3% (33/35), which was significantly higher than that by routine endoscopy (22.9%, 8/35) (P<0.01). The pit patterns of 31 cases of intestinal metaplasia (IM) appeared as type E in 18 cases (58.1%), type D in 8 cases (25.8%) and type C in 5 cases (16.1%). Fourteen out of 18 patients (77.8%) with complete type (type I) of IM appeared as type E of pit patterns, whereas only 4 of 13 (30.8%) patients with incomplete type (types II and III) of IM appeared as type E (P<0.05). Collecting venules in the anterior of lower part of gastric corpus were subgrouped into types R (regular), I (irregular) and D (disappeared). H pylori infection was found in 12.2%(9/74), 60%(9/15) and 84.3%(43/51) cases in these types respectively. H pylori infection rate in type R was significantly lower than that in other two types (P<0.01).

CONCLUSION

Magnifying endoscopy may have an obvious value in diagnosing chronic atrophic gastritis, intestinal metaplasia and H pylori infection.

Construction of expression systems for flaA and flaB genes of Helicobacter pylori and determination of immunoreactivity and antigenicity of recombinant proteins

AIM: To clone flagellin genes A (flaA) and B (flaB) from a clinical strain of Helicobacter pylori (H pylori) and to construct prokaryotic expression systems of the genes and identify immunity of the fusion proteins.

METHODS: The flaA and flaB genes from a clinical H pylori isolate Y06 were amplified by high fidelity PCR. The nucleotide sequences of target DNA amplification fragments from the two genes were sequenced after T-A cloning. The recombinant expression vector pET32a inserted with flaA and flaB genes was constructed, respectively. The expressions of FlaA and FlaB fusion proteins in E. coli BL21DE3 induced by isopropylthio-β-D-galactoside (IPTG) at different concentrations were examined by SDS-PAGE. Western blot using commercial antibodies against whole cell of H pylori and immunodiffusion assay using self-prepared rabbit antiserum against FlaA (rFlaA) or FlaB (rFlaB) recombinant proteins were applied to the determination of the fusion proteins immunity. ELISA was used to detect the antibodies against rFlaA and rFlaB in sera of 125 H pylori infected patients and to examine rFlaA and rFlaB expression in 98 clinical isolates of H pylori, respectively.

RESULTS: In comparison with the reported corresponding sequences, the nucleotide sequence homologies of the cloned flaA and flaB genes were from 96.28%-97.13% and 96.31%-97.73%, and their putative amino acid sequence homologies were 99.61%-99.80% and 99.41%-100% for the two genes, respectively. The output of rFlaA and rFlaB expressed by pET32a-flaA-BL21DE3 and pET32a-flaB-BL21DE3 systems was as high as 40%-50% of the total bacterial proteins. Both rFlaA and rFlaB were able to combine with the commercial antibodies against whole cell of H pylori and to induce rabbits to produce specific antibodies with the same 1:2 immunodiffusion titers after the animals were immunized with the two recombinant proteins. Ninety-eight and zero point 4 and 92.80% of the serum samples from 125 patients infected with H pylori were positive for rFlaA and rFlaB antibodies, respectively. One hundred percent and 98.98% of the 98 tested isolates of H pylori were detectable for rFlaA and rFlaB epitopes, respectively.

CONCLUSION: Two prokaryotic expression systems with high efficiency of H pylori flaA and flaB genes were successfully established. The expressed rFlaA and rFlaB showed satisfactory immunoreactivity and antigenicity. High frequencies of FlaA and FlaB expression in different H pylori clinical strains and the general existence of specific antibodies against FlaA and FlaB in H pylori infected patients strongly indicate that FlaA and FlaB are excellent antigen candidates for developing H pylori vaccine.

Cloning, sequencing and bioinformatics analysis of adhesin gene babA2 of Helicobacter pylori

AIM

To obtain DNA of human Helicobacter pylori (Hp) adhesin gene babA₂ and the amplified fragment was inserted into plasmid pET-22b (+) for nucleotide sequencing analysis and to carry out bioinformatics analysis.

METHODS

The babA₂ DNA was amplified by PCR and inserted into the plasmid pET -22b (+) and sequenced. The biological property was analysed by the software ANTHEPROT V4.3c.

RESULTS

DNA sequencing analysis showed that the sequence of babA₂ DNA was the same as that published by GenBank. ANTHEPROT V4.3c software predicted its relative molecular mass(M_r) was 78 kD and it possessed good antigencity and hydrophobicity.

CONCLUSION

A confirmed babA₂ gene has been obtained and bioinformatics analysis showed that it had good immunogenicity. Our study lays a good foundation for recombination, expression and relevant research on adhesin gene babA2 of Helicobacter pylori.

Identification of antigens by monoclonal antibody PD4 and its expression in Escherichia coli

AIM

To clone and express the antigen of monoclonal antibody (MAb) PD4 for further investigation of its function.

METHODS

MGC803 cDNA expression library was constructed and screened with PD4 as probes to clone the antigen. After failed in the library screening, immunoprecipitation and SDS-polyacrylamide gel electrophoresis were applied to purify the antigen for sequence analysis. The antigen coming from Mycoplasma hyorhinis (M. hyorhinis) was further confirmed with Western blot analysis by infecting M. hyorhinis -free HeLa cells and eliminating the M. hyorhinis from MGC803 cells. The full p37 gene was cloned by PCR and expressed successfully in Escherichia coli after site-directed mutations. Immunofluorescence assay was used to demonstrate if p37 protein could directly bind to gastric tumor cell AGS.

RESULTS

The cDNA library constructed with MGC803 cells was screened by MAb PD4 as probes. Unfortunately, the positive clones identified with MAb PD4 were also reacted with unrelated antibodies. Then, immunoprecipitation was performed and the purified antigen was identified to be a membrane protein of Mycoplasma hyorhinis (M. hyorhinis) by sequencing of N-terminal amino acid residues. The membrane protein was intensively verified with Western blot by eliminating M. hyorhinis from MGC803 cells and by infecting M. hyorhinis-free HeLa cells. The full p37 gene was cloned and expressed successfully in Escherichia coli after site-directed mutations. Immunofluorescence demonstrated that p37 protein could directly bind to gastric tumor cell AGS.

CONCLUSION

The antigen recognized by MAb PD4 is from M. hyorhinis, which suggests the actions involved in MAb PD4 is possibly mediated by p37 protein or M. hyorhinis. As p37 protein can bind directly to tumor cells, the pathogenic role of p37 involved in tumorigenesis justifies further investigation.

FT-IR spectroscopic analysis of normal and cancerous tissues of esophagus

AIM: To investigate the special Fourier transform infrared spectroscopy (FT-IR) spectra in normal and cancerous tissues of esophagus.

METHODS: Twenty-seven pairs of normal and cancerous tissues of esophagus were studied by using FT-IR and the special spectra characteristics were analyzed in different tissues.

RESULTS: Different spectra were found in normal and cancerous tissues. The peak at 1550/cm was weak and wide in cancerous tissues but strong and high in normal tissues.The ratio of I 1647/I 1550 was 2.0 in normal tissues and 2.36 in cancerous tissues (P < 0.05). The ratio of I 1550/I 1080 was 4.5 in normal tissues and 3.4 in cancerous tissues (P < 0.01). The peak at 1453/cm was higher than at 1402/cm in normal tissue and lower than at 1402/cm in cancerous tissues.

CONCLUSION: The results indicate that FTIR may be used in clinical diagnosis.

Expression of NGF family and their receptors in gastric carcinoma: A cDNA microarray study

AIM: To investigate the expression of NGF family and their receptors in gastric carcinoma and normal gastric mucosa, and to elucidate their effects on gastric carcinoma.

METHODS: RNA of gastric cancer tissues and normal gastric tissues was respectively isolated and mRNA was purified. Probes of both mRNA reverse transcription product cDNAs labled with α-³³P dATP were respectively hybridized with Atlas Array membrane where NGF and their family genes were spotted on. Hybridized signal images were scanned on phosphor screen with ImageQuant 5.1 software after hybridization. Normalized values on spots were analyzed with ArrayVersion 5.0 software. Differential expression of NGF family and their receptors mRNA was confirmed between hybridized Atlas Array membranes of gastric cancer tissues and normal gastric mucosa, then their effects on gastric carcinoma were investigated.

RESULTS: Hybridization signal images on Atlas Array membrane appeared in a lower level of nonspecific hybridization. Both of NGF family and their receptors Trk family mRNA were expressed in gastric cancer and normal gastric mucosa. But adversely up-regulated expression in other tissues and organs. NGF, BDGF, NT-3, NT-4/5, NT-6 and TrkA, B and C were down-regulated simultaneously in gastric carcinoma in comparison with normal gastric mucosa. Degrees of down-regulation in NGF family were greater than those in their receptors Trk family. Down-regulation of NT-3 and BDGF was the most significant, and TrkC down-regulation level was the lowest in receptors Trk family.

CONCLUSION: Down-regulated expression of NGF family and their receptors Trk family mRNA in gastric cancer is confirmed. NGF family and their receptors Trk family probably play a unique role in gastric cancer cell apoptosis by a novel Ras or Raf signal transduction pathway. Their synchronous effects are closely associated with occurrence and development of gastric carcinoma induced by reduction of signal transduction of programmed cell death.

Construction of hpaA gene from a clinical isolate of Helicobacter pylori and identification of fusion protein

AIM: To clone hpaA gene from a clinical strain of Helicobacter pylori and to construct the expression vector of the gene and to identify immunity of the fusion protein.

METHODS: The hpaA gene from a clinical isolate Y06 of H. pylori was amplified by high fidelity PCR. The nucleotide sequence of the target DNA amplification fragment was sequenced after T-A cloning. The recombinant expression vector inserted with hpaA gene was constructed. The expression of HpaA fusion protein in E.coli BL21(DE3) induced by IPTG at different dosages was examined by SDS-PAGE. Western blot with commercial antibody against whole cell of H. pylori as well as immunodiffusion assay with self-prepared rabbit antiserum against HpaA fusion protein were applied to determine immunity of the fusion protein. ELISA was used to detect the antibody against HpaA in sera of 125 patients infected with H. pylori and to examine HpaA expression of 109 clinical isolates of H. pylori.

RESULTS: In comparison with the reported corresponding sequences, the homologies of nucleotide and putative amino acid sequences of the cloned hpaA gene were from 94.25%-97.32% and 95.38%-98.46%, respectively. The output of HpaA fusion protein in its expression system of pET32a-hpaA-BL21(DE3) was approximately 40% of the total bacterial proteins. HpaA fusion protein was able to combine with the commercial antibody against whole cell of H. pylori and to induce rabbit producing specific antiserum with 1:4 immunodiffusion titer after the animal was immunized with the fusion protein. 81.6% of the serum samples from 125 patients infected with H. pylori (102/125) were positive for HpaA antibody and all of the tested isolates of H. pylori (109/109) were detectable for HpaA.

CONCLUSION: A prokaryotic expression system with high efficiency of H. pylorihpaA gene was successfully established. The HpaA expressing fusion protein showed satisfactory immunoreactivity and antigenicity. High frequencies of HpaA expression in different H. pylori clinical strains and specific antibody production in H. pylori infected patients indicate that HpaA is an excellent and ideal antigen for developing H. pylori vaccine.

Relationship between expression of Bcl-2 and p53 protein and CagA+Helicobacter pylori in gastric cancer

AIM

The relationship between cytotoxin-associated protein (CagA)+Helicobacter pylori (H.pylori) infection and gastric cancer in China was reported inconsistently. Using enzyme-linked immunosorbent assay (ELISA) to detect serum anti-CagA antibody and ABC immunohistochemical staining to detect the expression of Bcl-2 and p53 proteins, this study is to explore the relationship between CagA H.pylori infection and expressions of p53 and Bcl-2 proteins in gastric cancer and chronic gastric diseases.

METHODS

Seventy-nine patients (50 with gastric cancer, 17 with chronic atrophic gastritis, 5 with gastric ulcer and 7 with chronic superficial gastritis) were diagnosed by endoscopy and biopsied under endoscopy for detection of H.pylori infection, and confirmed by pathological examination. Expression of Bcl-2 and p53 proteins was detected by immunohistoche-mistry. Rapid urease test and serum H.pylori antibodies with ELISA or Warthin-Starry silver stains were used for H.pylori diagnosis. H.pylori was defined as positive when 2 or 3 of these tests were positive. ELISA was used for the detection of serum anti-CagA antibody.

RESULTS

Anti-CagA antibody was present in 43/50(86%) gastric cancer and in 13/29 (41%) chronic gastric disease, CagA+H.pylori rate in gastric cancer was higher than those in chronic gastric diseases (P<0.01). The positive rate of Bcl-2 expression in gastric cancer was higher than that in chronic gastric diseases (62% vs 41%, P>0.05). In CagA+ gastric cancer it was higher than that in CagA- one (65% vs 43%, P>0.05), and in CagA+ chronic gastric diseases it was higher than that in CagA- one (77% vs 12%, P<0.01). The positive rate of mutant p53 expression in gastric cancer was higher than that in chronic gastric diseases (54% vs 28%, P<0.05), in CagA+ gastric cancer it was significantly higher than that in CagA- one (60% vs 14%, P<0.05), and in CagA⁺ chronic gastric diseases it was significantly higher than that in CagA- ones (46% vs 12%, P<0.05).

CONCLUSION

Expression of anti-CagA antibody is present in a significantly higher percentage of gastric cancer subjects than that in chronic gastric diseases. It is suggested that CagA⁺H.pylori infection may increase the risk of gastric cancer. The CagA factor may be involved in the development of gastric cancer through influencing the expression of Bcl-2 gene and mutant p53 gene.

Recombinant Helicobacter pylori catalase

AIM: To construct a recombinant strain which highly expresses catalase of Helicobacter pylori (H. pylori) and assay the activity of H. pylori catalase.

METHODS: The catalase DNA was amplified from H. pylori chromosomal DNA with PCR techniques and inserted into the prokaryotie expression vector pET-22b (+), and then was transformed into the BL21 (DE3) E. coli strain which expressed catalase recombinant protein. The activity of H. pylori catalase was assayed by the Beers&Sizers.

RESULTS: DNA sequence analysis showed that the sequence of catalase DNA was the same as GenBank’s research. The catalase recombinant protein amounted to 24.4% of the total bacterial protein after induced with IPTG for 3 hours at 37 °C and the activity of H. pylori catalase was high in the BL21 (DE3) E. coli strain.

CONCLUSION: A clone expressing high activity H. pylori catalase is obtained, laying a good foundation for further studies.

Expression of TFF2 and Helicobacter pylori infection in carcinogenesis of gastric mucosa

AIM: To investigate the expression of TFF2 and Helicobacter pylori infection in carcinogenesis of gastric mucosa.

METHODS: The expression of TFF2 was immunohistochemically analyzed in paraffin-embedded samples from 119 patients with endoscopic biopsy and subtotal gastrectomy specimens of gastric mucosal lesions, including 16 cases of chronic superficial gastritis (CSG), 20 chronic atrophic gastritis (CAG), 35 intestinal metaplasia (IM), 23 gastric epithelial dysplasia (GED) and 25 gastric carcinoma (CA), and Helicobacter pylori infection was detected by Warthin-Starry staining.

RESULTS: 1: TFF2 was located in the cytoplasm of gastric mucous neck cell. The expression of TFF2 was 100%, 100%, 0, 56.5% and 0 in CSGs, CAGs, IMs, GEDs and CAs, respectively. 2: The value of TFF2 positive cell density in CSG with Helicobacter pylori infection was higher than that without Helicobacter pylori infection. (52.89 ± 7.27vs 46.49 ± 13.04, P > 0.05); But the value of TFF2 positive cell density in CAG and GED with Helicobacter pylori infection was significantly lower than that without Helicobacter pylori infection (18.17 ± 4.09vs 37.93 ± 13.80, P < 0.01 and 14.44 ± 9.32vs 24.84 ± 10.22, P < 0.05).

CONCLUSION: Increase of TFF2 expression in CSG is perhaps associated with the protective mechanism after gastric mucosal injury. Decrease of TFF2 expression in CAG possibly attributes to the decrease in the number of gastric gland cell expressing TFF2. Re-expression of TFF2 in gastric epithelial dysplasia implies that TFF2 possibly contributes to the initiation of gastric carcinoma. The effect of Helicobacter pylori on the expression of TFF2 depends on the status of gastric mucosa.

Construction of clone expressing adhesin Hsp60 of Helicobacter pylori

AIM

To construct a recombinant vector containing gene encoding Hsp60 gene of Helicobacter pylori and to express the vector in E.coli BL21.

METHODS

The Hsp60 gene was amplified from H.pylori chromosome by PCR and inserted into the prokaryotie expression vector pET-22b (+). The recombinant vector was transformed and expressed in E.coli BL21 (DE3). Recombinant Hsp60 protein immunogenicity was studied by Western blot.

RESULTS

The 1.6 kb Hsp60 gene was successfully isolated. Recombinant E.coli strains expressed Hsp60 were obtained, the expression protein amounted to 27.2% of the total bacterial protein after induced with IPTG for 3 h at 37 ℃, which included inclusion body and soluble protein. Inclusion body was the major pattern of the expression that amounted to 76.6% of the insoluble protein. Western blot analysis of rHsp60 confirmed that it could be specially recognized by serum from Hp infected patients.

CONCLUSION

The gene coding for Hp Hsp60 is cloned and expressed successfully. The results obtained lay the foundation for constructing the H.pylori vaccine.

Effect of ZNRD1 gene antisense RNA on drug resistant gastric cancer cells

AIM: To investigate the expression level of ZNRD1 gene in gastric cancer cells SGC7901 and gastric cancer MDR (multidrug resistant) cells SGC7901/VCR, and to observe the drug sensitizing and proliferation effect of ZNRD1 antisense nucleic acid transduction on SGC7901/VCR cells.

METHODS: Amplification of sequences encoding ZNRD1 from SGC7901/VCR cDNA by PCR. The levels of ZNRD1 mRNA expression were demonstrated using semiquantitative reverse transcription polymerase chain reaction (RT-PCR). Eukaryotic expression vector pcDNA3.1-anti ZNRD1 was constructed and transfected into SGC7901/VCR cells by lipofectamine. Immunochemical method was used to detect the expression of protein in SGC7901/VCR cells and transfectants. The cell cycle alteration and the intracellular adriamycin (ADM) accumulation were observed by FACS. Growth curve and drug sensitization of cells for vincristine (VCR) were analyzed with MTT assay.

RESULTS: We cloned the open reading frame of full-length ZNRD1. The expression of ZNRD1 showed higher in SGC7901/VCR than in SGC7901 cells. The antisense ZNRD1 drug-resistant clones were selected after gene transfection. Immunochemical results showed that the expression level of ZNRD1 protein was lower in anti ZNRD1-SGC7901/VCR cells than that in non-transfectants. Comparing to SGC7901/VCR and pcDNA3.1-SGC7901/VCR, anti ZNRD1-SGC7901/VCR showed gradually accumulated in G₁ phase, with a concomitant decrease of cell population in S phase. FACS also suggested intracellular ADM accumulation increased 2fold in SGC7901/VCR cells after transfected with antisense ZNRD1. MTT assay showed that transfectants cells proliferation was lagged and more sensitive to VCR than non-transfectants.

CONCLUSION: ZNRD1 gene displayed highly expression in VCR resistant gastric cancer cells. Expression of ZNRD1 protein was effectively blocked in anti ZNRD1-SGC7901/VCR cells by gene transfection. ZNRD1 antisense nucleic acid transfection sensitized drug resistant gastric cancer cells to VCR, increased ADM accumulation and inhibited the cells proliferation. ZNRD1 antisense RNA transduction could reverse the MDR of human drug-resistant gastric cancer cell SGC7901/VCR to a degree.

Bile from a patient with anomalous pancreaticobiliary ductal union promotes the proliferation of human cholangiocarcinoma cells via COX-2 pathway

AIM: To explore the effects of COX-2 gene in the proliferative activity induced by bile from anomalous pancreaticobiliary ductal union (APBDU) on human cholangiocarcinoma cell line.

METHODS: Bile sample from APBDU and normal bile sample were used for this study. The proliferative effect of bile was measured by methabenzthiazuron (MTT) assay; COX-2 mRNA was examined by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Cell cycle was analyzed by flow cytometry (FCM), and the PGE₂ levels in the supernatant of cultured cholangiocarcinoma cells were quantitated by enzyme-linked immunoabsordent assay (ELISA).

RESULTS: Bile from APBDU can significantly promote the proliferation of human cholangiocarcinoma QBC939 cells compared with normal bile (P = 0.005) and up-regulated remarkably their COX-2 mRNA expression (P = 0.004). The proliferative activity of APBDU bile can be abolished by addition of cyclooxygenase-2 specific inhibitor celecoxib.

CONCLUSION: Bile from APBDU can promote the proliferation of human cholangiocarcinoma QBC939 cells via COX-2 pathway.

Anti-Helicobacter pylori immunoglobulin G (IgG) and IgA antibody responses and the value of clinical presentations in diagnosis of Helicobacter pylori infection in patients with precancerous lesions

AIM: To determine the prevalence of Helicobacter pylori (H. pylori) infection, the serum anti-H. pylori immunoglobulin G (IgG) and IgA antibody responses, and the value of clinical presentations in diagnosis of H. pylori infection in patients with gastric atrophy, intestinal metaplasia and dysplasia.

METHODS: H. pylori infection was detected by histology in 209 patients with mild chronic atrophic gastritis (CAG, n = 76), severe CAG (n = 22), mild intestinal metaplasia (IM, n = 22), severe IM (n = 58), or dysplasia (DYS, n = 31). Serum anti-H. pylori IgG and IgA were double sampled and evaluated by enzyme-linked immunoadsordent assays. 35 clinical presentations were observed and their relationship with H. pylori infection was analyzed by the k-means cluster method.

RESULTS: Both IgG and IgA levels in H. pylori positive patients were significantly higher than those negative for H. pylori (P < 0.001-0.01). The prevalence of H. pylori was highest in severe IM (84.5%), and lowest in mild CAG (51.3%) (P < 0.01). They were similar in severe CAG (68.2%), mild IM (72.7%), and DYS (67.7%). In H. pylori positive patients, the IgG levels in severe CAG were significantly higher than those in mild CAG (P < 0.01). In H. pylori negative patients, both IgG and IgA levels increased remarkably in severe IM, compared to those in mild IM (P < 0.01-0.05). H. pylori infection exhibited no association with patient’s gender (62.1% in males; 71.7% in females) and age (r = 0.0814, P = 0.241). The diagnostic accuracy based on 35 clinical presentations was 65.7%. It could be improved by 5.7% when only the assemblage of digestive symptoms were engaged, or by 8.6% when the pathogenic factors, general status and grossoscopy were combined. The diagnostic accuracy could be decreased when only the general symptoms were engaged, or when the pathogenic factors were accompanied with some common digestive symptoms.

CONCLUSION: H. pylori infection is a major risk factor for the process from atrophy, IM to DYS of gastric mucosa. Serum IgG and IgA are good indicators to evaluate this progress with a certain arrearage. Investigation on the effective assemblages of clinical presentations may provide a better understanding in the pathogenesis, diagnosis and treatment for H. pylori infection.

Loss of heterozygosity on chromosome 18 in microdissected gastric cancer cells

AIM: To detect loss of heterozygosity (LOH) on chromosome 18 in primary gastric carcinomas.

METHODS: Short insertion deletion polymorphism (SIDP) markers on chromosome 18 were analyzed using high fidelity-whole genome amplification (HF-WGA) and denatured high pressure liquid chromotography (DHPLC) to detect LOH in gastric cancer cells purified by laser capture microdissection (LCM).

RESULTS: LOH in 3 (MID148, MID150 and MID352) of 9 SIDP loci was found. Three of 10 samples of gastric cancer showed LOH at the same SIDP locus (MID150) (30%) and one of them also demonstrated LOH at the other 2 SIDP loci (MID148, MID352). No LOH was detected in 6 of 9 SIDP loci.

CONCLUSION: Detection of LOH in cancer cells can be achieved by the combination of LCM, HF-WGA and the analysis of SIDP marker by DHPLC. This study provides an alternative new way to map tumor suppressor genes on chromosome 18.

Association of cyclooxygenase-2 expression with Hp-cagA infection in gastric cancer

AIM: To observe the expression of cyclooxygenase-2 (COX-2) and to investigate the association between COX-2 expression and infection with cytotoxic-associated gene A (cagA) positive strain Helicobacter pylori (Hp) in human gastric cancer, and subsequently to provide fresh ideas for the early prevention of gastric cancer.

METHODS: 32 Specimens of gastric cancer and corresponding adjacent normal gastric mucosa were obtained from patients who had undergone surgical operations of gastric cancer. All the samples including 1 case of stomach malignant lymphoma and 31 cases of gastric adenocarcinoma were confirmed by pathology diagnosis. The expression of COX-2 in 32 specimens of gastric cancer and corresponding adjacent normal gastric mucosa was quantitatively determined and analyzed with Flow Cytometry, and the levels of COX-2 protein were compared between specimens with cagA⁺Hp infection and those without cagA⁺Hp infection. The cagA gene in 32 specimens of gastric cancer was detected by polymerase chain reaction (PCR) method.

RESULTS: Twenty-seven of 32 (84%) specimens of gastric cancer showed over-expression of COX-2, compared with the adjacent normal gastric mucosa. cagA⁺ gene were detected from 19 specimens of gastric cancer, but not from the other 13 specimens. The levels of COX-2 protein in 19 specimens of gastric cancer with cagA⁺Hp infection (the number of positive cells was 73.82 ± 18.2) were significantly higher than those in the 13 specimens without cagA⁺Hp infection (the number of positive cells was 35.92 ± 22.1).

CONCLUSION: COX-2 is overexpressed in gastric cancer and cagA⁺Hp infection could up-regulate the expression of COX-2 in gastric cancer in human. There may also exist another way or channel to regulate the expression of COX-2 in gastric cancer in addition to cagA⁺Hp infection. Therefore, applying COX-2 selective inhibitors could be an effective and promising way to prevent gastric cancer.

Expression of cyclooxygenase-2 in pancreatic cancer and its correlation with p53

AIM: To investigate the expressions of COX-2 and p53 in human pancreatic cancer and their correlation with biological behaviors of pancreatic cancer.

METHODS: The expressions of COX-2 and p53 in 51 specimens of human pancreatic ductal adenocarcinoma and 11 specimens of normal tissues adjacent human pancreatic ductal adenocarcinoma were detected with immunohistochemistry by Envision.

RESULTS: The detectable rate of COX-2 and p53 in pancreatic ductal adenocarcinoma were 74.5% and 60.8%, respectively; but none in adjacent normal tissues. The expression of COX-2 was significantly associated with the clinical stages and metastasis status of lymph nodes (P = 0.022, 0.036), but not with histological grade (P = 0.152). The expression of p53 was significantly correlated with the lymph node metastasis status (P = 0.035), but not with their histological grades and clinical stages (P = 0.131, 0.078). There was a significant correlation between the expression of COX-2 and p53 (r = 0.452, P = 0.001). Conditions such as age, sex, tumor size and location had no relation with expression of COX-2 or p53.

CONCLUSION: The cooperation of COX-2 and p53 may play a pivotal role in the carcinogenesis and the progression in pancreatic cancer. They may provide new targets for the therapy of pancreatic cancer.

TFF2 expression and H. pylori infection in gastric cancer tissues

AIM: To investigate the relationship between the expression of TFF2 and H. pylori infection in human gastric precancerous lesions and gastric cancer, and to explore the role of TFF2 and H. pylori in human gastric precancerous lesions and gastric cancer.

METHODS: The expression of TFF2 was immunohistochemic-ally analyzed in paraffin-embedded samples obtained by endoscopic biopsy and subtotal gastractomy specimens from 119 patients including chronic superficial gastritis(CSG, 16), chronic atrophic gastritis(CAG, 16), intestinal metaplasia(IM, 35), gastric epithelial dysplasia(GED, 23) and gastric cancer(CA, 25), and conditions of H. pylori infection were detected by means of Warthin-Starry staining.

RESULTS: TFF2 was located in the cell plasma of gastric mucous neck cells. The expressions of TFF2 were 100%, 100%, 0%, 56% and 0% in CSG, CAG, IM, GED and CA, respectively. The density of TFF2 positive cells was higher in CSG with H. pylori infection than that without H. pylori infection(52.9±7.3 vs 46.5±13.0, P > 0.05); but it was significantly lower in CAG and GED with H. pylori infection than that without H. pylori infection(18.2±4.1 vs 37.9±13.8, P < 0.01 and 14.4±9.3 vs 24.8±10.2, P < 0.05).

CONCLUSION: The high expression of TFF2 is associated with the protective mechanism after the gastric mucosal injury, the low expression of TFF2 in CAG might attribute to the decreased number of gastric gland cells secreting TFF2; but the re-expression of TFF2 in GED suggests that TFF2 is involved with the initiation of gastric cancer. The effect of H. pylori on the expression of TFF2 depends on the status of gastric mucosa.

Effect of Helicobacter pylori infection on bax protein expression in patients with gastric precancerous lesions

AIM: To evaluate the effect of Helicobacter pylori (H. pylori) infection on bax protein expression, and explore the role of H. pylori in the development of gastric carcinoma.

METHODS: H. pylori was examined by rapid urease test and Warthin-Starry method, and bax protein was examined by immunohistochemical staining in 72 patients with pre-malignant lesions.

RESULTS: Bax protein was expressed with different degree in intestinal metaplasia and gastric dysplasia, its positive rate being 63.9%. The positive rate of Bax protein expression in H. pylori-positive gastric precancerous lesions (72.3%) was significantly higher than that in H. pylori-negative gastric precancerous lesions (48.0%, x² = 4.191, P < 0.05). H. pylori infection was correlated well with the expression of Bax protein in gastric precancerous lesions(r = 0.978, P < 0.01). After eradication of H. pylori, the positive rate of bax protein expression was significantly decreased in H. pylori-positive gastric precancerous lesions(x² = 5.506, P < 0.05). In the persistent H. pylori infected patients, the positive rate of Bax protein expression was not changed.

CONCLUSION: H. pylori is involved in the expression of Bax gene. H. pylori infection increases the expression of Bax protein, this may be one of the mechanisms of H. pylori infection in the induction of gastric epithelial cell apoptosis. H. pylori might act as a tumor promoter in the genesis of gastric carcinoma. Eradication of H. pylori could inhibit the formation and development of gastric carcinoma.

Nimsulide suppresses the telomerase activity of SGC7901 gastric cancer cell line

AIM: To investigate whether nimsulide, a COX-2-specific inhibitor, could inhibit the proliferation viability and the telomerase activity of SGC7901 gastric cancer cell line.

METHODS: After SGC7901 was treated with different concentrations of nimsulide(0, 50, 100, 200 and 400 μmol/L, respectively), the cellular proliferation was evaluated by MTT assay and the telomerase activity was detected by PCR-ELISA assay. And the cell morphology and growth manner were observed under phase contrast microscope.

RESULTS: Nimsulide could inhibit the growth of SGC7901 gastric cancer cell line in the time and dose-dependent manner; and the telomerase activity of SGC7901 was significantly lower in the 50, 100, 200 and 400 μmol/L groups than that in the control group, their absorbance values were 2.12±0.11, 1.54±0.08, 1.13±0.09, 0.79±0.12 vs 2.76±0.06(P < 0.01), respectively.

CONCLUSION: COX-2-specific inhibitor could inhibit the telomerase activity of gastric cancer cell line, which provides a new pathway of COX-2-specific inhibitor in inhibiting the growth of gastric cancer.

Expression of E-cadherin and β-catenin in gastric carcinoma and its correlation with the clinicopathological features and patient survival

AIM: The E-cadherin-catenin complex is important for cell-cell adhesion of epithelial cells. Impairment of one or more components of this complex is associated with poor differentiation and increased invasiveness of carcinomas. We evaluated the expression pattern of E-cadherin and β-catenin in gastric carcinoma and dysplasia and analyzed their relationship with tumor clinicopathological features and patient survival.

METHODS: Immunohistochemical staining of E-cadherin and β-catenin was performed from paraffin specimens of 163 gastric carcinomas, 44 gastric mucosal dysplasia, and 25 intestinal metaplasia, 28 atrophic gastritis and 12 healthy controls.

RESULTS: Normal membrane staining was observed in intestinal metaplasia, atrophic gastritis and control biopsy specimens for E-cadherin and β-catenin. 36% and 16% of gastric dysplasia were stained abnormally for E-cadherin and β-catenin respectively. Abnormal expression of E-cadherin and β-catenin was demonstrated in 46% and 44% of gastric carcinoma respectively. Abnormal expression of E-cadherin and β- catenin occurred more significantly in Borrmann III/IV than in Borrmann I/II type (P < 0.005, respectively). A significantly higher proportion of signet-ring, mucinous and tubular adenocarcinomas were abnormally expressed for E-cadherin and β-catenin as compared with papillary adenocarcinomas (χ² = 8.47, P < 0.005, and χ² = 7.05, P < 0.01, respectively). Morever, abnormal E-cadherin and β-catenin staining occurred more frequently in diffuse than in intestinal type of tumor (χ² = 18.18 and 17.79, P < 0.005, respectively). There was a significant correlation between abnormal β-catenin expression and positive lymph node metastasis. A survival advantage was noted in tumors retaining normal membranous expression of β-catenin, independent of type, grade, or stage of the disease (P < 0.0005).

CONCLUSION: Abnormal expression of the E-cadherin-catenin complex occurs frequently in gatric carcinoma, closely related to its histogenesis. Abnormal expression of the E-cadherin- catenin complex in gastric dysplasia may be an early event in the tumorigenesis. The close correlation with poor survival suggests that abnormal β-catenin may be a useful prognostic marker.

Effect of apoptosis on gastric adenocarcinoma cell line SGC-7901 induced by cis-9, trans-11-conjugated linoleic acid

AIM: To determine the effect of apoptosis on gastric cancer cells (SGC-7901) induced by cis-9, trans-11-conjugated linoleic acid (c9, t11-CLA) and its possible mechanism in the inhibition of cancer cells growth.

METHODS: Using cell culture, flow cytometery and immunocytochemical techniques, we examined the cell growth, frequency of apoptosis and distribution of cell cycle, expression of ki67, bcl-2, Fas, and c-myc of SGC-7901 cells which were treated with various c9, t11-CLA concentrations (25, 50, 100 and 200 μmol·L^-1) of c9, t11-CLA for 24 h and 48 h, with a negative control (0.1% ethanol).

RESULTS: The growth of SGC-7901 cells was inhibited by c9,t11-CLA. Eight days after treatment with various concentrations of c9,t11-CLA, as mentioned above, the inhibition rates were 5.9%, 20.2%, 75.6% and 82.4%, respectively. The frequency of apoptosis on SGC-7901 cells induced by different concentrations of c9, t11-CLA (except for 25 μmol·L^-1, 24 h) was significantly greater than that in the negative control (P < 0.01). To further investigate the influence of the cell cycle progression, we found that apoptosis induced by c9, t11-CLA may be involved in blocking the cell cycle of SGC-7901 cells. Immunocytochemical staining demonstrated that SGC-7901 cells preincubated in media supplemented with different c9, t11-CLA concentrations for various time periods significantly decreased the expressions of ki67 (the expression rates were 18.70%-3.20%, at 24 h and 8.10%-0.20% at 48 h, respectively), bcl-2 (4.30%-0.15% at 24 h and 8.05%-0% at 48 h),and c-myc (4.85%-2.20% at 24 h and 4.75%-0.30% at 48 h) as compared with those in the controls (the expressions of ki67, bcl-2, and c-myc were 15.1% at 24 h and 13.5% at 48 h, 6.80% at 24 h and 8.00% at 48 h, 5.50% at 24 h and 5.30% at 48 h, respectively) (P < 0.01), whereas the expressions of Fas were increased (0.60%-2.75%, 24 h and 0.45%-5.95%, 48 h).

CONCLUSION: The growth and proliferation of SGC-7901 cells are inhibited by c9, t11-CLA via blocking the cell cycle, pathways of bcl-2-associated mitochondria with reduced expression of bcl-2 and Fas-associated death domain protein (FADD) with enhanced expression of Fas. But expression of c-myc on SGC-7901 cells is lower than that in negative control, which needs to be studied further.

Intravenous chemotherapy for resected gastric cancer: meta-analysis of randomized controlled trials

AIM: To assess the safety and efficacy of different intravenous chemotherapeutic regimens in patients with gastric carcinomas who had undergone gastrectomy.

METHODS: A meta-analysis of all the relevant randomized controlled trials (RCTs) was performed. Language was restricted to Chinese and English. RCTs were identified from Medline and Embase (1980-2001/4), and Chinese Bio-medicine Database (1990-2001/1). Literature references were checked at the same time. We included randomized and quasi-randomized trials comparing the efficacy of intravenous chemotherapy after gastrectomy with that of surgery alone in patients with confirmed gastric carcinomas who had undergone gastrectomy. Selection criteria were: randomized or quasi-randomized trials with following-up results; Trials could be double-blind, single-blind or not blind; Chemotherapy groups were given intravenous chemotherapy after gastrectomy without neo-adjuvant chemotherapy, intraperitoneal hyperthermic perfusion, radiotherapy or chemoimmunotherapy; Controlled group included those receiving gastrectomy alone. The following data were extracted: the number of survival and death by the end of the follow-up; the different agents and doses of the intravenous chemotherapy; the baseline of the chemotherapy group and the controlled arm; the serious adverse events; the statistical consideration; cost-effectiveness analysis. The statistical analysis was performed by RevMan4.1 software which was provided by the Cochrane Collaboration. A P value of < 0.05 was considered statistically significant. Meta-analysis was done with random effects model. Heterogeneity was checked by chi-square test. Sensitivity analysis was performed by excluding the trials in which Jadad-scale was only 1 score. The result was expressed with odds ratio (OR) for the categorical variable.

RESULTS: Fourteen trials involving 4543 patients were included. Meta-analysis was done with random effects model Heterogeneity and sensitivity analysis were performed also. The effect of intravenous chemotherapy after gastrectomy was better than surgery alone (odds ratio 0.56, 95%CI 0.40-0.79). There was a significant difference between the two groups by u-test (P = 0.0008). Sensitivity analysis revealed the same difference (odds ratio 0.81, 95%CI 0.70-0.94). Of fourteen trials, only three studies were of high quality according to the Jadad-scale (with three score). There was one meta-analysis trial and the others, about ten trials, were of low quality. There was no trial which mentioned sample-size calculation, allocation concealment, intention-to-treat analysis. Most of the trials didn’t describe the blind-procedure. There were five trials which detailed the side-effects according to the toxicity grade by WHO standard. The side-effects halting treatment were haematologic and biochemical toxicity, debilitating nausea and vomiting. There were two patients died of chemotherapy toxicity.

CONCLUSION: Based on the review, intravenous chemotherapy after gastrectomy may have positive treatment effect on gastric cancer. However, the evidence is not strong because of the general low methodologic quality of the RCTs. Therefore, we can’t make the conclusion that intravenous chemotherapy after gastrectomy may have better treatment effect on gastric cancer than that of surgery alone. Rigorously designed, randomised, double-blind, placebo-controlled trials are required.

Expression of Ku70 and Ku80 mediated by NF-kappa B and cyclooxygenase-2 is related to proliferation of human gastric cancer cells

Cyclooxygenase-2 (COX-2) expression is mediated by constitutive NF-kappaB and regulates human gastric cancer cell growth and proliferation. Inactivating Ku70 or Ku80 suppresses cell growth and induces apoptosis. It has been hypothesized that Ku70 and Ku80 expression may be associated with NF-kappaB activation and COX-2 expression and is involved in cell proliferation. In this study, we found that inhibition of constitutive NF-kappaB (by transfecting a mutated IkappaBalpha gene) and of COX-2 (by treatment with indomethacin and NS-398) suppressed Ku70 and Ku80 expression in cells. Treatment with prostaglandin E(2) adenocarcinoma gastric (AGS) increased expression of these Ku proteins in cells with low constitutive NF-kappaB levels. Inhibition of the Ku DNA end-binding activity by transfection with the C-terminal Ku80 expression gene suppressed cell proliferation. Ku70 or Ku80 overexpression by transfection with the Ku70 or Ku80 expression gene, respectively, enhanced proliferation of cells with low NF-kappaB levels. These results demonstrate that Ku70 and Ku80 expression is mediated by constitutively activated NF-kappaB and constitutively expressed COX-2 in gastric cancer cells and that the high Ku DNA end-binding activity contributes to cell proliferation. Ku70 and Ku80 expression may be related to gastric cell proliferation and carcinogenesis.

Effect of Nimesulide on proliferation and apoptosis of human hepatoma SMMC-7721 cells

AIM: Cyclooxygenase-2 (COX-2) has been suggested to be associated with carcinogenesis. We sought to investigate the effect of the selective COX-2 inhibitor, Nimesulide on proliferation and apoptosis of SMMC-7721 human hepatoma cells.

METHODS: This study was carried out on the culture of hepatic carcinoma SMMC-7721 cell line. Various concentrations of Nimesulide (0, 200 μmol/L, 300 μmol/L, 400 μmol/L) were added and incubated. Cell proliferation was detected with MTT colorimetric assay, cell apoptosis by electron microscopy, flow cytometry and TUNEL.

RESULTS: Nimesulide could significantly inhibit SMMC-7721 cells proliferation dose-dependent and in a dependent manner compared with that of the control group. The duration lowest inhibition rate produced by Nimesulide in SMMC-7721 cells was 19.06%, the highest inhibition rate was 58.49%. After incubation with Nimesulide for 72 h, the most highest apoptosis rate and apoptosis index of SMMC-7721 cells comparing with those of the control were 21.20% ± 1.62% vs 2.24% ± 0.26% and 21.23 ± 1.78 vs 2.01 ± 0.23 (P < 0.05).

CONCLUSION: The selective COX-2 inhibitor, Nimesulide can inhibit the proliferation of SMMC-7721 cells and increase apoptosis rate and apoptosis index of SMMC-7721 cells. The apoptosis rate and the apoptosis index are dose-dependent. Under electron microscope SMMC-7721 cells incubated with 300 μmol and 400 μmol Nimesulide show apoptotic characteristics. With the clarification of the mechanism of selective COX-2 inhibitors, These COX-2 selective inhibitors can become the choice of prevention and treatment of cancers.

Expression and function of classical protein kinase C isoenzymes in gastric cancer cell line and its drug-resistant sublines

AIM: To investigate the expression and function of classical protein kinase C (PKC) isoenzymes in inducing MDR phenotype in gastric cancer cells.

METHODS: Two cell lines were used in the study: gastric cancer cell SGC7901 and its drug-resistant cell SGC7901/VCR stepwise-selected by vincristine 0.3, 0.7 and 1.0 mg·L^-1, respectively. The expression of classical PKC (cPKC) isoenzymes in SGC7901 cells and SGC7901/VCR cells were detected using immunofluorescent cytochemistry, laser confocal scanning microscope and Western blot. The effects of anti-PKC isoenzymes antibody on adriamycin accumulation in SGC7901/VCR cells were determined using flow cytometric analysis.

RESULTS: (1) SGC7901 cells exhibited positive staining of PKC-α. SGC7901/VCR cells exhibited stronger staining of PKC-α than SGC7901 cells. The higher dosage vincristine selected, the much stronger staining of PKC-α was observed on SGC7901/VCR cells. (2) Both SGC7901 and SGC7901/VCR cells exhibited positive staining of PKC-β I and PKC-β II with no significant difference. (3) Compared with SGC7901, SGC7901/VCR cells had decreased adriamycin accumulation and retention. Accumulation of adriamycin in SGC7901 was 5.21 ± 2.56 mg·L^-1, in SGC7901/VCR 0.3 was 0.85 ± 0.29 mg·L^-1, in SGC7901/VCR 0.7 was 0.81 ± 0.32 mg·L^-1, and in SGC7901/VCR 1.0 was 0.80 ± 0.33 mg·L^-1; Retention of adriamycin in SGC7901 was 2.51 ± 1.23 mg·L^-1, in SGC7901/VCR 0.3 was 0.47 ± 0.14 mg·L^-1, in SGC7901/VCR 0.7 was 0.44 ± 0.15 mg·L^-1, and in SGC7901/VCR 1.0 was 0.41 ± 0.11 mg·L^-1. (4) Fluorescence intensity presented adriamycin accumulation in SGC7901/VCR cells was increased from 1.14 ± 0.36 to 2.71 ± 0.94 when cells were co-incubated with anti-PKC-α but not with anti-PKC-β I, PKC-α II and PKCγ antibodies.

CONCLUSION: PKC-α, but not PKC-β I, PKC-β II or PKCγ, may play a role in multidrug resistance of gastric cancer cells SGC7901/VCR.

Tumor suppressor gene p16 and Rb expression in gastric cardia precancerous lesions from subjects at a high incidence area in northern China

AIM

To further understand the molecular basis for gastric cardia carcinogenesis and to provide etiological clues.

METHODS

Endoscopic mucosa biopsy and histopathological examinations were made on 37 subjects from a high incidence area for both esophageal and gastric cardia carcinomas in northern China. All the biopsy samples were fixed in 850 ml. (-1)L alcohol and embedded in paraffin. Each block contained one piece of tissue and was serially section at 5 microm. Immunohistochemistry (ABC) was carried out on these gastric cardia samples to determine the alterations of p16 and Rb.

RESULTS

Based on the histopathlogical examination there were 11 cases of chronic superficial gastritis, 12 cases of chronic atrophic gastritis and 14 cases of dysplasia. The immunostaining demonstrated different levels of unclear immunostaining of p16 and Rb in normal gastric cardia tissue and the tissues with different severity of lesions. With the lesions progressing, the positive immunostaining rates for p16 protein had a decreasing tendency. In contrast, the positive immunostaining rate for Rb protein had an increasing tendency. There was a significant negative relationship between the two parameters. Changes of p16 was CSG 11(100%), CAG 7(58%), DYS 4(29%) and changes of Rb was CSG 2(18%), CAG 8(67%) and DYS 12(86%), (P<0.05).

CONCLUSION

The alterations of p16 and Rb protein may play a role in the early stages of gastric cardia carcinogenesis.

A study of recombinant protective H. pylori antigens

AIM: To construct a recombinant vector which can express M_r26000 outer membrane protein (OMP) from Helicobacter pylori (H. pylori), and to obtain the vaccine protecting against H. pylori infection and a diagnostic reagent kit quickly detecting H. pylori infection.

METHODS: The gene encoding the structural M_r26000 outer membrane protein of H. pylori was amplified from H. pylori chromosomal DNA by PCR, and inserted in the prokaryotic expression vector pET32a(+), which was transformed into the Top10 E. coli strain. Recombinant vector was selected, identified and transformed into BL-21(DE3) E. coli strain. The recombinant fusion proteins were expressed. The antigenicity of recombinant protein was studied by ELISA or immunoblotting and immunized Balb/c mice.

RESULTS: The gene of M_r26000 OMP was amplified to be 594 base pairs, 1.1% of the cloned genes was mutated and 1.51% of amino acid residues was changed, but there was homogeneity between them. The recombinant fusion protein encoded objective polypeptides of 198 amino acid residues, corresponding to calculated molecular masses of M_r26000. The level of soluble expression products was about 38.96% of the total cell protein. After purification by Ni-NTA agarose resin columniation, the purity of objective protein became about 90%. The ELISA results showed that recombinant fusion protein could be recognized by patient serum infected with H. pylori and rabbit serum immunized with the recombinant protein. Furthermore, Balb/c mice immunized with the recombinant protein were protected against H. pylori infection.

CONCLUSION: M_r26000 OMP may be a candidate vaccine preventing H. pylori infection.

Effect of cis-9, trans-11-conjugated linoleic acid on cell cycle of gastric adenocarcinoma cell line (SGC-7901)

AIM: To determine the effect of cis-9, trans-11-conjugated linoleic acid (c9,t11-CLA) on the cell cycle of gastric cancer cells (SGC-7901) and its possible mechanism in inhibition cancer growth.

METHODS: Using cell culture and immunocytochemical techniques, we examined the cell growth, DNA synthesis, expression of PCNA, cyclin A, B₁, D₁, P16^ink4a and P21^cip/waf1 of SGC-7901 cells which were treated with various c9,t11-CLA concentrations (25, 50, 100 and 200 μmol•L⁻¹)of c9,t11-CLA for 24 and 48 h, with a negative control (0.1% ethane).

RESULTS: The cell growth and DNA synthesis of SGC-7901 cells were inhibited by c9,t11-CLA. SGC-7901 cells. Eight day after treatment with various concentrations of c9,t11-CLA mentioned above, the inhibition rates were 5.92%, 20.15%, 75.61% and 82.44%, respectively and inhibitory effect of c9,t11-CLA on DNA synthesis (except for 25 μmol/L, 24 h) showed significantly less ³H-TdR incorporation than that in the negative controls (P < 0.05 and P < 0.01). Immunocytochemical staining demonstrated that SGC-7901 cells preincubated in media supplemented with different c9,t11-CLA concentrations at various times significantly decreased the expressions of PCNA (the expression rates were 7.2%-3.0%, 24 h and 9.1%-0.9% at 48 h, respectively), Cyclin A (11.0%-2.3%, 24 h and 8.5%-0.5%, 48 h), B₁ (4.8%-1.8% at 24 h and 5.5%-0.6% at 48 h)and D₁ (3.6%-1.4% at 24 h and 3.7%-0% at 48 h) as compared with those in the negative controls (the expressions of PCNA, Cyclin A, B₁ and D₁ were 6.5% at 24 h and 9.0% at 48 h, 4.2% at 24 h and 5.1% at 48 h, 9.5% at 24 h and 6.0% at 48 h, respectively) (P < 0.01), whereas the expressions of P16^ink4a and P21^cip/waf1, cyclin-dependent kinases inhibitors (CDKI), were increased.

CONCLUSION: The cell growth and proliferation of SGC-7901 cell is inhibited by c9,t11-CLA via blocking the cell cycle, with reduced expressions of cyclin A, B₁ and D₁ and enhanced expressions of CDKI (P16^ink4a and P21^cip/waf1).

Construction of cDNA representational difference analysis based on two cDNA libraries and identification of garlic inducible expression genes in human gastric cancer cells

AIM: To elucidate molecular mechanism of chemopreventive efficacies of garlic against human gastric cancer (HGC).

METHODS: HGC cell line BGC823 was treated with Allitridi (a kind of garlic extract) and Allitridi-treated and parental BGC823 cDNA libraries were constructed respectively by using λZAP II vector. cDNA Representational Difference Analysis (cDNA RDA) was performed using BamH I cutting-site and abundant cDNA messages provided by the libraries. Northern blot analysis was applied to identify the obtained difference products.

RESULTS: Two specific cDNA fragments were obtained and characterized to be derived from homo sapiens folate receptorα (FRα) gene and calcyclin gene respectively. Northern blot results showed a 4-fold increase in FRα gene expression level and 9-fold increase in calcyclin mRNA level in BGC823 cells after Allitridi treatment for 72 h.

CONCLUSION: The method of cDNA RDA based on cDNA libraries combines the high specificity of cDNA RDA with abundant cDNA messages in cDNA library; this expands the application of cDNA library and increases the specificity of cDNA RDA. Up-regulation of FRα gene and calcyclin gene expressions induced by Allitridi provide valuable molecular evidence for the efficacy garlic in treating HGC as well as other diseases.

Detection of H.pylori DNA in gastric epithelial cells by in situ hybridization

AIM

To investigate the presence of H.pylori DNA within gastric epithelial cells in patients with H.pylori infection and its possible carcinogenic mechanism.

METHODS

Total 112 patients, with pathologically confirmed chronic superficial gastritis, chronic atrophic gastritis, intestinal metaplasia, atypical hyperplasia or gastric cancer were studied. Among them, 28 were H.pylori negative and 84 H.pylori positive. H.pylori DNA in gastric epithelial cells was detected by GenPoint catalyzed signal amplification system for in situ hybridization.

RESULTS

In the H.pylori positive group, zero out of 24 chronic superficial gastritis (0.0%), four out of 25 precancerous changes (16.0%) and thirteen out of 35 gastric cancers (37.1%) showed H.pylori DNA in the nucleus of gastric epithelial cells, the positive rates of H.pylori DNA in the nucleus of gastric epithelial cells were progressively increased in chronic superficial gastritis, precancerous changes and gastric cancer groups (chi(2)=12.56, P=0.002); One out of 24 chronic superficial gastritis (4.2%), eleven out of 25 precancerous changes (44.0%) and thirteen out of 35 gastric cancers (37.1%) showed H.pylori DNA in the cytoplasm of gastric epithelial cells (chi(2)=10.86, P=0.004). In the H.pylori negative group, only one patient with gastric cancer was found H.pylori DNA in the nucleus of gastric epithelial cells; Only two patients, one patient with precancerous changes and another with gastric cancer, showed H.pylori DNA in the cytoplasm of gastric epithelial cells. Furthermore, H.pylori DNA must have been in the cytoplasm as long as it existed in the nucleus of gastric epithelial cells.

CONCLUSION

H.pylori DNA exists both in the nucleus and the cytoplasm of gastric epithelial cells in patients with H.pylori infections. The pathological progression from chronic superficial gastritis, precancerous changes to gastric cancer is associated with higher positive rates of H.pylori DNA presence in the nucleus of gastric epithelial cells.

Distribution of nitric oxide synthase in stomach myenteric plexus of rats

AIM: To study the distribution of nitric oxide synthase (NOS) in rat stomach myenteric plexus.

METHODS: The distribution of NOS in gastric wall was studied in quantity and location by the NADPH-diaphorase (NDP) histochemical staining method and whole mount preparation technique.

RESULTS: NOS was distributed in whole stomach wall, most of them were located in myenteric plexus, and distributed in submucosal plexus. The shape of NOS positive neurons was basically similar, most of them being round and oval in shape. But their density, size and staining intensity varied greatly in the different parts of stomach. The density was 62 ± 38 cells/mm² (antrum), 43 ± 32 cells/mm² (body), and 32 ± 28 cells/mm² (fundus), respectively. The size and staining intensity of NOS positive neurons in the fundus were basically the same, the neurons being large and dark stained, while they were obviously different in antrum. In the body of the stomach, the NOS positive neurons were in an intermediate state from fundus to antrum. There were some beadlike structures which were strung together by NOS positive varicosities in nerve fibers, some were closely adherent to the outer walls of blood vessels.

CONCLUSION: Nitric oxide might be involved in the modulation of motility, secretion and blood circulation of the stomach, and the significant difference of NOS positive neurons in different parts of stomach myenteric plexus may be related to the physiologic function of stomach.

Expression, deletion [was deleton] and mutation of p16 gene in human gastric cancer

AIM

To investigate the relationship between the expression of p16 gene and the gastric carcinogenesis, depth of invasion and lymph node metastases, and to evaluate the deletion and mutation of exon 2 in p16 gene in gastric carcinoma.

METHODS

The expression of p16 protein was examined by streptavidin-peroxidase conjugated method (S-P);the deletion and mutation of p16 gene were respectively examined by polymerase chain reaction (PCR) and polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP) in gastric carcinoma.

RESULTS

Expression of p16 protein was detected in 96.25% (77/80) of the normal gastric mucosa, in 92.00% (45/50) of the dysplastic gastric mucosa and in 47.54% (58/122) of the gastric carcinoma. The positive rate of p16 protein expression in gastric carcinoma was significantly lower than that in normal gastric mucosa and dysplastic gastric mucosa (P < 0.05). The positive rate of p16 protein expression in mucoid carcinoma 10.00% (1/10) was significantly lower than that in poorly differentiated carcinoma 51.22% (21/41), undifferentiated carcinoma 57.69% (15/26) and signet ring cell carcinoma 62.50% (10/16) (P < 0.05). The positive rate of p16 protein in 30 cases paired primary and lymph node metastatic gastric carcinoma: There was 46.67% (14/30) in primary gastric carcinoma, 16.67% (5/30) in lymph node metastatic gastric carcinoma. The positive rate of lymph node metastatic carcinoma was significantly lower than that of primary carcinoma (P < 0.05). There was of p16 gene mutation in exon 2, but 5 cases displayed deletion of p16 gene in exon 2 in the 25 primary gastric carcinomas.

CONCLUSIONS

The expression loss of p16 protein related to the gastric carcinogenesis, gastric carcinoma histopathological subtypes and lymph metastasis. The mutation of p16 gene in exon 2 may not be involved in gastric carcinogenesis. But the deletion of p16 gene in exon 2 may be involved in gastric carcinogenesis.