Maspin expression and its clinicopathological significance in tumorigenesis and progression of gastric cancer

AIM:To investigate maspin expression in tumorigenesis and progression of gastric cancer and to explore its relevant molecular mechanisms.METHODS:Formalin-fixed and paraffin-embedded tissues from normal mucosa (n=182), dysplasia (n=69), cancer (n=l13) of the stomach were studied for maspin expression by immunohistochemistry. Microvessel density (MVD) in gastric cancer was labeled using anti-CD34 antibody. Maspin expression was compared with clinical parameters and MVD of tumors. Caspase-3 expression was also detected in gastric carcinoma by immunohistochemistry. The relationship between Caspase-3 and maspin expression was concerned as well.RESULTS:The positive rates of maspin expression were 79.8% (145/182), 75.4%(52/69) and 50.4%(57/113) in normal mucosa, dysplasia and cancer of the stomach,respectively.Cancer less frequently expressed maspin than normal mucosa and dysplasia (P<0.05).Maspin expression showed a significantly negative association with invasive depth, metastasis, Lauren‘s and Nakamura‘s classification (P<0.05),but not with tumor size, Borrmann‘s classification,growth pattern or TNIVl staging (P>0.05). The positive rate of Caspase-3 was significantly lower in gastric cancer than in normal gastric mucosa (P<0.05,32.7% vs 50.4%). It was noteworthy that maspin expression was negatively correlated with MVD, but positively correlated with expression of Caspase-3 in gastric cancer (P<0.05).CONCLUSION:Down-regulated maspin expression is a late molecular event in gastric carcinogenesis. Reduced expression of maspin contributes to progression of gastric cancer probably by inhibiting cell adhesion, enhandng cell mobility,decreasing cell apoptosis and facilitating angiogenesis.Additionally altered expression of maspin underlies the molecular mechanism of differentiation of gastric cancer and supports the different histogenetic pathways of intestinal and diffuse gastric cancers. Maspin expression can be considered as an effective and objective marker to reveal biological behaviors of gastric cancer.     

Transcription factor Sp1 expression in gastric cancer and its relationship to long-term prognosis

AIM: To explore the expression of Spl in gastric carcinoma as well as its association with other clinicopathologic features, and to evaluate the role of Spl as a prognostic indicator of gastric carcinoma.METHODS: By using immunohistochemistry, we examined the Sp1 expression patterns in 65 cases of human gastric cancer, and 40 normal gastric mucosa specimens. Simultaneously, the correlation between Sp1 expression and clinical outcome or clinicopathologic features was investigated.RESULTS: The percentage of Spl expression was 12.5% (5/40) in normal gastric mucosa, and the Sp1 protein was mainly expressed in the nuclei of cells located in the mucous neck region. In sharp contrast, strong Sp1 expression was detected in tumor cells, whereas no or faint Sp1 staining was detected in stromal cells and normal glandular cells surrounding the tumors. The expression rate of Sp1 in gastric cancer lesions was 53.85% (35/65). The medium survival duration in patients who had a tumor with negative, weak and strong Sp1 expressions was 1700, 1560 and 1026d, respectively (P<0.05). Sp1 protein expression was closely related to the depth of tumor infiltration (x^2=13.223, P<0.01) and TNM stage (x^2=11.009, P<0.05), but had no relationship with the number of lymph nodes and Lauren‘s classification (P>0.05). Cox regression model for multivariate analysis revealed that high Spl expression (P<0.05) and advanced stage (P<0.01) were independent predictors of poor survival.CONCLUSION: Normal and malignant gastric tissues have unique Sp1 expression patterns. Spl might serve as an independent prognostic factor, by influencing the tumor infiltration and progression.     

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.     

Expression of gastric cancer—associated MG7 antigen in gastric cancer,precancerous lesions and H.pylori—associated gastric diseases

AIM: To investigate the relationship between the antigen MG7 antigen expression and gastric cancer as well as precancerous condition; to study the relationship between the MG7 antigen expression and H. pyloriinfection in benign gastric lesions in order to find out the effect of H. pylori infection on the process of gastric cancer development.METHODS: The level of MG7 antigen expression was determined by immunohistochemical method in 383 gastric biopsied materials. The intestinal metaplasia was determined by histochemistry method. The H. pyloriinfection was determined by HE stain, PCR and ELISA in 291 specimens, among which only 34 cases of H. pylori-associated gastric lesions were followed up.RESULTS: The positive rate of MG7 expression in normal gastric mucosa, intestinal metaplasia, dysplasia and gastric cancer increased gradually in ascending order (P＜0.01). The positive rate of MG7 antigen expression in type Ⅲ intestinal metaplasia of gastric mucosa was higher than that of type Ⅰand Ⅱ intestinal metaplasia, being highly significant (P＜0.05).The positive rate of MG7 antigen expression in superficial gastritis, atrophic gastritis and gastric cancer increased gradually (11.9 %, 64.8 %, 91.2 %, P＜0.01). There was no significant difference between H.pylori-negative and H. pyloripositive intestinal metaplasia, atrophic gastritis and dysplasia of gastric epithelium in the positive rate of MG7 antigen expression. There was no expression of MG7 antigen in H. pylori-negative superficial gastritis. The positive rate of MG7 expression in H. pylori-positive superficial gastritis was 20.5 %, and the difference between them was significant (P＜0.05). During following up, one of the three H. pylori negative cases turned positive again, and its MG7 antigen expression turned to be stronger correspondingly. 3 of 31 H. pyloripositive cases were detected as early gastric cancer, among which one with "+++" MG7 antigen expression was diminished after H. pylori eradication.CONCLUSION: MG7 antigen expression is highly specific in gastric cancer and can be used as a good marker for screening of gastric cancer; type Ⅲ intestinal metaplasia, atrophic gastritis and dysplasia should be followed up and MG7 antigen expression has high clinical value in the dynamic follow-up study; although the positive -MG7 in positiveH. pylorisuperficial gastritis show benign morphology in features, there is still the potential risk of developing into gastric cancer, hence special attention should be paid to those showing increasing MG7 antigen expression.     

PTEN encoding product： a marker for tumorigenesis and progression of gastric carcinoma

AIM: To detect the expression of PTEN encoding productin normal mucosa, intestinal metaplasia (IM), dysplasia andcarcinoma of the stomach, and to investigate its clinicalimplication in tumorigenesis and progression of gastriccarcinoma.METHODS: Formalin-fixed paraffin embedded specimens from184 cases of gastric carcinoma, their adjacent normal mucosa,IM and dysplasia were evaluated for PTEN protein expressionby SABC immunohistochemistry. PTEN expression wascompared with tumor stage, lymph node metastasis, Lauren'sand WHO's histological classification of gastric carcinoma.Expression of VEGF was also detected in 60 cases of gastriccarcinoma and its correlation with PTEN was concerned.RESULTS: The positive rates of PTEN protein were 100 %(102/102), 98.5 %(65/66), 66.7 % (4/6) and 47.8 %(88/184)in normal mucosa, IM, dysplasia and carcinoma of the stomach,respectively. The positive rates in dysplasia and carcinomawere lower than in normal mucosa and IM (P＜0.01).Advanced gastric cancers expressed less frequent PTEN thanearly gastric cancer (42.9 % v567.6 %, P＜0.01). The positiverate of PTEN protein was lower in gastric cancer with thanwithout lymph node metastasis (40.3 % v563.3 %, P＜0.01).PTEN was less expressed in diffuse-type than in intestinal-type gastric cancer (41.5 % v557.8 %,P＜0.05). Signet ringcell carcinoma showed the expression of PTEN at the lowestlevel (25.0 %, 7/28); less than well and moderatelydifferentiated ones (P＜0.01). Expression of PTEN was notcorrelated with expression of VEGF (P＞0.05).CONCLUSION: Loss or reduced expression of PTEN proteinoccures commonly in tumorigenesis and progression of gastriccarcinoma. It is suggested that PTEN can be an objective markerfor pathologically biological behaviors of gastric carcinoma.     

Relation of overexpression of S phase kinase-associated protein 2 with reduced expression of p27 and PTEN in human gastric carcinoma

AIM: To investigate the significance of S phase kinase associated protein 2 (Skp2) expression in human gastric carcinoma and the relation between expressions of Skp2, p27 and PTEN. METHODS: Immunohistochemical analysis was performed on 138 gastric carcinoma specimens, their paired adjacent mucosa specimens, 102 paired lymphatic metastatic carcinoma tissue specimens, 30 dysplasia specimens, 30 intestinal metaplasia specimens, 10 chronic superficial gastritis specimens and 5 normal gastric mucosa specimens for Skp2 expression and on 138 gastric carcinoma specimens for p27 and PTEN expression. RESULTS: Skp2 labeling frequency was significantly higher in intestinal metaplasia (12.68±0.86) and adjacent mucosa (19.32±1.22) than in normal gastric mucosa (0.53±0.13) and chronic superficial gastritis (0.47±0.19) (P = 0.000); in dysplasia (16.74±0.82) than in intestinal metaplasia (P = 0.000); in gastric primary carcinoma (31.34±2.17) than in dysplasia and adjacent mucosa (P = 0.000); in metastasis gastric carcinoma in lymph nodes (39.76±2.00) than in primary gastric carcinoma (P = 0.037), respectively. Skp2 labeling frequency was positively associated with differentiation degree (rho = 0.315, P = 0.000), vessel invasion (rho = 0.303, P = 0.000) and lymph node metastasis (rho = 0.254, P = 0.000) of gastric cancer. Expression of Skp2 was negatively associated with p27 (rho = -0.451, P = 0.000) and PTEN (rho = -0.480, P = 0.000) expression in gastric carcinoma. p27 expression was positively associated with PTEN expression in gastric carcinoma (rho = 0.642, P = 0.000). CONCLUSION: Skp2 overexpression may be involved in carcinogenesis and progression of human gastric carcinoma in vivo, possibly via p27 proteolysis. PTEN may regulate the expression of p27 by negatively regulating Skp2 expression.     

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

AIM: To determine the prevalence of Helicobacter pylori(H. pylon) 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. pyloriwas 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. pyloripositive patients,the IgG levels in severe CAG were significantly higher than those in mild CAG (P<0.01). In H. pylorinegative patients,both IgG and IgA levels increased remarkably in severe IM,compared to those in mild IM (P<0.01-0.05). H. pyhri infection exhibited no association with patient‘s gender (62.1% inmales; 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. pyloriinfection.     

Significance and relationship between Yes-associated protein and survivin expression in gastric carcinoma and precancerous lesions

AIM： To analyze the differences and relevance of Yesassociated protein （YAP） and survivin, and to explore the correlation and significance of their expression in gastric carcinoma and precancerous lesions.
METHODS： The PV9000 immunohistochemical method was used to detect the expression of YAP and survivin in 98 cases of normal gastric mucosa, 58 intestinal metaplasia （IM）, 32 dysplasia and 98 gastric carcinoma.
RESULTS： The positive rates of YAP in dysplasia （37.5%） and gastric carcinoma （48.0%） were significantly higher than that in normal gastric mucosa （13.3%）, P 〈 0.01. The positive rates of survivin in IM （53.4%）, dysplasia （59.4%） and gastric carcinoma （65.3%） were significantly higher than in normal gastric mucosa （11.2%）, P 〈 0.01. Survivin expression gradually increased from 41.7% in well differentiated adenocarcinoma through 58.3% in moderately differentiated adenocarcinoma to 75.6% in poorly differentiated adenocarcinoma, with significant Rank correlation, rk = 0.279, P 〈 0.01. The positive rate of survivin in gastric carcinoma of diffused type （74.6%） was significantly higher than that in intestinal type （51.3%）, P 〈 0.05. In gastric carcinoma with lymph node metastasis （76.9%）, the positive rate of survivin was significantly higher than that in the group without lymph node metastasis （41.2%）, P 〈 0.01. In 98 cases of gastric carcinoma, the expression of YAP and of survivin were positively correlated, rk = 0.246, P 〈 0.01.
CONCLUSION： YAP may play an important role as a carcinogenic factor and may induce survivin expression. Detecting both markers together may help in early diagnosis of gastric carcinoma.     

胃癌前组织和胃癌中hTERT、Bcl-2蛋白的表达及其相互关系

目的 探讨胃癌前组织及胃癌中人端粒酶催化亚单位(human telomerase catalytic subunit,hTERT)的表达状况及其与Bcl-2蛋白表达的关系。方法 应用免疫组织化学技术检测45例慢性胃炎和19例胃癌中hTERT和Bcl-2蛋白的表达。结果 hTERT蛋白表达率在萎缩性胃炎、肠化生、异形增生和胃癌等不同胃黏膜癌变过程中呈递增趋势;hTERT蛋白的表达率在胃癌组织中显著高于异形增生、肠化生和萎缩性胃炎组织(P<0.05);在异形增生组织中显著高于肠化生和萎缩性胃炎组织(P<0.05);在肠化生组织中显著高于萎缩性胃炎组织(P<0.05)。Bcl-2蛋白表达率在萎缩性胃炎、肠化生、异形增生和胃癌等不同胃黏膜癌变过程中呈递增趋势;Bcl-2蛋白的表达率在胃癌组织中显著高于异形增生、肠化生和萎缩性胃炎组织(P<0.05);在异形增生组织中显著高于萎缩性胃炎组织(P<0.05),亦高于肠化生,但是相差无显著性;在肠化生组织中显著高于萎缩性胃炎组织(P<0.05)。Bel-2蛋白阳性患者hTERT蛋白表达率为71.43％,Bcl-2蛋白阴性患者hTERT蛋白表达率34.44％,hTERT蛋白表达率在Bcl-2蛋白阳性患者中显著高于Bcl-2蛋白阴性患者(P<0.01)。结论 在胃癌和胃癌前病变阶段,端粒酶(telomerase)与Bcl-2均可能发挥重要作用,促进了胃癌的发生、发展;Bcl-2表达增加可能是胃     

放大内镜联合端粒酶逆转录酶对胃癌前病变的诊断价值

目的探讨放大内镜和人端粒酶逆转录酶（hTERT）在胃黏膜癌前病变中的诊断价值。方法应用放大内镜对154例病人进行检查,放大内镜下做出实时诊断,取活组织分别送病理学检查和实时荧光定量PCR检测hTERTmRNA的表达。放大内镜下胃小凹分为A、B、C、D、E5型。A型：圆点状小凹;B型：线状小凹;C型：稀疏而粗大的线状小凹;D型：斑块状;E型：绒毛状。结果放大内镜下B—E4种胃小凹形态肠上皮化生发生率差异有统计学意义（X^2=17．58,P〈0．05）,并且肠上皮化生的严重程度逐渐加重（Pearson列联系数=0．531,P〈0．05）;C—E3种胃小凹形态与不典型增生的严重程度关系密切（X^2=10．256,Pearson列联系数=0．549,P〈0．05）;B、C、D、E4型胃小凹形态间hTERT mRNA表达量差异有统计学意义（F=3．274,P〈0．05）。若以胃癌中hTERT mRNA表达量作为胃癌的诊断标准,病理未诊断为胃癌而放大内镜下表现为E型胃小凹的病人中65％符合该标准。结论放大内镜下胃黏膜微细结构形态可反映病变程度的轻重;hTERT是一重要的胃癌标志物,随访E型胃小凹和高hTERT表达的患者有助于早期发现胃癌。     

Alterations of telomerase activity and terminal restriction fragment in gastric cancer and its premalignant lesions

AIMS: In order to explore the role of alterations of telomerase activity and terminal restriction fragment (TRF) length in the development and progression of gastric cancer. METHODS: Telomerase activity was detected in 176 specimens of gastric mucosa obtained through an operation or endoscopical biopsy by using the telomeric repeat amplification protocol (TRAP) assay. Meanwhile, the mean length of TRF was measured with the use of a Southern blot in part of those samples. RESULTS: Telomerase activity was detected in 14 of 57 (24.6%) chronic atrophy gastritis patients, six of 18 (33.3%) intestinal metaplasia patients, three of eight (37.5%) dysplasia patients and 60 of 65 (92.3%) gastric cancer patients, respectively. Normal gastric mucosa revealed no telomerase activity. No association was found between telomerase activity and any clinicopathological parameters. The mean TRF length was decreased gradually with age in normal mucosa and in gastric cancer tissue. Regression analysis demonstrated that the reduction rate in these tissues was 41 +/- 12 base pairs/year. Among 35 gastric cancers, TRF length was shown to be shorter in 20 cases (57.1%), similar in 12 cases (34.3%) and elongated in three cases (7.6%), compared to the corresponding adjacent tissues. The mean TRF length tended to decrease as the mucosa underwent chronic atrophy gastritis, intestinal metaplasia, dysplasia and into gastric cancer. The mean TRF length in gastric cancer was not statistically correlated with clinicopathological parameters and telomerase activity. CONCLUSIONS: Our results suggest that telomerase is expressed during the early stage of gastric carcinogenesis, and that the clinical significance of TRF length appears to be limited in gastric cancer.