Evaluation of malignancy using Ki-67,p53,EGFR and COX-2 expressions in gastrointestinal stromal tumors

AIM:To investigate the role of expressions of Ki-67, p53,epidermal growth factor receptor(EGFR)and cyclooxygenase-2(COX-2)in gastrointestinal stromal tumor(GIST)grading and prognosis. METHODS:Tumor tissue was collected retrospectively from 96 patients with GIST.Antibodies against Ki-67, p53,EGFR and COX-2 were used for immunohistochemical staining.Tumor grading was designated according to a consensus system and the staining was quantified in 3 categories for each antibody in the statistical analysis. RESULTS:The Ki-67 expression in GISTs was significantly associated with the size of the tumors,mitotic rate and the risk of malignancy(x2=15.51,P=0.02; x2=22.27,P<0.001;x2=20.05;P<0.001).The p53 expression was also significantly correlated with mitotic rate and the risk of malignancy(x2=9.92,P= 0.04;x2=9.97;P=0.04).Over-expression of Ki-67 was strongly correlated with poor survival(x2=10.44, P=0.006),but no correlation was found between the expression of p53,EGFR or COX-2 and survival. Multivariate analysis further demonstrated that Ki-67 expression(relative risk=15.78,95%CI:4.25-59.37) could be used as an independent prognostic value for GIST patients.Adjuvant imatinib therapy could improve clinical outcomes in the patients with high risk and intermediate risk of recurrence after complete tumor resections(median survival time:52 mo vs 37 mo, x2=7.618,P=0.006). CONCLUSION:Our results indicated that the expression of Ki-67 could be used as an independent prognostic factor for GIST patients.

DNA methyltransferase3a expression is an independent poor prognostic indicator in gastric cancer

AIM: To explore the alteration of DNA methyltransferase expression in gastric cancer and to assess its prognostic value.METHODS: From April 2000 to December 2010, 227men and 73 women with gastric cancer were enrolled in the study. The expression of DNA methyltransferases(DNMTs), including DNMT1, DNMT3a and DNMT3b,in the 300 cases of gastric carcinoma, of which 85 hadpaired adjacent normal gastric mucus samples, was evaluated by immunohistochemistry using a tissue microarray. Serum anti-Helicobacter pylori(H. pylori) IgG was detected by enzyme-linked immunosorbent assay(ELISA). The relationships between the above results and the clinicopathological characteristics were analyzed. Their prognostic value was evaluated using the Cox proportional hazards model.RESULTS: In gastric cancer, expression of DNMTs was mainly seen in the nucleus. Weak staining was also observed in the cytoplasm. Expression of DNMT1, DNMT3a and DNMT3b in gastric cancer was significantly higher compared to that in the paired control samples(60.0% vs 37.6%, 61.2% vs 4.7%, and 94.1% vs 71.8%, P < 0.01). The overall survival rate was significantly higher in the DNMT3a negative group than in the DNMT3a positive group in gastric cancer patients(Log-rank test, P = 0.032). No significant correlation was observed between DNMT1 and DNMT3b expression and the overall survival time(Log-rank test, P = 0.289, P = 0.347). Multivariate regression analysis indicated that DNMT3a expression(P = 0.025) and TNM stage(P < 0.001), but not DNMT1(P = 0.54) or DNMT3b(P = 0.62), were independent prognostic factors in gastric cancer. H. pylori infection did not induce protein expression of DNMTs.CONCLUSION: The results suggest that expression of DNMT3a is an independent poor prognostic indicator in gastric cancer. DNMT3a might play an important role in gastric carcinogenesis.

CD24 genetic variants contribute to overall survival inpatients with gastric cancer

AIM: To investigate the role of single nucleotide polymorphisms(SNPs) in CD24 gene in susceptibility and overall survival of gastric cancer(GC).METHODS: We genotyped 3 tagging SNPs of CD24-P-534 in the promoter region, P170 in the coding region of exon 2 and P1527 in the 3′ untranslated region- using polymerase chain reaction-restriction fragment length polymorphism in specimens from 679 histologically-confirmed GC cases, 111 gastric atrophy(GA) cases and 976 tumor-free controls. Serumimmunoglobulin G antibodies to Helicobacter pylori(H. pylori) of all subjects were detected by enzyme-linked immunosorbent assay. CD24 expression was evaluated by immunohistochemistry in 131 GC specimens. Correlations between SNPs and risk of GC or GA were shown by P values and odd ratios(ORs) with 95% confidence intervals(95%CI) compared with the most common genotype of each SNP using the unconditional logistic regression model after adjusting for age, sex and H. pylori infection. Survival within each SNP group was plotted by Kaplan-Meier method and compared by log-rank test(recessive model). Hazard ratios with 95%CIs were computed by Cox regression model after adjusting for age, sex, histological type, tumor differentiation, clinical stage and post-operational chemotherapy.RESULTS: All of the three loci were in Hardy-Weinberg equilibrium in the control group. Median followup time for the 600 GC patients included in the survival analysis was 36.2 mo(range, 2.1-66.7 mo; 95%CI: 34.3-36.5 mo). Patients with the P-534 A/A genotype had significantly shorter survival(HR = 1.38, 95%CI: 1.01-1.88, P = 0.042) than did the C/C or C/A genotype carriers after adjusting for age, sex, histological type, tumor differentiation, clinical stage and post-operational chemotherapy. This trend was more evident in patients who lived longer than 2.5 years(HR = 7.55, 95%CI: 2.16-26.32, P = 0.001). The P170 T/T genotype was associated with a shorter lifespan than the non-T/T genotypes, but not significantly so. None of the three genetic variants was found to be associated with risk of GC(including tumor stage, grade and distant metastasis) or with risk of gastric atrophy. Furthermore, no difference of CD24 expression was found among the genotypes.CONCLUSION: The P-534 site in CD24 gene affects the overall survival of gastric cancer and may serve as a prognostic marker for gastric cancer.

Increased expression of tyrosine phosphatase SHP-2 in Helicobacter pylori-infected gastric cancer

AIM:To explore the alteration of tyrosine phosphatase SHP-2 protein expression in gastric cancer and to assess its prognostic values.METHODS:Three hundred and five consecutive cases of gastric cancer were enrolled into this study.SHP-2 expression was carried out in 305 gastric cancer specimens,of which 83 were paired adjacent normal gastric mucus samples,using a tissue microarray immunohistochemical method.Correlations were analyzed between expression levels of SHP-2 protein and tumor parameters or clinical outcomes.Serum anti-Helicobacter pylori(H.pylori) immunoglobulin G was detected with enzyme-linked immunosorbent assay.Cox proportional hazards model was used to evaluate prognostic values by compassion of the expression levels of SHP-2 and disease-specific survivals in patients.RESULTS:SHP-2 staining was found diffuse mainly in the cytoplasm and the weak staining was also observed in the nucleus in gastric mucosa cells.Thirty-two point five percent of normal epithelial specimen and 62.6% of gastric cancer specimen were identified to stain with SHP-2 antibody positively(P < 0.001).Though SHP-2 staining intensities were stronger in the H.pylori(+) group than in the H.pylori(-) group,no statistically significant difference was found in the expression levels of SHP-2 between H.pylori(+) and H.pylori(-) gastric cancer(P = 0.40).The SHP-2 expression in gastric cancer was not significantly associated with cancer stages,lymph node metastases,and distant metastasis of the tumors(P = 0.34,P = 0.17,P = 0.52).Multivariate analysis demonstrated no correlation between SHP-2 expression and disease-free survival(P = 0.86).CONCLUSION:Increased expression of SHP-2 protein in gastric cancer specimen suggesting the aberrant upregulation of SHP-2 protein might play an important role in the gastric carcinogenesis.

Suspension Polymerization of Methyl Methacrylate Stabilized Solely by Palygorskite Nano Fibers

A kind of fibrous clay, palygorskite （PAL）, was used as the sole stabilizer in suspension polymerization without the using of any other stabilizer usually used, especially polymeric stabilizers. In order to improve the compatibility with the organic monomer, PAL nano fibers were organically modified with silane coupling agent methacryloxypropyltrimethoxysilane （MPS）. Transmission electron microscopy （TEM） and Fourier-transform infrared （FTIR） spectroscopy results show that the hydrolyzed MPS was attached onto PAL surface through Si--O--Si bonds formation without morphology change of PAL. At a loading amount of PAL to monomer as low as 0.36 wt%, effective stabilization could be achieved. After suspension polymerization, spherical poly（methyl methacrylate） （PMMA） particles were obtained. Scanning electron microscopy （SEM） analysis on both the outer surface and the inner cracked surface of the spherical PMMA particles indicates that the PAL particles reside on the surface of the PMMA spheres. The densely stacked PAL together with attached silane coupling agent stabilized the droplets throughout the suspension polymerization.