| Resumo: |
Gastric cancer is the fourth most common cancer and the second leading cause of cancerrelated death worldwide. In Pará State, this neoplasia is a serious public health problem due to its late diagnosis that leads to low survival rates. These facts reinforce the severity of this pathology and the necessity of new studies aiming to change this panorama. Aim: 1) to compare the expression profiling of gastric adenocarcinoma and the matched non-neoplastic gastric tissue. 2) to identify deregulated proteins and to discover pathways and networks involved in gastric carcinogenesis. 3) to evaluate the mRNA and protein expression of ENOA/ENO1, HSPB1, NPM1 and 14-3-3ɛ/YWHAE in neoplastic and non-neoplasic gastric samples and associate the expression of the selected genes to clinicopathological characteristics of gastric adenocarcinomas. Methods: the protein profile was evaluated by two-dimensional gel electrophoresis in 15 pairs of neoplastic and the matched non-neoplastic gastric samples of individuals from Pará State. To select the differentially expressed proteins, we performed parametric tests with resampling. After protein identification, we performed cluster analysis, and the proteins were classified according to cellular location, biological process, molecular function and gene location. Bioinformatic analysis was used to discover the main canonical pathways and the physical and/or functional networks involved in gastric carcinogenesis. The expression of ENOA/ENO1, HSPB1, NPM1 and 14-3-3ɛ/YWHAE were evaluated by real-time quantitative PCR and by western blot. Results: 111 proteins were associated to gastric carcinogenesis. The cluster analysis revealed the presence of two main groups: one group composed by only non-neoplastic samples and the other group presented all tumor samples and two misclassified non-neoplastic samples. The computational analysis revealed several proteins involved in the energy production processes. By proteomic analysis, we observed two ENOA spots presenting elevated expression in neoplastic samples compared to non-neoplastic. The mean of ENOA expression by western blot was significantly reduced in gastric tumors. The reduced ENOA expression was associated to lower tumor invasion (T1/T2). By proteomic analysis, one spot of HSPB1 was observed with elevated expression in gastric cancers. By western blot, the HSPB1 expression did not differed between neoplastic and non-neoplastic gastric samples. The expression of NPM1 and 14-3-3e was significantly reduced in gastric tumors compared to non-neoplastic samples. The reduced expression of NPM1 was associated with a poor prognosis. The reduced expression of 14-3-3e was associated with diffuse-type and early onset gastric tumors. Conclusion: The present study identified several differentially expressed proteins, enhancing efforts to generate and expand knowledge about gastric carcinogenesis, especially in individuals from Pará State. NPM1 and 14-3-3e have a role as tumor suppressors in gastric carcinogenesis. The identified proteins may be useful biomarkers for assessment of diagnosis and prognosis, as well as may be possible targets for anticancer therapy. |
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