Up-regulation of tumor necrosis factor-α pathway survival genes and of the receptor TNFR2 in gastric cancer.

BACKGROUND: Gastric carcinogenesis can be induced by chronic inflammation triggered by Helicobacter pylori (H. pylori) infection. Tumor necrosis factor (TNF)-α and its receptors (TNFR1 and TNFR2) regulate important cellular processes, such as apoptosis and cell survival, and the disruption of which can lead to cancer. This signaling pathway is also modulated by microRNAs (miRNAs), altering gene expression. AIM: To evaluate the mRNA and miRNAs expression involved in the TNF-α signaling pathway in gastric cancer (GC) tissues and its relationship. METHODS: Quantitative polymerase chain reaction (qPCR) by TaqMan® assay was used to quantify the RNA transcript levels of TNF-α signaling pathway (TNF, TNFR1, TNFR2, TRADD, TRAF2, CFLIP, NFKB1, NFKB2, CASP8, CASP3) and miRNAs that targets genes from this pathway (miR-19a, miR-34a, miR-103a, miR-130a, miR-181c) in 30 GC fresh tissue samples. Molecular diagnosis of H. pylori was performed by nested PCR for gene HSP60. A miRNA:mRNA interaction network was construct using Cytoscape v3.1.1 from the in silico analysis performed using public databases. RESULTS: Up-regulation of cellular survival genes as TNF, TNFR2, TRADD, TRAF2, CFLIP, and NFKB2, besides CASP8 and miR-34a was observed in GC tissues, whereas mediators of apoptosis such as TNFR1 and CASP3 were down-regulated. When the samples were stratified by histological type, the expression of miR-103a and miR-130a was significantly increased in the diffuse-type of GC compared to the intestinal-type. However, no influence of H. pylori infection was observed on the expression levels of mRNA and miRNAs analyzed. Moreover, the miRNA:mRNA interaction network showed several interrelations between the miRNAs and their target genes, highlighting miR-19a and miR-103a, which has as predicted or validated target a large number of genes in the TNF-α pathway, including TNF, TNFR1, TNFR2, CFLIP, TRADD, CASP3 and CASP8. CONCLUSION: Our findings show that cell survival genes mediated by TNF/TNFR2 binding is up-regulated in GC favoring its pro-tumoral effect, while pro-apoptotic genes as CASP3 and TNFR1 are down-regulated, indicating disbalance between apoptosis and cell proliferation processes in this neoplasm. This process can also be influenced by an intricate regulatory network of miRNA:mRNA.

kDNA gene signatures of Trypanosoma cruzi in blood and oesophageal mucosa from chronic chagasic patients.

Trypanosoma cruzi presents a high degree of intraspecific variability, with possible implications for the pathogenesis of Chagas disease. The aim of this study was to evaluate T. cruzi kDNA minicircle gene signatures using the low-stringency single-specific-primer PCR technique in both peripheral blood and oesophageal mucosa from chronic chagasic patients, with or without megaesophagus, alone or in combination with cardiopathy and megacolon. It was not possible to identify a uniform pattern of shared bands between blood and oesophageal mucosa samples from individuals with the same clinical form or mixed forms, suggesting multiple T. cruzi infections with differential tissue tropism. Thus, the results indicate that there is an intense intraspecific variability in the hypervariable regions of T. cruzi kDNA, which has so far made it impossible to correlate the genetic profile of this structure with the clinical manifestations of Chagas disease.

Implications of genetic variability of Trypanosoma cruzi for the pathogenesis of Chagas disease

Trypanosoma cruzi, the etiological agent of Chagas disease, presents a high degree of intraspecific genetic variability, with possible implications for the clinical forms of the disease, like the development of cardiopathy, megaesophagus, and megacolon, alone or in combination. This tissue tropism involved in the pathogenesis of Chagas disease has still not been totally elucidated. Thus, the current review approaches key aspects of T. cruzi genetic diversity, the clinical forms of Chagas disease, and the infection of the host cell by the parasite and the immune response. Other aspects discussed here include the release of immunosuppressive factors by the parasite, acting in the host's immune response pathways; host cell apoptosis inhibition; the pathogenesis of chagasic megaesophagus, which can be related to host-parasite interaction; and finally the association between megaesophagus and increased risk for the development of squamous-cell esophageal carcinoma. However, despite great advances in the understanding of this disease, it is still not possible to establish the true relationship between the parasite's genetic variability and the clinical form of Chagas disease.

O Trypanosoma cruzi, agente etiológico da doença de Chagas, apresenta elevado grau de variabilidade genética intra-específica, com possíveis implicações na forma clínica da doença, como o desenvolvimento de cardiopatia, do megaesôfago e do megacólon de forma isolada ou em associação. Este tropismo tecidual envolvido na patogênese da doença não está totalmente esclarecido. Assim, nesta revisão são abordados alguns aspectos referentes à diversidade genética dos parasitas isolados, às formas clínicas da doença de Chagas, ao processo de infecção do parasita na célula hospedeira e resposta imune. Outros aspectos também são enfocados, como os fatores imunossupressivos liberados pelo parasita que atuam na regulação das respostas imunes, a inibição da apoptose da célula hospedeira, assim como da patogênese do megaesôfago chagásico que pode estar relacionada à interação hospedeiro- parasita e sua associação com risco aumentado para o desenvolvimento do carcinoma epidermóide do esôfago. Porém, apesar dos avanços no entendimento desta doença, ainda não é possível estabelecer o verdadeiro perfil da variabilidade genética do parasita com a forma clínica da doença de Chagas.

Implications of genetic variability of Trypanosoma cruzi for the pathogenesis of Chagas disease.

Trypanosoma cruzi, the etiological agent of Chagas disease, presents a high degree of intraspecific genetic variability, with possible implications for the clinical forms of the disease, like the development of cardiopathy, megaesophagus, and megacolon, alone or in combination. This tissue tropism involved in the pathogenesis of Chagas disease has still not been totally elucidated. Thus, the current review approaches key aspects of T. cruzi genetic diversity, the clinical forms of Chagas disease, and the infection of the host cell by the parasite and the immune response. Other aspects discussed here include the release of immunosuppressive factors by the parasite, acting in the host's immune response pathways; host cell apoptosis inhibition; the pathogenesis of chagasic megaesophagus, which can be related to host-parasite interaction; and finally the association between megaesophagus and increased risk for the development of squamous-cell esophageal carcinoma. However, despite great advances in the understanding of this disease, it is still not possible to establish the true relationship between the parasite's genetic variability and the clinical form of Chagas disease.

Cytogenetic alterations in chagasic achalasia compared to esophageal carcinoma.

Patients with chagasic achalasia (megaesophagus) are liable to have an additional 1.7-20% possibility of developing esophageal squamous cell carcinoma (ESCC). We applied a fluorescence in situ hybridization technique in 20 such patients and found aneuploidies of chromosomes 7, 11, and 17 in 60% (12 of 20 specimens) and deletion of the TP53 gene in 54.5% (6 of 11 specimens; it was only possible to obtain data by FISH technique from 11 of the 20 achalasia patients). The main aneuploidies detected were chromosome 7 monosomy or trisomy (35%) in mid-third megaesophagus cases, and chromosome 17 monosomy or trisomy (25%) in distal-third cases. TP53 gene deletion was more frequent in mid-third (62.5%) than in distal-third megaesophagus cases (40%). In chagasic megaesophagus, no amplification of the cyclin D1 gene (CCND1) was observed. Comparing chagasic megaesophagus to ESCC, we found a higher frequency of aneuploidies in all 10 tumors. The main alterations were trisomy or tetrasomy of chromosomes 17 (90%), 11 (70%), and 7 (70%). Amplification of CCND1 was evidenced as a cluster in 70% of the tumors (22-99% of nuclei), while TP53 gene deletion occurred in 100%. To our knowledge, this is the first cytogenetic analysis of chagasic megaesophagus to show that aneuploidies of chromosomes 7, 11, and 17, and TP53 gene deletion might be related to increased risk for malignancy.