Abstract
BackgroundGastric carcinoma (GC) is the third leading cause of death among malignant tumors worldwide, causing approximately 900,000 deaths/year. Changes in oncogenes that encode tyrosine kinase receptors play an important role in the pathogenesis of GC. MET gene is a proto-oncogene that encodes a tyrosine kinase receptor c-MET and it is required for embryonic development and tissue repair. The hepatocyte growth factor (HGF) is the only known ligand for c-Met receptor. The MET oncogene activation suppresses apoptosis and promotes the survival, proliferation, migration, differentiation and angiogenesis of cells. Among the angiogenic factors, VEGF is the main regulator. Its biological function includes the promotion of endothelial cells mitosis to stimulate cells proliferation. These biomarkers expression in GC is relatively recent and population-based studies are required to define the expression pattern. The aim of this study was to determine qPCR technical standardization to evaluate quantitatively, in paraffin tissue samples, the presence of gene 23 expression of the MET, HGF and VEGF in diffuse and intestinal GC types.MethodsTwenty GC patients were studied, 10 patients were intestinal-type GC (average age 72.1 years) and 10 diffuse-type (average age 50.1 years). In all patients, tissue samples were analyzed from the tumor and distant areas of the tumor tissue. The relative expressions of the tumor markers c-Met, HGF and VEGF were performed by qPCR technique by comparing tumor and non-tumoral samples and they were normalized with the GAPDH constitutive gene. Statistical analysis was performed through T-test.ResultsFor c-Met, 18/20 (90%) patients expressed the marker and 9/20 (45%) overexpressed this gene, in which three were intestinal-type GC and six were diffuse-type GC. For HGF, only 7/20 (35%) patients expressed this gene and it was overexpressed in 4/20 (20%), in which two were intestinal-type GC and two were diffuse-type GC. For VEGF, 20/20 (100%) patients expressed this marker and in 12/20 (60%) were observed overexpression, in which eight patients had diffuse-type GC and four had intestinal-type GC.ConclusionsqPCR technique was standardized and suitable for expression analysis of the three biomarkers using paraffin embedded tissue samples. Further studies should be carried out to characterize the expression pattern of these biomarkers in GC in the Brazilian population.
Highlights
Gastric carcinoma (GC) is the third leading cause of death among malignant tumors worldwide, causing approximately 900,000 deaths/year
Four distinct molecular subtypes of gastric cancer have been described: the first one is the Epstein-Barr virus (EBV)-positive subtype; the second shows high microsatellite instability (MSI), where mutations tend to accumulate in repeated Deoxyribonucleic acid (DNA) sequences; the third and fourth subtypes have an alteration in the somatic copy number
The amplification was performed in triplicate using 30 ng of Complementary deoxyribonucleic acid (cDNA) by reaction on a StepOnePlusTM Real-Time Polymerase Chain Reaction (PCR) System (Applied Biosystems, United States of America (USA)) under the Results Table 1 displays characteristics of all GC patients included in the study by intestinal and diffuse histologic subtypes, age and sex group, where it is shown a significant difference among the ages of the two GC subtype groups (p < 0.001)
Summary
Gastric carcinoma (GC) is the third leading cause of death among malignant tumors worldwide, causing approximately 900,000 deaths/year. According to Laurén, the neoplasias can be classified into two main types: 1-intestinal, in which there is formation of clearly identifiable glands, with varying degrees of differentiation, whose cells are large and defined, pleomorphic, with hyperchromatic nuclei, frequently exhibiting gastric wall invasion. It is observed prevalence in populations at high risk for GC and in male patients, at a more advanced age; or 2diffuse, in which consists of the proliferation of isolated cells, in signet ring, with monomorphic and regular nuclei, without glandular formation, with a tendency to accumulate intracellular mucus that infiltrates into the gastric wall individually. This classification is believed to enable treatments to be tailored to individual patients according to the specific genetic features of their tumors
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