Prognostic and diagnostic implications of MMP-2, MMP-9, and VEGF-α expressions in colorectal cancer.

PURPOSE: Angiogenesis and tumor invasion are complex processes that are mediated by various proteins, such as vascular endothelial growth factor (VEGF-α) and the matrix-degrading enzymes metalloproteinase-2 and -9 (MMP-2, MMP-9). The aim of this study was to determine what roles MMP-2, MMP-9, and VEGF-α play in colorectal cancer (CRC) by correlating their expression levels with the cancer TNM stage, modified Dukes criteria, degree of cell differentiation, and long-term patient survival. METHODS: The present series consisted of tissue samples obtained from 180 patients who had undergone large bowel resection during 1995 and 2005 at the Luis Antonio Hospital. Archival paraffin-embedded CRC tissue samples were used to generate tissue microarray blocks, which were immunohistochemically stained for MMP-2, MMP-9, and VEGF-α. Three different grading systems were applied to evaluate staining intensity. Chi-squared Person test and Kaplan-Meier survival curves were used, and values of p<0.05 were considered statistically significant. RESULTS: MMP-2 expression showed a significant association with more invasive cancer stages (p<0.001) and death (p<0.041). VEGF-α expression correlated with a high TNM stage (p<0.009), the degree of cell differentiation (p<0.025) and patient death as a result of disease (p<0.035). The Kaplan-Meier survival estimated that patients with strong staining for MMP-2 (log-rank x(2)=34.09; p<0.0001), MMP-9 (log-rank x(2)=12.83; p<0.0003) and VEGF (log-rank x(2)=33.9; p<0.0001) showed a greater tendency towards death during 60 months of follow up. CONCLUSIONS: The quantification of VEGF-α, MMP-2 and MMP-9 expression in colorectal cancer may be related to survival. These data add to the growing epidemiological and experimental evidence that VEGF-α, MMP-2 and MMP-9 may play a role in colorectal tumorigenesis.

Vertical and temporal variation in phytoplankton assemblages correlated with environmental conditions in the Mundaú reservoir, semi-arid northeastern Brazil.

The goal of this study was to analyse the vertical structure of the phytoplankton community at the Mundaú reservoir, located in the semi-arid region of northeastern Brazil, and to correlate it to environmental conditions over two distinct seasons, dry and rainy. Samples were collected bimonthly at eight depths in the dry and rainy season for analyses of the physical and chemical variables of the water, as well as density, abundance, dominance, species diversity index and equitability of the community. Analysis of variance (ANOVA-two way) was used to analyse the vertical and seasonal differences, and Canonical Correspondence Analysis (CCA) was used to assess associations between phytoplankton and environmental variables Cylindrospermopsis raciborskii (Woloszynska) Seenaya and Subba Raju was the only dominant species and Geitlerinema amphibium (C. Agardh) Anagnostidis, Merismopedia punctata Meyen and Synedra rumpens Kützing. Others six taxa were abundant in at least one of the samples. Distinct vertical distribution patterns were observed for the abundant taxa between depths and seasons. The cyanobacteria, with the exception of C. raciborskii, showed similar seasonal patterns, with higher densities in the dry season. The CCA showed a strong correlation between the density of the phytoplanktonic species and abiotic variables. The vertical changes in abundant taxa revealed distinct patterns regulated by the variation in the environmental factors that were directly linked to seasonality, with the success of one or more species being dependent on their life strategies and ecological needs. The present study restates the importance of environmental and seasonal factors for phytoplankton composition and distribution in a freshwater tropical reservoir through a vertical gradient.