A microRNA-152 that targets the phosphatase and tensin homolog to inhibit low oxygen induced-apoptosis in human brain microvascular endothelial cells.

Brain damage caused by perinatal asphyxia is dangerous for neonatal infants, but the mechanism by which it occurs remains elusive. In this study, microRNA-152 (miR-152) expression was induced by low oxygen levels in rat models of hypoxia brain damage, as well as in human brain microvascular endothelial cells (HBMECs) cultured in vitro. Analysis of the sequence of miR-152 revealed that the phosphatase and tensin homolog gene (PTEN) is probably the target of miR-152 both in humans and rats. When HBMECs were transfected with miR-152 mimics, PTEN expression was inhibited at both the mRNA and protein levels. Moreover, transfection with the miR-152 mimic also inhibited apoptosis induced by hypoxia. Furthermore, expression of the pro-apoptotic gene Bax was downregulated while the anti-apoptotic gene Bcl2 was upregulated after miR-152 mimic transfection. Taken together, these results indicate that miR-152 induced by hypoxia suppresses cell apoptosis and acts as a protective factor during hypoxia by repressing PTEN.

Matrix metalloproteinase-2 and metalloproteinase-9 activities are associated with blood-brain barrier dysfunction in an animal model of severe sepsis.

There is no description on the mechanisms associated with blood-brain barrier (BBB) disruption during sepsis development. Thus, we here determined changes in permeability of the BBB in an animal model of severe sepsis and the role of matrix metalloproteinase (MMP)-2 and MMP-9 in the dysfunction of the BBB. Sepsis was induced in Wistar rats by cecal ligation and perforation. BBB permeability was assessed using the Evans blue dye method. The content of MMP-2 and MMP-9 in the cerebral microvessels was determined by western blot. The activity of MMP-2 and MMP-9 was determined using zymography. An inhibitor of MMP-2 and MMP-9 or specific inhibitors of MMP-2 or MMP-9 were administered to define the role of MMPs on BBB permeability, brain inflammatory response, and sepsis-induced cognitive alterations. The increase of BBB permeability is time-related to the increase of MMP-9 and MMP-2 in the microvessels, both in cortex and hippocampus. Using an MMP-2 and MMP-9 inhibitor, or specific MMP-2 or MMP-9 inhibitors, the increase in the permeability of the BBB was reversed. This was associated with lower brain levels of interleukin (IL)-6 and lower oxidative damage. In contrast, only the inhibition of both MMP-9 and MMP-2 was able to improve acute cognitive alterations associated with sepsis. In conclusion, MMP-2 and MMP-9 activation seems to be a major step in BBB dysfunction, but BBB dysfunction seems not to be associated with acute cognitive dysfunction during sepsis development.

The GSTT1 polymorphism of the glutathione S-transferase system in the intratumoral microvessel density of breast cancer patients.

It is well established that hypoxic microenvironment contributes to breast cancer progression by activation of transcriptional genes that promote angiogenesis. By promoting the antioxidant activity of glutathione, glutathione S-transferases (GSTs) are likely to facilitate the hypoxia-inducible factor-1α (HIF-1α) activity, therefore stimulating the angiogenesis. We investigated herein the influence of the GSTM1 and GSTT1 polymorphisms in the intratumoral angiogenesis of 87 patients with sporadic breast cancer. The intratumoral microvessel density (IMVD) of formalin-fixed paraffin-embedded tissues samples from all patients was determined by immunohistochemistry. The high IMVD was defined as a median microvessel counting higher than 18.7 after the analysis of histogram with all the results. The high IMVD was more common in patients with the GSTT1 wild genotype than in those with the GSTT1 null genotype (P = 0.04). Our results suggest, for the first time, that the GSTT1 polymorphism constitutes an inherited determinant of intratumoral angiogenesis in sporadic breast cancer.