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©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 18 (4): gmr18213 M.L.A. Cirino et al. 2 and miR-222. We did not observe significant differences in miRNA expression in brain tissue in rats submitted to cerebral ischemia, physical exercise and both treatments when compared with the control group. However, miR-222 expression increased in the cerebral ischemia group submitted to physical exercise, which may help promote cerebrovascular regeneration.

Glioblastomas are the most common primary malignant brain tumors, and despite current advances in therapy, they are still extremely resistant to treatment. The tumorigenic potential of glioblastomas is due to a subpopulation of neoplastic cells, called cancer stem cells (CSCs), which in culture form a suspension cluster called neurospheres. Their properties include tumorigenesis, chemoresistance, and radioresistance. Several miRNAs exhibit altered expression levels during gliomagenesis; thus they constitute one of the key mechanisms for CSC regulation. We evaluated whether temozolomide and ionizing radiation modulate the expression of the tumor suppressor microRNAs-15, -16 and of the ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 18 (2): gmr18095 A.R. Rodrigues et al. 2oncogenic miR-21 in neurospheres and attached cells in a glioblastoma cell line culture (U343-MG). The methods included staining with Trypan blue to verify cell viability and real time PCR to quantify the expression of microRNAs after exposure to treatments. We observed that miR-16 was more highly expressed in neurospheres than in attached cells 48h after treatment with temozolomide, and miR-21 was highly expressed in attached cells compared to neurospheres treated with temozolomide at time 0 h (30 min after treatment); at 48 h this microRNA was highly expressed in neurospheres treated with temozolomide in association with ionizing radiation. We concluded that the microRNAs were differentially expressed when comparing the different cell types and treatment modalities. The higher expression of miR-21 in neurospheres at time 48 h may suggest a pathway of CSC radioresistance and chemoresistance, with further rapid tumor growth and recurrence or resistance to other treatment modalities.

Stroke is a major public health problem, with high mortality rates, and a high frequency of disability. Between 1990 and 2010, stroke increased from the fifth to the third leading cause of disability. In addition, its incidence has increased among younger people, with severe health consequences and increased social costs. There is evidence that physical exercise promotes neuroprotective effects when used as a therapeutic treatment. However, the mechanisms of neuroprotection are not yet well known. The objective of the study was to evaluate the expression profile of microRNAs miR-16, miR-21 and miR-155 and the CASPASE-3 and Bcl-2 genes previously related to apoptosis in the tissue (ischemic focus). Forty-eight Wistar rats were divided into four experimental groups: control group, ischemia group, ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 19 (4): gmr18594 L.B. Porsani et al. 2 exercise group and exercise + ischemia group. Before the ischemic procedure, the animals in the exercise and exercise + ischemia groups were submitted to a treadmill training protocol for four weeks. The training lasted 30 min a day at a speed of 18 m / min. For real-time PCR analysis, a fragment of the ischemic area was collected from each animal using a punch to analyze the expression of miRNAs; miR16, miR-21, miR-155, CASPASE-3 and Bcl-2 genes. In the animals that had physical exercise, there appeared to be a neuroprotective effect by the action of microRNAs and CASPASE-3, although no significant difference was observed. Further studies are needed to elucidate the role of apoptosis mechanisms in cerebral ischemia associated with physical exercise, as well as the role of microRNAs in the modulation of targets associated with this mechanism.