Preliminary investigation of methylation status of microRNA-124a in spinal cords of rat fetuses with congenital spina bifida.

OBJECTIVE: We investigated the expression of microRNA-124a and its methylation status in the spinal cords of rats with congenital spina bifida versus rats with normal fetuses. METHODS: Real-time quantitative reverse transcription-polymerase chain reaction was used to compare the expression of microRNA-124a in the spinal cords of 42 rats with all-trans retinoic acid induced congenital spina bifida and 42 rats with normal fetuses. The DNA methylation status in the promoter region of miRNA-124a was detected using methylation specific-PCR. RESULTS: Compared with rats with normal fetuses, expression of microRNA-124a was significantly decreased in rats with congenital spina bifida fetuses. The percentages of spinal cords with DNA hypermethylation in the microRNA-124a promoter were 81% and 14% in the congenital spina bifida and normal control groups, respectively. The difference was statistically significant. Further apoptosis testing revealed increased apoptosis cell numbers in the congenital spina bifida samples. Meanwhile, the phosphorylated mitogen-activated protein kinase protein expression level dramatically decreased in the congenital spina bifida samples. CONCLUSION: Aberrant DNA methylation was responsible for down-regulation of microRNA-124a by regulating the mitogen-activated protein kinase pathway, suggesting that microRNA-124a is a potential diagnostic biomarker in congenital spina bifida.

Altered microRNA expression profiles in a rat model of spina bifida.

MicroRNAs (miRNAs) are dynamically regulated during neurodevelopment, yet few reports have examined their role in spina bifida. In this study, we used an established fetal rat model of spina bifida induced by intragastrically administering olive oil-containing all-trans retinoic acid to dams on day 10 of pregnancy. Dams that received intragastric administration of all-trans retinoic acid-free olive oil served as controls. The miRNA expression profile in the amniotic fluid of rats at 20 days of pregnancy was analyzed using an miRNA microarray assay. Compared with that in control fetuses, the expression of miRNA-9, miRNA-124a, and miRNA-138 was significantly decreased (> 2-fold), whereas the expression of miRNA-134 was significantly increased (> 4-fold) in the amniotic fluid of rats with fetuses modeling spina bifida. These results were validated using real-time quantitative reverse-transcription polymerase chain reaction. Hierarchical clustering analysis of the microarray data showed that these differentially expressed miRNAs could distinguish fetuses modeling spina bifida from control fetuses. Our bioinformatics analysis suggested that these differentially expressed miRNAs were associated with many cytological pathways, including a nervous system development signaling pathway. These findings indicate that further studies are warranted examining the role of miRNAs through their regulation of a variety of cell functional pathways in the pathogenesis of spina bifida. Such studies may provide novel targets for the early diagnosis and treatment of spina bifida.

Expression of vascular endothelial growth factor (VEGF) and VEGF-C in serum and tissue of Wilms tumor.

BACKGROUND: Angiogenesis and lymphogenesis which were promoted by vascular endothelial growth factor (VEGF) and VEGF-C are important in the growth and metastasis of solid tumors. The high level of VEGF and VEGF-C were distributed in numerous types of cancers, but their distribution and expression in Wilms tumor, the most common pediatric tumor of the kidney, was unclear. METHODS: To learn about the distribution, mass spectroscopy and immunohistochemistry were used to measure the level of VEGF and VEGF-C in serum and tissue of Wilms tumor. RESULTS: The expression level of VEGF in serum of Wilms tumor was the same as in pre-surgery and control, so it was the same case of VEGF-C. Both of these factors were chiefly located in Wilms tumor tissue, but not in borderline and normal. In addition, the higher clinical staging and histopathologic grading were important elements in high expression of VEGF and VEGF-C. Gender, age and the size of tumor have not certainly been implicated in expression level of VEGF and VEGF-C. CONCLUSIONS: The lymph node metastasis and growth of tumors resulted from angiogenesis and lymphogenesis which were promoted by VEGF and VEGF-C in Wilms tumor. The autocrine and paracrine process of VEGF and VEGF-C were the principal contributor to specific tissues of Wilms tumor but not to the entire body.