The Role of miR-143 and miR-145 in the Invasion of Glioblastoma

Glioblastoma multiforme (GBM) is the most common and most malignant type of primary brain tumor. It is highly invasive and therefore difficult to treat. The life expectancy of patients harboring GBM is around 12-18 months, even in the best clinical trials. GBM invasion prevents a surgical cure; by the time the diagnosis is made, tumor cells have invaded normal tissue remote from the tumor mass. Small noncoding RNAs may contribute to the invasive phenotype of GBM. MicroRNAs (miRNAs) are small, single stranded noncoding regulatory RNA molecules that function to modulate the activity of specific mRNA targets and play important roles in a wide range of physiological and pathological processes. A previously established in vitro method was used to create GBM sub-populations with enhanced invasion (IM3 subpopulations). Comparison of micro-RNA expression profiles between GBM parental cell lines and IM3 sub-populations revealed differentially expressed miRNAs between the two cell lines. Two of these miRNAs, miR-143 and mIR-145 were found to be largely overexpressed in the IM3 subpopulations and may serve as potential mediators of the invasive phenotype. Knockdown of these miRNAs in U87 cell lines showed an alteration in GBM invasion. These miRNAs may serve as therapeutic targets that decrease tumor invasion

Serial selection for invasiveness increases expression of miR-143/miR-145 in glioblastoma cell lines

<p>Abstract</p> <p>Background</p> <p>Glioblastoma multiforme (GBM) is the most common primary central nervous system malignancy and its unique invasiveness renders it difficult to treat. This invasive phenotype, like other cellular processes, may be controlled in part by microRNAs - a class of small non-coding RNAs that act by altering the expression of targeted messenger RNAs. In this report, we demonstrate a straightforward method for creating invasive subpopulations of glioblastoma cells (IM3 cells). To understand the correlation between the expression of miRNAs and the invasion, we fully profiled 1263 miRNAs on six different cell lines and two miRNAs, miR-143 and miR-145, were selected for validation of their biological properties contributing to invasion. Further, we investigated an ensemble effect of both miR-143 and miR-145 in promoting invasion.</p> <p>Methods</p> <p>By repeated serial invasion through Matrigel^®-coated membranes, we isolated highly invasive subpopulations of glioma cell lines. Phenotypic characterization of these cells included <it>in vitro </it>assays for proliferation, attachment, and invasion. Micro-RNA expression was compared using miRCURY arrays (Exiqon). In situ hybridization allowed visualization of the regional expression of miR-143 and miR-145 in tumor samples, and antisense probes were used investigate <it>in vitro </it>phenotypic changes seen with knockdown in their expression.</p> <p>Results</p> <p>The phenotype we created in these selected cells proved stable over multiple passages, and their microRNA expression profiles were measurably different. We found that two specific microRNAs expressed from the same genetic locus, miR-143 and miR-145, were over-expressed in our invasive subpopulations. Further, we also found that combinatorial treatment of these cells with both antisense-miRNAs (antimiR-143 and -145) will abrogated their invasion without decreasing cell attachment or proliferation.</p> <p>Conclusions</p> <p>To best of our knowledge, these data demonstrate for the first time that miR-143 and miR-145 regulate the invasion of glioblastoma and that miR-143 and -145 could be potential therapeutic target for anti-invasion therapies of glioblastoma patients.</p