Expression patterns of microRNAs are altered in hypoxic human neuroblastoma cells

There was a report that microRNA (miRNA) controls multiple genes. In addition, there are some reports that the presence of neoplastic cells that are hypoxic because of rapid tumor development is related to prognosis. As a step toward identifying the role of miRNA in hypoxic tumor cells, the present study was designed to determine which miRNAs have increased expression and which have decreased expression in hypoxic neuroblastoma cells.

For this study, we used seven neuroblastoma cell lines. In four with MYCN was amplified; in the other three MYCN was non-amplified. Neuroblastoma cells were cultured under hypoxic conditions. The expression levels of 662 kinds of miRNA in the hypoxic cells were quantified by gene array.

We found that the expression of 85 kinds of miRNA was increased. Expression of six of these mRNAs was increased in two or more cell lines. Hsa-miR-143, -145, and -210 were each expressed in four of the seven cell lines. In addition, expression of 48 kinds of miRNA was decreased. Expression of five was decreased in two cell lines. There was no relation between the expression of miRNA and the amplification of MYCN.

Our results thus suggest a possible causal relation between these three miRNAs and the malignancy of neuroblastoma in hypoxic conditions.