enrichment of a rare subpopulation of mir-302-expressing glioma cells by serum deprivation

objective: mir-302-367 is a cluster of polycistronic micrornas that are exclusively expressed in embryonic stem (es) cells. the mir-302-367 promoter is functional during embryonic development but is turned off in later stages. motivated by the cancer stem cell hypothesis, we explored the potential expression of mir-302 in brain tumor cell lines. materials and methods: in the present experimental study, we have tried to expand our knowledge on the expression pattern and functionality of mir302 cluster by quantifying its expression in a series of glioma (a-172, 1321n1, u87mg) and medulloblastoma (daoy) cell lines. to further assess the functionality of mir-302 in these cell lines, we cloned its promoter core region upstream of the enhanced green fluorescent protein (egfp) or luciferase encoding genes. results: our data demonstrated a very low expression of mir-302 in glioma cell lines, compared with that of embryonal carcinoma cell line nt2 being used as a positive control. the expression of mir-302 promoter-egfp construct in the aforementioned cell lines demonstrated gfp expression in a rare subpopulation of the cells. serum deprivation led to the generation of tumorospheres, enrichment of mir-302 positive cells and upregulation of a number of pluripotency genes. conclusion: taken together, our data suggest that mir-302 could potentially be used as a novel putative cancer stem cell marker to identify and target cancer stem cells within tumor tissues.