radiation-induced bystander effects of adipose-derived mesenchymal stem cells

Objective: the interaction of tumor cells with surrounding stem cells such as adipose-derived mesenchymal stem cells (ascs) would be a crucial mechanism of tumor progression. it has been shown that irradiation can affect tumor microenvironment through different mechanisms. given that, we aimed to examine the bystander radiation-induced effects of ascs on different cancer cell lines. materials and methods: in this experimental study, ascs were extracted from five healthy donors, cultured and then irradiated with a 5gy of gamma radiation. following 72 hours of incubation, irradiated ascs-conditioned media (iacm) and non-irradiated ascs-conditioned media (niacm) were collected. following incubation of different cell lines, jurkat, lncap, u87-mg, mda-mb-231 and mcf-7, in different media, dmem, niacm, and iacm, aldefluor assay and wound healing assays, were conducted. using quantitative real-time polymerase chain reaction (qrt-pcr), the expression of atp-binding cassette transporter genes, abca1 and abcg2, was measured in these cell lines. results: niacm significantly increased aldh activity in mda-mb-231 cell (p=0.02), while iacm was associated with significant decrease in the lncap and mcf-7 cell lines, respectively p=0.02, p=0.03, compared to dmem as the control. the area of the scratch site was significantly reduced in mda-mb-231 cells cultured with niacm compared to dmem (p=0.04). furthermore, abca1 mrna expression was considerably decreased in iacm- but not in dmemtreated lncap line (p=0.01). conclusion: it seems, after exposing to radiation, ascs modify to prevent tumor development and metastasis through their radiation-induced bystander effects. therefore, a better understanding of ascs function in the tumor microenvironment may provide new insights into therapeutic strategies to surmount radio-resistance in cancer treatment.