Laboratory of Gene and Molecular Therapy, Institute of Clinical Physiology, Area della Ricerca CNR,Via Moruzzi,1, Pisa 56124, Italy.
Mol Cancer. 2013 Jun 5;12(1):52. doi: 10.1186/1476-4598-12-52.
Circulating microRNAs (miRNAs) have been found in many body fluids and represent reliable markers of several physio-pathological disorders, including cancer. In some cases, circulating miRNAs have been evaluated as markers of the efficacy of anticancer treatment but it is not yet clear if miRNAs are actively released by tumor cells or derive from dead tumor cells.
We showed that a set of prostate cancer secretory miRNAs (PCS-miRNAs) were spontaneously released in the growth medium by DU-145 prostate cancer cells and that the release was greater after treatment with the cytotoxic drug fludarabine. We also found that the miRNAs were associated with exosomes, implying an active mechanism of miRNA release. It should be noted that in fludarabine treated cells the release of miR-485-3p, as well as its association with exosomes, was reduced suggesting that miR-485-3p was retained by surviving cells. Monitoring the intracellular level of miR-485-3p in these cells, we found that miR-485-3p was stably up regulated for several days after treatment. As a possible mechanism we suggest that fludarabine selected cells that harbor high levels of miR-485-3p, which in turn regulates the transcriptional repressor nuclear factor-Y triggering the transcription of topoisomerase IIα, multidrug resistance gene 1 and cyclin B2 pro-survival genes.
Cytotoxic treatment of DU-145 cells enhanced the release of PCS-miRNAs with the exception of miR-485-3p which was retained by surviving cells. We speculate that the retention of miR-485-3p was a side effect of fludarabine treatment in that the high intracellular level of miR-485-3p plays a role in the sensitivity to fludarabine.
循环 microRNAs（miRNAs）已在许多体液中发现，是多种生理病理紊乱（包括癌症）的可靠标志物。在某些情况下，循环 miRNAs 被评估为抗癌治疗效果的标志物，但尚不清楚它们是否是由肿瘤细胞主动释放的，还是来源于死亡的肿瘤细胞。
我们表明一组前列腺癌分泌的 miRNAs（PCS-miRNAs）可由 DU-145 前列腺癌细胞自发释放到生长培养基中，且在使用细胞毒性药物氟达拉滨处理后释放增加。我们还发现 miRNA 与外泌体相关，提示 miRNA 释放的是一种主动机制。需要注意的是，在氟达拉滨处理的细胞中，miR-485-3p 的释放及其与外泌体的关联减少，表明 miR-485-3p 被存活的细胞保留。在这些细胞中监测 miR-485-3p 的细胞内水平，我们发现 miR-485-3p 在治疗后几天内稳定上调。作为一种可能的机制，我们提出氟达拉滨选择了高 miR-485-3p 水平的细胞，反过来 miR-485-3p 又调节转录抑制因子核因子-Y，触发拓扑异构酶 IIα、多药耐药基因 1 和细胞周期蛋白 B2 等生存基因的转录。
氟达拉滨处理 DU-145 细胞增强了 PCS-miRNAs 的释放，但 miR-485-3p 除外，它被存活的细胞保留。我们推测 miR-485-3p 的保留是氟达拉滨治疗的副作用，因为高细胞内 miR-485-3p 水平在对氟达拉滨的敏感性中起作用。
