Mature microRNAs (miRNAs) produced from precursor microRNAs (pre-miRNAs) by the RNase Dicer have showed significant potential for cancer diagnosis and prognosis due to their key regulatory roles in various pathological processes. However, discriminatory detection of low-abundance miRNAs and pre-miRNAs remains a key challenge since the mature sequence is also present in the pre-miRNA forms. Herein, we report a novel cascade reaction to sensitively distinguish miRNAs versus pre-miRNAs in living cells based on two pairs of programmable hairpin oligonucleotide probes with a simple sequence design. The programmable hairpin probes can metastably coexist until the introduction of miRNAs or pre-miRNAs, which can trigger a specific hybridization chain reaction (HCR), respectively, leading to the self-assembly of nicked DNA duplex structures and a remarkable specific fluorescence intensity increase. The system can readily and sensitively assess the miRNA or pre-miRNA abundance in a homogeneous solution. The intracellular miRNA and pre-miRNA expression level assessment in different living cells is realized. Thus, we provide a novel investigation tool for discriminatorily and accurately assessing miRNA and pre-miRNA abundance, which could be useful for the biomedical application of miRNAs.

中文翻译：

---

灵敏地区分细胞内前体和成熟 microRNA 丰度†

RNase Dicer 从前体 microRNA (pre-miRNA) 产生的成熟 microRNA (miRNA) 由于其在各种病理过程中的关键调节作用，在癌症诊断和预后方面显示出巨大的潜力。然而，低丰度 miRNA 和 pre-miRNA 的区分检测仍然是一个关键挑战，因为成熟序列也存在于 pre-miRNA 形式中。在此，我们报告了一种新颖的级联反应，基于两对具有简单序列设计的可编程发夹寡核苷酸探针，可灵敏地区分活细胞中的 miRNA与pre-miRNA。可编程发夹探针可以亚稳态共存，直到引入 miRNA 或 pre-miRNA，分别触发特异性杂交链式反应 (HCR)，导致带切口的 DNA 双链体结构的自组装和显着的特异性荧光强度增加。该系统可以轻松、灵敏地评估均质溶液中 miRNA 或 pre-miRNA 的丰度。实现了不同活细胞中胞内miRNA和pre-miRNA表达水平的评估。因此，我们提供了一种新的研究工具，用于有区别地、准确地评估 miRNA 和 pre-miRNA 丰度，这可能有助于 miRNA 的生物医学应用。