It has been reported that dysregulation of microRNA-155 expression and function is associated with tumorigenesis, growth, tumor subtypes, invasion, and poor survival rates. Peptide nucleic acid (PNA), an artificially synthesized nucleic acid mimic, has been applied for molecular diagnosis. In this study, a PNA sequence that undergoes complementary binding to miR-155 was labeled with ^99mTc to evaluate whether the tracer could visualize the expression of miR-155 in breast cancer. Both antisense PNA (anti-PNA, fully complementary bound to human mature miR-155, referred to as “anti-PNA-155”) and mismatched PNA (referred to as “mis-PNA”) single strands containing 23-mer were synthesized. The relative expression of miR-155 in MCF-7 cells and tumors was higher than that in MDA-MB-231 cells and tumors. Single-photon emission computed tomography (SPECT) scan showed that radioactivity mainly accumulated in kidney. MCF-7 tumors, but not MDA-MB-231 tumors, were clearly visualized after [^99mTc]anti-PNA-155 injection. MCF-7 tumors were less visible when coinjected with 100-fold excess of anti-PNA-155 or injected with [^99mTc]mis-PNA, which suggested specific binding. Biodistribution study results were consistent with SPECT imaging. We successfully demonstrated that [^99mTc]anti-PNA-155 could visualize miR-155 expression in vivo, suggesting it may be a promising probe applied in breast cancer.

据报道，microRNA-155表达和功能的失调与肿瘤发生，生长，肿瘤亚型，侵袭和不良的存活率有关。肽核酸（PNA）是一种人工合成的核酸模拟物，已用于分子诊断。在这项研究中，将与miR-155互补结合的PNA序列标记为^99m Tc，以评估示踪剂是否可以可视化miR-155在乳腺癌中的表达。两种反义PNA（anti-PNA，与人类成熟miR-155完全互补结合）合成了称为23-mer的单链，称为“抗-PNA-155”和错配的PNA（称为“ mis-PNA”）单链。miR-155在MCF-7细胞和肿瘤中的相对表达高于MDA-MB-231细胞和肿瘤中的相对表达。单光子发射计算机断层扫描（SPECT）扫描显示放射性主要在肾脏中积累。注射[ ^99m Tc]抗PNA-155后，可以清楚地看到MCF-7肿瘤，而不是MDA-MB-231肿瘤。当共同注射100倍过量的抗PNA-155或注射[ ^99m Tc] mis-PNA时，MCF-7肿瘤不那么明显，这表明它们具有特异性结合。生物分布研究结果与SPECT成像一致。我们成功地证明了[ ^99mTc] anti-PNA-155可以在体内可视化miR-155的表达，表明它可能是应用于乳腺癌的有前途的探针。