Myogenetic oligodeoxynucleotides as anti-nucleolin aptamers inhibit the growth of embryonal rhabdomyosarcoma cells

Background: Embryonal rhabdomyosarcoma (ERMS) is the muscle-derived tumor retaining myogenic ability. iSN04 and AS1411, which are myogenetic oligodeoxynucleotides (myoDNs) serving as anti-nucleolin aptamers, have been reported to inhibit the proliferation and induce the differentiation of myoblasts. The present study investigated the effects of iSN04 and AS1411 on the growth of multiple ERMS1 cell lines in vitro. Methods: Three patient-derived ERMS cell lines, ERMS1, KYM1, and RD, were used. Nucleolin expression and localization in these cells was confirmed by immunostaining. The effects of iSN04 or AS1411 on the growth of ERMS cells were examined by cell counting, EdU staining, quantitative RT-PCR (qPCR), and three-dimensional culture of tumorspheres. Results: In all ERMS cell lines, nucleolin was abundantly expressed, and localized and concentrated in nucleoli, similar to myoblasts. Both iSN04 and AS1411 (10-30 μM) significantly decreased the number of all ERMS cells; however, their optimal conditions were different among the cell lines. iSN04 (10 μM) markedly reduced the ratio of EdU+ cells, indicating the inhibition of cell proliferation. qPCR demonstrated that iSN04 suppressed the cell cycle, partially promoted myogenesis, but did not induce apoptosis. Finally, both iSN04 and AS1411 (10-30 μM) disrupted the formation and outgrowth of RD tumorspheres mimicking in vivo tumorigenesis. Conclusions: ERMS cells expressed nucleolin, and their growth was inhibited by the anti-nucleolin aptamers, iSN04 and AS1411. The present study provides the first evidence that anti-nucleolin aptamers can be used as nucleic acid drugs for chemotherapy against ERMS.

Nucleolin Improves Heart Function During Recovery From Myocardial Infarction by Modulating Macrophage Polarization

Background: Nucleolin has multiple functions within cell survival and proliferation pathways. Our previous studies have revealed that nucleolin can significantly reduce myocardial ischemia-reperfusion injury by promoting myocardial angiogenesis and reducing myocardial apoptosis. In this study, we attempted to determine the role of nucleolin in myocardial infarction (MI) injury recovery and the underlying mechanism. Methods: Male BALB/c mice aged 6–8 weeks were used to set up MI models by ligating the left anterior descending coronary artery. Nucleolin expression in the heart was downregulated by intramyocardial injection of a lentiviral vector expressing nucleolin-specific small interfering RNA. Macrophage infiltration and polarization were measured by real-time polymerase chain reaction, flow cytometry, and immunofluorescence. Cytokines were detected by enzyme-linked immunosorbent assay. Results: Nucleolin expression in myocardium after MI induction decreased a lot at early phase and elevated at late phase. Nucleolin knockdown impaired heart systolic and diastolic functions and decreased the survival rate after MI. Macrophage infiltration increased in the myocardium after MI. Most macrophages belonged to the M1 phenotype at early phase (2 days) and the M2 phenotype increased greatly at late phase after MI. Nucleolin knockdown in the myocardium led to a decrease in M2 macrophage polarization with no effect on macrophage infiltration after MI. Furthermore, Notch3 and STAT6, key regulators of M2 macrophage polarization, were upregulated by nucleolin in RAW 264.7 macrophages. Conclusions: Lack of nucleolin impaired heart function during recovery after MI by reducing M2 macrophage polarization. This finding probably points to a new therapeutic option for ischemic heart disease.

Identification of a Role for Nucleolin in Rabies Virus Infection

Rabies virus replicates in the cytoplasm of host cells, but rabies virus phosphoprotein (P-protein) undergoes active nucleocytoplasmic trafficking. Here we show that the largely nuclear P-protein isoform P3 can localize to nucleoli and forms specific interactions with nucleolin. Importantly, depletion of nucleolin expression inhibits viral protein expression and infectious virus production by infected cells. This provides the first evidence that lyssaviruses interact with nucleolin and that nucleolin is important to lyssavirus infection.