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

Abstract 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.