Fig. 1

circ-Dnmt1 enhanced cell survival. a Comparison of circRNA levels in eight human breast cancer cell lines relative to human breast cell line MCF-10A by using the Agilent Human circular RNA microarray. b RT-PCR showed that expression of circ-Dnmt1 in human non-cancer cell lines (HaCaT, 293T, BEAS2B, Jurkat, HUVEC, and MCF10A), breast cancer cell lines (MCF-7, MDA-MB-468, MDA-MB-231, HTB126, and SK-BR-3), and other tumor cell lines (H460, LnCap, Du145, PC3, JHH1, SNU449, HepG2, and Hela). c Total RNAs were isolated from tumor tissues and adjacent tissues of breast carcinoma patients and subjected to qPCR. The levels of circ-Dnmt1 were significantly higher in the tumor tissues relative to the adjacent tissues. d Structure of circ-Dnmt1 and a designed circ-Dnmt1 expression construct. e Total RNA was extracted from mock- or circ-Dnmt1-transfected MCF-7 cells and incubated with or without RNAse R at 37 °C for 10 min, followed by gel electrophoresis and northern hybridization using circ-Dnmt1 sequence as a probe to confirm overexpression of circ-Dnmt1 and its resistance to RNAse R treatment. The lower portion was the photo of Ethidium Bromide staining. f Left, RT-PCR showing product from vector- and circ-Dnmt1-transfected cells. Right, The PCR product was cloned and sequenced. This confirmed the correct junction (arrow) sequence of circ-Dnmt1. g Circ-Dnmt1-, vector-transfected, and wild-type MCF-7 cells were seeded in 96-well plates at the density of 1 cell per well in DMEM containing 10% FBS. Cell numbers were counted for up to 13 days