Circular RNAs (circRNAs), a novel class of endogenous RNAs, have been recognized to play important roles in physiology and diseases. However, the molecular mechanisms that circRNAs coordinates directly in cell malignant transformation and its relationship to the proteotoxic stress response has never been defined. By comparing cells with high and low malignant potential alongside their non-transformed counterparts, we identified expression profiles of circRNAs specific to cell malignant transformation and distinct from proteotoxic stress response.