RRM2 and neoplasm: Notably, RRM2 exhibited significant inverse correlations with let-7f-5p (R = -0.14525, P = 0.001), let-7b-3p (R = -0.23631, P = 7.29E-08), and let-7b-5p (R = -0.32575, P = 6.1E-14), suggesting that these miRNAs may function as tumor suppressors by negatively regulating RRM2 expression.