It has been reported that Dicer downregulation was involved in the process of tumor proliferation, invasion and metastasis through tumor specific suppressing miRNAs, such as miR-141 in colorectal cancer [18], let-7, miR-128b, and miR-200c in non-small cell lung cancer [44, 53], miR-125a or miR-125b in breast cancer [54], and miR-7 in glioma [55]. The gene discussed is DICER1; the disease is breast cancer.