In our previous studies, we found that in prostate cancer impaired recruitment of Drosha to the precursor of miR-7 (pri-miR-7) reduces production of mature miR-7, which leads to overexpression of its target gene Kruppel like factor 4 (KLF4), one of the key stemness gene, to enhance the stemness of PCSCs for promotion of tumor growth and metastasis (Chang et al., 2015). This evidence concerns the gene KLF4 and prostate cancer.