Deletion of NKX3.1 via CRISPR/Cas9 Induces Prostatic Intraepithelial Neoplasia in C57BL/6 Mice

Several techniques have been employed for deletion of the NKX3.1 gene, resulting in developmental defects of the prostate, including alterations in ductal branching morphogenesis and prostatic secretions as well as epithelial hyperplasia and dysplasia. To investigate whether the CRISPR/Cas9-mediated technique can be applied to study prostate carcinogenesis through exon I deletion of NKX3.1 gene, alterations in the prostatic intraepithelial neoplasia (PIN) and their regulatory mechanism were observed in the prostate of NKX3.1 knockout (KO) mice produced by the CRISPR/Cas9-mediated NKX3.1 mutant gene, at the ages of 16 and 24 weeks. The weight of dorsal-lateral prostate (DLP) and anterior prostate (AP) were observed to be increased in only the 24 weeks KO mice, although morphogenesis was constant in all groups. Obvious PIN 1 and 2 lesions were frequently detected in prostate of the 24 weeks KO mice, as compared with the same age wild type (WT) mice. Ki67, a key indicator for PIN, was densely stained in the epithelium of prostate in the 24 weeks KO mice, while the expression of p53 protein was suppressed in the same group. Also, both the 16 and 24 weeks KO mice reveal inhibition of the PI3K/AKT/mTOR pathway in the prostate. However, prostate specific antigen (PSA) levels and Bax/Bcl-2 expressions were decreased in the prostate of 16 weeks KO mice, and were increased in only the 24 weeks KO mice. Taken together, the results of the present study provide additional evidence that CRISPR/Cas9-mediated exon 1 deletion of the NKX3.1 gene successfully induces PIN lesions, along with significant alterations of Ki67 expression, EGFR signaling pathway, and cancer-regulated proteins.