Repression of Mafb promotes foreskin fibroblast proliferation through upregulation of CDK2, cyclin E and PCNA.

Mafb plays a significant role in the development and differentiation of various organs, tissues and cells. Nevertheless, its role in the control of external genital cell proliferation and function in the mechanism of hypospadias remains unknown. In this study, the expression of Mafb in foreskin fibroblasts was inhibited by siRNA. The Cell Count Kit-8 (CCK-8) assay showed cell proliferation increased after transfection, and the number of cells entered the S phase significantly increased via flow cytometry. Both mRNA and protein levels of cyclin E, cyclin-dependent kinase 2 (CDK2) and proliferating cell nuclear antigen (PCNA) were significantly upregulated in the siRNA group. Meanwhile, twenty-five prepuce tissue samples were collected from hypospadias repair surgery. These samples were divided into two groups: the severe and mild groups. Normal prepuce tissue specimens were obtained during circumcision as the normal control. The upregulated expression of cyclin E, CDK2 and PCNA and downregulated Mafb expression were observed in the hypospadias group. This study reveals for the first time that the reduction in Mafb promotes the foreskin fibroblast proliferation. Thus, downregulated Mafb expression may cause hypospadias by upregulating CDK2, cyclin E and PCNA. These findings can shed new light on the embryonic development of the urethra.