MiR-543/Numb promotes proliferation, metastasis, and stem-like cell traits of prostate cancer cells.

MiR-543 and Numb are associated with various malignancies, including prostate cancer (PCa). However, whether miR-543 regulates Numb in PCa development remains unclear. In this study, we identified Numb as a direct target of miR-543. The role of miR-543 was examined both in vitro and in vivo. The in vivo effects of miR-543 were investigated using tumor transplantation experiments and a lung metastasis model. The in vitro effects of miR-543 on proliferation, migration, invasion, and cancer stem-like cell (CSC)-associated properties were also examined. The binding sites of Numb were predicted using bioinformatics tools and confirmed by luciferase and rescue assays. QRT-PCR and western blot analyses were used to detect target expression levels. Expression levels of both miR-543 and Numb were manipulated in CD44+ and CD44-PCa cells followed by a series of functional assays. The results demonstrated that miR-543 promoted PCa growth and metastasis both in vivo and in vitro. Luciferase reporter assays, qRT-PCR, and western blot analyses revealed Numb as a direct target of miR-543. The function of miR-543 was abolished by Numb, as shown in rescue experiments. Moreover, miR-543 was verified to promote CSC properties, whereas Numb elicited the opposite effects. MiR-543 also influenced the expression of several stem-like factors, including Dll4, NF-κB, c-myc, and Oct-4, and the Numb/p53 signaling pathway. Taken together, these results demonstrate that miR-543 plays an oncogenic role by negatively controlling Numb, revealing the existence of an miR-543/Numb/p53 regulatory pathway in PCa tumorigenesis and development.