The expression of MYC is strongly dependent on the circular PVT1 expression in pure Gleason pattern 4 of prostatic cancer.

PVT1 is a long-noncoding RNA and is highly expressed in various cancers including prostate cancers with stabilizing MYC protein. To characterize the objective biological features of the different morphological components such as Gleason patterns (GP) in prostate cancer, biopsy specimens containing only single pure GP (GP3, GP4, GP5) are used to analyze the relationship between PVT1 expression and MYC protein expression. The expressions of PVT1 and MYC were analyzed by quantitative PCR and the labeling index (LI) of MYC protein by immunohistochemical staining. PVT1, MYC, and MYC protein were highly expressed in GP 4, and interestingly the expression between PVT1 and MYC LI significantly correlated only in GP 4. In vitro experiments, the expression of MYC protein was slightly reduced by small interfering RNA against PVT1, while strongly reduced against specifically circular PVT1, splicing variants derived from the PVT1. Taken together, the expression characteristics of PVT1, MYC, and MYC protein differed depending on the GP. In particular, circular PVT1 might be strongly involved in the stabilization of MYC protein in GP4 and suggest different biological features.