Impact of circ<i>PVT1</i> Expression on Prostate Cancer Malignancy and Tumor Growth

The long non-coding RNA <i>PVT1</i> reportedly forms a circular RNA variant (circ<i>PVT1</i>). As circ<i>PVT1</i> is expressed in various cancers and has been implicated in promoting cancer cell proliferation and tumor progression, it is considered a potential biomarker and therapeutic target. We previously confirmed that circ<i>PVT1</i> expression varies according to the Gleason pattern, a morphological indicator of malignancy in prostate cancer. In this study, we assessed the expression of circ<i>PVT1</i> using BaseScope^TM assay with prostate cancer tissues and evaluated the correlation with the Grade Group (based on Gleason pattern), an indicator used to morphologically evaluate the degree of malignancy of prostate cancer. The relationship between circ<i>PVT1</i> expression and tumor proliferation was evaluated using cells in which circ<i>PVT1</i> expression was suppressed using the clustered regularly interspaced short palindromic repeats (CRISPR)/RfxCas13d system. BaseScope^TM assay confirmed that circ<i>PVT1</i> expression was significantly higher in Grade Group 2-5 (intermediate- and high-grade groups) than Grade Group 1 (low-grade group). <i>In vitro</i> experiments using the CRISPR/RfxCas13d system showed that specific suppression of circ<i>PVT1</i> expression resulted in a significant reduction in the number of prostate cancer cells. The results of this study suggest that circ<i>PVT1</i> is involved in tumor growth in prostate cancer and may serve as a therapeutic target for moderately and highly malignant prostate cancers that express circ<i>PVT1</i>.