circCRKL suppresses the progression of prostate cancer cells by regulating the miR-141/KLF5 axis

Background: Prostate cancer (PCa) is a prevalent human malignancy in males. Circular RNA circCRKL (Hsa_circ_0001206) was reported to be lowly expressed in PCa tissues. However, the regulatory role of circCRKL in PCa is poorly defined. Methods: Levels of circCRKL, microRNA-141 (miR-141), and Kruppel-like factor (KLF5) were measured by realtime quantitative polymerase chain reaction (RT-qPCR). Cell cycle progression, apoptosis, migration, and invasion were examined by Flow cytometry, Wound healing, and transwell assays. The underlying relationship between miR-141 and circCRKL or KLF5 was predicted by starBase, and then verified by a dual-luciferase reporter, RNA Immunoprecipitation (RIP), and RNA pull-down assays. The protein level of KLF5 was assessed by western blot assay. The biological role of circCRKL was detected by a xenograft tumor model in vivo. Results: CircCRKL and KLF5 were decreased, and miR-141 was increased in PCa tissues and cells. The functional analysis discovered that the overexpression of circCRKL repressed cell cycle progression, migration, invasion, and boosted apoptosis of PCa cells. Mechanically, circCRKL could positively regulate KLF5 expression by sponging miR-141. In addition, circCRKL upregulation could hinder PCa tumor growth in vivo. Conclusion: These findings revealed that circCRKL inhibited the progression of PCa through upregulating KLF5 expression by sponging miR-141, elucidating a novel regulatory pathway in PCa cells. Our research suggested an underlying circRNA-targeted therapy for PCa.