Circular RNA hsa_circ_0003221 (circPTK2) promotes the proliferation and migration of bladder cancer cells.

Emerging studies have shown that circular RNAs could be ideal biomarkers and even potential therapeutic targets for some tumors, including bladder cancer. However, only a few studies have investigated the circular RNAs in human bladder cancer. The key circular RNA molecules are closely related to bladder cancer and their roles remain largely unknown. Here, we investigated a novel circular RNA molecule, hsa-circ-0003221(circPTK2), which is differentially expressed in bladder carcinoma. Significant differential expression levels of circPTK2 were confirmed with quantitative PCR in 40 pairs of tissue and blood samples from patients with bladder carcinoma. Moreover, circPTK2 levels both in tissue and blood were significantly correlated with several clinicopathologic characteristics, including poor differentiation (P = 0.0103 in tissue, P = 0.024 in blood), N2-N3 lymph node metastasis (P = 0.0065 in tissue, P = 0.016 in blood), and T(II-III-IV) stage (P = 0.008 in tissue, P = 0.0003 in blood). Quantitative PCR results confirmed that circPTK2 is highly expressed in migrated cells separated by Transwell assay and in metastatic lymph nodes of tumors transplanted in nude mice. In vitro silence of circPTK2 by small interfering RNA inhibited the proliferation and migration of bladder cancer cells. On the contrary, circPTK2 overexpression promoted proliferation and migration. This study showed that circPTK2 promotes proliferation and migration of cells and may be a novel potential biomarker and therapeutic target for bladder cancer diagnosis and therapy.