1. Department of Medical Imaging, Tongji Hospital, Tongji University School of Medicine, Xincun road No. 389, Shanghai, China
2. Department of Orthopedics, Shanghai general hospital of Shanghai Jiaotong university, WujinRoad No. 85, 200080, shanghai, China.
3. Department of Human Anatomy and Neurobiology, Nantong University, School of Medicine, Qixiu road No. 19, Nantong 226001, Jiangsu, China.
4. Department of Urology, Huashan Hospital, Fudan University, Urumuqi Road No.12, 200040, Shanghai, China
5. Department of Urology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jingwuweiqi Road No.324, Jinan 250001, Shandong, China.
# Contributed equally
Background: Circular RNAs (circRNAs), a novel class of endogenous noncoding RNAs, are involved in a variety of diseases, including several types of cancers. We hypothesized that circRNAs are involved in the tumorigenesis and development of clear cell renal cell carcinoma (ccRCC).
Methods: To verify our hypothesis, we explored the circRNA expression profiles in 4 pairs of ccRCC tissues and their adjacent non-carcinoma tissues via microarray analysis. Selected circRNAs were further validated by qPCR. Moreover, hsa_circ_0005875 was selected for further study and the potential clinical values of hsa_circ_0005875 were investigated in 60 pairs of ccRCC tissues and adjacent normal controls. In addition, the role of hsa_circ_0005875 in ccRCC progression were performed using colony formation assay, Transwell assay and Martrigel-Transwell assay respectively. Finally, interactions between the circRNAs and miRNAs were predicted using Arraystar's miRNA target prediction software. Luciferase reporter assays were performed to evaluate the interaction between hsa_circ_0005875 and hsa_miR-145-5p.
Results: The microarray data showed 1988 circRNAs were significantly dysregulated circRNAs, including 1033 upregulated and 955 downregulated ones in the ccRCC tissues. Hsa_circ_0005875 was confirmed to be significantly upregulated in the ccRCC tumor tissues and renal carcinoma cells. Further analysis revealed that hsa_circ_0005875 expression was associated with tumor size, pathological TNM stage, histological differentiation, and lymphatic metastasis. Functional experiments demonstrated that overexpression of hsa_circ_0005875 increased proliferation, migration and invasion abilities. Moreover, bioinformatics analysis and luciferase reporter assays suggest that hsa_circ_0005875 may serve as a ceRNA (competing endogenous RNA) of miR-145-5p to relieve the repressive effect of miR-145-5p on target ZEB2.
Conclusions: These data indicate that hsa_circ_0005875 might play a role in promoting tumor growth and metastasis and be a potential biomarker of ccRCC.
Keywords: circRNAs, clear cell renal cell carcinoma, microarray analysis, miRNA sponge, biomarker, hsa_circ_0005875