Circular RNAs are a new class of RNA which have a covalently closed structure. Circular RNAs have many functions, they can act as oncogenes or tumor suppressors, and are often dysregulated in various cancers, including hepatocellular carcinoma. Circular RNAs are synthesized during the process called backsplicing that depends on canonical spliceosomal machinery and both cis-acting and trans-acting factors such as RNA-binding proteins. Upregulated expression of RNA-binding proteins NONO and PCBP2 is statistically significantly negatively correlated with poorer survival of liver cancer patients. The aim of the thesis was to examine the role of NONO and PCBP2 in the regulation of the expression of selected circular RNAs that are dysregulated in liver cancer tumors. In vitro analysis was performed in the human hepatocellular cell line Huh-7. In this thesis we successfully overexpressed both RNA-binding proteins, NONO and PCBP2, measured the expression of circular RNAs in cells with overexpressed proteins and control cells using qPCR, and determined the relative change in the expression of selected circular RNAs. We confirmed that RNA-binding proteins can affect the expression of selected circular RNAs.
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