APOBEC proteins are cytidine deaminases that catalyse the deamination of cytosine to uracil on single-stranded DNA and RNA molecules. Because they can alter the nucleotide composition of DNA and RNA molecules, this process is one of the key defence mechanisms in viral infections, but is also responsible for the occurrence of mutations in host cells and the development of cancers. Researchers have found that APOBEC proteins are a major source of somatic mutations in cervical cancer, which is largely linked to HPV infection. The cadherin E, cyclin D1, p53, caspase 3 and C-MYC genes are responsible in cells for adhesion, cell cycle regulation, cell proliferation and differentiation, programmed cell death, tumour suppression and regulation of transcription of specific target genes, and it is therefore particularly important that their expression levels are regulated. In our research work, we were interested in whether silencing APOBEC genes affects the expression of these genes. We used real-time PCR to examine the expression of target genes in human wild-type and HFK16 keratinocytes with silenced APOBEC3A and APOBEC3B proteins. In wild-type HFK keratinocytes, we found no statistical differences in the expression of the genes examined between samples. In HFK16 keratinocytes, statistically significant differences were present for p53 and C-MYC genes, while no differences were observed for cadherin E, cyclin D1 and caspase 3 genes. We also tested whether there were statistical differences in the expression of target genes between the HFKWT and HFK16 groups. Similar findings were found, with statistically significant differences present for p53 and C-MYC genes. We concluded that silencing of APOBEC3A and APOBEC3B has an effect on the expression of p53 and C-MYC genes, while it has no effect on the expression of cadherin E, cyclin D1 and caspase 3 genes. Caution is needed in the interpretation of these results as the study was performed on a small number of samples. In future, the study should be repeated on a larger number of samples.
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