Bioinformatic Analysis of mRNA and miRNA Expression Patterns In p53 Knock-out C666-1 cells [mRNA]

Unlike other EBV-associated human tumors, nearly 100% wild-type p53 gene is found in NPC, p53 protein is also frequently found to accumulate in NPC biopsies. However, the role of p53 in EBV-positive nasopharyngeal carcinoma is unclear. The expression profiles of mRNAs and miRNAs of EBV-positive NPC cells are unknown. To elucidate the function of p53 in EBV-positive NPC, we used the CRISPR-Cas9 gene editing system to p53 knockout C666-1 cells with Epstein-Barr virus and performed mRNA and miRNA sequencing in p53 KO C666-1 and their control cells. Gene Ontology (GO), KEGG and STRING analyses were implemented to identify significant functions, pathways of differentially expressed mRNAs. Through comparative analysis of p53-regulated genes from EBV-positive C666-1 cells and EBV-negative HONE2 cells with p53 target genes from 16 high throughput data sets, we found that the number of target genes and KEGG pathways downregulated by p53 in EBV-positive C666-1 cells were much less than in EBV-negative HONE2 cells, but “p53 signaling pathway” and related cell cycle arrest and apoptosis genes were significantly downregulated after knockout of p53 gene in C666-1 cells. To explore the effect of p53 on cell cycle and apoptosis, we established stable p53 C666-1-KO cell lines with stable expression of exogenous p53-WT and their control cell lines. Using the established cell lines, we observed that stable expression of p53 repressed cell proliferation, increased cell apoptosis and blocked G1/S phase progression. In conclusion, our results show that the accumulated p53 protein in EBV-positive C666-1 cells still has some tumour suppressor functions such as blocking cell-cycle progression and promoting apoptosis, but the ability of p53 to downregulate gene expression is inhibited. Overall design: mRNA expression profiles of C666-1 (control) and KO C666-1 cells.