Relation between TP53 GOF mutation and Osimertinib treatment in EGFR mutant lung cancer
Background: Although TP53 gain-of-function (GOF) mutations promote cancer survival, its effect on EGFR-TKI efficacy remains unclear. We established EGFR-mutant lung cancer cell lines expressing various TP53 genotypes using CRISPR-Cas9 technology and found that TP53-GOF mutant cells develop an early resistance to EGFR-TKI osimertinib.The goal of this study is to elucidate the mechanisms underlying resistance to osimertinib treatment in TP53 GOF mutations through comprehensive gene analysis using RNA-seq with next-generation sequencing (NGS). Methods: Total RNA was isolated from PC-9 cells overexpressing TP53 R248Q mutation (PC9/p53R248Q: TP53 GOF mutation) and PC-9 cells overexpressing empty vector plasmid (PC9/p53EV: TP53 null) treated with DMSO or osimertinib for 24hours, using the RNeasy Micro Kit , in accordance with the manufacturer's instructions. RNA samples were quantified by NanoDrop-2000 spectrophotometer, and the quality was confirmed with a 2200 TapeStation. rRNA was removed using MGI Easy rRNA Depletion Kit  according to manufacturer's instructions followed by library construction using MGIEasy RNA Directional Library Prep Set (MGI). MGI DNBseq-G400 FAST was used to perform the amplicons deep sequencing following the standard operation protocol. The sequence format was 150bp pair read for all samples. All sequencing reads were trimmed low-quality bases and adapters with Trimmomatic (v.0.38) , and RNA sequencing reads were mapped to hg38 using HISAT2 software . Raw counts for each gene were estimated in each sample using RSEM version 1.3.0 and Bowtie 2. Calculation of the log fold-change (log FC) and p-value were performed using edgeR. Results: We explored the functions of specifically upregulated genes in TP53 GOF mutation after osimertinib treatment by KEGG pathway-enrichment analysis and found that the cytokine-cytokine receptor interaction was the most significantly altered pathway. Hallmark pathway analysis identified the TNF-a/NF-?B pathway was significantly enriched. Furthermore, TRRUST analysis showed enhanced activity of transcription factors especially RELA (p65) and NF-kB1. Conclusions: TP53 GOF mutaion induces osimertinib resistance by activating TNF-a/NF-?B pathway. Overall design: mRNA profiles of PC9/p53R248Q cells and PC9/p53EV cells treated by osimertinib or DMSO (control) for 24 hours.